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DSSP21 Build 061102 User Guide

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1. 16 5 1 Diameter and Station Records 18 5 2 Length MidHull Nose Pitch Roll Tail and Yaw Records 19 5 3 BaseArea Deck HullSep Keel Label LoD ResiDragR RoughAllow and Source Records acne nent es ad al ge a a 22 0 4 POP nevedoeneutiend oy es Sin eee oe ae ae mn a ay a eae do NU ee 23 6 Root geo Level 2 Lift Input 422 23 641 The Plantorm Recordio ere rene eerenee a nerenemtene entorse 27 6 2 Type Records LBowplane Rudder Sail Sailplane SBowplane ShipStab Sternplane and Tail 28 DRDC Atlantic TM 2006 252 v 10 11 12 13 14 vi 6 3 Control Type Records AllMoving and Flapped 29 6 4 Control Parameter Records DelNonLin Del Delta DeltaLim FlapGap FlaProDrag and WeightDCI 30 6 5 Control Dynamics Records DelRateLim and DeltaDyn 31 6 6 Endplate Records HasEndP and IsEndP 31 6 7 Save Records Kill and Save 32 6 8 Copy Records Reflected and Rotated 32 6 9 Camber CXJ CXZero Label TailEff ToC and Twist Records 33 Root geo Level 2 OOPCalc Input 34 7 1 Hull KParam Lambda and Lift Records 35 Ro
2. 2222 19 4 DeltaLim Reference Rho Text and WeightDCI Records 20 Root sim Level 2 Coefficnt Input 20 1 Coefficient Definition Records Del Delta Derivs Length Output PReverse Ukt and Ums 20 2 Control Deflection Derivative Level 3 Input 20 3 CB CG DeltaLim Reference Rho and Text Records 21 Root sim Level 2 Captive Input 2 21 1 DeltaLim Reference Rho Text and WeightDCI Records 21 2 Del Delta and TimeHistry Records 21 3 Euler Iterate Mass MomInertia NoHStat and PQRtol Records 22 Root sim Level 2 Free Input 22 1 Vehicle Initialization Records CB CG Del Delta DeltaLim Reference and Target 22 2 Condition Initialization Records Depth Heading Origin Rho RPM Ukt Ums and WeightDCI 22 3 Simulation Initialization Records GimbaLock Interpl Isothermal NoMass SVDecomp TimeStep and Tolerance 22 4 Command Records AutoDepth AutoHead AutoProp AutoRoll Blow Del Delta Dummy Flood Prop Propulsor Start Stop and Vent ess eaten hin add beled Wali SON Ee Ud RARE LE Lande heeded 23 Running the Program and Interactive
3. 49 Figure 10 Maple plot screen shot 50 Figure 11 MatLab plot screen shot using the keyword Colour 51 Figure 12 MatLab plot screen shot using the keyword White 51 Figure 13 VRML plot from ModelPress Reader shaded rendering 52 Figure 14 VRML plot from ModelPress Reader wire frame rendering 53 Figure 15 A variation of figure 8 ballast blowing 60 viii DRDC Atlantic TM 2006 252 1 Introduction DRDC Submarine Simulation Program version 2 1 DSSP21 is a code for evaluating underwater vehicle hydrodynamics and manoeuverability The key calculations of hy drodynamic loads on the vehicle are done with component based semiempirical methods that are sufficiently accurate for at least preliminary design and routine manoeuvering analysis Investigations are continuing to further improve these methods and widen their scope of application Developmental status of the code is indicated by a build number consisting of the release date in yymmdd format In output from the program an additional character may be appended A B or X indicating that the build is considered to be a preliminary limited or experimental release respectively After sufficient validation the qualifier will be dropped This guide applies to build 061102 subsequent builds will be accompanied by updates and additions to the guide as re
4. DRDC Atlantic TM 2006 252 NOMASS ONE P PITCHLIMIT POP PREVERSE Q REFLECTED REVDYNAM ROLCONGAIN ROOT SAIL SHORTEST STATIC STRPROP TARGET TIME TORPEDO TYPEZERO UMSERRGAIN VOLUME WAKE ZERO NONE OOPCALC PHASELEAD PLANFORM PORT PROP QUATERNION RELATIVE REVLIMIT ROLERRGAIN ROTATED SAILPLANE SOURCE STATION SVDECOMP TEXT TIMEHISTRY TRATIO U UP VRML WEIGHTDCI DRDC Atlantic TM 2006 252 NORMAL OPEN PHI PLOT POWER PROPULSOR R RESET REVRATELIM ROLL ROUGHALLOW SAVE STAMP STBD TAG THE TIMESTEP TWIST UKT V W WHITE NOSE ORIGIN PID POD PQRTOL PSI RADIUS RESIDRAGR RHO ROLLNEG RPM SBOWPLANE STARBOARD STERNPLANE TAIL THRERRGAIN TOC TWOPARAM UKTERRGAIN VEHICLE WAGBINIT WTC OCCUPANCY OUTPUT PITCH POINTS PRESSURE PWRERRGAIN REFERENCE REVCONGAIN RIGHT ROLLPOS RUDDER SHIPSTAB START STOP TAILEFF THRUST TOLERANCE TYPEONE UMS VENT WAGENINGB YAW 93 Annex C Program Unit Lists Build 061102 source code is organized in a series of Fortran files as follows The program unit names are cited in error messages Dssp21 for the highest level routines Unit DSSP21 GEO_L1 GEO_L2_AUTO GEO_L2 HPA GEO_L2_HUL GEO_L2_LFT GEO_L2_LMP GEO_L2_MBT GEO_L2_00P GEO_L2_PLT GEO_L2_PRP GEO_L2_WIN GEO_L2_WTC INP_L2_REF SIML1 SIM_L2_CAP SIM_L2_COF SIM_L2_FRE SIM_L2_MLD SIM_L2_STA Function main program process Root process Root pro
5. Dictionary lists are included in the output generated by the Help command which always gives the most up to date listings Keywords are upper case in the dictionary but user input is not case sensitive The compass heading dictionary list of build 061102 comprises NORTH NE E SEBYS SBYW WSW WNW NBYW N NEBYE EBYS SSE SSW WBYS NWBYW NBYE ENE ESE SBYE SWBYS WEST NW NNE EBYN SEBYE SOUTH SW W NWBYN The main dictionary list of build 061102 comprises ACONCOEFF ALL AUTOPROP BG CAPTIVE COEFFICNT DECK DELTA DEPERRGAIN DOWN EULER FLOOD FWD HEDCONGAIN HULFOM INERTIAL ISOTHERMAL KRIGING LENGTH LOOKAHEAD MASS MLD 92 ACROSPIN ALLMOVING AUTOROLL BLOW CB COLOUR DEFAULT DELTADYN DEPTH DSSPTWO FAUXBLOW FOREPLANE GIMBALOCK HEDERRGAIN HULFOR INITDELTAS ITERATE LABEL LIFT LOOP MASSFLOW ADDEDMASS ALPHA AZIMUTH BOHLMANN CG CXJ DEL DELTALIM DERIVS DUMMY FLAPGAP FORM HARMONIC HELP HULL INTERPL KEEL LAMBDA LIFTSEGMNT LUMP MATLAB AFT AUTODEPTH BASEAREA BOWPLANE CLEAR CXZERO DELNONLIN DEMPSEY DIAMETER EMERGENCY FLAPPED FORWARD HASENDP HOERNER HULLSEGMNT IRREGULAR KILL LBOWPLANE LOCATION MAIN MBT MOMINERTIA NEURALNET NODEBUG NEBYN EAST SE S SWBYW WBYN NNW ALFA AUTOHEAD BETA CAMBER COEF DEBUG DELRATELIM DEPCONGAIN DIAMRATIO ESAM FLAPRODRAG FREE HEADING HPAIR HULLSEP ISENDP KPARAM LEFT LOD MAPLE MIDHULL NOHSTAT
6. culations are done for each evaluation of tailplane efficiency in a simulation Additional corrections are made for the influence of tail cone angle and dis placement thickness at small angles of incidence as discussed in reference 19 DRDC Atlantic TM 2006 252 33 If the keyword argument is Dempsey Kwp is calculated by Dempsey s method 18 and k wp is derived using the inviscid efficiency ratio these values are then constant with respect to speed For numerical input the first value is Kwg The second value if present is kwp otherwise kwp is derived using the inviscid efficiency ratio in either case these values are constant for all speeds The limits for numerical input are 0 lt Kwg lt 1 5 and 0 lt kwe lt Kwp ToC t c This record overrides the default value of 0 12 for section thickness chord ratio t c The argument is mandatory and has a permitted range of 0 0 lt t c lt 0 25 Twist Qb This record overrides the default value of 0 0 for geometric section twist ap defined as the angle of attack at the tip relative to the root The argument is mandatory its value is in degrees and has a permitted range of 30 lt ay lt 30 Twist is positive in the sense of rotating the appendage local z axis into the x axis This record is ignored with a warning for triangular planforms and for planforms that include twist in the Planform specification 7 Root geo Level 2 OOPCalc Input Background to the out o
7. planes etc and may be different again from how a heading or depth control autopilot is implemented In order to accommodate these differences several control deflection command modes are available The three principal modes of command can be summarized as e direct input which allows the user to specify an individual appendage to be de flected e quasi direct input which indicates the type s of appendages and implied sense of their deflection and e indirect input which indicates the desired response of the vehicle and equivalent magnitude of the deflection There are also a few global control input commands Control deflections in a static calculation and commanded deflections in a manoeuver ing simulation remain set until they are changed by another Delta command Under DRDC Atlantic TM 2006 252 53 autopilot control in a manoeuvering simulation on the other hand the commanded deflections which are in indirect mode are dynamic To balance these different re quirements the modes of deflection command are limited in how they work together In addition indirect input sets flags that allow only continued indirect input to the affected appendages until canceled by a Clear command This has its origin in re quirements for autopilot control a direct or quasi direct command is not permitted to kick out an autopilot In general multiple deflection commands to the same ap pendage are not permitted however some combinat
8. propeller model based on the four quadrant single screw behind model wind tunnel data reported in reference 14 The propulsive efficiency Kr Kg Js 27 of this model is unrealistically high at large Js WageningB This specifies a large main propulsor propeller model based on two quadrant open water data for the Wageningen B4 70 series 15 The method includes semiempirical calculations for wake fraction and thrust de duction 16 and approximates optimum pitch diameter ratio Level 2 propulsor input records are described in section 8 Propulsor keyword As Prop above WagBInit 14 Announces level 2 input for initializating WageningB propulsors this input is described in section 9 DRDC Atlantic TM 2006 252 4 5 The Reference Record This record is required to set or override the default reference axes and origin in Root geo level 1 Furthermore a new reference definition which will supercede this one can be supplied with simulation level 2 input in Root sim At any stage it will avoid problems if the reference origin is in the vicinity of the vehicle CB and CG and if the reference axes correspond to conventional hydrodynamic axes section 3 4 Reference keyword If this record has the keyword CB or CG as an argument then there is no level 2 input and the reference origin is located at the CB or CG of the vehicle with the reference axes directed along the vehicle axes Otherwise the reference orig
9. B Ti 4A A B T A F etc to Ng And if station spacing is irregular it is Zin Bi T Ar F Zin Bo T A2 F etc to Nsa Ti Ai and F are enclosed in nested brackets to indicate that they are progressively optional from right to left 5 2 Length Midhull Nose Pitch Roll Tail and Yaw Records Hull component location and attitude and therefore the definition of its local axis system is determined by a combination of the keywords Length MidHull Nose Pitch Roll Tail and Yaw The local x axis is directed forward and passes through the hull tailpoint midpoint and nosepoint However the hull may have camber in the direction of its z axis in which case MidHull is simply the mean of Nose and Tail To fully define hull location and attitude the user must provide an unambiguous combination of these records Redundant data are checked for consistency inconsistency generates a fatal error By default the axis rotations taken in order Y are assumed to be zero Some examples are given at the end of this section L Defines hull length between tailpoint and nosepoint Length plus one of Nose MidHull or Tail provides an unambiguous hull axis definition for the default zero rotation Rotation angles may be defined as required to override the default values DRDC Atlantic TM 2006 252 19 MidHull Nose Pitch Roll Tail Yaw Lm 5 Um Zm Defines the midpoint of the hull compon
10. Defence R amp D Canada Atlantic Unclassified 3 TITLE DSSP21 Build 061102 User Guide 4 AUTHORS M Mackay 5 DATE OF PUBLICATION December 2006 7 DESCRIPTIVE NOTES DRDC Atlantic Technical Memorandum 8 SPONSORING ACTIVITY 6a NO OF PAGES 117 6b NO OF REFS 26 9a PROJECT OR GRANT NO 11GP02 10a ORIGINATOR S DOCUMENT NUMBER DRDC Atlantic TM 2006 252 11 DOCUMENT AVAILABILITY Unlimited 12 DOCUMENT ANNOUNCEMENT if different from 11 9b CONTRACT NO 10b OTHER DOCUMENT NOS 13 ABSTRACT DSSP21 is a semiempirically based computer code for evaluating the dynamics and manoeuverability of streamlined underwater vehicles including submarines The purpose of this user guide is to facilitate preparation of the input files that are required for a definition of the vehicle and its systems and for controlling the calculations and manoeuvering simulations to be done It contains detailed descriptions of input syntax and options together with brief discussions of the output produced and some background information on the code structure and algorithms 14 KEYWORDS Underwater Vehicles Submarines Manoeuvering Simulation DRDC Atlantic TM 2006 252 Unclassified 111 This page intentionally left blank This page intentionally left blank Defence R amp D Canada R amp D pour la d fense Canada Canada s leader in defence Chef de file au Canada
11. Starboard Up and WeightDCI A record beginning with any other keyword terminates the sequence Control deflection derivatives are associated with one of the indirect commands the sense of which is immaterial in this context None take an argument Thus Down or Up results in calculation of vertical plane derivatives Port Stbd or Starboard results in calculation of horizontal plane derivatives and Roll1Neg or RollPos results in calculation of roll command derivatives WeightDCI records are included in this sequence to determine which appendages the above commands apply to and how the appendages are weighted They follow the syntax of section 19 4 70 DRDC Atlantic TM 2006 252 An example of control deflection derivative input is included in the Root sim listing in annex E 20 3 CB CG DeltaLim Reference Rho and Text Records These records can be input for most of the calculations and simulations on Root sim they redefine basic vehicle and simulation parameters that then remain unchanged until redefined in a subsequent run The syntax and caveats applying to DeltaLim Reference and Rho are as presented in section 19 4 Hydrodynamic coefficients and other quantities are estimated with respect to the redefined reference A Text record is simply output to Root spr when it is encountered CB TB YB B Redefines the three components of CB in vehicle axes CG LG YG ZG Redefines the three components of CG in vehicle axe
12. There can be only one initialization record with the keyword RPM Ukt or Ums Ukt Ue Defines the initial forward speed in kt and thus defines indirectly initial values of RPM for the propulsors There can be only one initialization record with the keyword Ukt Ums or RPM Ums Us Defines the initial forward speed in m s and thus defines indirectly initial values of RPM for the propulsors There can be only one initialization record with the keyword Ums RPM or Ukt 22 3 Simulation Initialization Records GimbaLock Interpl Isothermal NoMass SVDecomp TimeStep and Tolerance GimbaLock keyword By default the gimbal lock singularity when the vehicle is pitched exactly 90 degrees 25 is avoided by using a quaternion representation of the Euler angles the angles themselves are derived at each timestep for output Euler angles can be calculated explicitly by including this record with the keyword argument Euler The alternative argument Quaternion is redundant in this version of the program Interpl At keyword Defines an output interpolation interval At in seconds Output in Root spr and simnnn txt is given at each time t kAt where k is integer although internal calculations are still done with the adaptive timestep for error control The optional keyword second argument indicates a fourth order interpolant to use it is TypeZero or TypeOne for respectively C or C1 continuity 8 9 The former which is th
13. and f are exactly equivalent to each other and the values in each of formats a to f represent the compass heading relative to zero North 58 DRDC Atlantic TM 2006 252 16 Root sim MBT Blowing and Venting Commands Ballast blowing is commanded during a free manoeuver by the keyword Blow sec tion 22 4 which is followed by one or two arguments The first identifies the tank or tanks to be blown the second identifies the HP air bottle group s to be used The second argument is optional since blowing can be determined by BG MBT associations section 11 if it is not specified otherwise The blowing command is Blow argument 1 argument 2 where argument 1 is one of Np the index of the MBT to be blown the Ng tank defined on Root geo has the index Np label string the label of the MBT to be blown Aft Forward Fwd all MBTs of the type indicated are to be blown All all MBTs are to be blown Stop stop blowing all MBTs and the optional argument 2 is one of Nag the index of the BG to be used the Ng bottle group defined on Root geo has the index Na label string the label of the BG to be used Aft Forward Fwd Main all BGs of the type indicated are to be used All all BGs associated with the tank s identified by argument 1 are to be used Stop stop blowing the tank s identified by argument 1 The default for argument 2 is All The following examples illustrate how these argu ments are combined Blo
14. if it is increased may have to be increased Current experience adjusting these parameters suggests that their input values should be of the same order If hmin is increased relative to e sufficiently that the requested tolerance cannot be achieved the program will report a fatal error Unexpected IND 3 from DDNORK But note that there may be other reasons for failing to meet tolerance see section 3 3 A similar error IND 2 will result if Amin gt hmaz DRDC Atlantic TM 2006 252 Tolerance This record defines a value for integration tolerance 8 9 it must not be neg ative The default value unless redefined by a previous free run in the same Root sim file is 0 001 See TimeStep for the relationship between tolerance and minimum timestep 22 4 Command Records AutoDepth AutoHead AutoProp AutoRoll Blow Del Delta Dummy Flood Prop Propulsor Start Stop and Vent Recall that these records have the format t keyword argument s where t is the absolute value in seconds of time at which the command will be issued Time t is absolute because the simulation is not constrained to start at t 0 but is started at the time of the earliest command Similarly it is stopped at the time of the latest command In free runs control deflections RPM etc are dynamic quantities so the value specified in a command is not attained instantly The parameters defining control and propulsor
15. or global Delta arguments discussed in section 14 can be used on this record Multiple Del records can be present so long as a command conflict section 14 5 is avoided Delta Delta arguments see section 14 As Del above Target TT YT ZT The point defined by x7 yr zr in vehicle axes replaces the reference point as the target tracked in chart axes on files Root spr and auxnnn txt see section 3 4 22 2 Condition Initialization Records Depth Heading Origin Rho RPM Ukt Ums and WeightDCI Rho and WeightDCI records can be input for most of the calculations on Root sim their syntax is as presented in section 19 4 Depth Z0e Defines initial depth zoe in m it must not be negative By default zoe 0 this must be changed to an appropriate value if the simulation includes blowing venting or flooding Heading string Defines initial compass heading using one of the argument string formats de scribed in section 15 By default it is zero Origin Lee Yeo Defines initial chart axis x and y coordinates of the target point in m the initial ze coordinate is defined by Depth Zee Ze By default tee Yee 0 78 DRDC Atlantic TM 2006 252 RPM ne Defines initial values of RPM for the propulsors and thus defines indirectly the initial speed If there is only one propulsor ne can be on the same record otherwise a value of ne for each propulsor is given in a following data block three to a record
16. 0 may be appropriate The user may be able to deduce suitable values by tuning predictions with trials data HullSep Nsep This record forces hull separation to occur at hull station Nsep where Nsep is the mandatory integer argument A large value of the argument say 99 will set Nsep equal to the last station Ng Specifying Nsep allows the user to address the No minimum found in dA dx DT2 for separation error section 3 3 or to override the estimated lo cation of separation which is output on the Root 1log file Keel NYk NNk Defines load corrections for the presence of a keel The hydrodynamic sideforce will be multiplied by ny and the yawing moment by nyz Default values are 1 0 1 0 i e there is no keel While there are no systematic data from which to select these corrections reference 12 illustrates a case for which values of 1 7 0 9 may be appropriate The user may be able to deduce suitable values by tuning predictions with trials data Label label string This record provides a user defined component label The label string consists of or followed by up to 24 alphabetic characters case is ignored If there is no Label record the default label is HULLnnn where nnn is the number of this hull component as encountered in the input file i e nnn 001 for the first 002 for the second etc LoD L Dm Overrides the calculated value of length diameter ratio for the current hull compo
17. 15 6 7 7 7 Sim 2 reverse rudder at 15 deg port heading and so on Text Standard pitch sweep as in a model test Loop Alfa 30 30 2 Coef Delta Starboard Down WeightDCI WeightDCI WeightDCI Down WeightDCI Output coef PReverse Sim 3 All Zero 6 100 7 100 All Reset 62 7968 DRDC Atlantic TM 2006 252 Note Rho is still 1025 2 Use associated types with current weights as above Zero all current weights Turn on stbd sailplane turn on port sailplane and do for them alone Back to baseline weights Sternplane root quarter chord 103 Captive Sim 4 Rho 1022 Redefine Rho DEL PortSternplane 5 Initialize sternplanes DEL StarboardSternplane 5 TimeHistry tinyhist txt Example in section 21 2 Free Sim 5 Text A flooding scenario however this is far from a standard Text recovery procedure but is used to illustrate various Text options in the program Note that vertical control Text authority is initially poor see sternplane reversal Text speed estimate in sim 3 Several features of this including use of autopilots and blowing and flooding make this run slower than sim 1 by a factor of about 20 Reducing the default integration tolerance by an order of magnitude Tolerance 0 01 mitigates the problem to a factor of about only 1 3 with no significant impact on key run time histories such as depth and pitch However such a change should always be tested
18. 4 Otherwise the order of records and the mixing of initialization and command records is immaterial Al lowing this mixing facilitates input trial and error in simulating a manoeuver since new commands being tested can be placed at the end of the input where they are easily mod ified without concern whether they are correctly placed in sequence of time However it is recommended that the input be reorganized into a rational sequence for archiving once a manoeuver is satisfactory The following are the initialization record keywords for level 2 free run input Keyword Function CB redefine CB location CG redefine CG location 76 DRDC Atlantic TM 2006 252 Del Delta DeltaLim Depth GimbaLock Heading Interpl Isothermal NoMass Origin Pop Reference Rho RPM SVDecomp Target Text TimeStep Tolerance Ukt Ums WeightDCI initialize control appendage deflection s initialize control appendage deflection s reset control appendage deflection limits initialize depth in m avoid or allow gimbal lock initialize compass heading set output interpolation parameters use isothermal ballast blowing do not update inertial properties for a mass change initialize position in chart axes force termination of input see section 5 4 redefine reference origin and axes redefine fluid density initialize propulsor RPM s use SVD algorithm to invert the I A matrix define target point output run information or other descriptive te
19. Coefficnt Captive and Free If the first run on Root sim does not include redefinition of water density a warning is issued to remind the user that the default value is 1000 for fresh water 18 2 Help and Text Records Help Text When the Help record is encountered help text is sent to Root log and the program is stopped This provides a quick reference for the user if this guide is not readily available its principal components are dictionary listings and a user input summary text string A Text record provides titles and other information each one is output to Root spr as it is encountered DRDC Atlantic TM 2006 252 63 19 Root sim Level 2 Static Input Static hydrodynamic loads are calculated for a given state vector u v w p q r 6 T where 6 is a generic control surface deflection The translational velocities u v w can be defined indirectly using incidence angles a and total velocity U Multiple state inputs can be generated by making one parameter per run the argument of a Loop record A set of steady forces and moments for each state is output on simnnn txt The following table summarizes the keyword records for level 2 static run input Keyword Function Alfa define angle of attack Alpha define angle of attack Beta define angle of drift Del set control appendage deflection s Delta set control appendage deflection s DeltaLim reset control appendage deflection limits Loop iterate a parameter between
