Polar Explorer
Contents
1. U U Io I U U ohnson FVLR 2 ohnson FVLR 1 FVLR 1 FVLR 1 ohnson ohnson ohnson FVLR 1 FVLR 1 FVLR 2 ohnson FVLR 1 FVLR 2 ohnson ohnson ohnson ohnson FVLR 2 FVLR FVLR FVLR FVLR FVLR FVLR 1 ohnson ohnson ohnson FVLR 1 FVLR 2 FVLR 2 FM FVLR 1 FVLR 2 HE NNFEFN Johnson FVLR 2 FVLR 1 ohnson ohnson ohnson ohnson ohnson ohnson ohnson ohnson ohnson Comment Seals installed Profiled wing Smoothed wings With ail interconn Mod w leading edge No ail interconn 634 Original wing Profiled wing Flaps 8 8 deg Flaps 0 deg 172. e D1 DFVLR 1 Flugmessungen mit 25 Segelflugzeugen by H Laurson and H Zacher DFVLR Institute Germany 1972 e D2 DFVLR 2 Flugmessungen an 35 Segelflugzeugen und Motorseglern by H Laurson and H Zacher DFVLR Institute Germany 1976 e D3 DVL Flugmessungen mit Segelflugzeugen von 12 bis 13 M Spannweite by Hans Zacher DVL M nchen Riem Germany 1965 Polar Explorer Version 2 2 Short Guide 14 e M FFM Flight performance measurements on twelve sailplanes by H J Merklein and H Zacher Scientific Flight Research Establishment Munich FFM 1964 List of Gliders in the POLAR Library The glider definitions currently included in the glider library POLAR are listed in this section The following example illustrates the meanings of different elements used in this list 105 Mini Nimbus N871T 16 J Johnson Seals installed 105 Serial number in the POLAR library Mini Nimbus Glider type N871T Glider registration number 16 Factory serial number J Polar source Johnson Polar source Seals installed Additional comment No Glider Source Comment 1 Ahrens Delphin V2 D3 DVL 2 AK 1 D KEUL D2 DFVLR 2 3 ASH 25 N80WK 4 J Johnson 4 ASH 26E C Calculated polar 5 ASK 13 D 2018 D1 DFVLR 1 6 ASK 16 D KEIK D2 DEVLR 2 7 ASK 21 N362KS 225 J Johnson 8 Astir CS D 7290 D2 DFVLR 2
3. W S 34 4 D 6680 D N274W 321 D2 M IE D J Polar Explorer Version 2 2 Short Guide Source J J J Comment Johnson Johnson Johnson Johnson Johnson Johnson DFVLR 1 DF VLR DF VLR DEF VLR FFM DFVLR 1 DFVLR 2 DFVLR 2 R 2 R 2 15m 15m 17m sealed Ballasted No winglets With winglets H NIN DFVL DFVL DFVLR 2 Johnson Johnson Johnson Johnson Johnson Johnson ohnson DFVLR 1 DFVLR 1 DFVLR 1 DFVLR 1 Corrected profile 5610 Sealed Mod wheel fairings 34107 DFVLR 2 Johnson Johnson ohnson Johnson DFVLR 2 Johnson DFVLR 2 ohnson FFM HB 604 c Data DFVLR 2 Johnson German Test German Test German Test Johnson Data Data Data ndi d D 104 No 105 106 107 108 109 110 111 112 1 134 114 T1154 116 LIA 118 119 120 T21 122 123 124 125 126 127 128 129 130 131 132 E33 134 135 136 137 138 139 140 LA 14 14 14 14 14 14 Vega N37510 1927 Ventus A N47JD 29 Ventus A 16 6 Ventus A 16 6 148 149 T503 151 UDO i0 PN P LS 4A N430RH 384 Glider J Mini Nimbus N871T 16 Mistral D 4998 D2 Mosquito N46898 J Mu 22 b D 1848
4. 1000xCD bugs Smallest irregularity Second derivative Scale Show Color Edit polar Entering polar points Polar waviness Second derivative SD lines Rules for smoothing the polar curve Saving a new glider definition Introduces X Country Calculator that has been added to Polar Explorer in Version 2 1 Estimated playing time 64 minutes No ODO NDUIDSWNA 9 FG CAL Topic About X Country Calculator Loading a glider Customizing the atmosphere model Defining a special thermal updraft model Entering a task example of a 400 mile triangle Dist W u Alt 1 Alt 2 General settings Wind Flying Tactics Glider condition Alt Free and fixed altitude modes Recalculate Working altitude W cl V stf V W Results for each leg V ci Bank T cl L D rel Crab V xc T total Summary results for the whole task symbol Advanced use of X Country Calculator Comparing cross country performance method A Comparing cross country performance method B Special cases that cannot be calculated Optimize V stf Introduces Final Glide Calculator that has been added to Polar Explorer in Version 2 1 Estimated playing time 27 minutes No O DONDQUIAWNNA ADVANCED Topic About Final Glide Calculator Atmosphere model Alt Free and fixed altitude modes General settings Final glide parameters Alt 2 Dist W cl Recalculate Working altitude W cl V 4 stf V W Calculated results Alt 1 L D grnd
5. 2 2 Short Guide 7 Script Commands e When a tutorial script is playing it takes full control over program execution and only allows you to use the following commands e Press Esc or click the right mouse button to move immediately to the next command or message window e Hold down the Esc key or the right mouse button to perform a fast forward Generally the right mouse button advances through the script much faster than the Esc key e Press any key except Esc once or click either left or middle mouse button to interrupt pause playing e When the playing is paused press any key or click any mouse button to resume it Note that when T delay is negative the script automatically pauses after issuing a message window e Press Alt 7 hold down the Alt key while pressing the key to terminate playing This will leave you in the environment that was set up by the script You can use this method to try out things on your own e Press Alt topic number to jump directly to any of the topics listed in the script s table of contents For example to jump to topic number 5 press Alt 5 If a topic has a two digit number for example 22 then hold down the Alt key while pressing the 2 key twice For this purpose use only the numeric keys on the main alphanumeric keypad e You can press Alt 0 zero at any point to jump directly to the end of the script This will also reset the data sheet and bring you back
