Raven User`s Manual - Featherweight Altimeters
Contents
1. comm ports show up in the dialog box the highest numbered one will probably be the one with the Raven connected to it The FIP will check to see which of the 5 flight indexes have data in them and will begin to provide real time information from the Raven including barometric pressure in atmospheres accelerometer readings and temperature Raven Status and Data Download The status tab of the FIP shows the current status of the Raven The Flight Data box shows the status of each of the Raven s 5 memory banks and which flight corresponds to each data location COM Raven Checking status of altimeter on Port COMT Connecting to altimeter on COMT _ _connected Checking flight data for light number 1 lt valid gt Checking flight data for flight number z lt valid gt Checking flight data for light number 3 lt valid gt Checking flight data for flight number 4 lt enpty gt Checking flight data for flight number 5 lt vwalid gt Beading bank 0 configuration memory done gt Entering wait mode Live Data 168 014 18 gt 25 4180 025 Live Data Bank 1 AdialGs 0 18 Bank Lateral Gs 0 97 Bank 3 VApogee 41 80 VMain 41 60 Vand 41 80 V4th 41 40 Altitude 5643 BaraAtm Temperature In the example above 4 out of the 5 flight banks are full The most recent flight 6 is located in bank 3 The live data box provides real time status and measurements from the Raven To download2. data select the button Download for the flight data you re interested in and follow the dialog box instructions to save the data to a file The FIP automatically detects the end of the flight but you can interrupt the download before the end of the flight if desired After the download is complete the FIP switches to the data viewing window A data file from a previous download can be opened for viewing using the File Open command Configuring the Raven using the FIP To program and verify the deployment options programmed into your Raven click the Configure tab Apogee Pyro Channel At Apogee Accelerometer Main Pyro Channel At Low Altitude na 3rd Pyro Channel At Apogee Barometric bd 4h Pyro Channel At Low Altitude Backup Lift of detected required Acceleration gt Accel Acceleration lt Accel Time lt user timer value Time gt user timer value a 0o 0 0 u Height Above Pad lt AGLI Height Above Pad gt AGL o 0 0 0o am Sooaa Al A GG Height Above Pad lt AGLI Pressure increasing O K O K O K Pressure decreasing Velocity lt Yel Velocity gt Vel Velocity lt Omph SOO GAOARAAAAGA O Gas GH Gas Hoes E Time delay E Delay 1 50 After Bumout of Motor Number Hold the switch closed continuously E Changes made above are not applied until you use the Program Altimeter Button gt gt Program the Altimeter The logic used for
3. each deployment output is represented as a column of check boxes in the dialog box The headings Apogee Main ond correspond to the text labels on the altimeter All of the channels can be programmed to be used for any purpose though channels 3 and 4 have higher current capability for airstarts The text boxes arranged along the right side are set points that you can change that control the speed altitude etc the altimeter will check for when deciding when to fire the output A deployment channel is triggered when all of the checked flight events are true Note that most flight events like acceleration lt 0 can switch from true to false and back again throughout the flight Other events like time gt user timer value can have no more than one transition during the flight The time delay option will delay the start of the output by the specified time delay after all other conditions are met Note that once the deployment conditions are met the deployment will happen after the time delay regardless of any changes in the deployment conditions after the delay timer has started Each output will be activated for second unless the Hold the switch closed continuously option is selected for that output The continuous output option is designed to turn on a non deployment load like a transmitter This option is not recommended for use with deployment charges because charges can have residual shorts that could drain the
4. flight simulation is available on the cal test tab of the FIP Follow the on screen directions and button labels to perform the flight You can control the duration of the 5G acceleration even turning it on and off to simulate multiple stage flights or air starts The Raven records all the data just as if it were a real flight so you can familiarize yourself with the Raven operation and data review The simulated flight assumes that the Apo output channel is used for apogee deployment and the Main output channel is used for main deployment When the apogee channel fires the simulation applies a 100 ft second descent rate When the main output fires a descent rate of 20 feet second is applied The other two outputs have no effect on the simulated flight trajectory Although the Raven can be mounted in your rocket with either end up the simulated flight must be conducted with the screw terminal block up This is because the simulated thrust is implemented as a test mode of the accelerometer chip that applies the acceleration in a single direction only Caution Do not run a flight simulation with e matches or igniters connected unless the igniters e matches are located away from flammable materials and adequate ventilation is provided In particular do not run a flight simulation with black powder charges or motors connected Viewing the data A data file from a previous download can be opened for viewing using the File Open command The def