20. DRDC Atlantic TM 2006 252 99 Lift Sail Label Sail Sail 4 1772 Planform 20 4000 0 4 4690 20 4000 0 10 5468 32 0552 0 10 5468 32 0552 0 4 4690 ToC 0 2 CXJ 0 12 Lift Label StarboardSternplane Tail 2 1733 3 8855 Flapped 0 0 1 0 0 5660 Planform 58 8438 2 4528 0 0 60 2290 4 8606 0 0 64 1145 4 8606 0 0 64 1145 1 1873 0 0 1 TailEff dempsey FlaProDrag 0 ToC 0 15 DelRateLim 5 0 Save Lift Label PortSternplane Rotate 180 Lift Label UpperRudder Rotate 270 Lift Label LowerRudder Rotate 90 Lift 100 Label StarboardSailplane Sailplane 1 1655 4125 AllMoving 1 0 Planform 22 4400 1 0819 7 2163 23 4600 3 8855 7 2163 24 1400 3 8855 7 2163 24 1400 1 1642 7 2163 ToC 0 15 DelRateLim 5 0 WeightDCI 0 0 0 Save Sail junction drag estimate Commented out will use default Ignore flap profile drag Stbd plane rotated 180 deg Rotated sternplane all tail appendages As above Decoupled are identical DRDC Atlantic TM 2006 252 Lift Label PortSailplane Reflected Plot O0Pcalc Lift Sail KParam 1 Prop Location 65 9600 Right Handed Diameter 3 9090 RevLimit 220 0 RevRateLim 11 0 WagBInit Diameter 7 6 AutoDepth Autopilot parameters LookAhead 68 0 AutoHead HedErrGain 1 0 AutoProp UmsErrGain 5 0 Text Ballast system organized like HPair Label BGOne Fwd Pressure 260 Volume 2 0 HPair Label BGTwo Mai
21. Dialogues 24 gt Ou utput Piles a nno sas toio Rire de ee gta ne eatin aetna ate taeda DRDC Atlantic TM 2006 252 69 70 71 71 72 72 73 75 78 78 79 vii 25 Conchiding Remarks 35 05 5 224458 eaa ae ae ob aa tie mia etais tisse 86 R f rences ass ee RU SNS en deed RSA ges Yea ees AR AN See 87 Annex A Program Change List 90 Annex B Dictionary Lists f ceceiebecececetecevecetececekacecerecetecerecetes 92 Annex C Program Unit List 94 Annex D Example Root geo Input File 99 Annex E Example Root sim Input File 103 Nomenclature feces Fist sorts RE san tue Set does etes Menus eue Mek don See 105 List of Figures Figure 1 Principal earth fixed and boat fixed axis systems 9 Figure 2 Earth fixed axis systems in the plane of the surface 10 Figure 3 Hull definition nomenclature 17 Figure 4 Appendage definition nomenclature 24 Figure 5 Hull sail input nomenclature Les nn 25 Figure 6 Endplate input nomenclature 25 Figure 7 Flapped appendage input nomenclature 26 Figure 8 Schematic of three bottle groups and three ballast tanks 44 Figure 9 AcroSpin plot screen shot
22. Report 2510 Naval Ship Research and Development Center DRDC Atlantic TM 2006 252 25 Phillips W F Hailey C E and Gebert G A 2000 A Review of Attitude Kinematics for Aircraft Flight Dynamics AIAA paper 2000 4302 In AIAA Modeling and Simulation Technologies Conference Denver CO American Insti tute of Aeronautics and Astronautics 26 Press W H Teukolsky S A Vetterling W T and Flannery B P 1992 Nu merical Recipes in Fortran Second Edition Cambridge CUP DRDC Atlantic TM 2006 252 89 Annex A Program Change List DSSP20 DSSP20 the predecessor to DSSP21 had the same objective of predicting the hydro dynamic characteristics and manoeuverability of an underwater vehicle but was im plemented as a suite of interacting programs References 1 and 2 are user guides for build 981009 Subsequent builds of DSSP20 to 010830 improved and expanded a number of the hydrodynamic load algorithms but the input specification described in these guides changed very little Although the individual programs worked well main tainability of the suite as a whole became more difficult as their complexity increased DSSP21 A number of DSSP21 builds previous to 061102 have been archived but not formally documented only the principal prior benchmark build 050401 is noted here in addition to the current build Build 050401 The individual programs in DSSP20 were combined into one resulting in about fifty p
23. Ukt Ums Function redefine CB location redefine CG location control derivative definition control derivative definition reset control appendage deflection limits do a DERIVS type calculation reference length for coefficients define output for simnnn txt force termination of input see section 5 4 do plane reversal estimates redefine reference origin and axes redefine fluid density output run information or other descriptive text set total velocity in kt set total velocity in m s 20 1 Coefficient Definition Records Del Delta Derivs Length Output PReverse Ukt and Ums These records control various aspects of coefficient and stability index 23 estimation The coefficients are nondimensionalized in the standard form 24 and are output mul tiplied by 1000 on Root spr Del Level 3 input that defines the control deflection derivative calculations will follow The records that constitute this input are discussed in section 20 2 Delta As Del above Derivs This record is redundant since the DERIVS code three point fit method is cur rently the only option for estimating coefficients and is the default Length Define reference length for nondimensionalizing the coefficients It denotes vehicle length in the standard submarine equations of motion 24 In DSSP21 defaults to hull length if there is only one hull present otherwise or to override the default a Length record must be provide
24. between the nose and tail These data may be interpolated to a different set of stations The minimum information required is diameter at each station for an axisymmetric hull and a direct or indirect definition of the nose and tail points in vehicle axes The tail section may be closed with zero 16 DRDC Atlantic TM 2006 252 diameter or truncated with a nonzero diameter In the latter case base drag can be modeled Additional optional input for each station includes breadth and height in the case of non axisymmetry cross section area and camber which is only used for plotting geometry in this version of the program Vehicle Axes Figure 3 Hull definition nomenclature Values of residual drag coefficient Cay or roughness allowance k may be input to override the default values Lateral loads are increased if there is a deck casing or keel There is no reliable way to estimate these increases at present the user must supply appropriate factors on the Deck and Keel records The following table summarizes the keyword records used to characterize hull compo nents Keyword BaseArea Deck Diameter HullSep Keel Label Length LoD MidHull Function define hull base area adjust sideforce and yawing moment for a deck casing diameter data block to follow force afterbody separation adjust sideforce and yawing moment for a keel component label define component length define length diameter ratio define midpoi
25. corner points for a non vertical or non horizontal appendage that is more easily defined in the vehicle xy or xz plane and then rotated into its correct orientation The current appendage configuration will be used and then saved for a subse quent copy 6 8 Copy Records Reflected and Rotated The keywords which control copying the most recently saved appendage are Reflected and Rotated Only planform corner points are modified by a copy all other physical attributes of the appendage remain the same The label is not transferred so that a Label record is required for the new appendage or the default will be used These keywords cannot be used in combination with any others in level 2 input except for a Label record Reflected Rotated 32 The saved appendage is reflected in the vehicle xz plane This operation is illustrated for a sailplane in annex D R The saved appendage is rotated r degrees about the vehicle x axis The argument is mandatory Or is positive rotating from the y axis to the z axis DRDC Atlantic TM 2006 252 and there is no restriction on its value This operation is illustrated for tail appendages in annex D 6 9 Camber CXJ CXZero Label TailEff ToC and Twist Records Keywords Camber CXJ CXZero Label TailEff ToC and Twist override default values of various lifting surface parameters Camber CXJ CXZero Label TailEff f This record overrides the default value of 0 0 for no
26. described in section 3 1 This guide does not detail the load calculations however discussion of many of the algorithms can be found in references 3 4 5 and added mass calculations are discussed in reference 6 2 DRDC Atlantic TM 2006 252 To specify hydrodynamic and manoeuvering simulations the user must provide a second input file The present simulation options are Static load calculation Static loads for example as measured in a captive model experiment are calculated for defined values of the velocities control deflections and incidence angles Coefficient generation At present the approach implemented in the DERIVS pro gram 7 is employed Stability derivatives and other hydrodynamic quantities are estimated from predefined static runs Captive dynamic manoeuver simulation Dynamic loads for example as measured in a captive model experiment are calculated from time histories of the velocities and control deflections Free running manoeuver simulation The equations of motion and a number of auxiliary equations are integrated over time using an order 3 4 Runge Kutta adaptive timestep routine with optional interpolation of the output to regular time increments 8 9 MLD curve generation Not presently implemented it will require a predefined series of free manoeuvers with pass fail termination criteria 3 General Considerations 3 1 File Nomenclature The naming scheme for most DSSP21 input and output
27. equivalent within truncation error Nose 3 4567 899 Tail 7 2922 01012 2 44 Roll 27 5 Again the same configuration but with redundant information in pitch and yaw Nose 3 4567 899 Tail 7 2922 01012 2 44 Yaw 2 484513 Pitch 17 958312 Roll 27 5 Redundancy is overlooked however a small change or error in the data such entering Zn as 889 instead of 899 in this example will generate a fatal error because of inconsistency in input A hull component of length 5 3025 with midpoint located at 0 0 0 rotated implicitly by 90 degrees in pitch Rotation in yaw defaults to zero Nose 0 0 2 65125 Tail 0 0 2 65125 The same result is obtained by explicitly defining the pitch angle MidHull O O 0O Length 5 3025 Pitch 90 DRDC Atlantic TM 2006 252 21 5 3 BaseArea Deck HullSep Keel Label LoD ResiDragR RoughAllow and Source Records These records provide additional hull parameters for the program BaseArea Ap Defines a hull base area which defaults to Ang for the hull base drag calcu lation It is required that 0 lt Ap lt max Aj Deck NYd gt Nd Defines load corrections for the presence of a deck casing The hydrodynamic sideforce will be multiplied by nya and the yawing moment by nya Default values are 1 0 1 0 i e there is no deck casing While there are no systematic data from which to select these corrections reference 12 illustrates a case for which values of 1 2 1
28. files has the form Root Ext Root is a user defined string up to eight characters long dssp21 is used by default and Ext indicates the function of the file In addition each simulation may generate files simnnn txt and auxnnn txt where nnn is the number of the simulation in the input file sequence An arbitrarily named time history input file is required for a captive simulation Root may be input as a command line parameter so that the program can be run from another without any user intervention Without a command line parameter Root is requested from the user as described in section 23 In either case Root is truncated to eight characters if it is longer File names are interpreted as follows File Function Root geo input file for geometry and systems setup Root gpr geometry and systems printer output Root gp1l geometry plotting output DRDC Atlantic TM 2006 252 3 Root log run log output Root sim simulation sequence input file Root spr simulation sequence printer output simnnn txt tabulated output from simulation nnn auxnnn txt tabulated auxiliary output from simulation nnn The absence of Root geo generates a fatal error All input and output files consist of ASCII characters and can be read and manipulated with a text editor The tabular output files simnnn txt and auxnnn txt can be opened directly by most spreadsheet and graphical analysis software 3 2 User Prepared Input Input files Root geo and Root
29. future 6 Root geo Level 2 Lift Input The nomenclature used to define basic lifting appendage geometry is illustrated in fig ure 4 The four corner points cl c2 c3 and c4 must be given in vehicle axes Appendage sections are assumed to be NACA 4 digit and thickness chord ratio and other parame ters are optional An isolated appendage is assumed to be mounted on a reflecting plane at the root i e loading is finite at the root because of lift carry over An unattached symmetrical wing would therefore be modeled by two isolated appendages one for each semispan All other appendage configurations require a type specification Rudder Sail etc in order to model interference effects Figures 5 6 and 7 illustrate a number of the additional geometric parameters needed to account for interference they are defined in the nomenclature The general approach to interference is modification of the local angle of attack so that the appendage normal Z and axial X forces in nondimensional coefficients are of the form DRDC Atlantic TM 2006 252 23 Cz Cza amp 1 CZaaa Qo Cx Cxo Cxraa ais Pei 3 where amp a amp 2 and a z are equivalent angles of attack that are functions of local geometric angles of attack a and deflection 6 and of the interference parameters That is Qa 1 a T bezp bi bo s etc 4 A number of non geometric parameters may be defined where it is necessary to override defau
30. initial Euler angles and the Euler angles themselves constitutes redundant information because the velocities and angles can be derived from each other Estimating Euler angles from the velocities requires integration and is susceptible to drift errors so the angles themselves are used DRDC Atlantic TM 2006 252 71 as the primary source of data if they are all three available If both quantities are present a fatal error TIMEHISTRY file P data is inconsistent or Q or R is generated if tabulated and estimated values do not agree Without all three Euler angles on the time history file the velocities any of which defaults to zero if it is not present are used to estimate the angles ignoring any tabulated values The velocities Euler angles control deflections and estimated loads are output to a simnnn txt file estimated accelerations are output to an auxnnn txt file The following table summarizes the keyword records for level 2 captive run input Keyword Function Del set control appendage deflection default s Delta set control appendage deflection default s DeltaLim reset control appendage deflection limits Euler define initial Euler angles Iterate parameters for iteration of Euler angle estimates Mass input model mass MomInertia input model moments of inertia NoHStat omit hydrostatic loads Pop force termination of input see section 5 4 PQRtol tolerance for derivation of p q r from E
31. maintainability would be better served by a single multifunctional program DSSP21 is programmed in Fortran The source code was revised to compile under Fortran 95 syntax rules only a handful of features will not compile under Fortran 77 The library routine required to extract the optional command line parameter is compiler dependent DSSP21 was developed on a Microsoft Windows PC using the Salford FTN95 Win32 version 2 00 compiler Salford Software Ltd www salfordsoftware co uk DRDC Atlantic TM 2006 252 1 and checked with STI s Understand for Fortran version 1 4 Scientific Toolworks Inc www scitools com Although the code is virtually platform independent this guide assumes a Windows platform where relevant The main function of this user guide is to facilitate preparation of the input files Min imum input requirements are quite simple but optional parameters are available to accommodate a wide range of vehicle configurations and to fine tune the simulations The hydrodynamic models and other aspects of the program are mostly described else where they are discussed here in only sufficient detail as required to define the input and will be more fully described in a companion document to be published later New users are advised to first read this guide completely with particular attention to section 3 General Considerations and to the examples throughout the text More expe rienced users will likely only need to refer to
32. of the appendage and x is obtained from the cross product of y and z In a few instances printed output is in local axes The main reason for the user to be aware of them is that individual control deflections are defined in appendage local axes positive for rotation of z into x Earth Fixed Axes PE Reference x Trajectory Ca P Initial Ref i x o Axes y b Vehicle z Axes y Reference Axes Yp Z Subscripts 5 u upper s lower p port Tail Appendage s starboard Y Local Axes Figure 1 Principal earth fixed and boat fixed axis systems DRDC Atlantic TM 2006 252 9 Examples of these axis systems are sketched in figure 1 In this case the vehicle axis origin is at the bow of the submarine For all moving rudders on the same shaft the definition of appendage local axes results in deflections of opposite sign on the upper and lower rudders the same observation applies to other pairs of control planes With one exception noted in section 4 2 all geometrical input must be given in the vehicle axis system On the other hand loads and other hydrodynamic quantities are output in reference axes There is another earth fixed axis system to note in connection with free running ma noeuvers chart axes Ze Ye Ze In this system ze is directed North y East and ze down At present they serve no purpose other than to locate the target point of the vehicle on a notional chart but may be useful for future deve
33. of the hull component in vehicle coordinates y and z are optional and default to zero Tail plus one of Nose or MidHull provides an unambiguous hull definition including yaw and pitch rotation angles a Roll record is explicitly required to override the roll angle default Tail plus Length assumes the default zero rotation angles unless one or more of Yaw Pitch or Roll is also provided y Defines yaw rotation of the local axis system with respect to the vehicle axis system in degrees Rotations are taken in the conventional order yaw pitch roll value for will be calculated if at least two records with the keyword Nose MidHull or Tail are present Otherwise W will take the default value zero if a Yaw record is not provided The following examples illustrate combinations of these keywords 20 DRDC Atlantic TM 2006 252 il iii iv vi A hull component of length 10 829485 with midpoint located at 2 1461 0 23341 0 7705 in the vehicle axes By default local axes are aligned with vehicle axes MidHull 2 1461 23341 7705 Length 10 829485 The same component given explicit rotations so that local axes are no longer aligned with the vehicle axes MidHull 2 1461 23341 7705 Length 10 829485 Yaw 2 484513 Pitch 17 958312 Roll 27 5 The previous component with two hull points defined and therefore having im plicit rotations in yaw and pitch This and the previous example are exactly
34. on representative runs in a series before applying it widely 104 Rho 1025 2 Redefine Rho Depth 65 Heading East Ukt 4 Interp 1 Interpolate with a 1 sec interval 0 Start Unnecessary the next will start it O Autodepth 110 Depth change to 110 m 0 Prop 78 Increase speed for control authority 158 Flood mid 0 08 Flood starts as depth passes 90 m 195 Autodepth Stop Start recovery 197 del up 25 Planes manually to rise 209 del up 5 Ease off planes as pitch passes zero 209 Blow 2 1 Get some buoyancy 219 Blow stop Secure blow after 10 s 240 Flood Stop Secure flood 250 Vent 2 Dump additional buoyancy 250 Prop 104 Speed to approx 8 kt 250 Del Up 15 Rise 270 Autodepth 20 Hold depth at 20 m 480 Stop DRDC Atlantic TM 2006 252 Nomenclature c 1i l 4 Ci CB Co CE Cr CG Cx Cz Cx Cxo Cxaa CZa CZaaa added mass matrix hull base area hull station area semispan of isolated appendage or measured from hull centerline spanwise location of endplate exposed appendage span spanwise location of sailplanes on exposed sail spanwise location of inboard and outboard flap extent buoyancy force hull station breadth metacentric height metacentric distance vector appendage chord mean chord mean flap chord appendage planform corner points loads on vehicle component i interaction loads for vehicle components and j center of buoyancy vector autopilot control
35. perhaps it should have been changed Continue execution Y N Warning from PRPCOM Invalid second argument keyword not in dictionary Information from GEO_L2_HUL HULFOR number of stations not defined default 21 assumed A handful of fatal errors have a less obvious solution We summarise some of these here but the reader may need to refer forward in the guide to follow the explanations Others are noted elsewhere in the text A truncated or very bluff hull afterbody may generate the following error Fatal Error in HULLH1_HUL4 No minimum found in dA dx DT2 for separation very bluff afterbody force separation indicating that the hull load algorithm has failed to find a minimum needed in the slope of the afterbody cross sectional area to locate flow separation The user should check for irregularities in the afterbody offset data If they appear satisfactory the region of likely separation if known can be specified with a Hul1Sep record section 5 3 The time integration in a free manoeuvering simulation may generate an error of the form Fatal Error in SPRINT Unexpected IND N from DDNORK interpolated stepped output inconsistent timesteps and or tolerance where N is one of 1 an internal limit on the number of function evaluations has been exceeded this condition should not be possible in DSSP21 2 the current minimum timestep is greater than the maximum this should not be po
36. same total volume will avoid the problem The pressure of the single source Potali can be obtained from ProtaiViotal gt P Vi where 7 runs over the BGs used Isothermal and adiabatic blowing are discussed in section 16 the combined BG model gives identical results to blowing with individual BGs isothermally and quite similar results to blowing with them adiabatically unless the initial pressures are very different A bottle group is announced by a HPAir record The following table summarizes the level 2 input that characterizes it Keyword Function Aft set BG type Forward set BG type Fwd set BG type Label BG label Main set BG type Pop force termination of input see section 5 4 Pressure set BG initial pressure Volume set BG volume The Label definition is analogous to that of other components If there is no Label record the default label is HPBGnnn where nnn is the number of this BG as encountered in the input file The other records are described in section 11 1 A ballast tank is announced by a MBT record The following table summarizes the level 2 input that characterizes it Keyword Function Aft set MBT type Forward set MBT type Fwd set MBT type Label MBT label Location set location of MBT centroid MassFlow set initial blowing mass flow into MBT Pop force termination of input see section 5 4 Vent set air mass flow venting rate Volume set MBT blowable volume The Label definition is analogous to
37. the input record descriptions in sections 4 to 22 2 The DSSP21 Component Based Model The program uses a breakdown of the vehicle into a small number of components whose individual and interactive hydrodynamics can be estimated or measured Since for the most part it has a physical basis this may be characterized as a rational flow approach For two components subscripted 1 and 2 the hydrodynamic load vector F as a function of the extended state vector u u v w p q T 0 0 Y 6 where u v w p q r are translational and rotational velocities 6 6 are the Euler angles and 6 represents control surface deflections and other parameters is expressed as F u Ci u Co u Ci2 u C21 U 1 in which C u and C2 u are the individual loads on each component and C1 2 u and C21 u are the interactions of each with the other It is implied that each of the terms in equation 1 is estimated or measured in a local axis system for local flow and then transformed into a common axis system for summation In the present build there are many more terms but the scheme is still limited to two component interactions F u gt Ci u gt C u 2 i jJAi The calculations that are implemented in DSSP21 model streamlined hulls and low aspect ratio lifting surfaces Parameters required to model hull appendage interactions are included as part of the appendage data in the geometry input file file nomenclature is
38. the matrix comprising the inertial plus added mass properties of the submarine it must be inverted to decouple the equations of motion for integration in time Since internal DSSP21 calculations are dimensioned some elements of the matrix grow rapidly as the reference origin is moved away from the principal axes of the vehicle making it ill conditioned for inversion Nondimensionalizing this part of the calculations may alleviate the problem but that is outside the scope of current code development 8 DRDC Atlantic TM 2006 252 In a free running manoeuver there is a set of earth fixed axes xo yo 20 that are parallel to the reference axes at the start of the simulation with their origin on the surface rather than at initial depth 26 Consequently 0 yo 20 start 0 0 Zoe where here as elsewhere in this guide subscript e indicates an initial condition The trajectory of the reference origin in Zo yo Zo coordinates is tabulated on file simnnn txt which includes the state variables u v w p q and r in the reference coordinate system Internally the program uses a separate local axis system for each component For a hull component the origin is at its longitudinal CB local x is directed forward along the longitudinal axis and y and z are determined from vehicle axes or are user defined For a lifting appendage the origin is at the root mid chord local y is outward along the mid chord line z is normal to the effective plane