6. 9 ASW 15 D 0510 D1 DEVLR 1 10 ASW 15 D 0791 D1 DFVLR 1 11 ASW 17 N45JD J Johnson 12 ASW 17 20m D 1110 D2 DFVLR 2 13 ASW 17S 21m D 2119 D2 DFVLR 2 14 ASW 19 D 4525 D2 DFVLR 2 15 ASW 19 N19KL J Johnson 16 ASW 20 N104WR 17 J Johnson 17 ASW 20 9 N104WR 17 J Johnson Flaps 9 deg 18 ASW 20 8 0 N104WR 17 J Johnson Flaps 8 amp 0 deg 19 ASW 22 22m N27023 15 J Johnson 20 ASW 22 24m N27023 15 J Johnson 21 ASW 24 D German Test Data 22 ASW 27 C Calculated polar 23 Bergfalke II D 1217 M FFM 24 Bergfalke III D 1737 D1 DFVLR 1 25 Bergfalke IV D 1005 D2 DFVLR 2 26 Blanik L 13 F Factory 27 Bocian D 1578 M FFM 28 Calif A 21 S D 2176 D2 DFVLR 2 29 Cirrus D 0471 D1 DFVLR 1 30 Cirrus D 0471 D2 DFVLR 2 31 Club Libelle D 3695 D2 DFVLR 2 32 D 34 b Aphrodite D 4607 M FFM 33 D 34 d D3 DVL 34 D 34 d D 4607 M FFM 35 D 36 V1 D 4685 D1 DFVLR 1 36 D 37 Artemis D 2278 D2 DEVLR 2 37 D 37 Artemis D KEDD D2 DFVLR 2 38 D 38 D 0938 D2 DFVLR 2 39 DG 300 N33HB E47 J Johnson Sealed clean holes 40 DG 100 D 1076 D2 DFVLR 2 41 DG 100 D 7099 D2 DFVLR 2 42 DG 101 G N101TX E168 J Johnson oa Polar Explorer Version 2 2 Short Guide No CO 00 QUI Sw Glider DG 20 DG 60 DG 60 DG 60 Disc
7. Crab V grnd T glide Influence of different factors on a final glide Demonstrates Polar Explorer s advanced polar editing capabilities and shows how to explore the consequences of different glider modifications Estimated playing time 42 minutes Z o OONDOAARWDND Topic About glider modifications Increasing the wing span Sink rate and L D comparison C Cp analysis Circling performance comparison Adding winglets Sink rate and L D comparison C Cp analysis Circling performance comparison Reducing the parasite drag Sink rate and L D comparison C Cp analysis Circling performance comparison Polar Explorer Version 2 2 Short Guide 11 55 Comparing cross country performances About Glider Polars All Polar Explorer s performance calculations are based on a glider definition which normally includes a speed sink polar as its central part The quality of the obtained results therefore largely depends on the accuracy of the polar being used The question of polar accuracy is quite intricate and must be evaluated separately for each particular case For example it is very likely that the polars of two gliders of a same type will be noticeably different if they come from different sources even when reduced to the same wing loading In a case like that it is important to figure out whether the polars are different because of calculation or measurement errors or because the two gliders actually have diffe
8. D1 Mu 26 D 0726 1971 D1 Mu 26 D 0726 1972 D1 Nim 3 22 9 N493JD 19 Nim 3 24 5 N493JD 19 Nim 3 24 5 Mod J Nim II D 0107 D1 Nim II D 0699 D1 Nim II D 2111 D2 Nimbus II Smooth N45DJ Phoebus C D 0559 D1 Pik 20 A OY XCR D2 Pik 20 A I N100DC 8 Pik 20 B Mod N46JD J Pik 20 D 78 N19YZ J Pik 20 No AI N100DC 8 J Pilatus B4 PC11 HB 1127 D2 RF 5 B Sperber D KOKS D2 Sagitta PH 319 D1 Salto 15 mod D 2220 SB 10 D 6085 D2 SB 8 V2 D 6085 D1 SB 9 D 6085 D1 Schweizer 1 26E N33904 Schweizer 1 35 N17976 J Schweizer 1 36 N362IT J SF 27 A D 6068 D1 SF 28 Tandem D KFAJ D2 SF 30 Club Spatz D 3697 D2 Skylark 3 F RAF 146 M Std Cirrus D 0483 D1 Std Cirrus D 3261 D2 Std Cirrus B N5CC J Std Cirrus 16m D 3261 D2 SZD 30 Pirat D 3660 D1 SZD 55 1 N3176T J J J J J J AnNNN N CCC CCO 0 J J D2 J J Mod Ventus B N139P J Zuni N14XZ 14 J Zuni 8 8 N14XZ 14 Zuni 0 N14XZ 14 J J J Polar Explorer Version 2 2 Short Guide Johnson Source J J J J J J J J J J J J J J J D J D D D J J J D D D U D D U c 1 I D D D D D D D J J J D D D F D D I D D I U I
9. so should benefit the most from using this program Whether you are a student pilot or a seasoned veteran you should find Polar Explorer to be a source of valuable information for years to come Polar Explorer comes with a library of over 150 mostly measured polars so you can start using it right away In case the glider you are interested in is not included in this library you can easily enter its polar and the few additional parameters yourself or you can modify any existing polar from the library After that you can analyze the performance of your glider and compare it to any other glider from the library In fact you can compare up to five different gliders or one glider in five different settings at a time We tried to make Polar Explorer as complete as possible In doing so we realized that the classic MacCready speed to fly theory couldn t be used in case of stationary and semi stationary updrafts e g lee waves This lead to the development of a generalized speed to fly theory which has been applied in writing the program What Can Polar Explorer be Used For Polar Explorer is designed to answer many specific questions about various aspects of glider performance As a result you can use it for many different purposes The following are a few examples e Complement the books and articles on glider performance and soaring tactics by working out practical examples e Find out the optimum circling technique for any glider a