5. 5 minutes more The liftoff mode will continue and deployment outputs will function if necessary after the end of the data recording The liftoff mode only ends when landing is detected When the flight conditions assigned for each output are true See configuring the Raven using the FIP section the output switch will turn on The default deployment conditions are the following in deployment depioymeni deployment Altimeter output Main 4th Label Upward velocity lt 400 ft sec lt 400 ft sec lt 0 ft sec lt 400 ft sec from accel Baro altitude Increasing or Decreasing Increasing or Decreasing M aa Altitude above pad above Altitude above pad Any lt 700 feet lt 700 feet feet lt 700feet lt 700feet feet Time delay ee A A BumoutComer 1 n i 1 These default output settings can easily be changed using the Featherweight Interface Program FIP Post flight operation When the Raven is below 2000 feet above the launch pad it watches for the barometric readings to become constant to detect landing After landing the altitude at apogee will be beeped out once and then the red LED will flash once per second These features save battery life To hear the peak altitude after recovery pick up the rocket or av bay and tilt it one direction and then another When the Raven detects that it has been flipped over it will beep out the altitude again The Raven will beep out each decimal of a 5 d
6. E E E seen E E E 12 Contaci Tile Ol AON eseria dead aslewas acetone ccdoseutadonae seed EEEE 12 Mounting and Installation The Raven is mounted with its long axis parallel to the direction of flight Either end can be up the altimeter senses the orientation while on the pad and will work either way The mounting holes accommodate 2 size screws Two 2 56 screws two spacers and two 2 56 nuts are provided Deployment Connections The following diagram and picture show how to connect the Raven for deployments using a single switch that turns on the unit and arms the deployment charges F g Button Mini _ Typical Connections ion CE ats oS be i kis ry one a mw x v i s T Capacitor Buzzer iY f NGE DEY ke switch lo Ha ae 99 eE el L Featherweig Screw switch oe sold separately im T Ps atl A 2 aaz A description of the default program for the 4 outputs is given in the deployment programming section of this document Caution e Do not use this or any other altimeter for deployments until you have performed a ground test to verify that the Raven will work correctly in your rocket and with your pre launch procedures See ground test section Flying the Raven in a rocket with motor ejection or another altimeter you are familiar with is recommended for your first Raven flights Each Raven has passed a basic functional test before shipment but you alone are responsible for ensuring tha
7. In the case of the Raven3 the single beep will also happen if the battery voltage is below 3 85V The Raven will emit a high beep for each channel that is connected and has a voltage applied The original Raven indicated the number of connected charges by beeping once for each connected charge The Raven2 beeps once for each channel and indicates the continuity for each channel by giving a high beep for channels with high continuity voltage and a single beep for channels without a charge connected The order of the channel beeps is the same as the order of the channel outputs along the terminal block First is the Apogee channel then main then ae then 4 In prelaunch mode the blue LED will flash once per second and the red light will flash during beeps The button located on the terminal block side of the board can be used to switch between wait and prelaunch modes The diagram right shows the different operating modes of the butto Raven and the transitions from NNN anded one mode to another NSN Yio Liftoff Baro steady Solid Red Accel gt 3 0 Gs amp Velocity gt 3 ft sec Caution If electronic deployments are expected do not launch unless the Raven is beeping with the expected number of connected output charges Liftoff Detection and flight In prelaunch mode the Raven is watching the axial accelerometer to detect liftoff Any readings less than 3 0 Gs are ignored The Raven is also updating the acceler
8. Raven User s Manual Updated 6 1 2012 for the Raven3 altimeter i rate Table of Contents TORO Gey el keene ee ence te ree te ere eee ee eee eee ere ere 1 Moune ANG MIST ANAMON eseese 2 Deployment C OC COS sossen gae r E R aAa aini 2 POVO e E nen sn ene sccs danse ec ates evaentesnecenee eorceseatsac igs 2 Pon S e E E E E 3 e i 10 TNS BICC A A EA 3 Pe O E E E I E E 3 Litto Detecuon and TUt Dls seperni EE 4 POCE ODO O e E E E 5 Co omp ter Aitached OperdHi ons sosnesgrinsriskadgn nesne Ra eE naaa ER 5 Featherweight Interface Program FIP Installation noesssooeennsssssssseerrssssssssserrssssss 5 Connecting to the Raven using the FIP essesssssseeessssssssseeressssssssceressssssseceeresssssseeeeeee 5 Raven Status and Data Download sccssesacssecssasereccencedensinnaeneesnasatvesdaccueariencedeodsertneisoactuveseste 6 Configuring the Raven using the FIP nneessssssssseerssssssssseerrsssssssseeersssssssesreresssssseeeeree 7 Deployment triggers details and examples cccccccsssssssssccccceceeeeessssecceeeeesaaaeeseeeeeees 8 Cait ati Te ACCC leLOMe 1 ol are EE 10 Running a flight simulation 20 0 eeccccccccccceessesseecccececeaeseeeeeccceeeesaaeesseeeeeseeesaeeeseeeeeees 11 VC EL E E E E eae sae ne E A A sass tues es 11 Calibration and PAC CUVACY ga aiicictecctencpensdeesensetecesaaaiatadencteacbensdcessnsetecetsaaiaieadeesteachensseeneataueede 1 BS CLIN AUN ON ete eerste on cp uassns se eenmn en