39. to the flap hinge line as shown in the figure The first two arguments of Flapped are optional as a pair the third argument is also optional Thus if only one argument is present it is assumed to be cf if two are present they are assumed to be b1 be and b2 bexp Default values for the arguments are 0 0 1 0 and 0 25 respectively and their permitted ranges are 0 0 lt b1 bezp lt 1 0 b1 beap lt b2 beap lt 1 0 and 0 0 lt GF E lt 1 0 DRDC Atlantic TM 2006 252 29 6 4 Control Parameter Records DelNonLin Del Delta DeltaLim FlapGap FlaProDrag and WeightDCI These records set or redefine additional parameters for a control appendage Del is a synonym for Delta making it a keyword allows the common abbreviation Del to be used without ambiguity DelNonLin This record enables the calculation of effective flap angle de lt 6 for an appendage with a trailing edge flap 4 The keyword record Flapped must also appear in the appendage specification Without the DelNonLin record de Del de Defines an initial value e in degrees for the control deflection the default is zero The initial deflection may have the effect of offsetting the reference for some control commands It can be redefined at several places in the Root sim file This record applies to both AllMoving and Flapped control types Delta de As Del above DeltaLim OMax 5 Min Sets control deflection limits Our gt 6 gt Min The def
40. turn on all the appendages to indirect control commands except those numbered two and three we can input WeightDCI All One WeightDCI 2 000 WeightDCI 3 000 WeightDCI records should precede indirect Delta commands to which they apply Information on the initial status of some of the above quantities notably the vehicle reference and indirect control weights is output in the Configuration Summary section at the beginning of file Root spr Most changes that result from resetting these and other parameters are recorded subsequently on the file as they occur 20 Root sim Level 2 Coefficnt Input This option uses a series of internally generated static load calculations to estimate some linear hydrodynamic coefficients and stability and control indices At present coefficients are obtained using three point fit code adapted with minor modifications from the DERIVS program 7 The user is cautioned that the algorithms assume the vehicle has port starboard symmetry and that many of the coefficients will be incorrect if this is not the case More general algorithms providing the higher order coefficients and cross coefficients required for a coefficient based simulation model will be developed for future builds of DSSP21 The following table summarizes the keyword records for level 2 Coefficnt input 68 DRDC Atlantic TM 2006 252 Keyword CB CG Del Delta DeltaLim Derivs Length Output Pop PReverse Reference Rho Text
41. 0 Loop Delta Port 15 15 1 WeightDCI All One 3 3 Error Messages This guide is not except in the broadest terms concerned with the architecture of the code However some familiarity with it is useful because error messages cite the DRDC Atlantic TM 2006 252 5 program unit i e subroutine function etc in which the error occured thus providing a context for understanding the problem A list of program units and their functions is given in annex C Error messages are issued to both the terminal and Root log They have four levels of severity fatal warning with pause warning and information Fatal error messages are generated by a condition or problem that forces termination of program execution A warning with pause indicates an actual or potential problem for which the user may wish to terminate program execution the default response is to continue Simple warnings are issued to indicate an actual or potential problem while allowing program execution to continue automatically In a few instances an information message is issued this indicates that the program is flagging at worst a benign anomaly that the user should be aware of The general format for an error message is Fatal Error in program_unit_name or Warning from program_unit_name or Information from program_unit_name message line 1 message line 2 If a warning includes a pause it is followed by Continue execution Y N and the user s r
42. 08 and Cr 0 45 Flood ControlRoom Stop secure flood in labeled WTC Note that Flood 1 0 is the same as Flood 1 Stop If a new flood is started in a watertight compartment where one is already in progress flooding continues with the new parameters Dr and Cr Therefore to represent an additional flood in the same WTC the value of Dr should correspond to the combined area of the existing and new breaches 18 Root sim Level 1 Input Root sim level 1 input defines a sequence of calculations or simulations to be run Each run is defined by a block of level 2 input records and the run is executed before control is passed back to level 1 There may be up to 999 runs in the sequence An example of Root sim is given in annex E The Root sim keyword records at level 1 are Keyword Function Captive run captive vehicle manoeuvering load calculations Coef generate a set of hydrodynamic coefficients Coefficnt generate a set of hydrodynamic coefficients Free run a free swimming vehicle simulation Help send help output to Root log MLD generate Manoeuvering Limitation Diagram curves inactive Static run a set of static load calculations Text title or other information 18 1 Calculation and Simulation Records Captive Coef Coefficnt Free MLD and Static These records announce level 2 input for various calculations and simulations Execution of each one adds to Root spr output and generates a new simnnn txt output file A Fr
43. 224 Defence Research Establishment Atlantic Limited Distribution Enright W H Jackson K R Norsett S P and Thomsen P G 1986 Inter polants for Runge Kutta Formulas ACM Transactions on Mathematical Software Vol 12 No 3 Association for Computing Machinery Enright W H Jackson K R N rsett S P and Thomsen P G 1988 Effective Solution of Discontinuous IVPs Using a Runge Kutta Formula Pair with Inter polants Applied Mathematics and Computation Vol 27 Amsterdam Elsevier Etkin B 1972 Dynamics of Atmospheric Flight Second Edition New York Wiley Hooft J P 1986 Hydrodynamic Forces on Tear Drop Bodies MARIN Report No 07659 1 MO Maritime Research Institute Netherlands Limited Distribu tion DRDC Atlantic TM 2006 252 87 12 13 14 15 16 17 18 19 20 21 22 23 24 88 Mackay M 2006 Estimating the In Plane Hydrodynamic Loads on a Submarine Hull at Incidence DRDC Atlantic TM 2006 020 Defence R amp D Canada Atlantic Mackay M 1992 DREA Submarine Simulation Program Version 0 2 DSSP02 Release Notes DREA TC 92 308 Defence Research Establishment Atlantic Limited Distribution Watt G D and Fournier E Y 1995 Submarine Propulsion Testing in the IAR 9 m Wind Tunnel In Third Canadian Marine Hydrodynamics and Structures Conference Halifax Technical University of Nova Scotia van Lammeren W P A van Mane
44. Copy No EJ Defence Research and Recherche et d veloppement Development Canada pour la d fense Canada ry DEFENCE D FENSE DSSP21 Build 061102 User Guide Mike Mackay Defence R amp D Canada Atlantic Technical Memorandum DRDC Atlantic TM 2006 252 December 2006 Isi Canada This page intentionally left blank DSSP21 Build 061102 User Guide M Mackay Defence R amp D Canada Atlantic Technical Memorandum DRDC Atlantic TM 2006 252 December 2006 ins N Pegg Head Warship Performance A ed for release by K Foster Af Chair Do ument Review Committee Her Majesty the Queen as represented by the Minister of National Defence 2006 Sa majest la reine repr sent e par le ministre de la d fense nationale 2006 Abstract DSSP21 is a semiempirically based computer code for evaluating the dynamics and ma noeuverability of streamlined underwater vehicles including submarines The purpose of this user guide is to facilitate preparation of the input files that are required for a definition of the vehicle and its systems and for controlling the calculations and ma noeuvering simulations to be done It contains detailed descriptions of input syntax and options together with brief discussions of the output produced and some background information on the code structure and algorithms R sum Le DSSP21 est un code informatique base semi empirique servant valuer la dy namique et l
45. Sternplane Tail TailEff ToC Twist WeightDCI define flap profile drag correct for having an endplate on this appendage correct for this appendage being an endplate save for a copy but do not use this appendage component label define appendage type as Large Bowplane appendage corner data block follows force termination of input see section 5 4 copy saved appendage by reflecting copy saved appendage by rotating define appendage type as Rudder define appendage type as Sail define appendage type as Sailplane save this appendage for subsequent copy define appendage type as Small Bowplane define appendage type as Ship Stabilizer define appendage type as Sternplane define appendage type as Tail define tail efficiency define section thickness chord ratio apply geometric twist set indirect control deflection weights A keyword record other than one of these will terminate input for the current component After processing of level 2 data is completed the input stream is backspaced and the new record is re read at level 1 The records are described below in terms of the functional group that they belong to 6 1 The Planform Record The appendage planform is described by four corner points as illustrated in figure 4 For a triangular appendage points c2 and c3 should be made coincident Planform The next four records contain coordinates of the four appendage corner points in vehicle axes The corner points are input one
46. TC Flooding Commands A flood in a watertight compartment WTC is initiated during a free manoeuver by the keyword Flood section 22 4 which is followed by one two or three arguments The first argument identifies the WTC to be flooded and the second and third are parameters for the breach that the flood originates from The flooding record is Flood argument 1 argument 2 argument 3 where argument 1 is one of Nc the index of the WTC to be flooded the Nct WTC defined on Root geo has the index Nc label string the label of the WTC to be flooded Stop secure floods in all WTCs optional argument 2 is one of Dr the diameter of the breach which is assumed to be circular otherwise use the diameter of a circle with the same area as the breach Stop secure the flood in the WTC identified by argument 1 and optional argument 3 is Cr the coefficient of discharge of the breach By default Cr 0 6 DRDC Atlantic TM 2006 252 61 If the first argument is a WTC index or label then the second argument is mandatory The third argument is only used if the second is Dr Unless the user has information about the value to use for a specific system breach argument 3 can be omitted the default coefficient of discharge will give acceptable results for most purposes The following examples illustrate how the arguments are combined Flood Stop secure all floods in progress Flood 2 0 08 0 45 flood in WTC 2 with Dr 0
47. V record cannot appear in the same Static run as indirect translational input section 19 2 w The mandatory argument is normal velocity heave in m s The default is zero A W record cannot appear in the same Static run as indirect transla tional input section 19 2 Indirect State Variable Records Alfa Alpha Beta Ukt and Ums Q The mandatory argument is angle of attack a tan w u in degrees The default is zero An Alfa record cannot appear in the same Static run as direct translational input section 19 1 Q As Alfa above p The mandatory argument is angle of drift 8 tan v u in degrees The default is zero A Beta record cannot appear in the same Static run as direct translational input section 19 1 DRDC Atlantic TM 2006 252 65 Ukt U The mandatory argument is total velocity U Vu v w in kt the default value is 1 944 kt 1 m s A Ukt record cannot appear in the same Static run as direct translational input section 19 1 or a Ums record Ums U The mandatory argument is total velocity U Vu v w in m s the default value is 1 m s A Ums record cannot appear in the same Static run as direct translational input section 19 1 or a Ukt record 19 3 The Loop Record The Loop record is used to iterate a state parameter between limits A typical appli cation would be to cover a range of incidence angles although any of the parameters listed in sections 19 1 and 19 2 can be
48. a man uvrabilit des vaisseaux subaquatiques effil s dont les sous marins Ce guide d utilisation vise a faciliter la pr paration des fichiers qu il faut entrer pour d finir le vaisseau et ses syst mes le contr le des calculs et la simulation des manceu vres Il contient une description d taill e de la syntaxe des donn es d entr e et des options connexes ainsi que quelques mots sur les donn es produites a la sortie et de Vinformation contextuelle sur la structure et les algorithmes du code DRDC Atlantic TM 2006 252 i This page intentionally left blank DRDC Atlantic TM 2006 252 Executive Summary Introduction DRDC Submarine Simulation Program version 2 1 DSSP21 was developed to predict the manoeuverability of submarines and smaller underwater vehicles It generalizes the capability of an earlier Oberon specific code that was used to study the tactical and safety implications of modifications to the submarine or to operating procedures these investigations included towed array operation ballast loss sonar dome replacement and diving limit redefinition DSSP21 can model a wide range of vehicles and estimate their manoeuvering characteristics for a broad spectrum of system studies and evaluation even preliminary design Its direct predecessor DSSP20 was used for a systematic study of the effect of a hull plug e g for Air Independent Power on manoeuvering and to support development of the CF Remote Minehunti
49. aleurs par d faut qui perme ttent de d finir la plupart des types de vaisseaux et de man uvres avec relativement peu de param tres Ce guide d utilisation vise surtout faciliter la pr paration des donn es d entr e qui comportent la d finition du vaisseau et de ses syst mes et la d finition des simulations hydrodynamiques et des simulations de man uvres faire Ces derni res comprennent le calcul des charges statiques et dynamiques sur vaisseau captif la g n ration des coefficients hydrodynamiques et les man uvres de vaisseau libre Le guide s adresse la fois aux utilisateurs exp riment s et aux nouveaux utilisa teurs Projets de d veloppement Des fonctions additionnelles seront ajout es aux versions venir du DSSP21 notamment la compensation et l assiette et la g n ration automatique des courbes des sch mas de limitation des man uvres plus long terme on songe d velopper un mode de calcul hybride pour tirer le maximum des donn es exp rimentales et de l analyse de la dynamique des fluides num rique M Mackay 2006 DSSP21 Build 061102 User Guide DRDC Atlantic TM 2006 252 R amp D pour la d fence Canada Atlantique iv DRDC Atlantic TM 2006 252 Table of Contents Abstract 285 Las nr nan da dt ana ni de Den Da sea nd ren ET an a i R SUM isro aeo Ses eee esse Uaioe ees toe vetoes tele ee E Wane Wace e i Executive Summary 352 eree E ee ee ee weer iii DOMMMAINS gt 2 E den A Ac
50. always precede a following comment by an EOR character Unless noted keywords discussed in this guide are contained in the main dictionary These keywords may be abbreviated by truncation so long as the result is not am biguous For example keywords Left and Length can be abbreviated by Lef and Len respectively but Le is ambiguous On the other hand an unabbreviated keyword is distinguished from any abbreviations that may be identical Delta and DeltaLim are therefore recognized as separate keywords For this reason keyword abbreviation should be used with care since the result may be unexpected Finally it should be noted that the same keyword may be used for different purposes in different parts of the input its interpretation depending on the context 4 DRDC Atlantic TM 2006 252 With keyword controlled input records can in general appear in any order in the input file In DSSP21 this freedom is limited to within an input level input is initially at Level 1 and is switched to Level 2 and higher by specific keywords Moreover input order is significant is within a data block i e a sequence of physical records that is is treated as a single logical record And some simulations notably for static load estimation execute records in the Root sim file in input order so that changing that order may affect the results Text records provide indentification and other information for printed output They consist of the keyword Text o
51. ame control appendage the time history data are used and the default is ignored Delta arguments see section 14 As Del above TimeHistry filename The mandatory argument is the name of the time history file its length including extension cannot exceed twelve characters The time history file comprises a header record with a case insensitive name for each of the data columns and a series of data records it can also include com ment or Text records which are respectively ignored or output to Root spr The first data column must be time monotonically increasing identified on the header by Time The only other required data column is u identified by U Columns of v w p q r 0 and identified by V W P Q R Phi The and Psi are optional as are control deflections identified by Del Nz for appendage Nr Other than Time the columns can be in any order need not be aligned and those identified by names not mentioned above are ignored Translational velocities must be in m s rotational velocities in deg s and angles and control deflections in degrees There is insufficient room to illustrate a typical time history file here but the following trivial example illustrates some of the key points above text this is tiny time w u del4 THE Since not all three Euler angles are input the lt The gt column is ignored 1 0 2 6 1 2 In addition p q and r default to 2 1 8 6 1 25 zero so the Euler angles used
52. an dard textbooks e g Etkin 10 There are two principal body fixed axis systems in DSSP21 vehicle axes in which vehicle geometry and most other input is defined and reference axes in which output quantities such as hydrodynamic forces and moments are defined Both systems are righthanded Vehicle axes are determined indirectly by the x y z coordinates of vehicle geometry which are initially defined in file Root geo All components of the vehicle must use vehicle axes for their definition Coordinates and lengths are in metres and angles are in degrees Reference axes default to vehicle axes shifted to an origin at the hull CB of a single hulled vehicle for other configurations reference axes must be defined by the user To be most meaningful reference axes should coincide with conventional hydrodynamic axes i e with x directed forward y to starboard and z downward Likewise but also for reasons of computational stability in a free manoeuver the reference axis origin should be in the vicinity of the vehicle CB and CG The reference origin trajectory is always output in a free manouever but the user may define an additional point called the target which is also tracked This is typically a point of interest such as the attachment point for a towed array Defining it as the target avoids numerical difficulties that could be encountered when shifting the reference origin to achieve the same result The problem is principally with
53. and Because of the way DSSP21 determines the bounds of the simulation from the earliest command to the latest it provides an easily recognizable way of defining the stop time DRDC Atlantic TM 2006 252 83 Vent string The argument string is a combination of the ballast tank arguments discussed in section 16 A ballast tank can only be referred to once in a bundle of simultaneous Vent commands 23 Running the Program and Interactive Dialogues DSSP21 has been written to run from the input files with virtually no user intervention Unless the Root character string that is required to identify input and output files is detected as a command line parameter the user is asked to supply it at the start of the program Enter file name root default dssp21 A string up to eight characters long is expected Enter Return indicates the default dssp21 Not finding the geometry input file Root geo generates a fatal error The methods for calculating hull residual drag section 5 3 are likely inaccurate for truncated hulls for which the base is large Since there is not a good criterion for largeness in this context the program asks Calculate residual drag for truncated hull Y N It may be incorrect The default sets the residual drag to zero The message is suppressed by supplying a value for ResiDragR section 5 3 An unlikely case requiring user intervention occurs with the DSSPtwo propulsor model This model
54. appendage flap gap correction deck sideforce and yawing moment corrections keel sideforce and yawing moment corrections pitch angle depth autopilot pitch limit propulsor local axis pitch axis rotation in pitch hull bound vortex distribution parameters water density phase lead autopilot anticipation time constant roll angle or appendage anhedral or dihedral angle vehicle reference axis directions angle of rotation for a copied appendage axis rotation in roll yaw angle heading initial heading commanded heading propulsor local axis yaw axis rotation in yaw RPM rate frequency control response frequency vector angular velocity DRDC Atlantic TM 2006 252 109 Reference Axes and Loads Acronyms and Abbreviations AIP BG CB CF CFD CG EOR GUI HP LBP MBT MLD ODE PID ROV SVD UUV VRML WTC 110 Air Independent Power HP air Bottle Group vehicle Center of Buoyancy Canadian Forces Computational Fluid Dynamics vehicle Center of Gravity End Of Record Graphical User Interface High Pressure Length Between Perpendiculars Main Ballast Tank Manoeuvering Limitation Diagram Ordinary Differential Equation Proportional Integral Derivative control Remotely Operated Vehicle Singular Value Decomposition Unmanned Underwater Vehicle Virtual Reality Modeling Language WaterTight Compartment DRDC Atlantic TM 2006 252 Unclassified DOCUMENT CONTROL DATA 1 ORIGINATOR 2 SECURITY CLASSIFICATION
55. are 3 1i1 4 6 2 1 27 all zero 5 12 4 6 2 1 28 H 6 09 4 1 6 1 1 282 There will be however loads in six 7 02 3 9 5 5 1 285 degrees of freedom because de1004 9 06 3 4 4 8 1 1 is a vertical rudder 21 3 Euler iterate Mass Mominertia NoHStat and PQRtol Records These records control various aspects of load estimation DRDC Atlantic TM 2006 252 73 Euler Iterate Mass Qe 0e e If the Euler angles of the model are not tabulated on the time history file they are estimated from rotational velocities using initial values that default to zero This record is required to define non zero initial values 7 is optional The Euler angle calculations are coupled and the initial values of and are not simply added to their resulting time histories This means that e and 0 must be correct in order to correctly generate the dynamics of the simulation There is no reason to provide this record if angle time histories are present If that is done a fatal error results if the input and time history initial angles are inconsistent Niter gt Citer An iterative trapezoidal integration is used to derive Euler angles from rotational velocities The arguments on this record are the maximum number of iterations Nr default 30 and the tolerance for conver gence jter default 0 0001 Conditions under which nonconvergence in dicated by the fatal error Euler angle estimates did not converge p q r resoluti
56. as deg s to compare angular accelerations If inconsistency is found a fatal error of the form TIMEHISTRY file P Q R data is inconsistent is generated While increasing may remove the error in marginal cases it is preferable and generally necessary to rigorously eliminate inconsistencies from the time history file If the Euler angle values are unreliable the simplest way to ignore them and use the estimated values instead is to rename one of the Euler angle columns in the time history file with an unrecognized string such as foo 22 Root sim Level 2 Free Input The Free keyword record initiates a manoeuvering simulation run for a free swimming vehicle The equations of motion and various auxiliary differential equations for control dynamics etc are integrated over time using an order 3 4 Runge Kutta method with adaptive timestep for local error control 8 Output may be obtained at each timestep or at a regular interval by means of interpolation 9 Even while interpolating actual timesteps are output to the Root 1log file for diagnostic purposes At the end of each manoeuvering simulation estimates of computer time for the simu lation and for additional overhead usually negligible and the ratio of simulated time to elapsed computer time are output to Root spr The ratio which is generally of the order of 10 will help determine whether a particular manoeuver or selected options are unduly slowing down the ca
57. at the resistance and propulsion models in DSSP21 are quite general and may not predict these quantities very accurately for a particular submarine Power and thrust are output to the auxnnn txt file It is advisable to establish speed power and speed thrust relationships with a few simple simulations before inputting specific demand values for these quantities AutoRoll keyword keyword e 82 The optional first keyword argument may be Shortest which is redundant and should be omitted or Stop Following Stop associated control surfaces are set to zero unless they are acting under other indirect commands The second optional keyword determines autopilot type see AutoDepth The optional third argument is commanded roll angle e in degrees By default dc is zero Thus a command record t AutoRoll is interpreted as try to maintain zero roll angle under autopilot control however most underwater vehicles will have insufficient roll control authority to do so unless roll control is integral to their design DRDC Atlantic TM 2006 252 Blow Del Delta Dummy Flood Prop string The argument string is a combination of the bottle group and ballast tank arguments discussed in section 16 ballast tank can only be referred to once in a bundle of simultaneous Blow commands Label String or Nz or keyword 6 Any of the direct quasi direct indirect or global Delta arguments discussed in section 14