10. tests if all the files needed for playing the 0 INTRO script are present on the current directory TUTORIAL GL These three files GLO GL1 and GL2 contain the tutorial glider library required for playing tutorial scripts TUTORIAL PE These three files PEO PE1 and PE2 contain the tutorial sheet library required for playing tutorial scripts S Files containing tutorial scripts with around 7 hours of online instructions POLAR GL Glider library with over 150 glider definitions mostly based on flight test data published by Johnson and Zacher POLAR PE Sheet library with sample data sheets SCR Source files of tutorial scripts You can use them to customize tutorial scripts any way you wish MSC EXE Macro Script Compiler decompiler program used to compile SCR source files into S script files and vice versa Running Polar Explorer Rnning Polar Explorer in a DOS Command Window To run Polar Explorer 2 2 in a DOS command window first change to the drive and directory set up for it Next type PE22 and press Enter You can also use several command line parameters with the following effects IM Runs Polar Explorer in mono mode suitable for some laptops S xxxx Automatically starts executing a command script where xxxx is the name of the script Do not include the extension it is assumed to be S T yy Sets the time delay constant T delay to the value specified by yy This parameter is normally used tog
11. CCIDS ceo ree e to deris o ie sesto e dae Dav aS 7 Playine speed and T delay rnr elenina 7 ScapeCommalideca aio acea e md E EE med SE 8 Contents OF Tutorial Serpico o 8 O INTRO ipo a E E NU EVA an 8 E bays tod OEE eter pee Beret E E bielle 9 CIRCE derr e e uaea aa ra e eg 9 S CL CD EEEE D ge p e arida red edit 9 Z SHEET ces ees NM D sia aoe eg Ee cl s 9 ORAPH gliere iaia ene 10 O FUNC illa RR Ra 10 TEDT aloe eee ees ee 10 I cue aii ae ht il ae aa he a A Dale eh tae ROG ee mus 11 CIALE ORE CORE AR Du ael 11 ADVANCED orli a 11 About Glider Polars idet eed need razzie 12 Calculated Polars dco ede t aee d i et 12 NMieasured Polars gt s certe E e eite uid RN ala 12 Performance Differences Between Gliders of a Same Type 13 Incomplete Polars See tire et uos itu ioci uot icto Cer d 14 Glider Library Included with Polar Explorer eee 14 SOUFCES dco olio eie p cedere pla fre pie tee eius 14 List of Gliders in the POLAR Library ieri 15 Polar Explorer Version 2 2 Short Guide 2 About the Short Guide This Short Guide is designed to be used together with the online tutorial to help you get Polar Explorer up and running before the proper User s Manual becomes available This booklet contains an introduction to Polar Explorer the instructions on how to install and run the program and the online tutorial the contents of the tutorial and a reference to the glider librar
12. Entering and editing glider definitions 66 8 XC CAL X Country Calculator TI 9 FG CAL Final Glide Calculator 88 ADVANCED Exploring different glider modifications OONDOARWDND Polar Explorer Version 2 2 Short Guide 8 1 BASIC Introduces basic cross country and climb performance curves Basic XC Climb Estimated playing time 29 minutes No Topic 1 General notes 2 Basic performance curves 3 Curve 1 V 4 rel air W abs sink 4 Curve 2 V Jair L D rel E 5 XC Cross country performance curves 6 Curve 3 V stf W climb 7 Speed to fly and irregular polars 8 Curve 4 V stf W climb W sink 9 Curve 5 W climb Vxc average 11 Curve 6 W updraft Vxc average 22 Climb performance curves 33 Curve 7 W updraft Bank angle Q 44 Curve 8 W updraft V circling 55 Curve 9 W updraft W climb 2 CIRCL Introduces circling performance curves Also explains different circling modes and the concept of optimum circling Estimated playing time 19 minutes No Topic About circling performance curves Circling Settings and circling Mode Curve 1 Radius V circling Optimum circling airspeed Curve 2 Radius W sink Curve 3 Radius Bank angle Direct correlation between circling airspeed sink rate and bank angle Sink rate comparison between Optimum mode and circling with a DO NDUIDSWNN constant C 3 CL CD Introduces four different types of lift coefficie
13. Polar Explorer Version 2 2 Short Guide Polar Explorer Version 2 2 Short Guide Copyright 1993 2006 by Branko Stojkovic All Rights Reserved Last Revision January 2 2006 The author makes no warranties with respect to this documentation and disclaims any implied warranties of merchantability or fitness for a particular purpose Information in this document is subject to change without notice The author assumes no responsibility for errors that appear in this document CuSoft and Polar Explorer are trademarks of Branko Stojkovic All other brand or product names are trademarks or registered trademarks of their respective holders Polar Explorer Version 2 2 Short Guide 1 Table of Contents Abouttbe Short Glde sora 3 About Polat Bxplofer ccipire dorati nd ario E 3 General Notes C 3 What Can Polar Explorer be Used POr 5 ee aea et eed eane seen antt 3 PertorridBce CULYBS ous etek icio eed ese nalis cuite he dilaga 4 Interactive Performance Calculations eene 4 What Can be Varied in Performance Calculations esses 5 Gettin Started conati lalla 6 SxstenvReguiremenis 4 este ee aidret eee egli 6 Installing Polar Explorer 2 1 on a Hard Disk eee 6 Polar Explorer s Files sualiui desde iie lo andes eiit osea ed 6 Starting Polar Tx planer averli aspi E mu une dames aede 6 Startuine Folar Exploter EH 6 Online Tutorial oie Rr e ini eue ee ai 7 Playing Tutorial S