58. ate of air blowing into MBT mass flow rate of air venting from MBT DRDC Atlantic TM 2006 252 n nM nu NsegH NsegL Nversion no Ne NB Nc Na Nu Niter propulsor RPM maximum RPM RPM rate limit number of hull cross section segments for plotting number of appendage cross section segments for plotting VRML format version number self propulsion RPM initial RPM MBT index WTC index HP air BG index hull index iteration limit for estimating Captive Euler angle time histories lifting appendage index propulsor index number of hull stations for load calculation station for hull separation number of hull stations input WTC occupancy roll pitch and yaw rate initial HP air BG pressure propeller pitch arbitrary quantity or parameter local hull radius maximum hull radius viewing distance for VRML plots chord Reynolds number exposed appendage area area of moving part of all moving appendage time or appendage thickness time step hull station height thrust ratio for it propulsor axial lateral and normal velocity DRDC Atlantic TM 2006 252 107 u U U Ver VHP W Wp Wru Wir T Y Z x T0 YO 20 TB UB 2B TBG YBG BG TBT YBT 2BT TC YC 2C state vector total velocity initial forward speed MBT volume HP air BG volume weight weights for indirect control of depth heading and roll vehicle axis coordinates local axes distance downstream from origin of hull boundary l
59. aults are 35 and 35 These limits can be redefined at several places in the Root sim file The record applies to both AllMoving and Flapped control types FlapGap n This record overrides the default value of 1 0 for the flap balance and gap effi ciency correction 7 It is valid only for an appendage with a trailing edge flap the keyword record Flapped must also appear in the appendage specifica tion The argument is mandatory and has a permitted range of 0 8 lt 7 lt 1 25 FlaProDrag ks This record overrides the default value of 0 5 for the coefficient of profile axial force i e negative drag associated with a trailing edge flap deflection ks which is nondimensionalized with respect to exposed appendage area It is valid only for an appendage with a trailing edge flap the keyword record Flapped must also appear in the appendage specification The argument is mandatory and has a permitted range of 2 0 lt ks lt 0 0 WeightDCI Wyp Win Wir It will be seen in section 14 that there is an indirect method of vehicle control in which an effective deflection angle is associated with all appendages capa 30 DRDC Atlantic TM 2006 252 ble of controlling the vehicle in a particular mode depth heading or roll using subcommands like Up Starboard etc The indirect method provides the mechanism for autopilot control of the vehicle Appendages are assigned weights that determine the degree to which they re
60. ayer coordinates in earth fixed axes center of buoyancy coordinates components of BG vector coordinates of MBT location coordinates of WTC location Le Verres t S14 appendage corner point coordinates Le Ye Ze Tee Yeo TG YG ZG Zin t 1 Ns Tm Ym 2m Tn Yn Zn To Yo o TP YP ZP Tt Yt Zt TT YT T TS V6 25 X Y Z 20e Q Qb 1 amp 2 3 108 chart axes initial chart position center of gravity coordinates hull station axial coordinate hull midpoint coordinates hull nose coordinates vehicle reference origin propulsor location coordinates hull tail coordinates target point coordinates control surface location axial lateral and normal forces initial depth angle of attack or phase lead autopilot amplitude gain appendage geometric twist equivalent angles of attack for local appendage forces angle of drift control surface deflection effective flap angle of deflection DRDC Atlantic TM 2006 252 OMax Min m Oe Eiter ESVD Ew Cn G5 n Yd NNd NY ks NNk 0 OL Op Ai A2 p T Po 9o Vo OR Y Ve We wp U Wn Ws Q maximum and minimum control deflection angles control deflection rate limit initial control deflection time integration tolerance tolerance for estimating Captive Euler angle time histories tolerance for SVD matrix inversion tolerance for Captive Euler angle consistency RPM rate damping control deflection damping
61. be the same type The initialization estimates optimum Js and RPM kt values for given operational conditions Wageningen B4 70 propeller thrust and torque characteristics are derived from lookup tables taken from table 7 in reference 15 It is assumed that all propellers contribute to forward thrust for initialization the total thrust is apportioned between them in a specified ratio The same form of calculation is used for all so the program does not accurately handle the situation of a main propulsor of this type on the hull axis with an auxiliary propulsor on each sternplane i e effectively in open water The following table summarizes the keyword records for level 2 WagBInit input Keyword Function Diameter define a hull reference diameter Open use open water propeller option PoD set pitch diameter ratio Pop force termination of input see section 5 4 Rho set fluid density for propeller initialization TRatio set thrust ratios for multiple propellers Ukt ahead speed for propeller initialization in kt Ums ahead speed for propeller initialization in m s 9 1 Diameter Open PoD Rho TRatio Ukt and Ums Records Diameter Du The argument Dm is the maximum diameter of the hull that is used to form the ratio Dp Dy for estimating wake fraction and thrust deduction coefficients If the vehicle has only one hull Dy defaults to its calculated maximum diameter if there is none or more than one hull a value for Dm must be
62. can be used on this record Multiple simultaneous Del and Delta commands can be input so long as a command conflict section 14 5 is avoided Label String or Nz or keyword 6 As Del above The Dummy command generates no command action However it can be used as a time marker since like all command records it stops and restarts the integration string The argument string is discussed in section 17 it identifies the WTC to be flooded and defines the flooding breach A WTC can be referred to only once in a bundle of simultaneous Flood commands Label String or Np n If the first argument is omitted and there is only one propulsor then that propulsor is commanded to n RPM but if there is more than one propulsor a fatal error is generated However if the first argument is present the propulsor identified by the label string or index Np is commanded to n RPM Propulsor Label String or Np n Start Stop As Prop above The Start command is currently implemented similarly to Dummy in that it generates no commanded action however it cannot be later in time than any other command Because of the way DSSP21 determines the bounds of the simulation from the earliest command to the latest it provides an easily recognizable way of defining the start time The Stop command is currently implemented similarly to Dummy in that it generates no commanded action however it cannot be earlier in time than any other comm
63. cess Root process Root process Root process Root process Root process Root process Root process Root process Root process Root process Root sim level 1 input process Root process Root process Root process Root process Root process Root geo level 1 input geo autopilot level 2 input geo HPAir level 2 input geo Hull level 2 input geo Lift level 2 input geo Lump level 2 input inactive geo MBT level 2 input geo DOPCalc level 2 input geo Plot level 2 input geo Propulsor level 2 input geo WagBInit level 2 input geo WTC level 2 input geo and Root sim Reference level 2 input sim Captive level 2 input sim Coefficnt level 2 input sim Free level 2 input sim MLD level 2 input inactive sim Static level 2 input Sp21cint for time simulation integration Unit DDNORK INTPCO INTPC1 Function order 3 4 Runge Kutta integrator fourth order interpolation C continuous fourth order interpolation C continuous Sp21esam for added mass estimation This file comprises the core subroutine ESAMCR and associated program units adapted with only minor modifications from the ESAM added mass program 6 To avoid future 94 DRDC Atlantic TM 2006 252 naming conflicts the program units are listed here ESAMCR AMMATX AMOUTP BCZB CHGSGN CHIR COS2Z INERCO QKE SWITCH UEU VFIELD and ZEROIF There should be no errors reported from within this set of routines Sp21prep for geometry and sy
64. commands The second optional keyword determines autopilot type see AutoDepth The optional third argument is commanded heading pe expressed in one of the argument string formats described in section 15 By default Ye is made equal to the current heading i e t AutoHead is interpreted as maintain current heading with autopilot AutoProp keyword keyword Qe The first keyword argument is mandatory it determines the propulsion con trol parameter In the absence of autopilot control the propulsion model uses constant RPM With autopilot control RPM is adjusted according to de manded power speed or thrust the choice is indicated by this keyword being Power Ukt or Ums or Thrust respectively Alternatively if the keyword is Stop propulsion control is stopped and RPM is maintained at the current value until changed by another command The second optional keyword determines autopilot type see AutoDepth The optional third argument is a demand value for the control parameter If the first keyword is Power Qe is power in W if Ukt it is speed in kt if Ums it is speed in m s and if Thrust it is thrust in N By default Qe is made equal to the current value of power speed or thrust according to the first keyword Thus a command record t AutoProp Power is interpreted as maintain current propulsion power under autopilot control If specifying a demand value for power or thrust the user should recall th
65. d DRDC Atlantic TM 2006 252 69 Output keyword The keyword argument indicates the type of output to be put onto simnnn txt If it is Coef or Coefficnt the output is a list of the total vehicle coefficients multiplied by 1000 If it is Root the output is a table of roots of the vertical stability equation for zero to critical speed As presented in this table the roots may be discontinuous with speed Otherwise or if the Output record is absent simnnn txt will not be saved PReverse T lys zs This record initiates a small perturbation plane reversal speed estimate 23 for a control surface located at 25 ys 25 in vehicle axes Optional arguments ys and zs default to zero Ukt U Define total velocity U Vu v w for nondimensionalizing the coeffi cients in kt the default value is 1 944 kt 1 m s It is only necessary to set this parameter if there is a significant Reynolds number effect in the static load calculations Ums U Define total velocity U Vu v w for nondimensionalizing the coeffi cients in m s the default value is 1 m s It is only necessary to set this parameter if there is a significant Reynolds number effect in the static load calculations 20 2 Control Deflection Derivative Level 3 Input Following a Del or Delta record a sequence of records is required to define the con trol deflection derivatives to be estimated The associated keywords are Down Port RollNeg RollPos Stbd
66. d the points of application of its forces and moments may have to be considered Diameter Dp This record defines propulsor diameter Dp in metres it is mandatory Location TP yp zp The propulsor local origin p yp zp in vehicle axes is the point at which estimated thrust and torque are applied yp and zp may be omitted in which case they both default to zero For most purposes the location of the propulsor hub can be used A Location record must be present Pitch Op 0p defines the pitch of the local propulsor axes with respect to vehicle axes in degrees The order of axis rotation is wp Op If this record is omitted 0p defaults to zero 36 DRDC Atlantic TM 2006 252 Yaw wp wp defines the yaw of the local propulsor axes with respect to vehicle axes in degrees The order of axis rotation is wp 0p If this record is omitted wp defaults to zero 8 2 Propulsor Parameter Records Left RevLimit and Right Left The propulsor is left handed For self propulsion ahead the propulsor has counterclockwise rotation looking forward so that torque on the vehicle is positive Right handedness is the default RevLimit NM Argument nm is maximum RPM it must be positive The default value is 15 433 Dp sec i e RPM for Jg 1 at 30 kt Right The propulsor is right handed For self propulsion ahead the propulsor has clockwise rotation looking forward so that torque on the vehicle is negative This record is redun
67. dant since right handedness is the default 8 3 Propulsor Dynamics Records RevDynam and RevRateLim RevDynam n Wn Argument is the nondimensional change of RPM damping and wn is the change of RPM response frequency in rad s These parameters together with ny determine RPM time histories by way of a second order ODE for each propulsor Damping must be positive and a warning is given if it is gt 1 0 the default value is 0 9 Frequency w must be positive its default value is 10nm nm where ny is maximum RPM RevRateLim ny Argument nay is the maximum change of RPM rate in RPM s it must be positive The default value is 10 RPM s 8 4 Save Copy Records Reflected and Save Similarly to lifting appendages sections 6 7 and 6 8 a propulsor may be saved and copied however only Save and Reflected records are applicable Note that the propul sor label is not saved while all other attributes are DRDC Atlantic TM 2006 252 37 Reflected The saved propulsor is reflected in the vehicle xz plane A Label record is required for the new propulsor or the default PROPnnn will be used Save The current propulsor will be used and then saved for a subsequent copy This overwrites a previous save 9 Root geo Level 2 WagBlnit Input Input discussed in this section is used to initialize propulsors with type WageningB sec tion 4 4 i e Wageningen B4 70 series propellers 15 If this type is used all propulsors must
68. dral kg defined below The notation 0 is similar to that in the previous section it indicates a deflection of 6 with the appropriate sign for the appendage Delta keyword 6 Where the keyword is one of Down appendages with type LBowplane SBowplane and Sailplane are deflected by W7pkg to produce a downward force and appendages with type Sternplane and Tail are deflected by Wypkg6 to produce an upward force Port appendages with type Rudder and Tail are deflected by W k40 to produce a force to starboard RollNeg appendages with type Tail are deflected by W7pR6 to produce a negative roll moment i e counterclockwise looking forward RollPos appendages with type Tail are deflected by W7pr to produce a positive roll moment i e clockwise looking forward DRDC Atlantic TM 2006 252 55 Stbd as Starboard below Starboard appendages with type Rudder and Tail are deflected by Wyyzk d to produce a force to port Up appendages with type LBowplane SBowplane and Sailplane are deflected by Wypkg to produce an upward force and appendages with type Sternplane and Tail are deflected by Wypkg6 to produce a downward force Stbd is a synonym for Starboard making it a keyword allows the common abbreviation Stbd to be used without ambiguity The vehicle response indicated is for a positive value of 6 the response is opposite if is negative Therefore Up 10 produc
69. dynamics are discussed in sections 6 5 and 8 3 respectively The keyword and arguments in a command record are interpreted as follows AutoDepth keyword keyword zoc The first optional keyword determines control options see section 10 it may be Depth to use depth control only Pitch to use pitch control only TwoParam to use both or Stop to stop depth control The default is TwoParam Following Stop associated control surfaces are returned to their initial deflection in the simulation unless they are acting under other indirect commands The second optional keyword determines autopilot type it may be PhaseLead or PID these options and the default settings are described in section 10 1 The optional third argument is commanded depth in m If this argument is omitted zoc is made equal to the current depth a command record t AutoDepth is interpreted as maintain current depth with autopilot AutoHead keyword keyword string The first optional keyword argument determines the direction to turn into the commanded heading it may be Port Stbd Starboard requiring the turn to be made in the specified direction Shortest meaning take whichever di rection is shortest or Stop to stop heading control The default is Shortest DRDC Atlantic TM 2006 252 81 Following Stop associated control surfaces are returned to their initial deflec tion in the simulation unless they are acting under other indirect
70. e default is computationally more economical but may perform less well in some circumstances In the absence of this record calculations are output at the adaptive timesteps Only the extended state variable set is interpolated other quantities will nor mally have a value calculated at the last integration timestep The output file principally affected is auxnnn txt which tabulates a number of intermediate and derived quantities Those quantities for which interpolation results in an unacceptable loss of precision on output are recalculated at the interpolation timesteps DRDC Atlantic TM 2006 252 79 Isothermal NoMass This record forces the simple isothermal model for ballast tank blowing the default is an adiabatic blow change in the mass of the submarine during a ballast blow for example is by default reflected in an adjustment of all its inertial properties and requires recalculation and inversion of the inertial plus added mass matrix I A at each time step following the change The NoMass record is an option to reduce the associated overhead by the approximation of keeping the inertial properties constant while simply adding the resulting additional forces and moments to the equations of motion This approximation appears to be acceptable for simulating the blow of a typical reserve of buoyancy of ten percent on a submarine but for larger mass changes such as may occur in smaller vehicles the validity of the approxima
71. ed U kt This record overrides the default value of 5 kt for vehicle speed used to initialize Js and RPM kt for WageningB propellers There can be only one Ukt or Ums record U m s This record overrides the default value of 2 57222 m s 5 kt for vehicle speed used to initialize Jg and RPM kt for WageningB propellers There can be only one Ums or Ukt record 10 Root geo Level 2 Autopilot Input Before listing level 2 autopilot input a brief outline of the control algorithms will be useful DRDC Atlantic TM 2006 252 39 The error signal Jp for a quantity Q i e heading roll etc is in general Je Q Q Cz 5 where Qe is the commanded value of Q and Cg in units of Q7 is an error gain required to normalize Jg to within 1 gt Jg gt 1 for a typical maximum response Such definitions are deliberately vague some trial and error will be required to find optimum values for the gains and other autopilot parameters For propulsion control the error signal has the form Q Q Cr where n 1 3 if Q is power n 1 if Q is speed or n 1 2 if Q is thrust and the units of Cg correspond in each case The depth error signal is also a little more complex than equation 5 as it depends on pitch angle 0 in addition to depth zo l sin 07 JE depth zo zo 1 sin CE depth 6 l sin 07 where l is the lookahead distance making it appear that depth is sensed l ahead of the co
72. ee simulation also adds a new auxnnn txt file Coef is a synonym for Coefficnt 62 DRDC Atlantic TM 2006 252 Captive A Captive simulation estimates hydrodynamic load time histories for prede termined vehicle manoeuvers Its original purpose was to be employed as a diagnostic tool to interpret Free manoeuvers but it can also be used for example to estimate hydrodynamic balance loads in MDTF captive model experiments The level 2 input records are described in section 21 Coef From a series of static load calculations generates hydrodynamic coefficients and optionally makes small perturbation stability and plane reversal estimates The level 2 coefficient input records are described in section 20 Coefficnt As Coef above Free This keyword initiates the time simulation of a single free swimming vehicle that is manoeuvering in response to a series of control deflection and propulsor commands The level 2 input records are described in section 22 MLD This option is a placemarker for future development it will be used to estimate MLD curves from a series of free swimming vehicle simulations Static This keyword initiates calculation of the loads on a captive vehicle under static conditions e g a model in a fixed attitude towing tank or rotating arm experiment The level 2 input records are described in section 19 In the following sections level 2 input is described in order of complexity of the calcu lations required Static
73. eed must be defined if required with a Ukt or Ums record There can be only one Loop record in a Static run 19 4 DeltaLim Reference Rho Text and WeightDCI Records These records can be input for most of the calculations and simulations on Root sim DeltaLim Reference Rho and WeightDCI redefine basic vehicle and simulation para meters that then remain unchanged until redefined in a subsequent run Text record is simply output to Root spr when it is encountered DeltaLim label string or NL max OMin Resets control deflection limits on the lifting appendage identified by the label string or by the integer Nz so that Mar gt gt min The appendage must be either Al1lMoving or Flapped Deflection limits on a particular appendage cannot be reset more than once per run but multiple DeltaLim records can be used to reset limits for different appendages Reference keyword Rho Redefines the vehicle reference axes and origin If the argument is keyword CB or CG the reference origin is located at the CB or CG of the vehicle with the reference axes directed along the vehicle axes Otherwise a reference origin and axes must follow in a data block as two triplets of real numbers the full syntax is given in section 4 5 Despite the recommendation in section 3 4 against a drastic redefinition of the reference there are no serious consequences from doing so in a Static or Captive run However there may be numerical difficul
74. en mati re and National Security de science et de technologie pour Science and Technology la d fense et la s curit nationale DEFENCE oy DEFENSE www drdc rddc gc ca
75. ent in vehicle coordinates Ym and zm are optional and default to zero MidHull plus one of Nose or Tail provides an unambiguous hull definition including yaw and pitch rotation angles a Roll record is explicitly required to override the roll angle default MidHul1 plus Length assumes the default zero rotation angles unless one or more of Yaw Pitch or Roll is also provided Tn Yn Zn Defines the nose point of the hull component in vehicle coordinates y and zn are optional and default to zero Nose plus one of MidHull or Tail provides an unambiguous hull definition including yaw and pitch rotation angles a Roll record is explicitly required to override the roll angle default Nose plus Length assumes the default zero rotation angles unless one or more of Yaw Pitch or Roll is also provided Defines pitch rotation of the local axis system with respect to the vehicle axis system in degrees Rotations are taken in the conventional order yaw pitch roll A value for will be calculated if at least two records with the keyword Nose MidHull or Tail are present Otherwise will take the default value zero if a Pitch record is not provided Defines roll rotation of the local axis system with respect to the vehicle axis system in degrees Rotations are taken in the conventional order yaw pitch roll If a Roll record is not provided will take the default value zero Tt we zt Defines the tail point
76. equivalent to 10 x maximum rate maximum deflection 6 6 Endplate Records HasEndP and IsEndP The keywords which control endplate specifications are HasEndP and IsEndP HasEndP h b bep d The current appendage has an endplate the first argument is mandatory the second is optional Parameters h b and bep are endplate height appendage semispan and spanwise location of the endplate the last two measured from the hull centerline if appropriate see figure 6 Permitted range of the first DRDC Atlantic TM 2006 252 31 IsEndP argument is 0 0 lt h b lt 2 5 The default value of the second argument is 1 0 and its permitted range is 0 0 lt bep b lt 1 0 h h The current appendage is an endplate the argument is optional Parameters h and h are point of attachment relative to the full span and the full span h 2b or height The default value of the argument is 0 5 and its permitted range is 0 0 lt kh h lt 1 0 6 7 Save Records Kill and Save An appendage configuration can be saved with or without itself being used for re use through reflection or rotation The keywords which control saving are Kill and Save both overwrite a previous save Note that the component label is not part of the configuration it is not saved while all other attributes are Kill Save The current appendage configuration will be saved for a subsequent copy but will not itself be used The user thus does not have to calculate
77. ercent of the original code being rewritten Most of the additional changes in this build addressed consistency and usability issues the hydrodynamic load algorithms were largely unchanged Changes included e Allowing a tab as an input delimiter e Eliminating questionable Fortran usage such as floating point equality and in equality testing Addressing inconsistencies in angular rate input and output now deg s is used for all state rotations and rad s is used for control parameters e Modifying Hull discretization to allow arbitrary station spacing and numbers within limits e More rational Propulsor input Rationalizing input and estimation of BG CB and CG Implementing simnnn txt and auxnnn txt output for postprocessing e Implementing the DERIVS hydrodynamic coefficient estimation algorithms Implementing the quaternion representation of Euler angles 90 DRDC Atlantic TM 2006 252 Build 061102 Additions implemented in build 061102 include Autopilots and compass heading and course commands VRML 1 plotting output Optional command line input of the Root string Isothermal and adiabatic ballast blowing and venting Captive vehicle simulations Out of plane load time history calculations Bohlmann Spreiter tailplane efficiency calculations Watertight compartment flooding Improved hull load calculations provision for deck and keel corrections DRDC Atlantic TM 2006 252 91 Annex B Dictionary Lists
78. es the same result as Down 10 For Up Down Port and Stbd the commanded deflection is multiplied by anhedral factor ky cos where is appendage anhedral in the appropriate crossflow direction horizontal or vertical Indirect deflection commands are processed independently according to whether they are associated with depth control Up and Down heading control Port and Stbd or roll control Rol1Neg and RollPos Although multiple input in any one mode is not permitted mixed indirect input is allowed Thus for X rudders with type Tail the following mixed input Del Stbd 10 Del Down 5 will result in the rudders being deflected so as to produce both responses simultaneously An appendage under indirect control requires a Clear command before it can be given a direct or quasi direct deflection command 14 4 Global Deflection Input Delta All keyword The only valid first argument for global input is the keyword A11 more options may be added in future versions of the code The second keyword must be one of Clear all control surfaces are returned to their initial deflection and control flags are cleared The primary use of this command is to cancel indirect input Unlike Reset below Clear can be combined with other control deflection commands regardless of order the global Clear is executed first then the other commands Reset all control surfaces are returned to their initial deflection and control flag
79. esponse is noted in the Root 1log file as one of Execution terminated by user or Execution continued by user Message line 2 is to clarify the error report on line 1 and is only present if required As the code was assembled some error conditions have become trapped in higher level routines and corresponding lower level error checks have become redundant Such errors are noted on line 2 as impossible Since a number of such errors may have been missed or misidentified if this message is encountered please inform the author at mike mackay drdc rddc gc ca providing input files and other supporting information Other error messages may include the notation system error on line 2 indicating that they originate from compiler or platform related errors These are typically ERR exits from a Fortran READ WRITE or OPEN command The last for example may result from DSSP21 attempting to open an output file that is already open in another program Syntax and other errors in user input should be straightforward to identify because the input is echoed record by record to the Root 1log file and in most cases the error message will be displayed just after the offending input record An example of each type of error message follows 6 DRDC Atlantic TM 2006 252 Fatal Error in GEO_L2 HUL Unsavable label label string is duplicated or invalid Warning from SIM_L2_CAP Default RHO 1000 000 for the first sim
80. esult is a patch plot with patches that are yellow on hull components cyan on non controlling appendages and red on controlling appendages The default is White in which the patches are white and the standard lighted view appears in greyscale The white patch image also permits a wireframe view by the user invoking hidden off at the MATLAB command line hidden line removal is turned off and the patches are made transparent This does not work with coloured patches DRDC Atlantic TM 2006 252 To examine the image it is easiest to invoke Camera Toolbar from the figure window View menu and then use the camera controls to orient the image and to adjust perspective viewpoint etc Example screen shots are shown in figures 11 and 12 Figure 11 MatLab plot screen shot produced from the example input in annex D using the keyword Colour the axis box is hidden Figure 12 MatLab plot screen shot produced from the example input in annex D using the default keyword White and additional external lighting red to port green to starboard yellow above and blue below DRDC Atlantic TM 2006 252 51 VRML era Root gpl is output in VRML 1 format if nyersion 1 In future builds of the code VRML 2 format will be available if nyersion 2 The argument is optional VRML 1 is used by default Components are coloured hulls are yellow non controlling appendages are cyan and controlling appendages are red VRML was devel
81. etate ES esos tet a te Bae ttl iv Table of Contents csetsreisk eae enti he min mener ne chs Mens een ch tt v Eist of Figures issus ete ek oak ae eee eae ee ee viii 1 Introductio ge mare ane manette eu oe artenlteeots eat dre nine mdrr rendront 1 2 The DSSP21 Component Based Model 2 3 General Considerations 3 3 1 File Nomenclature 3 3 2 User Prepared Input 4 io HETOY MGSSAGOS LE LUE Lit Le Et LR AR LR Etes Er te et ae 5 Bide AXIS SYSL MS 14 ten anne net ete Anca ech r Eaa te nee een 8 3 5 Applicability of the Program 10 4 Root geo Level L Input sas sentant eee Vee eves vee eee ee 11 4 1 AddedMass and Inertial Records 12 42 BG CB and CG Records aires a ee el oe ee 12 4 3 Hull Lift and OOPCalc Records 13 4 4 Propulsor and WagBlnit Records 14 4 5 The Reference Record 15 4 6 Autopilot Records AutoDepth AutoHead AutoProp and AUTOR OL es Enr ale estate eos UN Re ete dar aiet nt se ee 15 4 7 HPAir MBT and WTC Records 15 4 8 Other Records Help Plot and Text 16 5 Root geo Level 2 Hull Input
82. eter Length Location aNd OCCUPANCY 2e ne oe ea E 48 Root geo Level 2 Plot Input 222 48 13 1 AcroSpin HullSegmnt LiftSegmnt Maple MatLab and VRME Records se deht sects oes cnt he cet URC athe ete wes cette 49 Root sim Control Deflection Commands 53 DRDC Atlantic TM 2006 252 14 1 Direct Deflection Input 14 2 Quasi Direct Deflection Input 14 3 Indirect Deflection Input 14 4 Global Deflection Input 14 5 Conflicting Deflection Commands 15 Root sim Heading Commands 16 Root sim MBT Blowing and Venting Commands 17 Root sim WTC Flooding Commands 18 Root sim Level Vapi sia 2csicserseei are Sasa is best 18 1 Calculation and Simulation Records Captive Coef Coefficnt Free MLD and Static 18 2 Help and Text Records 19 Root sim Level 2 Static Input 19 1 Direct State Variable Records Del Delta P Q R U Vand W 19 2 Indirect State Variable Records Alfa Alpha Beta Ukt and Ums 19 3 The Loop Record
83. ewer for MathWare Derive version 5 http www mathware com but appears to be no longer available AcroSpin produces a wire frame screen plot with fast zoom rota tion and translation capabilities An example screen shot is shown in figure 9 Figure 9 AcroSpin plot screen shot produced from the example input in annex D HullSegmnt NsegH This record overrides the default value of nsegz the number of hull cross section segments The argument is mandatory and must be one of 4 6 8 12 or 24 By default nsegy 24 DRDC Atlantic TM 2006 252 49 LiftSegmnt NsegL Maple This record overrides the default value of nsegz the number of lifting compo nent cross section segments The argument is mandatory and must be one of 2 4 or 8 By default nseyr 8 Root gpl is formatted for a Maple http www maplesoft com procedure DSSPplot mpl written by George Watt at DRDC Options include solid modeling patch plot or wire frame with zoom rotation translation and perspective capabilities A basic patch plot is shown in figure 10 Figure 10 Maple plot screen shot produced from the example input in annex D component colour is related to its input order not type The axis box is optional MatLab 50 keyword Root gpl is formatted for a MATLAB http www mathworks com script DSSPplot m written by the author for MATLAB Version 6 0 Release 12 The optional keyword argument may be Colour in which case the r
84. f plane load calculations implemented in DSSP21 is given in reference 20 These loads occur on a hull with asymmetric appendages attached the most common case being the out of plane normal force and pitching moment due to the sail on a submarine In DSSP21 out of plane loads are calculated by default for each appendage with the type Sail using the nearest hull if there is more than one The OOPCalc record and associated level 2 input are used to override default parameters to specify calculations for other than the default condition or to suppress the out of plane calculations altogether To suppress them use OOPCalc None furthermore any use of an OOPCalc record suppresses all the default calculations For dynamic captive and free simulations the out of plane calculations create a time history by convecting the load distribution aft at the instantaneous value of u If u becomes large there may be too few points defining the distribution to maintain precision in the load estimates and a warning is issued Warning from OOPSTEP Depth of OOP stack less than four data points precision lost in load integration The user must decide whether accurate out of plane loads are significant for the ma noeuver under consideration and reduce the step size accordingly However it is gen 34 DRDC Atlantic TM 2006 252 erally safe to ignore this warning over short periods especially if vehicle depth is under autopilot control The f
85. f the appendage axis system in metres and must not be negative x defaults to zero Sternplane r rm Tail The appendage is defined as a sternplane Argument r is the mid root hull radius r gt 0 Optional argument rm is maximum hull radius required for Dempsey s calculation of tailplane efficiency 18 by default ry r Tailplane efficiency may be specified with a TailEff record T rm The appendage is defined to be a tail fin Argument r is the mid root hull radius r gt 0 Optional argument rm is maximum hull radius required for Dempsey s calculation of tailplane efficiency 18 by default ry r Tailplane efficiency may be specified with a TailEff record 6 3 Control Type Records AllMoving and Flapped The records which define control type are AllMoving and Flapped AllMoving Sm Sexp Flapped The appendage is an all moving control surface the argument is optional Parameters Sm and Sezp are area of the moving part and total exposed area of the appendage The default value of Sm Sexn is 1 0 and its permitted range is 0 1 lt Sin Senp lt 1 0 b1 bexp bz deap cr d The appendage is a control surface with a trailing edge flap The arguments are the inner and outer spanwise flap fractions and the chordwise flap fraction see figure 7 Note that is sometimes defined from mid trailing edge to mid leading edge and CF is aligned accordingly however it is preferable to make them normal
86. g them will require some trial and error depending on the geometric and other characteristics of the vehicle None of the records listed in sections 10 1 to 10 4 is mandatory However if a record is input all the arguments for it must be included 10 1 AutoDepth Level 2 Records DepConGain DepErrGain LookAhead PhaseLead PID and PitchLimit DepConGain Ce depth Depth control gain Cc depth 18 in degrees and should be positive Since the commanded deflection depends on appendage dihedral and control weight Wrp sections 6 4 and 14 3 this parameter can exceed the maximum deflection on an appendage Its default value is 20 degrees DepErrGain Cp depth Depth error gain Cc depth S in m_ and should be positive Based on a lookahead of 2 and the default pitch limit 10 degrees below its default value is 12 m7 LookAhead L The depth control look ahead parameter l is input in m By default if there is only one Hull component l is set to 2 otherwise a warning pause message is issued with the option to zero l PhaseLead Q depth 7 depth The depth phase lead controller parameters default to Q depth 3 0 T depth 2 0 PID k1 depth 2 depth ZP depth KT depth XD depth The depth PID controller parameters default to k depth 0 5 k depth 1 0 Kp depthh 1 2 Ky depth 0 0 Kp depth 0 3 PitchLimit 6 Depth control pitch limit 0z is in degrees and should be po
87. gain autopilot error gain flooding coefficient of discharge center of gravity vector axial and normal force coefficients junction axial force coefficient appendage zero lift axial force coefficient appendage induced drag axial force coefficient appendage linear normal force coefficient appendage nonlinear crossflow drag normal force coefficient DRDC Atlantic TM 2006 252 105 h h hmin hmar AIE EAN Jc JE Js k k k2 kr kwB k kg K M N Kp Kr Kp MBTe MBV 106 hull residual drag coefficient diameter of WTC flooding breach diameter maximum hull diameter propeller diameter appendage camber hydrodynamic load vector hull station camber total endplate height or integration timestep endplate height from attachment lower and upper limits of timestep h inertial matrix moments and cross products of inertia autopilot control signal autopilot error signal advance coefficient based on vehicle speed out of plane load distribution parameter PID autopilot error damping equation coefficients hull roughness allowance tailplane efficiency for a control deflection appendage flap profile drag appendage anhedral factor roll pitch and yaw moment PID autopilot coefficients propulsor thrust coefficient propulsor torque coefficient tailplane efficiency for incidence reference length for nondimensionalizing typically LBP depth autopilot lookahead distance hull length length of WTC mass initial mass flow r
88. h degrees azimuth on the compass g N North NbyE NbyW compass heading See annex B for the valid keywords they may not be abbreviated for input h North value East N value W etc compass quadrant heading in degrees The keywords may not be abbreviated for input Note that DSSP21 outputs current heading in the range 180 lt w lt 180 if quater nions are used to represent the Euler angles section 22 3 but heading is unbounded otherwise Compass heading is always output in the range 0 to 360 degrees The following examples illustrate commanded subscript c heading resulting from the various input formats It is assumed that the initial compass heading in the manoeuver was East and that the current heading y is 20 degrees i e a compass heading of 110 degrees Format Argument String We Compass a 25 25 00 65 00 b 2 Points 42 50 132 50 Cc 15 Port 5 00 95 00 d 3 Points Port 13 75 76 25 e 25 Relative 5 00 85 00 f 25 Azimuth 115 00 335 00 g NWbyW 146 25 303 75 h S40E 50 00 140 00 While a great deal of flexibility is provided in these options it should be obvious that mixing commands based on current heading and compass heading in the same input file is a potential source of confusion users should exercise due care The compass heading and the current heading default to zero Therefore for the purpose of inputting a specific initial heading formats a e
89. h tank The connections are modeled in the program by associations between BGs and MBTs Associations are set up by assigning a type to the components or are otherwise estab lished by default Although only one BG of each type is usually necessary to charac terize a ballast system DSSP21 allows more that one BG of each type The rules for association are e a BG of type Main is associated with all MBTs e a BG of type Forward or Aft is associated with all tanks of the same type and e remaining BGs are paired off with remaining MBTs in the order in which they are specified on the Root geo file Gate Valve Check Valve Nozzle ey MBTI BG1 gt lt _ MBT2 NG 7 gt lt BG2 A MBT3 BG3 Figure 8 Schematic of connections between three bottle groups and three ballast tanks BG1 can blow MBT1 and MBT2 individually or together BG2 can blow any of the three tanks individually or together and BG3 can blow only MBT3 44 DRDC Atlantic TM 2006 252 For example the connections of figure 8 can be established by giving BG1 MBT1 and MBT2 type Forward giving BG2 type Main and giving BG3 and MBT3 type Aft Blowing a tank with more than one BG is computationally inefficient in the current blowing model If the simulation consists of a single blow of this type combining the BGs to be used into a single source of the
90. icle axes of the centroid of the MBT In the present build changes of mass resulting from a blow are assumed to occur at this point MassFlow MBTe This record is mandatory It defines the initial blowing mass flow rate of air into the MBT in kg s At typical HP air pressures this quantity is determined by the nozzle that releases air into the tank Vent MBV This record defines the venting mass flow rate of air from the MBT in kg s The rate is constant for the duration of the simulation independent of depth In the absence of this record mpy 0 no venting Volume Ver This record is mandatory It defines the blowable volume of the MBT Var in m 12 Root geo Level 2 WTC Input There can be up to eight watertight compartments WTCs defined in the vehicle they are required for modeling a flood during a Free simulation Each watertight compartment is announced by a WTC record and defined by subsequent level 2 input A WTC is assumed to be a circular cylinder defined by diameter length the location of its center and occupancy the fraction of its volume that is already occupied and therefore not available for flooding The moment due to floodwater is estimated as a function of both flooded volume and pitch angle The following table summarizes WTC level 2 input Keyword Function Diameter set WTC diameter Label WTC label Length set MBT length Location set location of WTC center point Occupancy set WTC occ
91. ies and as a benchmark for further development 86 DRDC Atlantic TM 2006 252 References For proprietary and other reasons references denoted Limited Distribution or Private Communication are not for public release 10 11 Mackay M 1999 DSSP20 Beta Edition User Guide to the Preprocessing Modules DREA TM 1999 108 Defence Research Establishment Atlantic Mackay M 1999 DSSP20 Beta Edition User Guide to the Simulation Mod ules DREA TM 1999 109 Defence Research Establishment Atlantic Mackay M 1995 Estimation of the Force due to a Submarine Sail or Similar Appendage In Third Canadian Marine Hydrodynamics and Structures Confer ence Halifax Technical University of Nova Scotia Mackay M 1995 A Review of Semiempirical Methods for Predicting Appendage Forces DREA Report 95 102 Defence Research Establishment Atlantic Lim ited Distribution Mackay M 2003 The Standard Submarine Model A Survey of Static Hy drodynamic Experiments and Semiempirical Predictions DRDC Atlantic TR 2003 079 Defence R amp D Canada Atlantic Watt G D 1988 Estimates for the Added Mass of a Multi Component Deeply Submerged Vehicle Part I Theory and program Description DREA TM 88 213 Defence Research Establishment Atlantic Watt G D 1998 Estimating Underwater Vehicle Stability and Control Deriv atives using ESAM and a Preliminary version of DSSP20 DREA TM 98
92. in and axes angles of rotation from vehicle axes in order in degrees must follow as triplets of real numbers on a two record data block To Yo Zo Yo Oo Qo 4 6 Autopilot Records AutoDepth AutoHead AutoProp and AutoRoll AutoDepth keyword AutoHead keyword AutoProp keyword AutoRoll keyword There are four autopilots available for manoeuvering simulations in DSSP21 for depth heading propulsion and roll They are provided primarily to sim plify the task for the user for example to automatically maintain depth dur ing a turn The records listed above announce input of parameters for the appropriate autopilot The optional keyword argument indicates a default au topilot type see the discussion in section 10 it can be PhaseLead or PID In the absence of this argument the depth heading and roll autopilots default to PhaseLead and the propulsion autopilot to PID Optional level 2 input records that follow are described in section 10 Use of the autopilots in a simulation is described in section 22 4 4 7 HPAir MBT and WTC Records Up to nine HPAir bottle group eight MBT and eight WTC components can be defined HPAir Announces a new bottle group component The level 2 HPAir input records are described in section 11 DRDC Atlantic TM 2006 252 15 MBT WTC Announces a new main ballast tank component The level 2 MBT input records are described in section 11 Announces a new watertight compartment compone
93. input explicitly 38 DRDC Atlantic TM 2006 252 Open PoD Rho TRatio Ukt Ums Forces the open water condition of wake fraction and thrust deduction equal to zero and may be appropriate for using WageningB propellers in the old twin screw submarine arrangement The default is to estimate wake fraction and thrust deduction for propellers in the wake of a coaxial hull Pp Dp This record overrides the default estimate of optimum pitch diameter ratio for WageningB propellers It should be within the range 0 6 gt Pp Dp gt 1 4 If it is input or calculated in the range 0 5 gt Pp Dp gt 0 6 it is simply reset to 0 6 If Pp Dp lt 0 5 or 1 4 lt Pp Dp the user is given the option to continue using the limiting value 0 6 or 1 4 respectively otherwise the program is terminated p This record overrides the fluid density default value of 1000 kg m for WageningB propeller initialization i e it does not permanently reset p The argument should be in the range 990 lt p lt 1035 T i 1 For initializing multiple WageningB propellers the ratio T of thrust devel oped by each one to the total thrust can be specified There must be one value of T for each propeller They will be normalized by their total gt T and so can be in a convenient form such as estimated thrust values or percentages If this record is absent T defaults to the disk area of the i propeller so that each one is nominally equally load
94. ions of multiple indirect commands are allowed Command conflicts are discussed in section 14 5 14 1 Direct Deflection Input The command is directed at a specific appendage Delta label string or Nz or keyword If the second argument is 6 a control deflection of 6 degrees in local coordinates is applied to the lifting appendage identified by the label string or by the integer Nr Attention must be given to sign because of the local coordinate convention section 3 4 For example to deflect horizontal sternplanes to generate upward force the starboard plane requires positive while the port plane requires negative 6 Alternatively the second argument to Delta can be a keyword specifically one of Clear Reset or Zero Clear the control surface is returned to its initial deflection and control flags are cleared The primary use of this command is to cancel indirect input Unlike Reset below Clear can be combined with another control deflection command regardless of order Clear is executed first then the other command Reset the control surface is returned to its initial deflection and control flags are cleared Reset cannot be combined with another control deflection command Zero the control surface is set at zero deflection and control flags are cleared Zero cannot be combined with another control deflection command 14 2 Quasi Direct Deflection Input The command is applied to one or more appendage types that a
95. is not Argument r is the mid root hull radius r gt 0 Rudder r rm The appendage is defined as a rudder Argument r is the mid root hull radius r gt 0 Optional argument rm is maximum hull radius required for Dempsey s calculation of tailplane efficiency 18 by default ry r Tailplane efficiency is specified with a TailEff record Sail r The appendage is defined as a sail Argument r is the mid root hull radius r gt 0 Sailplane T Dsp exp bexp The appendage is defined as a sailplane both arguments are mandatory Argu ment r is the mid root to sail centerline distance about half the sail thickness r gt 0 Parameters bsp exp and bezp are exposed sailplane height i e above the sail root and exposed sail span see figure 5 The permitted range of the argument is 0 0 lt bsp exp bezp lt 1 0 SBowplane r o The appendage is defined as a small bowplane Argument r is the mid root hull radius r gt 0 Optional argument is the dihedral or anhedral angle sign is immaterial with respect to the hull tangent in degrees The default value of is 0 and its permitted range is 90 lt lt 90 28 DRDC Atlantic TM 2006 252 ShipStab r ae The appendage is defined as a ship stabilizer Argument r is the local hull radius r gt 0 Optional argument x is downstream distance between the origin of the hull boundary layer typically near the forwardmost point of the hull and the origin o