14. airfoils usually exhibit a lower maximum lift coefficient and higher drag coefficient when compared to the theoretical ones e Many sources of parasite drag are difficult to account for These include things like imperfect fit of the canopy dive brakes or landing gear doors as well as various points where air leaks can occur e The laminar separation bubble which is difficult to predict can appear at certain angles of attack Whenever it forms it substantially increases the profile drag and consequently the sink rate e Last but not least the calculated polar is in many cases a powerful marketing tool so the glider designer may be under considerable pressure to make a few optimistic assumptions when doing the calculations However such practice can easily become counter productive if the glider manufacturer becomes notorious for publishing polars that are regularly too optimistic In recent years the accuracy of the calculated polars has improved quite dramatically The new computerized methods have made the aerodynamic calculations easier and more precise Also the theoretical and experimental research has produced more reliable data and some glider designers are now using the wind tunnel tests as a part of the design process As a result the calculated polars of some of the latest types of gliders are fairly close to their actual performance Measured Polars Measured polars are usually not supplied by glider manufacturers The ted
15. ctory script As already mentioned you can invoke a script and adjust the time delay constant by using the S and T command line parameters when starting Polar Explorer For example if you type the following at the DOS prompt POLAR S 1 BASIC T 0 5 and press Enter the program will automatically start playing the 1 BASIC script and the time delay constant will be set to 0 5 The Play script function in the File menu can be used to start playing a tutorial script from within Polar Explorer After activating Play script you will be asked to supply the name of the script file you wish to play That can be done in two ways e By typing the name of the script into the dialogue box do not include the extension it is assumed to be S e You can also enter an empty string or supply the path to the directory containing script files After that you will be prompted to select one of the available scripts from a bar menu WARNING The majority of tutorial scripts rely on using the TUTORIAL glider and sheet libraries The following files containing the two libraries should be present on your current directory e TUTORIAL GL GLO GL1 GL2 Glider library e TUTORIAL PE PEO PE1 PE2 Sheet library If you make any changes to these two libraries or delete any of these files some tutorial scripts may not play properly Playing Speed and T delay The overall script playing speed can be adjusted by modi
16. especially at a small radius and the minimum radius will increase substantially This will also degrade the calculated climb performance and the corresponding cross country performance Note Many glider definitions included in the POLAR library have polars with either one both ends cut short because these polars had been published that way and we tried not to make any modifications to the original data If you have to use such a polar we suggest that you try to extend its low speed end by making it similar to the calculated polar for the same type or to the polar of a similar glider Otherwise you might as well avoid any performance analysis that involves circling flight Glider Library Included with Polar Explorer Sources Polar Explorer comes with a library of glider definitions that are mostly based on measured polars published by different authors Although we have made every effort to transfer the data as accurately as possible we cannot guarantee that the polars included in this library are identical to the published ones In most cases we had to scale the curves from the diagrams which were hand drawn and usually too small for accurate measurements The source of each polar in the Polar Explorer s library is indicated in parentheses in both the glider name and the comment The following are the main sources that have been used e J Johnson Flight Test Evaluations of by Richard H Johnson published in the Soaring magazine
17. ether with S xxxx See the next chapter for details on T delay Rnning Polar Explorer Directly from Windows To run Polar Explorer 2 2 directly from Window simply double click on PE22 EXE in the Windows explorer or double click on the shortcut to PE22 EXE on your desktop Polar Explorer Version 2 2 Short Guide 6 Online Tutorial Polar Explorer s online tutorial consists of 11 tutorial scripts each covering a number of related topics The tutorial with a total estimated playing time of around 7 hours contains a detailed description of all Polar Explorer s functions and the instructions on how to use the program A script is a collection of commands and text messages stored in a script file with the extension S Script files are not ASCII text files so they cannot be edited or listed with the DOS TYPE command Instead we have provided the source files for all tutorial scripts which can be printed out and edited If you wish you can modify any of the tutorial scripts by editing its source file SCR and then compiling it with the Macro Script Compiler program MSC EXE Playing Tutorial Scripts There are several ways of activating the Polar Explorer s online tutorial The easiest one is by typing TUTORIAL at the DOS prompt and pressing Enter This will start the TUTORIAL BAT batch file which will first check if all necessary files are present and if they are start Polar Explorer and instruct it to play the 0 INTRO introdu