96. iterated For a parameter Q the syntax of this record is Loop Argument s Q From QTo AQ where numerical values QFrom and QT are the limits between which parameter Q is to be iterated and AQ is the increment for iteration A single first argument which must be one of Alfa Alpha Beta P Q R U Ukt Ums V or W identifies parameter Q However if the first argument is Del or Delta an additional argument is required a label string or integer index for a direct command or an appropriate keyword for a quasi direct or indirect command as described in sections 14 1 to 14 3 The following are examples of valid Loop records Loop Beta 30 30 2 Loop Delta Up 10 10 5 Loop del 3 10 15 2 5 Loop ukt 0 5 5 0 5 loop q 1 2 loop r 6 12 2 The increment has been omitted from the penultimate example this results in the loop executing just the Q From and Qro values If QFrom and QT are inconsistent with the sign of AQ they are interchanged so the last example above will be executed as if it were loop r 12 6 2 QTo Q From need not be an integer multiple of the increment The number of increments is set to most closely approach Qro on the final iteration A loop takes on the characteristics of parameter Q in particular whether Q is a direct or indirect state variable For example if Q is r 1 e R direct speed must be defined 66 DRDC Atlantic TM 2006 252 by a U record whereas if Q is a Alpha indirect sp
97. lculation For example small time steps when blowing a ballast tank from more than one bottle group may slow the calculation by nearly an order of magnitude One way to alleviate the problem is to increase minimum step size and tolerance in the integration so long as convergence tests show that an acceptable level of precision is maintained Initially the vehicle is moving in a horizontal straight line parallel with the earth fixed zo axis section 3 4 in level trim and neutrally buoyant initial depth and speed are defined by the user These conditions are maintained until a command is given that causes them to change The 20 yo z0 axes can be equivalenced to an initial compass heading and chart axis location In the current build of the program compass heading is optionally used for autopilot control and chart location is not required at all however both are output In future builds they might be used for relating manoeuvers to a specific bottom topog raphy a current field etc Free input at level 2 in Root sim consists of initialization records which provide data for defining or initializing various run and vehicle parameters and command records DRDC Atlantic TM 2006 252 75 which specify a control action to take place during the simulation Command records are sorted into bundles of one or more simultaneous commands Time integration from one command bundle to the next is called a sprint The simulation is terminated whe
98. le some of the options in this section are presently redundant they may be required in a compass heading description of the trajectory for future developments It may be useful to refer to figure 2 Heading angle increases in a turn to starboard Within DSSP21 instantaneous heading is the azimuthal angle w relative to the initial heading i e Ye 0 In a free manoeuver this is tabulated on simnnn txt together with the equivalent compass heading based on an initial compass heading input by the user section 22 2 By default this initial heading is zero degrees or North Commanded heading can be defined in either system Heading input comprises a string of up to three words that are treated as a single argument in the commands that start the heading autopilot or set the initial compass heading DRDC Atlantic TM 2006 252 57 For a heading autopilot command neither the current heading w nor the initial com pass heading is necessarily zero The commanded heading is then evaluated from the argument string as follows where value is numerical value azimuthal degrees relative to the initial reference value Points azimuthal angle in points relative to the current heading value Port Stbd Starboard degrees to port or starboard of the current heading aaow value Points Port Stbd Starboard points to port or starboard of the current heading value Relative degrees relative to the current heading f value Azimut
99. limits P set state variable p Pop force termination of input see section 5 4 Q set state variable q R set state variable r Reference redefine reference origin and axes Rho redefine fluid density Text output run information or other descriptive text U set state variable u Ukt set total velocity in kt Ums set total velocity in m s V set state variable v W set state variable w WeightDCI reset indirect control deflection weights Alfa and Alpha are synonyms 19 1 Direct State Variable Records Del Delta P Q R U V and W Del Delta arguments see section 14 Any of the direct quasi direct indirect or global Delta arguments discussed in section 14 can be used on this record Multiple Del records can be present so long as a command conflict section 14 5 is avoided 64 DRDC Atlantic TM 2006 252 Delta 19 2 Alfa Alpha Beta Delta arguments see section 14 As Del above P The mandatory argument is roll rate in deg s The default is zero q The mandatory argument is pitch rate in deg s The default is zero r The mandatory argument is yaw rate in deg s The default is zero U The mandatory argument is axial velocity surge in m s A U record must be present for direct translational input on the other hand one cannot appear in the same Static run as indirect translational input section 19 2 v The mandatory argument is lateral velocity sway in m s The default is zero A
100. ll The roll phase lead controller parameters default to the same values as for depth control section 10 1 PID ky roll gt ko roll Kp roll gt Kr roll Kp roll The roll PID controller parameters default to the same values as for depth control section 10 1 11 Root geo Level 2 HPAir and MBT Input The blowing model in DSSP21 allows representation of a number of typical water ballast system configurations There can be up to nine HP air bottle groups BGs and eight main ballast tanks MBTs in the system Figure 8 illustrates an arrangement of three BGs and three MBTs in which one of the BGs is dedicated to a single MBT one can DRDC Atlantic TM 2006 252 43 be used with two of them and the third can be used with any of the three Isolation of the HP air sources from each other by check valves as shown in the figure is assumed similar arrangement to figure 8 is found in some submarine systems that employ a main HP blowing source which in the figure would be BG2 with additional augmen tation or emergency sources BG1 and BG3 In some cases tanks can only be blown together for example if MBT1 and MBT2 were connected to BG1 with a single gate valve instead of separate ones In DSSP21 this distinction is not made in the definition of the components but can be made with Blow commands section 16 Small UUVs typically have simpler systems comprising either a single source or an individual source integrated with eac
101. lopments such as defining density as a spatial variable In chart axes the target initial position and heading are defined by Origin and Heading records section 22 2 as illustrated in figure 2 Target coordinates x7 yr zr in chart axes are output on files Root spr and auxnnn txt the latter also tabulates target translational velocities ur vr and wr in reference axes Heading Target Os Xp Y r2r Trajectory Ye Figure 2 The target trajectory xo yo Zo axes and reference axes x y z relative to the chart axis system 3 5 Applicability of the Program It is implicit in many algorithms used in the current version of DSSP21 that the vehicle is streamined and at moderate incidence i e the vehicle components are reasonably slender and have their hydrodynamic axis the longitudinal axis of a hull or the chordline of a lifting appendage oriented more or less in the direction of motion or against the direction of incident flow The program cannot model bluff or irregular underwater vehicles such as ROVs but can model submarines many UUVs and towfish 10 DRDC Atlantic TM 2006 252 Vehicle geometry is currently described by up to two hull components and up to twelve lifting appendages there can be up to three propulsors 4 Root geo Level 1 Input Root geo input defines component geometry in simple terms e g hull breadth and height Since vehicle components are input independently interference calcula
102. lt values assigned by the code These include coefficients for junction drag Cx and zero lift drag Cx a flap gap correction 7 flap profile drag ks and tailplane efficiency Kwa kwe appendage local axes C4 C2 Vehicle Axes X Ca y zY y Figure 4 Appendage definition nomenclature 24 DRDC Atlantic TM 2006 252 Figure 5 Hull sail input nomenclature a non axisymmetric hull b equivalent axisymmetric hull and c sailplane location Figure 6 Endplate input nomenclature DRDC Atlantic TM 2006 252 25 HINGELINE Figure 7 Flapped appendage input nomenclature The following table summarizes the keyword records used to characterize lifting ap pendages Keyword AllMoving Camber CXJ CXZero DelNonLin DelRateLim Del Delta DeltaDyn DeltaLim FlapGap Flapped 26 Function define control type as All Moving apply geometric camber define junction axial force coefficient define zero lift axial force coefficient enable nonlinear flap calculation set control deflection rate limit set initial control deflection set initial control deflection set control dynamic parameters set control deflection limits define flap balance and gap correction define control type as Flapped DRDC Atlantic TM 2006 252 FlaProDrag HasEndP IsEndP Kill Label LBowplane Planform Pop Reflected Rotated Rudder Sail Sailplane Save SBowplane ShipStab
103. n 200 3 4 Pressure Volume HPair Label BGThree Aft Pressure 300 Volume 1 1 DRDC Atlantic TM 2006 252 Stbd plane reflected Use default VRML Force k 1 Propulsor hub on hull axis Redundant Handed is ignored Hull diameter for prop initialization have not been optimized for this case Lz L 1 deg 1 m s figs 8 and 15 in the user guide 101 MBT MBT MBT WTC 102 Label TankOne Fwd Location 4 0 0 1 2 Volume 70 0 MassFlow 14 0 Vent 10 0 Label TankTwo Fwd Location 8 0 0 1 0 Volume 50 0 MassFlow 12 0 Vent 6 0 Label TankThree Aft Location 58 5 0 0 8 Volume 48 MassFlow 11 2 Vent 6 0 Only one input Label MidCompartment Diameter 7 72 Length 23 8 Location 32 3 0 0 Occupancy 0 22 DRDC Atlantic TM 2006 252 Annex E Example Root sim Input File This is not a typical input file it is somewhat more elaborate than usual in order to illustrate various input options For housekeeping purposes it is preferable not to mix so many run types on a single input file Free Sim 1 Text 15 15 zigzag with manual depth control using sailplanes Text target is 1 m over the duration of the sim Both Text depth control and rudder timing found by trial and error Rho 1025 2 Depth 100 Ukt 10 0 Del 16 Del 50 del 50 del 55 Del 80 del 80 del 96 Del 105 del 105 del 137 Stop Static port 15 port 15 6 8 7 8 port 15 6 4 7 4 port
104. n J D and Oosterveld M W C 1969 The Wageningen B Screw Series SNAME Transactions Vol 77 New York Society of Naval Architects and Marine Engineers Kennedy J L 1998 Private Communication Defence R amp D Canada Atlantic Hoerner S F 1958 Fluid Dynamic Drag Midland Park NJ published by the author Dempsey E M 1977 Static Stability Characteristics of a Systematic Series of Stern Control Surfaces on a Body of Revolution DTNSRDC Report 77 0085 David Taylor Naval Ship Research and Development Center Mackay M Bohlmann H J and Watt G D 2002 Modeling Submarine Tailplane Efficiency In Challenges in Dynamics System Identification Control and Handling Qualities for Land Air Sea and Space Vehicles RTO MP 095 Paris NATO RTO Mackay M 2004 A Review of Submarine Out of Plane Normal Force and Pitching Moment DRDC Atlantic TM 2004 135 Defence R amp D Canada Atlantic El Hawary M E 1984 Control System Engineering Reston VA Reston Pub lishing Mackay M 1996 Submarine Turning Circle Experiments in a Towing Tank In RINA Warship 96 Symposium Naval Submarines 5 London Royal Institution of Naval Architects Mackay M 2001 Some Effects of Tailplane Efficiency on Submarine Stability and Manoeuvering DRDC Atlantic TM 2001 031 Defence R amp D Canada Atlantic Gertler M and Hagen G R 1967 Standard Equations of Motion for Subma rine Simulation NSRDC
105. n the last sprint is complete Null commands Start and Stop are provided to start and stop the simulation without any control action clearly stopping with a control action is unproductive since the action will not have any effect Initialization records are executed as they are encountered and have the typical form keyword argument s whereas command records are distinguished by having a floating point numerical value time as the first word in the record time keyword argument s and are executed at the indicated time during the simulation They currently specify control deflections changes in propulsor RPM autopilot control ballast blowing or venting and compartment flooding An error in a command record may not be flagged by the program until the sprint including the command is executed The same keyword may have somewhat different interpretations in an initialization record and in a command record because the context is different For example as we shall see in sections 22 1 and 22 4 Delta UpperRudder 2 initializes the appendage named UpperRudder at a setting of 2 0 degrees before the simulation is started whereas 100 0 Delta UpperRudder 2 commands the appendage to commence deflecting to an angle of 2 0 degrees at time t 100 s during the simulation The order of initialization records is significant in one case WeightDCI records should precede indirect Delta initialization as was noted in section 19
106. nd should be positive Based on a rough estimate of power required for a small submarine at about 1 kt its default value is 0 12 W RevConGain CC prop Propulsion revolutions control gain Cc prop is in RPM and should be positive Based on a speed of about 1 kt its default value is 12 RPM 42 DRDC Atlantic TM 2006 252 ThrErrGain Cg prop thrust Thrust error gain CG prop thrust 18 in N 1 2 and should be positive Based on a rough estimate of thrust required for a small submarine at about 1 kt its default value is 0 0375 N 2 UktErrGain C E prop speed The UktErrGain record is used to input the speed error gain CG prop speed in kt the value should be positive Its default value is 1 kt UmsErrGain C E prop speed The UmsErrGain record is used to input the speed error gain CC prop speed in m s the value should be positive Its default value is 1 0 514 m s i e 1 kt 10 4 AutoRoll Level 2 Records RolConGain RolErrGain PhaseLead and PID RolConGain Ce roll Roll control gain Cc ron is in degrees and should be positive Since the commanded deflection depends on appendage dihedral and control weight WIR sections 6 4 and 14 3 this parameter can exceed the maximum deflection on an appendage Its default value is 20 degrees RolErrGain Cg rol Roll error gain Cc ron is in degrees and should be positive Its default value is 0 05 degrees PhaseLead Q roll gt T ro
107. ndimensional geometric section camber f The argument is mandatory and is positive in the direction of increasing z in the local appendage axis system Cx This record overrides the default value of 0 0 for the junction axial force co efficient C x i e junction drag The argument is mandatory and must not be positive Cxo This record overrides the default value of 0 01 for the zero lift axial force coefficient C xo which is nondimensionalized with respect to appendage area The argument is mandatory and must not be positive label string This record provides a user defined component label consisting of or followed by up to 24 alphabetic characters case is ignored If there is no Label record the default label is LIFTnnn where nnn is the number of this lifting appendage as encountered in the input file keyword or Kwe kw This record controls estimation of the tailplane efficiency associated with a vehicle at incidence Kwg and the tailplane efficiency associated with a control deflection kwp The argument is a keyword Bohlmann or Dempsey or one or two numerical values For all tailplane appendages Rudder Sternplane Tail Bohlmann Spreiter calculations 19 are done for inviscid flow and the resulting efficiency ratio kwe Kwe is saved If the keyword argument is Bohlmann or if the TailEff record is absent al together the efficiency ratio is ignored and viscous Bohlmann Spreiter cal
108. ne or more delimiters and a string of any characters in the DSSP21 character set On output case in a Text string is preserved A label string uniquely identifies a vehicle component It consists of 1 to 24 alphabetic characters preceded by a label character or Labels are useful for clarifying the object of control commands and may be defined by the user they default to HULLO01 LIFTOO1 PROPOO1 etc Labels are not case sensitive Numerical values are also parsed An integer input can have no more than 20 characters and is read right justifed in Fortran 120 format A floating point input can have no more than 30 characters Initially it is read right justified in 130 format and converted to a double precision variable if that fails it is re read in F30 0 format into a double precision variable Blank lines in input are ignored and purely comment lines should start with an EOR character otherwise the parser will try to interpret the first delimited string as a keyword The following are typical input records that illustrate a number of the concepts intro duced above They were picked arbitrarily and do not represent a continuous segment of data input Text Model UT at nominal full scale HELP Reference 1 26 2 0 0 1 2 This is a data block 0 0 0 1C3 rho 1025 This is a comment Label XRudderSevenThirty Labels are optional PReverse 49 8 5e0 7d0 Interpl 5 TypeOne WeightDCI 7 00
109. nent The argument is mandatory and has a permitted range of 4 lt L Dm lt 16 22 DRDC Atlantic TM 2006 252 ResiDragR Caf or keyword Defines a hull residual drag coefficient Caf or the method for its estima tion The two methods available are the semiempirical expression given by Hoerner 17 for bodies of rotation keyword Hoerner or a fit to data for torpedo like bodies keyword Torpedo If the numerical argument is given then it is required that 0 lt Cay lt 0 5 The default for hull residual drag is calculation by Hoerner s method RoughAllow kr Defines a coefficient k for the hull roughness allowance in hull drag By default ky 0 0004 the user input value must be 0 lt kp lt 0 001 Source keyword The HulFoM default hull load calculations use lookup tables derived from model test data There are two sets of tables in the present build one derived from Kriging interpolation the other from neural network generalization they are discussed in reference 12 The keyword argument indicates which to select Kriging or NeuralNet The default is Kriging 5 4 Pop The Pop record forces termination of level 2 input completing processing of the current component and returning to level 1 an instance in which the order of input records is important Normally an unrecognized keyword or the end of file triggers this sequence but the proliferation of keywords with program development may make this difficult in
110. ng System Significance DSSP21 is still in development However the current edition of the code is being frozen and documented at this time since it is a useful tool which has already found application The documentation will be updated as further progress with development is made Although input to the program initially appears complex because of a large number of options defaults are provided that allow most vehicle types and manoeuvers to be defined with relatively few parameters This user guide is primarily intended to facilitate preparation of the input which comprises a definition of the vehicle and its systems and definition of the hydrodynamic and manoeuvering simulations to be done The latter include calculation of static and dynamic loads on a captive vehicle hydrodynamic coefficient generation and free vehicle manoeuvers The guide is intended for both experienced and new users Future Development Additional capabilities to be incorporated into future editions of DSSP21 include com pensation and trim and automatic generation of Manoeuvering Limitation Diagram curves In the longer term a hybrid calculation mode may be developed to take best advantage of available experimental data and CFD analysis M Mackay 2006 DSSP21 Build 061102 User Guide DRDC Atlantic TM 2006 252 Defence R amp D Canada Atlantic DRDC Atlantic TM 2006 252 iil Sommaire Introduction La version 2 1 du programme de simulation sous ma
111. ng or Nz The argument identifies the lifting appendage which may be of any type to be used in the calculation with a label string or integer Nr 8 Root geo Level 2 Propulsor Input Propulsor types are discussed above in section 4 4 The input discussed in this section is applicable to all propulsor types DSSPtwo STRprop and WageningB DRDC Atlantic TM 2006 252 35 The following table summarizes the keyword records used to characterize a generalized propulsor Keyword Function Diameter define propulsor diameter Label propulsor label Left left handed propulsor Location define propulsor local origin Pitch define local axis pitch Pop force termination of input see section 5 4 Reflected copy saved propulsor by reflecting RevDynam set RPM dynamic parameters RevLimit set maximum RPM RevRateLim set RPM change rate limit Right right handed propulsor Save save this propulsor for subsequent copy Yaw define local axis yaw The Label definition is analogous to that of other components If there is no Label record the default label is PROPnnn where nnn is the number of this propulsor as encountered in the input file 8 1 Propulsor Geometry Records Diameter Location Pitch and Yaw Diameter is self explanatory keywords Location Pitch and Yaw define via the propul sor s location and orientation the origin and orientation of its thrust and torque vectors The distinction between a propulsor s physical location an
112. nt DRDC Atlantic TM 2006 252 17 Nose define nose point Pitch define rotation in pitch Pop force termination of input for this component ResiDragR define hull residual drag coefficient or method of calculation Roll define rotation in roll RoughAllow define hull roughness allowance Source identify the data source for HulFoM load estimates Station station data block to follow Tail define tail point Yaw define rotation in yaw A keyword record other than one of these will terminate input for the current component After processing level 2 data is completed the input stream is backspaced and the new record is re read at level 1 The records are discussed below in terms of the functional group that they belong to 5 1 Diameter and Station Records These records and the data blocks that follow are alternative ways of defining hull section geometry Diameter Ns Station 18 Announces a data block of axial hull diameters at Ns equally spaced stations Ns lt 51 from nose to tail By default Ns 21 The data comprise three values of breadth B per record apart from the last which may have fewer values The format is B Bo B3 B Bs etc In generating the hull geometry T B and A rB 4 where T is height and A is cross section area If the number of stations for calculation Ng optionally specified on the Hull record is not equal to Ng the Diameter data will be interpolated Note in tha
113. nt The level 2 WIC input records are described in section 12 4 8 Other Records Help Plot and Text Help Plot Text When a Help record is encountered help text is sent to Root log and the program is stopped The help text is intended to be a quick reference for the user if this guide is not readily available its principal components are dictionary listings and a user input summary rose Announces level 2 geometry plotting information as described in section 13 Without this record the plot file Root gpl is not generated The optional argument ryjew determines the viewing distance for initially rendering VRML images in some viewing software in the present build it is ignored for other plotting formats By default ryiew is the length of the hull if there is only one otherwise it is zero text string This record comprises a string of up to 64 characters preceded by the keyword Text and one or more delimiters The string is not parsed and may therefore contain any character including delimiters and EOR characters The function of a Text record is to provide title and other information for the run Each one is output to Root gpr as it is encountered and the first ten Text records are saved as heading information for the simulation phase of program execution 5 Root geo Level 2 Hull Input The nomenclature used to define basic hull component geometry is illustrated in figure 3 A hull is defined at a series of stations
114. ollowing table summarizes the keyword records used in O00PCalc level 2 input Keyword Function Hull identify the hull component KParam define nonlinearity of the load distribution Lambda define the extent of the hull bound vortex Lift identify the lift component Pop force termination of input see section 5 4 Of these records only Lift is always mandatory 7 1 Hull KParam Lambda and Lift Records Hull KParam Lambda Lift label string or Ny The argument identifies the hull to be used in the calculation with a label string or integer Ny If this record is omitted the nearest hull is used k The form of the out of plane load distribution suggested in reference 20 con sists of a linear ramp function raised to the power m where m 1 k G to account for nonlinearity 6e is the sail angle of incidence in radians Reference 20 illustrates a number of submarine configurations for which 2 lt k lt 3 By default k 0 representing a linear load distribution A 2 The arguments define the extent of the hull bound vortex over which the out of plane load is distributed At the forwardmost extent 0 which corresponds to the sail trailing edge and at the aftmost Az 1 which cor responds to the hull AP It is required that 0 lt A lt Ag lt 1 By default A 0 and 2 1 It is concluded in reference 20 that there is at present little data to justify changing these values label stri
115. on or conditioning problem will occur have not been fully identified and some experimentation with these parameters will be re quired if the error is encountered m The argument m in kg replaces the default model mass estimated by a neutral buoyancy calculation Mass represented by m is independent of the density p used elsewhere in the program MomInertia NoHStat 74 This record is followed by a one or two record data block containing moments of inertia Izz lyy zz and optionally cross products of inertia Izy Izz Iyz all in kg m that will replace the default model values estimated from neutral buoyancy and uniform model density The data block format is Dyes dE May Lez Tye If the record containing cross products is omitted they are set to zero Input values of all these quantities are independent of the density p used elsewhere in the program They are assumed to be consistent with the reference origin specified for the simulation By default hydrostatic loads e g W B sing cos in the Y equation of motion 24 are included in a Captive simulation They are omitted if this record is present DRDC Atlantic TM 2006 252 PQRtol ew This record overrides the default tolerance used to check for consistency be tween p q r time histories and the values estimated from Euler angle time histories The default value of is 0 01 which the program interprets as deg s to compare angular velocities and
116. oped in the mid 1990s as a universal modeling standard While it did not reach that status it is still supported by a number of rendering programs and web browser plug ins many of which are free ware although some require licensing for certain types of commercial use The example screen shots shown in figures 13 and 14 were pro duced with the free ModelPress Reader Informative Graphics Corporation http www modelpress com A useful feature of this program for checking geometry is the ability to easily display the distance between nodes panel corner points on the model figure 13 68 0000 m 9 7212 m Figure 13 ModelPress Reader screen shot produced with VRML 1 output from the 52 example input in annex D illustrating shaded rendering with measurements DRDC Atlantic TM 2006 252 Figure 14 ModelPress Reader screen shot produced with VRML 1 output from the example input in annex D illustrating hidden line wire frame rendering on the default black background Panels are subdivided into triangles for the shading option in the Reader 14 Root sim Control Deflection Commands Control deflections are commanded in Root sim by the keyword Delta or its synonym Del They may also be controlled by one or more autopilots as described in section 10 Internally the program handles each control appendage as an independent entity this is different from the way that the operator commands deflection of the rudders stern
117. opilot commands update autopilot error and control signals process autopilot command records interpret Blow commands DRDC Atlantic TM 2006 252 95 BLOWVENT COEF D COMAND D_ABCD DYDT FLOOD FLUDCOM HEADFIND SPCOUT SPRINT STABILITY TIMHXN VENTCOM update BG and MBT data during a ballast blow or vent hydrodynamic coefficient calculation with the DERIVS method process free simulation command records three four point coefficient evaluation for COEF_D define the extended equations of motion F u t update WTC data during a flood interpret Flood commands process heading argument strings output free simulation to simnnn txt and auxnnn txt execute a free simulation sprint small perturbation stability analysis estimate loads for a captive time history interpret Vent commands Sp21subs for general subroutines Unit ADDMGEN ADDMMAT CANINC CANMOX CANMOZ CANVOL CFTURB CFWET DELASSOC DELCOM DELFIND DELLIM DYNAMV FLUDCG HULL_LOOK HYDRST INRTMAT IWEIGHTS KTKQO2 KTKQST KTKQWB NLOCGO NREFGO OOPGRADE 96 Function generate component added masses setup added mass matrix in reference axes calculate floodwater volume and centroid function for floodwater longitudinal moment function for floodwater vertical moment function for floodwater volume turbulent flow friction drag coefficient estimate hull friction drag set up control appendage Delta command associations process Delta commands interpret Del
118. or each lifting appendage with the type Sail 4 4 Prop Propulsor and WagBlnit Records Up to three propulsors can be defined Prop is a synonym for Propulsor making it a keyword allows the common abbreviation Prop to be used without ambiguity Three different propulsor types listed below are currently implemented The WagBInit record and associated level 2 input are required to override defaults used for an initial opti mization of WageningB type propulsors Prop keyword Announces a new propulsor The argument indicates propulsor type If present it must be one of DSSPtwo STRprop or WageningB the default is WageningB Mixing propulsor types is not recommended in any case WageningB propulsors cannot be mixed with other types A type specifies the method of estimating propulsor thrust and torque coef ficients Kr and Kg In DSSP21 these coefficients are derived as functions of the advance ratio based on ship speed Js u nDp not incorporating the wake fraction The three methods are DSSPtwo This is a small main propulsor propeller model approximating the model used in DSSPO2 13 for the Oberon class i e an older twin screw sub marine arrangement The model is based on simple functions of the propulsion ratio n no where ng is self propulsion RPM It may not represent single screw propulsion particularly well since the propeller inflow conditions are different STRprop This specifies a large main propulsor
119. ordinate origin and 0 is the autopilot pitch limit In formulating Jg depth the full equation 6 is used by default although use of the depth or pitch contributions alone can be invoked during a manoeuvering simulation section 22 4 In all cases Jg is clipped at 1 There are two methods in DSSP21 for deriving the corresponding control signal Jo The first is a phase lead algorithm Jo lt Je rJe Je 7 where qa is the amplitude gain of the transformation and 7 is the anticipation time constant 21 After rearrangement equation 7 is solved as a first order ODE in the time integration The second method for deriving Jc is a PID Proportional Integral Derivative algo rithm Je KpJe K Jedt Kp je 8 where Kp Kr Kp are the PID coefficients To solve this in the time integration a lightly damped error signal J is used in the derivative term k Je ko Je JE 9 The control signal is then obtained from two first order ODEs using both the damping equation coefficients kj and k2 and the PID coefficients Jc is clipped at 1 and multiplied by a control gain C in appropriate units degrees for control deflections RPM for propulsion revolutions to determine the control correction Time histories of Jg and Jg for the various autopilots are tabulated in the auxiliary output file auxnnn txt 40 DRDC Atlantic TM 2006 252 Defaults are provided for all the parameters discussed above but optimizin
120. orm density is used as the basis for the estimates The resulting added mass and inertial matrices are output to Root gpr 4 2 BG CB and CG Records The centers of buoyancy and gravity CB xp yp 2B and CG zG ya za are defined in vehicle axes and the full vector form of the metacentric distance is expressed as BG CG CB However its normal component zga za zp is identified with the metacentric height BG and that since it acts as a hydrodynamic quantity in various calculations should be expressed in reference axes Hence BG is the only geometric quantity to require input in the reference rather than the vehicle axis system The three records are 12 DRDC Atlantic TM 2006 252 BG CB CG tac yga BG Defines the components of BG in reference axes A single argument is taken to be BG while the other two components default to zero Otherwise all three arguments must be present BG must not be negative If there is only one Hull component BG defaults to Dj 20 where Dm is maximum diameter of the hull See the discussion below on combining BG CB and CG records TB YB ZB Defines the three components of CB in vehicle axes Default values are derived from the form displacement TG YG ZG Defines the three components of CG in vehicle axes Default values are derived from the BG and CB defaults Locating CB and CG and thereby determining BG requires any two of the three reco
121. ot generate a geometry plot file Prop propulsor component input to follow Propulsor propulsor component input to follow Reference define reference origin and axes DRDC Atlantic TM 2006 252 11 Text title or other information WagBInit initialize Wageningen B propellers WTC WTC component input to follow Reference is required with no hull otherwise these records are optional and may in general appear in any order on the file One exception is that association between BGs and MBTs may be implied by the order of HPAir and MBT records section 11 In the record descriptions following and elsewhere in this guide optional arguments are enclosed in brackets 4 1 AddedMass and Inertial Records These records control the estimation in reference coordinates of added masses and added moments of inertia and of inertial properties such as mass and moments of inertia In each case there is at present only one method of calculation available these records provide placemarkers for possible future development AddedMass keyword The argument may be one of Esam or None Esam is the default If the argument is None the calculation is omitted otherwise components of the ESAM code 6 are used and portions of the internal ESAM dialogue are sent to Root log Inertial keyword The argument may be the one of Form or None Form is the default If the argument is None the calculation is omitted otherwise form displacement assuming unif
122. ot geo Level 2 Propulsor Input 35 8 1 Propulsor Geometry Records Diameter Location Pitch and Yaw 36 8 2 Propulsor Parameter Records Left RevLimit and Right 37 8 3 Propulsor Dynamics Records RevDynam and RevRateLim 37 8 4 Save Copy Records Reflected and Save 37 Root geo Level 2 WagBInit Input 38 9 1 Diameter Open PoD Rho TRatio Ukt and Ums Records 38 Root geo Level 2 Autopilot Input 39 10 1 AutoDepth Level 2 Records DepConGain DepErrGain LookAhead PhaseLead PID and PitchLimit Al 10 2 AutoHead Level 2 Records HedConGain HedErrGain PhaseLead and PID ric aee es ee 42 10 3 AutoProp Level 2 Records PhaseLead PID PwrErrGain RevConGain ThrErrGain UktErrGain and UmsErrGain 42 10 4 AutoRoll Level 2 Records RolConGain RolErrGain PhaseLead ehate KA EA i D ney RE Moe ie hae hs Sree as Nene A Shs antl 43 Root geo Level 2 HPAir and MBT Input 43 11 1 HPAir Level 2 Records Aft Forward Fwd Main Pressure and Volume isesi p an nn Sosa Re AS 46 11 2 MBT Level 2 Records Aft Forward Fwd Location MassFlow Vent anid Volume surtt teed adaware sewed 46 Root geo Level 2 WTC Input 47 12 1 WTC Level 2 Records Diam
123. point per record and must be in order root leading edge tip leading edge tip trailing edge and root trailing edge The planform data block format is therefore Te1 Yel Zel To2 Yc2 c2 Te3 Yc3 3 TA VYca cd DRDC Atlantic TM 2006 252 27 6 2 Type Records LBowplane Rudder Sail Sailplane SBowplane ShipStab Sternplane and Tail The keywords which define appendage type are LBowplane Rudder Sail Sailplane SBowplane ShipStab Sternplane and Tail Defining the appendage type ensures that appropriate interference corrections are made to the appendage forces and may have additional implications For example although interference corrections are identi cal for types Rudder Sternplane and Tail these types respond differently to control commands Only one appendage type record may be supplied for each lifting compo nent if no type is specified it is treated as an isolated appendage Appendage type records have at least one argument a parameter r that is used to estimate lift carry over For the general case of an appendage mounted on a hull and where local dihedral is minimal i e the appendage is more or less normal to the hull surface r is the hull radius at the appendage mid root LBowplane T The appendage is defined as a large bowplane Whether a bowplane is con sidered large or small depends on the ratio of its dimensions to the local hull radius 4 A small bowplane is corrected for dihedral below a large one
124. quired Changes from previously benchmarked editions of the code are summarized in annex A DSSP21 proceeds in two phases e Geometry and systems setup The user must provide a file defining the vehicle geometry and systems The data is extensively checked and as much preprocess ing of it done as possible This includes for example estimation of hydrodynamic interference effects inertial and added masses and moments and propulsor char acteristics e Hydrodynamic and manoeuvering simulations The simulations to be run are de fined in sequence on an optional input file Those currently implemented include static and dynamic loads on a captive vehicle hydrodynamic coefficient genera tion and free vehicle manoeuvering If the simulation input file is absent there is no work done in the second phase The principal objective in developing a multifunctional code was to base all calcula tions and simulations on a common set of hydrodynamic modeling subroutines The underlying hydrodynamic models are therefore consistent and improvements and en hancements to the models will be applied universally In the previous version of the code DSSP20 1 2 the same objective was achieved by distributing the different calcu lations and simulations between a number of individual programs which shared the core set of hydrodynamic subroutines It was subsequently concluded that certain overheads incurred by this scheme were not justified and that future
125. rds Providing one or none causes the program to resort to the defaults while providing all three will result in a fatal error if they are inconsistent 4 3 Hull Lift and OOPCalc Records Up to two Hull components and twelve Lift i e appendage components can be defined Hull Lift OOPCalc keyword Ns Announces a new hull component The first optional argument selects the method for calculating hull loads It may be HulFor indicating that the HulFor code 11 is to be used or it may be Default or HulFoM indicating that the empirical method of reference 12 is used to calculate translational loads and HulFor used to calculate rotational loads anything else is ignored The default is HulFoM The second argument Ns which is only read if the first is present and recognized is the number of hull stations to be used in the load calculation 11 lt Ng lt 51 By default Ns 21 which is sufficient for typical submarine hulls The level 2 hull input records are described in section 5 Announces a new lifting appendage component The level 2 appendage input records are described in section 6 keyword If the optional keyword argument is None this record suppresses all out of plane load calculations Otherwise it announces the specification for a new calculation according to the level 2 input records described in section 7 By DRDC Atlantic TM 2006 252 13 default an out of plane load calculation is done f
126. re individually associated with a direction of the resulting control force The notation used below indicates that the sign of an appendage deflection depends on that direction its magnitude is Delta keyword 6 The keyword is one of 54 DRDC Atlantic TM 2006 252 Bowplane appendages with type LBowplane and SBowplane are deflected by 6 to produce an upward force Foreplane appendages with type LBowplane SBowplane and Sailplane are de flected by 6 to produce an upward force Rudder appendages with type Rudder are deflected by to produce a force to starboard Sailplane appendages with type Sailplane are deflected by 6 to produce an upward force Sternplane appendages with type Sternplane are deflected by 0 to produce an upward force In this list the resultant force direction is indicated for positive 6 it will be opposite for negative 6 Quasi direct input is appropriate for a cruciform arrangement of the aft appendages and for horizontal foreplanes X rudders and other non cruciform arrangements should have the type Tail which does not respond to quasi direct deflections 14 3 Indirect Deflection Input Indirect commands affect all control appendages that can contribute to the vehicle response indicated by the keyword The magnitude of the deflection is weighted indi vidually for each appendage according to Wp Wrz Wrr introduced in section 6 4 and takes account of its anhe
127. requires a scaling length equivalent to LBP and the following message is generated for a vehicle with no hull components KTKQ02 Enter scaling length LBP The value entered must be positive In addition there are a few conditions that result in a warning with pause section 3 3 for which the user is asked whether or not to continue with program execution They mostly occur during geometry and systems setup in the first phase of execution 24 Output Files For the most part output from DSSP21 is self explanatory It is also too voluminous to illustrate here For error checking the Root 1log file echoes all input from Root geo and Root sim reports a number of intermediate calculation steps and outputs all error 84 DRDC Atlantic TM 2006 252 messages Most errors in input can be identified by comparing the error message and the last echoed line of input Those in a Free simulation command however will not be flagged until the command is executed While a Root geo file is being processed input data intermediate results and hydro dynamic and other characteristics are output to Root gpr The vehicle components and systems therefore appear in the same order as on the input file At the end there is a summary of propulsor initialization a table of overall vehicle properties tables of the added and inertial masses and moments of inertia if calculated and a table of autopilot parameters The level of detail in Root gpr has been
128. rine de RDDC DSSP21 a t d velopp e afin de pr voir la man uvrabilit des sous marins et de vaisseaux subaqua tiques plus petits Ce programme tend les capacit s de l ancien code Oberon qui avait t utilis pour tudier les r percussions sur la tactique et la s curit qu aurait toute modification apport e au sous marin ou aux proc dures d op ration Ces tudes ont port entre autres sur l op ration de r seaux remorqu s la perte de ballast le rem placement du d me sonar et la red finition des limites de plong e Le DSSP21 peut muler un grand ventail de vaisseaux et estimer leurs caract ristiques de man uvra bilit pour un vaste corpus d tudes de syst mes et d valuations et m me pour l tude pr liminaire La version ant rieure le DSSP20 a servi une tude syst matique des effets d un bouchon de coque p ex pour l alimentation sans air sur les man uvres et au d veloppement du Syst me de d minage t l command des FC Importance Le d veloppement du DSSP21 se poursuit Cependant la version actuelle du code a t fig e pour qu on puisse la documenter car il s agit d un outil pratique qui on a d j trouv des applications La documentation sera mise jour mesure que le d veloppement continuera de progresser M me si l entr e de donn es dans le programme peut sembler complexe prime abord cause du grand nombre d options le syst me offre des v
129. roots of cubic equation matrix decomposition by Gaussian elimination and partial pivoting initialize the component label array get the next word in the input stream convert the next word in the input stream to double precision convert the next word in the input stream to integer get vector from a double precision ring array write program information to Root log write Root geo and Root sim input summaries to Root log find dictionary keyword matching a character string insert vector into a double precision ring array find component label matching a character string interpolation of a single valued tabulated function lookup table bilinear interpolation error message manager distance from a point to a line open a file with status checks quadrature using piecewise cubics DRDC Atlantic TM 2006 252 97 PYTHAG QSFM SOLVE SVBKSB SVDCMP TIQUAD TOLABL UCCHAR WORDIN robust solution of va b fourth order quadrature for evenly spaced abscissae solve linear system of equations decomposed by DECOMP solve linear system of equations decomposed by SVDCMP matrix singular value decomposition SVD method return coefficients for a three point quadratic fit add an entry to the component label list character case conversion and filtering find a word within a character string In addition the following Include files are required to define common blocks and shared parameters Sp2laaaa Sp2iadel Sp2laioa Sp2laplt Sp2lia
130. s 21 Root sim Level 2 Captive Input The aim of a Captive simulation is to estimate the loads seen by an internal model balance during a captive forced motion experiment A file tabulating some combination of velocity Euler angle and control deflection time histories is required to define the motion but of these quantities only values of time and forward speed u are mandatory Rates of change of the tabulated data are estimated with a three point quadratic fit Since captive models are rarely exactly neutrally buoyant and furthermore may have an atypical mass distribution compared with free swimming vehicles the user can input model mass and moments of inertia rather than rely on the default estimates The time history file format is consistent with Free simulation simnnn txt output so a Captive simulation can be run after a Free one using the simnnn txt file previ ously created However unless the inertial properties of the model are changed or the hydrostatic loads are omitted this is not a particularly useful exercise since the result is only the propulsor equivalent loads seen by the notional balance together with some transients arising from imprecision in the estimation algorithms The principal purpose of the captive simulation option is to estimate loads for manoeuvers such as arcs and combinations of harmonic motion using time history files generated by other software Having both the rotational velocities with default or input
131. s are cleared Reset cannot be combined with any other control deflection commands 56 DRDC Atlantic TM 2006 252 Zero all control surfaces are set at zero deflection and control flags are cleared Zero cannot be combined with any other control deflection commands 14 5 Conflicting Deflection Commands DSSP21 does not permit deflection command conflicts Between static runs or simul taneously for dynamic simulations only the following combinations of deflection com mands are allowed for any individual appendage e a direct command with Clear e a quasi direct command with Clear e an indirect depth indirect heading and indirect roll command with each other and with Clear e Reset or Zero A fatal error is generated for any other combination Commanded deflections stay in effect until legitimately canceled or replaced by a new command An appendage under indirect control requires a Clear command before or coincident with returning it to direct or quasi direct control Failure to do so generates a fatal error In a free manoeuvering simulation active depth heading and roll autopilots use indirect deflection control and the same rule applies Issuing a Stop command to an active autopilot cancels the indirect commands associated with it 15 Root sim Heading Commands The commands discussed in this section are used in a free manoeuver to define initial compass heading and to interpret commands to the heading autopilot Whi
132. sim are prepared by the user with a text editor The input character set for DSSP21 comprises upper and lower case letters the space digits 0 to 9 the printable characters lt gt 7 71 amp _ 1 and the tab Unrecognized characters generally result in a fatal error Most input is not case sensitive In order to allow these files to be more readable a simple input parsing scheme is employed Each line in the input file is treated as a separate record of up to 71 characters consisting of words separated by one or more delimiters and terminated by an optional end of record character The word delimiters are the space comma semicolon and tab The end of record EOR characters are the double quote exclamation point and percentage sign A word is a string of any other characters Input following an EOR character is ignored and may therefore constitute a comment Any input that is encountered after the input requirements of a record are fulfilled is similarly ignored Input is controlled by keywords A keyword consists of an alphabetic string of up to ten characters contained in one of the parser s dictionaries listings are given in annex B On input keywords are not case sensitive Most input records consist of a keyword followed by one or more arguments An argument may be numerical some non keyword text or another keyword Since some arguments are optional it is prudent to