18. fying the time delay constant T delay located in the File menu A lower value causes a shorter delay i e faster playing and vice versa Normal T delay is 1 T delay of 0 5 roughly doubles the playing speed while T delay of 2 cuts it in half T delay constant can be both positive and negative When it is positive the message windows displayed by a script are kept on the screen for a certain length of time determined by the size of the window and the value of T delay This way the entire script can be played without any input from the user When T delay is negative the program automatically pauses after issuing a messages window which is kept on the screen until you press a key or click a mouse button Playing speed of regular program commands e g moving the cursor and typing in the numbers is not affected by the sign of T delay The original setting of T delay is 1 which is well suited for viewing the tutorial scripts If the playing appears too fast or too slow you can change this value and you can also save the new T delay as default by using the Options sAve current options function Note At certain points tutorial scripts have to adjust various options and settings in order to proceed with playing This is usually done rather quickly so that minimum time is wasted Therefore if something is happening too fast for you to follow don t worry you aren t missing anything important Polar Explorer Version
19. h Average cross country speed e Climb performance o Updraft strength Rate of climb o Updraft strength Optimum bank angle o Updraft strength Optimum circling speed e Circling performance o Circling radius Circling airspeed o Circling radius Sink rate o Circling radius Bank angle e Lift coefficient versus Drag coefficient curves o CL Covi Cp viscous for Re 1 000 000 o C OCpy Cp viscous for Re that varies with C o C Cp Cp total for Re that varies with C o C Cp Cp induced Polar Explorer can show the above performance curves on a screen diagram or print their coordinates in a table that can be displayed on the screen sent to a text file or directly to the printer Interactive Performance Calculations In addition to performance curves Polar Explorer version 2 2 introduces two new functions designed to facilitate planning and analysis of cross country flights and final glides e X Country Calculator is an interactive spreadsheet in which you can directly calculate cross country performance on a given task with up to five independent legs It can calculate the following parameters for each leg o Climb rate plus optimum circling speed and bank angle in given updrafts Optimum cruising speed Percentage of time spent in climb Updraft relative glide ratio Crab angle required to offset the crosswind component Average cross country speed o Elapsed time X Country Calculator a
20. ified cruising speed in X Country Calculator and Final Glide Calculator o Starting and ending altitudes for each leg in X Country Calculator e When analyzing circling performance you can instruct Polar Explorer to calculate circling in one of the following modes o Optimum mode which produces the minimum possible sink rate at any given radius o Constant lift coefficient reserve below the maximum CL o Constant airspeed reserve between the circling airspeed and the minimum speed at that radius o Constant circling speed regardless of radius 00000 Polar Explorer Version 2 2 Short Guide 5 Getting Started System Requirements To be able to use Polar Explorer you need o IBM PC XT AT PS 2 or compatible o 512 kb RAM memory o Atleast one floppy drive double sided low or high density o VGA graphics card o MS DOS or PC DOS version 3 0 or later or any version of Windows Installing Polar Explorer 2 2 on a Hard Disk Simply unzip the contents of Polar Explorer 22 zip file to a new folder on your hard drive and place a shortcut to the PE22 EXE file on your desktop That should do it Polar Explorer s Files Polar Explorer Version 2 2 distribution file Polar Explorer 22 zip contains the following files PE22 EXE Polar Explorer program file Note that this is a MS DOS program and it will best tun in a DOS window TUTORIAL BAT Batch file that starts Polar Explorer 2 2 and invokes the 0 INTRO introductory tutorial script It also
21. ious flight testing and data processing has been done by soaring enthusiasts such as Paul Bikle Richard Johnson and Hans Zacher to name only those who should be given most credit Their work was usually supported by institutions such as Dallas Gliding Association and German DVL formerly DFVLR institute Although glider performance measurements can be done in many different ways only two flight testing methods were generally used the partial glide descent timing mostly Polar Explorer Version 2 2 Short Guide 12 used by Bikle and Johnson and the side by side comparison with a calibrated glider mostly used by Germans e Partial Glide Descent Timing is a procedure in which a test pilot measures the time it takes the glider to descend from one altitude level to another at a constant equivalent airspeed The sink rate is then calculated from the altitude difference and the duration of descent The procedure is repeated for different airspeeds and even several times for the same airspeed The airspeed system has to be calibrated in order to compensate for its errors After the flight testing is done the obtained speed sink points are converted to the sea level conditions in the Standard atmosphere and plotted on a diagram At the end the polar is drawn as the best fit curve through the measured points e This method results in a considerable scatter of the measured speed sink points mainly because the air in the atmosphere is never perfec