133. sitive Its default value is 10 degrees DRDC Atlantic TM 2006 252 41 10 2 AutoHead Level 2 Records HedConGain HedErrGain PhaseLead and PID HedConGain CG heading Heading control gain CG heading is in degrees and should be positive Since the commanded deflection depends on appendage dihedral and control weight Wry sections 6 4 and 14 3 this parameter can exceed the maximum deflec tion on an appendage Its default value is 20 degrees HedErrGain C E heading Heading error gain Co heading 18 in degrees and should be positive Its default value is 0 05 degrees PhaseLead Q heading T heading The heading phase lead controller parameters default to the same values as for depth control section 10 1 PID ky heading k2 heading Kp heading Ky heading gt Kp heading The heading PID controller parameters default to the same values as for depth control section 10 1 10 3 AutoProp Level 2 Records PhaseLead PID PwrErrGain RevConGain ThrErrGain UktErrGain and UmsErrGain PhaseLead Q prop T prop The propulsion phase lead controller parameters default to the same values as for depth control section 10 1 PID k1 prop 2 prop KP prop gt KT prop D prop The propulsion PID controller parameters default to ki prop 0 5 K2 prop 1 0 Kp prop 1 0 Ky prop 0 0 Kp prop 0 0 PwrErrGain Cg prop power Power error gain CG prop power 18 in W 1 3 a
134. spond in each of these indirect control modes Mandatory arguments Wyp and W7 y and optional argument W7p are nondi mensional weights for indirect depth indirect heading and indirect roll con trol respectively The weights multiply a commanded deflection and can be used for example to balance bowplane and sternplane response to depth control commands or with a value of zero to decouple a particular ap pendage from an indirect control mode These weights must be in the range 2 lt Wipxr lt 5 and are by default equal to 1 0 They can be redefined at several places in the Root sim file This record applies to both Al1Moving and Flapped control types 6 5 Control Dynamics Records DelRateLim and DeltaDyn Two records are used to specify the dynamics of a control deflection DelRateLim and DeltaDyn They apply to both AllMoving and Flapped control types DelRateLim m Argument m is the maximum control deflection rate in degree s it must be positive The default value is 9 degree s DeltaDyn CS ws Argument s is the nondimensional control deflection damping and ws is the control response frequency in rad s These parameters together with om determine control deflection time histories by way of a second order ODE for each control appendage Damping must be positive and a warning is given if it is gt 1 0 the default value is 0 9 Frequency ws must be positive its default value is 20 m Omaz Min Which is
135. ssible in DSSP21 unless these quantities have been input incorrectly with the TimeStep record see section 22 3 3 the integrator is unable to satisfy the accuracy required to continue Possible causes of this are that integration tolerance is too small relative to the minimum timestep DRDC Atlantic TM 2006 252 7 or that the matrix of inertial plus added mass properties is ill conditioned sec tions 3 4 and 22 3 The latter can alternatively result in an unexpected stop with the message DYDT sim stopped by zero negative forward speed The key here is that the stop is unexpected the program stops with this message because u ceases to be positive as would legitimately occur in simulating a crash back for example but the prior time history is not consistent with this condition If the problem is associated with a reference shift it may be avoided by redefining the vehicle s target point instead of the reference section 3 4 Please report time integrator errors with N 1 and N 2 if TimeStep appears correct to the author providing input files and other supporting information A captive model simulation may fail with the error TIMEHISTRY file P data is inconsistent or Q or R This generally indicates a fundamental error in the user supplied state variable time histories see section 21 3 3 4 Axis Systems The relationship between earth fixed and body fixed axis systems is discussed in st
136. stems preprocessing Unit ALBON ALBONC ALBONO AXIBBL HULLAX HULLGE HULLHY_HUL4 HULLH1_HUL4 HULLPT LIFTDL LIFTGE LIFTHY LIFTLO LIFTPT PLOTGE PLOTXA PLOTXM PLOTXP PLOTXV PLOTXW RUDCOF SPREIT_WB SPREIT_W_B THWAIT TRUCK WAGBINIT Function hull axial potential flow using Albone s methods hull axial potential flow for a hull with a closed tail hull axial potential flow for a hull with an open tail hull axial flow thin boundary layer check hull local axes specification process hull geometry hull hydrodynamic calculations using the HulFor method hull linear damping from HulFor save hull geometry definition for Root gpl appendage orientation parameters process appendage geometry appendage hydrodynamic calculations appendage local axis calculations save appendage geometry definition for Root gpl manipulate geometry for plotting write Root gpl in AcroSpin format write Root gpl in MatLab format write Root gpl in Maple format write Root gpl in VRML 1 format write Root gpl in VRML 2 format inactive Bohlmann Spreiter method for tailplane efficiency Spreiter s loading function for Kwg Spreiter s loading function for k weg hull axial laminar boundary layer Thwaite s method hull axial turbulent boundary layer Truckenbrodt s method initialize Wageningen B propellers Sp21sims for simulation run calculations Unit AUTOCOM AUTODOIT AUTOFIND BLOCOM Function set up parameters for aut
137. t the Hull record must have been given both its arguments in order to specify Ng e g Hull Default Ng If the station data are not equally spaced the Station record which permits specification of the station axial coordinate must be used NS n gt keyword Announces a block of section data for Ng stations Ng lt 51 By default Nsg 21 If the second optional argument is the keyword Irregular the DRDC Atlantic TM 2006 252 stations are not equally spaced and their axial coordinates must be provided in the data block A value must be given for Ng in order to specify irregular station spacing There is one record in the data block for each station proceeding from nose to tail If station spacing is irregular the first value on each record is the station axial coordinate in To simplify input this value is automatically scaled to hull length so that input may run from 0 nose to 1 tail for example The next or first for equal spacing value is hull breadth B followed by T optional A optional and z wise camber F also optional all these values must be dimensional Hull camber by analogy with appendage section camber is station mid height offset from the nose tail line positive downwards The example in annex D includes camber If F is omitted F 0 If A is omitted A TB T 4 and if T is omitted T B and A 7B 4 If the stations are equally spaced the Station data block format is
138. ta command strings reset control surface deflection limits estimate dynamic loads for the complete vehicle estimate floodwater centroid as a function of volume and pitch in plane hull load lookup tables rationalize BG CB and CG setup inertial matrix in reference axes process WeightDCI records DSSPtwo propulsor model STRprop propulsor model WageningB propulsor model save local axis systems in vehicle axes adjust local axis systems to reference axes update out of plane time histories DRDC Atlantic TM 2006 252 OOPSET OOPSTEP PRPCOM PRPFRC PRPINT PRPINX RATCOM REVPPT STATHL STATHL_HUL4 STATLM STATLT static out of plane calculation dynamic out of plane calculation process Propulsor command records calculate propulsor loads initialize propulsion condition estimate initial propulsor loads rationalize simulation commands and conflicts process CB CG or Reference redefinition Hull static forces and moments HulFor static load calculation Lump static forces and moments inactive Lift static forces and moments Sp21util for low level utilities Unit ADDRNG CHCOMP CIRCIH CIRCIT COMP3F CROOTS DECOMP DEFLBL GETCHR GETDBL GETINT GTDRNG HELP HELP_INP INDICT INDRNG INLABL INTRPL LOOKUP2 MESSAG NEARNESS OPENIT PCQUAD Function add vector to a double precision ring array word string comparison returns angle in range 7 to 7 returns angle in range 0 to 27 compare number triplets obtain
139. that of other components If there is no Label DRDC Atlantic TM 2006 252 45 record the default label is BALTnnn where nnn is the number of this MBT as encoun tered in the input file The other records are described in section 11 2 11 1 HPAir Level 2 Records Aft Forward Fwd Main Pressure and Volume Aft This record sets the BG to type Aft It will be associated with MBTs of type Aft Forward This record sets the BG to type Forward It will be associated with MBTs of type Forward Fwd Fwd is a synonym for Forward This record sets the BG to type Forward and the BG will be associated with MBTs of type Forward Main This record sets the BG to type Main It will be associated with all MBTs Pressure PH Pe This record is mandatory It defines the initial BG pressure Pype in bar pressure must be in the range 100 lt Pyp lt 400 bar Volume VHP This record is mandatory It defines the BG volume Vyp in m 11 2 MBT Level 2 Records Aft Forward Fwd Location MassFlow Vent and Volume Aft This record sets the MBT to type Aft It will be associated with BGs of type Aft Forward This record sets the MBT to type Forward It will be associated with BGs of type Forward Fwd Fwd is a synonym for Forward This record sets the MBT to type Forward and the MBT will be associated with BGs of type Forward 46 DRDC Atlantic TM 2006 252 Location TBT YBT ZBT This record is mandatory It defines the coordinates in veh
140. the user to check that the geometry has been input correctly Component intersections should be checked with a wire frame plot using no hidden lines so that the details are not obscured Plotting requires representation of the component cross sections which are artefacts not defined or used elsewhere in the program Hull cross sections are represented by an ellipse fitted to B and T the number of perimeter segments is defined by a parameter NsegH Lifting component cross sections at the root and tip only are represented by a NACA 4 digit section fitted to their chord and maximum thickness the number of perimeter segments is defined by a parameter nseyr The format of Root gpl is controlled by a number of optional input records at level 2 Keyword Function AcroSpin format Root gpl for Acrospin software HullSegmnt set hull section plotting parameter 48 DRDC Atlantic TM 2006 252 LiftSegmnt set lifting appendage section plotting parameter Maple format Root gpl for the Maple procedure DSSPplot mpl MatLab format Root gpl1 for the MATLAB script DSSPplot m VRML output Root gpl in VRML 1 format The Root gp1 default file format is VRML 1 13 1 AcroSpin HullSegmnt LiftSegmnt Maple MatLab and VRML Records AcroSpin Root gp1 is formatted for AcroSpin Version 2 0 for DOS This is an old pro gram the file format is compatible with the original DOS version of Acrospin actually version 2 3 that was at one time marketed as a vi
141. this guide The author is not aware of any reliable data for validation of either method but it is believed that an isothermal blow overestimates the blowing rate whereas the adiabatic blow as im plemented in DSSP21 likely underestimates it Adiabatic blowing is the default because it appears closest to reality while being conservative with respect to the effectiveness of the blow Isothermal blowing is initiated by the keyword Isothermal Gate Valve Check Valve Nozzle aed MBTI BG1 De 2 iS lt MBT2 BG2 D gt MBT3 BG3 Figure 15 A variation on figure 8 BG1 can only blow MBT1 and MBT2 together BG2 can blow any of the three individually or together and BG3 can blow only MBT3 The command to vent a ballast tank is simpler it is assumed that air is vented at the rate is set in MBT level 2 input section 11 2 this rate is constant and independent of depth There is no heat transfer associated with venting 60 DRDC Atlantic TM 2006 252 The venting command is Vent argument 1 argument 2 where argument 1 is one of Np the index of the MBT to be vented the Ng tank defined on Root geo has the index Np label string the label of the MBT to be vented All all MBTs are to be vented Stop stop venting all MBTs and optional argument 2 is Stop stop venting the tank s identified by argument 1 17 Root sim W
142. tion should be assessed before accepting it SVDecomp sva To try to circumvent ill conditioning of the inertial plus added mass matrix when the reference is moved away from the vicinity of the CB and CG sec tions 3 4 and 4 5 a singular value decomposition SVD matrix inversion algorithm from Press et al 26 is invoked with this record The optional ar gument syq is the threshold for discarding elements of the matrix 26 it has a default value of 1076 Note that in SVD some accuracy is lost If more than one element is discarded accuracy will likely deteriorate to an unacceptable level but discarding just one may not be sufficient to complete the matrix inversion Diagnostic output is provided in the Root log file to guide the selection of syq Unless the user has overpowering reasons to shift the reference it is preferable to select a target point section 22 1 to track a particular trajectory TimeStep hmin hmar 80 Defines limits in seconds on the internal adaptive timestep h Both should be positive and hmin lt Amaz but if either is zero the corresponding default is used e g to increase maximum step size to 5 seconds use TimeStep 0 5 The default for hmin is a small value based on the tolerance and computer roundoff error the default for hmaz is 2 seconds New timestep limits set by this record will apply to subsequent simulations in the same Root sim file As noted hmin is related to
143. tions need additional parameters such as the hull radius at the attachment point of an appendage The locations and characteristics of propulsors and other systems are needed to complete the description In this first phase of processing hydrodynamic quantities are calculated for fresh water density p 1000 kg m later they are scaled for a given density An example of Root geo is given in annex D Level 1 input is used to flag the vehicle components descriptions of which are then input at Level 2 and to provide overall program control Return to Level 1 from Level 2 occurs automatically when an out of context keyword is encountered The following table summarizes the keyword records at level 1 Keyword Function AddedMass define method for added mass and moment calculations AutoDepth depth autopilot parameter input to follow AutoHead heading autopilot parameter input to follow AutoProp propulsion autopilot parameter input to follow AutoRoll roll autopilot parameter input to follow BG define BG vector CB define location of CB CG define location of CG Help send help output to Root log HPAir HP air bottle group BG input to follow Hull hull component input to follow Inertial define method for calculation of inertial properties Lift lifting component input to follow Lump lump component input to follow inactive MBT main ballast tank MBT component input to follow OOPCalc out of plane load calculation input to follow Pl
144. ty in subsequent Free runs since they inherit the previous reference by default Coefficnt calculations will be incorrect if the reference is moved to a location without port starboard symmetry Angular motions and calculated moments are with respect to the redefined reference p Redefines fluid density the argument should be in the range 990 lt p lt 1035 kg m WeightDCI keyword keyword or WeightDCI label string or Nr Wip Win Wir Resets indirect control weights on all lifting appendages if the first argument is the keyword A11 otherwise only on the AllMoving or Flapped appendage identified by the label string or integer Nr DRDC Atlantic TM 2006 252 67 The weights Wrp depth Wry heading and Wy p roll are discussed in section 6 4 If the first argument is A11 the second can be one of Reset All weights are reset to their initial value section 6 4 One All weights are set to a value of 1 0 Zero All weights are set to a value of 0 0 For a specific appendage arguments Wyp and W7 y are mandatory and WFR is optional They must be in the range 2 lt Win xr lt 5 Multiple WeightDCI records can be used to reset weights for different appendages The global form of this record WeightDCI All only one of which is permitted per run overrides weight values on individual appendages and clears the associated flags Weights on specific appendages can then be reset individually For example to
145. uler angles Reference redefine reference origin and axes Rho redefine fluid density Text output run information or other descriptive text TimeHistry identify the time history file WeightDCI reset indirect control deflection weights 21 1 DeltaLim Reference Rho Text and WeightDCI Records These records can be input for most of the calculations and simulations on Root sim they redefine basic vehicle and simulation parameters that then remain unchanged until redefined in a subsequent run The syntax and caveats applying to DeltaLim Reference Rho and WeightDCI are as presented in section 19 4 Motions on the time history file are taken to be motions of the redefined reference and these should there fore be consistent with each other Loads are calculated with respect to the redefined reference A Text record is simply output to Root spr when it is encountered 21 2 Del Delta and TimeHistry Records Del Delta arguments see section 14 This sets default values for the one or more control deflections identified in the argument string Any of the direct quasi direct indirect or global Delta 72 DRDC Atlantic TM 2006 252 Delta arguments discussed in section 14 can be used on this record Multiple Del records can be present so long as a command conflict section 14 5 is avoided In the absence of a Del command the default for a control deflection is zero If the time history file described below contains deflection data for the s
146. un For a Free run it tabulates time histories the extended state variable data time speed Xo yo zo coordinates Euler angles compass heading translational and rota tional speeds in boat axes control deflections and RPM An auxnnn txt file tabulates time histories of some useful auxiliary data chart coordinates power thrust autopilot error and control signals bottle group pressures and temperatures water displaced from ballast tanks and floodwater mass It is noted above that some data in the auxnnn txt files are approximated during inter polation by their value at the last internal timestep Although the program recalculates those quantities for which the approximation would lead to an unacceptable loss of pre cision it is not done for those that are considered to be primarily for qualitative or diagnostic purposes e g thrust power autopilot signals and changes in vehicle mass DRDC Atlantic TM 2006 252 85 25 Concluding Remarks This document is a user guide to build 061102 of the underwater vehicle manoeuvering simulation code DSSP21 with particular emphasis on input preparation It is aimed at both experienced and new users Some features of the DSSP21 current build are still under review Validation of many of the algorithms is on going and improvements will continue to be made as new data become available Nevertheless the current build is amply capable to be documented in this guide for use in hydrodynamic stud
147. upancy Pop force termination of input see section 5 4 The Label definition is analogous to that of other components If there is no Label record the default label is WTCPnnn where nnn is the number of this WTC as encoun tered in the input file The other records are described in section 12 1 DRDC Atlantic TM 2006 252 47 12 1 WTC Level 2 Records Diameter Length Location and Occupancy Diameter Do This record is mandatory The argument Dc must be positive Note that this dimension is not checked for consistency with any other input such as a hull diameter Length Lo This record is mandatory The argument Lo must be positive Note that this dimension is not checked for consistency with any other input such as a hull length Location IC YC ZC This record is mandatory It defines the coordinates in vehicle axes of the centroid of the unoccupied cylinder modeling the WTC Note that this point is not checked for consistency with any other input such as hull location and dimensions Occupancy Oc This defines the occupancy Oc of the WTC The maximum amount of flood water that can enter is 2 Do Lc 1 Oc The argument is mandatory it must be in the range 0 05 lt Oc lt 0 95 In the absence of this record occupancy defaults to Og 0 3 13 Root geo Level 2 Plot Input If a Plot record is found at level 1 plotting output of the vehicle geometry is saved in ASCII format on file Root gp1 A plot enables
148. useful while the code is under development but is probably excessive for most purposes Some of it may be made optional in later builds Root spr presents a summary of conditions and results for each of the runs called for in Root sim Its purpose is to confirm that the run parameters and other conditions were properly set up especially if there are anomalies in the results The principal output of calculations and simulations is to the simnnn txt and auxnnn txt files and is in simple tabular form for importing into spreadsheet graphical or other post processing software Root spr starts with a vehicle configuration summary that includes a list of components by number and label indirect deflection control weights a table of appendages associ ated with various quasi direct and indirect commands and reference axes information For each run the number nnn of the corresponding simnnn txt and auxnnn txt files is given Static run output merely lists values of the run parameters and the number of iterations if a Loop is executed Coefficnt run output lists all the coefficients and stability indices calculated Free simulation output includes run initialization data and the target trajectory time history in chart axes i e t xr yr zr at each time or interpolation step A simnnn txt file tabulates loads for a Static run coefficients if the Output option is selected section 20 1 for a Coefficnt run and load time histories for a Captive r
149. uto Sp2iggeo Sp21labl Sp2istat Sp2istuf 98 cmn cmn cmn cmn cmn cmn cmn cmn cmn DRDC Atlantic TM 2006 252 Annex D Example Root geo Input File This is a fairly typical input file for a full scale submarine However for purposes of illustration more of the optional inputs have been used than are usually necessary Text Demo Text 68 m generic submarine with a deck and sailplanes Reference 30 2493 0 0 Reference at the precalculated hull 0 0 0 CB 0 444842 xe11 aft of nose BG 0 38 Form CB used for vehicle CB with CG displaced from it by BG Hull Default type and number of stations Label Hull Station Regular 21 stations 0 0000 0 0000 0 0000 0 0000 Camber is cosmetic 6 2499 6 2166 30 5152 0170 7 3481 7 5364 43 4940 0945 7 7030 8 1695 49 4248 2332 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 7717 8 3545 50 9949 2917 7 6500 8 1892 49 1731 2700 7 2012 7 5779 42 8592 1884 6 4219 6 5443 33 0078 0612 5 3122 5 3122 22 1635 0 0000 3 8719 3 8719 11 7744 0 0000 2 1012 2 1012 3 4676 0 0000 0 0000 0 0000 0 0000 0 0000 Nose 0 0 0 0 0 0 Vehicle origin at nose Tail 68 0 0 0 0 0 LoD 8 75 Source NeuralNet Most hull parameters take Deck 1 2 1 05 the default values
150. w 1 blow MBT 1 with all associated BGs Blow 2 Fwd blow MBT 2 with BGs of type Forward if associated Blow All Main blow all MBTs with Main BGs Blow Aft blow all MBTs of type Aft with Aft BGs Blow 3 Stop stop blowing MBT 3 Blow Stop is the same as Blow All Stop Care has to be exercised with blowing commands because BGs and MBTs are related only by simple association If there is any doubt what the associations are refer to the table that is output on Root spr for a free simulation In addition there are ambiguities in section 11 it was noted that a bottle group may be connected so that it can only blow two tanks together as is BG1 in figure 15 although a simple association does not DRDC Atlantic TM 2006 252 59 reflect that Therefore we would represent the system in figure 15 the same way as for figure 8 by giving BG1 MBT1 and MBT2 type Forward giving BG2 type Main and giving BG3 and MBT3 type Aft blowing MBT1 and MBT2 simultaneously from just BG1 is achieved with Blow Fwd Fwd or Blow A11 Fwd However there is nothing to prevent the user from using Blow 1 or other commands that may inadvertently result in BG1 blowing MBT1 alone which is consistent with figure 8 but not with figure 15 The present build of the program allows two types of ballast blows isothermal which is a common approximation in simulation codes and adiabatic the default they will discussed in more detail in the future companion document to
151. xt set lower and upper timestep limits set integration tolerance initialize axial velocity in kt initialize axial velocity in m s reset indirect control deflection weights The following are the command record keywords Keyword AutoDepth AutoHead AutoProp AutoRoll Blow Del Delta Dummy Flood Prop Propulsor Start Stop Vent Function command depth autopilot command heading autopilot command propulsion autopilot command roll autopilot blow MBT s command control appendage deflection s command control appendage deflection s a null command flood a WTC command propulsor RPM command propulsor RPM start the simulation stop the simulation vent MBT s A text record is simply output to Root spr when it is encountered DRDC Atlantic TM 2006 252 17 22 1 Vehicle Initialization Records CB CG Del Delta DeltaLim Reference and Target CB CG DeltaLim and Reference records can be input for most of the calculations on Root sim their syntax is as presented in sections 4 2 and 19 4 Note the caveats given in sections 3 4 and 4 5 regarding the reference for a free manoeuvering simulation Del and Delta are used to define initial control deflection s at the start of the simu lation These deflections are taken into account in establishing the initial condition of level flight with zero trim The standard Delta syntax is used Del Delta arguments see section 14 Any of the direct quasi direct indirect

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