22. l performance potential This usually includes installing seals at places such as wing roots dive breaks ailerons etc In case of gliders equipped with blow holes for boundary layer control some of them may be plugged and need to be cleaned On some glider types these simple modifications can improve the performance by several percentage points e As mentioned earlier the actual airfoil of a wing coming out of a factory is usually somewhat distorted This flaw can be corrected by filling and sending with the help of accurate airfoil templates Although this procedure has a potential of significantly increasing the performance it is not widely used because it requires a huge amount of labor Polar Explorer Version 2 2 Short Guide 13 e A gliders that has been repaired after a structural damage can suffer a performance loss especially if the damage was to the wings All this should be kept in mind before using any particular polar in performance calculations Even if you have obtained a precisely measured polar of a glider that is the same type as yours you should estimate whether your glider is in better or worse shape than the one tested If you conclude that there is a difference you should modify the original polar accordingly For example if you assume that your glider has a 2 performance advantage over the one tested you can use the sCale polar editing function to reduce the sink rate by 2 throughout the polar To do that specify
23. lso shows the averages and totals for the whole flight for example the average rate of climb and the total time e Final Glide Calculator is an interactive spreadsheet in which you can determine the following final glide parameters o Initial altitude required to complete the final glide Speed to fly Ground relative glide ratio Crab angle required to offset the crosswind component Duration of the final glide O O 0 0 0 O O O O Polar Explorer Version 2 2 Short Guide 4 What Can be Varied in Performance Calculations All performance curves cross country flights and final glides can be calculated in user specified conditions The following settings can be varied e Glider o Glider definition aerodynamic and geometry characteristics o Wing loading ballast o Surface contamination bugs e Environment o Model of the atmosphere Standard or custom Altitude within the limits of the atmosphere model Horizontal wind speed Horizontal wind angle Vertical velocity of the air between updrafts Coefficient of updraft drift Cua which determines whether the updrafts drift completely with the wind or are more or less stationary e Updraft thermal o Shape of the cross section o Fixed or variable diameter variable means that the updraft diameter increases with strength o Diameter when a fixed diameter is used o BDiameter strength ratio when a variable diameter is used e Cross country tactics o Speed ring setting o User spec
24. nt drag coefficient C Cp curves Estimated playing time 15 minutes No Topic 1 About C Cp performance curves 2 Lift Drag Settings 3 Curve 1 C Cp Cp visc MRe 1 4 Curve 2 C Cp Cp visc Re varies 5 Curve 3 C Cp Cp total Re varies 6 Curve 4 C Cp Cp induced 7 Comparing C Cp curves 4 SHEET Takes you on a tour through the data sheet Explains Sheet mode commands and the roles of various data fields Shows the effects of different settings on some of the basic and cross country performance curves Also introduces the coefficient of updraft drift Cua and some basic concepts regarding generalized speed to fly theory Estimated playing time 61 minutes No Topic 1 Using the mouse Main menu Help bar Main data sheet The rest of data sheet Moving around the data sheet 2 Types of data fields Editing data fields 3 Sheet Precision Calc Graph Print step 4 Sho amp Co fields for curves and glider cells 5 Low hi limits for diagrams and tables Polar Explorer Version 2 2 Short Guide 9 5 GRAPH V equivalent and W equivalent V and W Wcl max Updraft definition Updr Dia Variable Dia Settings in the bottom table Glider Alt P T Ro u Underlying different settings Using the key Bug W S Ball Mc Wind f Hor V Ver W Cud Generalized speed to fly theory Negative Mc setting Output Atmosphere Takes you through Polar Explorer s Graph mode and explains the Graph mode c
25. ommands Estimated playing time 43 minutes No O ONDUIDSWNA 6 FUNC Topic About Graph mode Display graph Mouse Cursor Diagram elements Basic graph mode commands Win Last Out Pan All Exit X Y Dist Annotating commands Line Rect Circ Text Eras Wipe Hide Xor Edit Graph Polar editing commands Move Drag Ins Rem Shift sCale Undo Grab Takes you through Polar Explorer s menu tree and describes the program functions Also shows how to use glider and sheet libraries Estimated playing time 54 minutes No OONDOABRWD 7 EDIT Topic Menu structure and program functions Glider Glider and sheet libraries Sheet Basic XC Climb Circling Lift Drag Options Sheet lib Glider lib Units Printing options Colors Zero suppress chr Warning sound Enter advance Input checking sAve current options Various diagram options File Exit to DOS DOS shell About Play script T delay Record script Explains Polar Explorer s glider definitions Also demonstrates how to enter a new polar and how to remove any unwanted polar curve irregularities waviness Estimated playing time 33 minutes No BROWN Topic Glider definition Polar type Input Atmosphere Entering a glider definition Glider Alt V W Wing span Wing area Dry mass weight W S Ball Wing planform Aspect ratio correction factor Polar Explorer Version 2 2 Short Guide 10 8 XC CAL Reynolds number exponent
26. rent performance In this chapter we will try to give you some general guidelines on how to assess polar accuracy and also some insight into why gliders of the same type may exhibit different performance We will start by analyzing the influence of the polar source i e whether it has been derived by calculations or in flight performance measurements on its accuracy Calculated Polars Calculated polars are usually produced by sailplane designers and or manufacturers and published in glider flight manuals advertising brochures or magazine ads Up until recently the calculated polars were mostly based on simplified theoretical and semi empirical methods which relied on published airfoil data However numerous comparisons between calculated and measured polars reveal that those methods often tend to overestimate the performance sometimes by more than 10 The following are some possible reasons for the discrepancy e It is very difficult to accurately calculate the interference drag such as the one caused by the wing fuselage connection e Most published airfoil data pertain to very smooth wing surfaces However the real world gliders especially the older wooden and metal ones do not attain the desired surface quality even when brand new e Itis impossible to manufacture wings with the perfect airfoil shape with any of the classic glider manufacturing techniques be it in wood metal or composite materials The actually produced
27. s of a Same Type So far we can conclude that any polar either calculated or measured has a certain margin of error and thus should be taken with some reserve Maybe even more important is to realize that two gliders of a same type may exhibit a noticeable difference in performance This can be caused by the following factors e Since manufacturing and finishing of composite gliders is primarily done by manual production methods the wings that come out of a same mould are not identical neither in mass nor in geometry The same applies even more to metal and wooden gliders As a result two brand new unmodified gliders of the same type can differ in performance as well as in handling characteristics e After several years of production the molds used for manufacturing of composite wings may become slightly deformed If that happens the gliders produced later in the series will most likely have inferior performance to the ones made from the new molds e As a glider gets older the quality of its surfaces begins to deteriorate resulting in loss of performance The extent of surface degradation depends mostly on the type of glider construction and the material used for surface coating It also depends on how well the glider surfaces have been maintained and protected from hostile elements like Sun UV rays rain dust extreme temperatures etc e After coming out of the factory most gliders need some touch up work in order to realize their ful
28. t any altitude and wing loading e Interactively plan and analyze cross country flights with up to five legs in the X Country Calculator spreadsheet e Calculate final glides in the Final Glide Calculator spreadsheet e Optimize configuration and wing loading for any meteo conditions e Apply generalized speed to fly theory to maximize cross country performance when using ridge lift or waves e Compare different gliders by their circling and cross country performances in addition to comparing their speed sink polars Polar Explorer Version 2 2 Short Guide 3 e Design and test speed rings and final glide computers for any wind altitude and wing loading e f you are contemplating any modifications to your sailplane for example adding winglets you can use Polar Explorer to estimate the effects on the maximum glide ratio circling performance average speed on a given task etc Performance Curves Polar Explorer can take any glider polar as a staring point and calculate different aspects of performance in a variety of conditions It can produce the following performance curves shown here grouped into five categories e Basic performance o Speed Sink polar o Speed Glide ratio e Cross country performance o Speed to fly Rate of climb o Speed to fly Rate of climb glider sink rate for direct use on a speed ring for the total energy variometer o Rate of climb Average cross country speed o Updraft strengt
29. the scale factor of 1 in the horizontal direction and the factor of 0 98 in the vertical direction Incomplete Polars In addition to all the uncertainties surrounding the question of polar accuracy you may run into another problem Namely a relatively large number of published polars measured ones in particular do not cover the entire airspeed range In some cases that can have negative consequences on the accuracy of certain performance calculations e Case A If the high speed end of a polar is cut short so it ends below the Vne Polar Explorer will use the cruising speeds only up to the value defined by the high speed end of the polar This is normally not a problem because the extremely high speeds are rarely used anyway In fact you may intentionally cut the high speed end in order to limit the cruising speeds used by the program e Case B Many measured polars and even some calculated ones do not start from the minimum airspeed but rather from a point close to the minimum sink speed Some even don t go below the best L D speed While this may be acceptable for evaluating the straight flight performance e g speed to fly it is totally inadequate for calculating circling performance The low speed end of the speed sink polar is of the foremost importance for realistic calculation of the optimum circling performance If a portion of the low speed end is missing the calculated circling sink rate will be unrealistically high
30. tly still The obtained polar is usually not very accurate unless a large number of points is used e Side By Side Comparison With a Calibrated Glider is a method in which the sailplane being tested is flown side by side with a calibrated glider whose polar is already known Both gliders start from approximately the same altitude and are flown at the same airspeed for a certain period of time During that time one of them usually looses more altitude than the other which can be measured by analyzing the photographs of the two gliders taken from a chase airplane at the beginning and at the end of the glide Since the sink rate of the calibrated glider at that airspeed is known the sink rate of the glider being tested can be determined The same procedure is then repeated for different airspeeds until enough points are obtained to draw the polar The scatter of thus obtained speed sink points is much less than in the descent timing method because the effects of vertical air movement are largely cancelled out by both gliders flying in the same airmass However the whole measurement is based on the assumption that the polar of the calibrated glider has been precisely determined since any error in it will be repeated in the test polar The performance of the calibrated glider is usually measured using the partial glide descent timing method with a very large number of points in order to minimize the error Performance Differences Between Glider
31. to the Play script menu where you can start playing another script Polar Explorer s scripts can only be played forward This also means that you cannot use the AlIt topic number command to jump to a topic that has already passed If you wish to go back you must follow these steps 1 Press Alt 0 to jump to the end of the script or use Alt 7 to terminate playing 2 Restart the same script by using the File Play script function 3 Advance to the desired point usually with the Alt topic number command Contents of Tutorial Scripts This chapter lists short descriptions and the tables of contents of all 11 tutorial scripts It can serve as a reference when using the online tutorial A similar list is given in the INDEX script 0 INTRO Introduces the Polar Explorer program and explains how to use the tutorial scripts Estimated playing time 34 minutes No Topic How to use tutorial scripts List of commands Playing speed and auto pause for message windows Starting scripts General notes on Polar Explorer Licence agreement List of files provided with the program New things in Polar Explorer Version 2 1 A quick tour through Polar Explorer 1 BASIC Basic cross country and climb performance 2 CIRCL Circling performance 11 3 CL CD Lift coef Drag coef C Cp performance 22 4 SHEET Sheet mode and the contents of data sheet 33 5 GRAPH Graph mode and its commands 44 6 FUNC Main menu and program functions 55 7 EDIT
32. u Discu Elfe Elfe Elfe FK 3 FS 24 FS 25 FS FS FS FS 29 29 29 29 O N200GA 2 101 0 15 N70205 J 0 15W N70205 J 0 17 N70205 J S A N52XX 33 J s A W N52XX 33 S3 HB 902 D1 S4 D 6301 D2 S4 D 6668 D2 D 0292 D1 Phonix T D 8385 M Curevo D 8141 D1 13 8m D 2929 D2 lom D 2929 D2 19m D 2929 D2 all D 2929 D2 J J Glasf Glasf Glasf Grob Grob Grob Grob Grob H 101 H 201 H 301 lugel 604 D 8085 D2 lugel 604 N57L J lugel 604 mod N57L J 102 Club IIIb N3981A J 103 Twin II N427BG J 103 Twin II mod J 103C Twin III J 109B N300BG 6390 Salto D 2040 D1 St Libelle D 0082 D1 Libelle D 9412 D1 J H 401 Hi 25 Horne J 4 J Janta Janta Janta Janta Janta Janus Janus Jasko K 7 K 8 K 8 K Ka 6 Ka 6 Ka 6 Ka 6 Ka 6 Ka 6 Kestr Kestr KORA Krani LS 4 LS 4 LS 4 4A Kestrel D 0245 D1 Kria D3 t D 7816 avelin N5TF r 1 NA6DB r 2A N980 r Std N51AS 880 r Std SE TOI D2 r Std 2 N45AS 1863 D 3111 D2 NA68F J lka Z O SZD 8ter D 1800 M D 1590 M M 48 D KIBO BR S D 8390 CR D3 CR D 1810 CR D 1810 CR D 4390 D D D2 J J J J J M D1 M D1 D2 M E D 3657 DE el D 0475 el su 500 1 D KORT D2 ch III D 1398 6446 D2 D 0558 D1 D 3252 D D 3252 D2 N45EW J D 2628 D D 2628
33. y supplied with Polar Explorer We have also included a section explaining what you should keep in mind when analyzing any particular polar since polars are the focal point of this program The comprehensive online tutorial contains all necessary instructions on how to use Polar Explorer It also includes many practical examples that illustrate the influence of various parameters on different aspects of glider performance We are currently working on a printed manual which will contain in depth information on the program and on the theory behind it We sincerely apologize for not having this manual available at this time The main reason is that we have severely underestimated the amount of work required to produce this program together with all necessary support files and printed documentation However as soon as the proper User s Manual comes out of print we will send it to you at no extra charge About Polar Explorer General Notes Polar Explorer is a highly specialized computer program designed for analyzing both theoretical and practical aspects of glider performance in any conditions As far as we know it is the only program of this kind available on the market today Polar Explorer was made with glider pilots in mind but it can also be used by hang glider pilots contest task setters glider designers and the people who make speed command and final glide instruments Among glider pilots the ones who fly cross country or intend to do
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