9. ated lookup and correction based on this data Specifications Brand WZA AT lai Model Raven3 Contact Information Axial Accel range and Bail aceite OGS 400HzZ na Axial Accelresolution 0 09 Gs featherweightaltimeters gmail com Lateral Accel range and Pop post a message at the forum at ElASA 35 Gs 200 Hz www featherweightaltimeters com Lateral Accel Resolution send a private message to Adrian A Download Interface USB mini via www rocketryforum com or Baro Range kft www rocketryplanet com Baro resolution Pyro Outputs 4 Single battery max output Amps 9 and 40 2 battery max output Amps 9 and 40 Temperature 4 continuity voltages all event logic Other recorded measurements battery V TOURER OPERNE 480 seconds Low rate download time 35 minutes 0 8 x 1 8 x Size 0 5 Mass
10. ault set of measurements shows the altitude above the pad in feet and the axial accelerometer trace Additional traces can be added to the plot using the Parameter selection tool bar Multiple measurements can be plotted on the same time scale by holding down the lt control gt key when selecting the traces The lower section of the parameter selection toolbar allows you to select flight event logic that was recorded during the flight The flight event logic states are the conditions that are measured by the Raven and used in the deployment control logic The deployment output fires when all of the checked logic conditions are true By plotting the voltage on each of the outputs and the flight event logic that was checked during the flight you can verify exactly what the altimeter was firing when and why This is useful for verifying a flight program by looking at the data recorded in a simulated flight which records data just as a real flight would Calibration and Accuracy The barometric sensor used in the Raven is a digital output sensor that contains the entire analog measurement chain on one chip The sensor is factory calibrated over a wide range of temperatures and pressures to provide exceptional accuracy under any rocketry conditions The combination of individual chip calibration and end to end temperature compensation provides barometric accuracy that raises the bar for rocketry altimeters The Raven has less than 1 mbar 0 1 full
11. ecimal altitude in feet starting with the 10 000 place A pause between sets of beeps indicates a change to the next decimal place A short low beep indicates a 0 in that decimal place For example 1024 feet is represented as lt low beep for zero in the 10 000 place gt pause lt one high beep gt pause lt one low beep gt pause lt 2 high beeps gt pause lt 4 high beeps gt The button can be used to switch between post landing mode and wait mode Whenever the mode is switched into wait mode the last apogee altitude will be repeated Computer Attached Operations Featherweight Interface Program FIP Installation Download the FIP installation package from the Featherweight site The installation package contains both the FIP and the USB drivers necessary for the Raven to interface with the computer Double click on the zip package and follow the installation package instructions Connecting to the Raven using the FIP The Raven uses a USB mini connector so a USB mini cable typically used in cell phones digital cameras PDAs etc will be compatible Start up the FIP If the Raven altimeter is already plugged in go to the Altimeter menu and select Connect If the Raven altimeter is not yet plugged in plug it in now and the FIP will detect the connection to the Raven The following dialog box will appear Aloestes Connect Select the correct altimeter model and the comm port to which the Raven is connected If multiple
12. et has gotten past the initial low altitude part of the flight Note that liftoff detection may occur a fraction of a second after 1 motion Height Above Pad gt AGL2 This condition is true when the height above the pad is greater than the user settable altitude AGL2 AGL2 can be set between 0 and 32736 feet in increments of 32 feet This trigger is useful for air start ignition of motors as it can be combed with the time lt TVal to ensure that the rocket is on its way to a nominal flight before igniting the next motor For example if a simulation predicts that the booster sustainer should achieve 7000 feet within 6 seconds you could set the AGL2 to 6000 feet and the Tval to 6 seconds to be assured that the sustainer won t fire if the rocket is tumbling or has a flight angle far from vertical To ensure that the measured pressure won t be affected by Mach transition transients you could also check to make sure that the pressure is decreasing and the velocity is lt 1000 ft second Height Above Pad lt AGL3 used for the default main backup channel This condition is true when the height above the pad is greater than the user settable altitude AGL3 AGL3 can be set between 0 and 32736 feet in increments of 32 feet This trigger is useful for triggering an event below the main altitude For example the main deployment altitude could be set to 1000 feet and a backup main deployment at 800 feet This trigger is also useful as part
13. he trigger will be true Unlike the burnout counter used in other altimeters this version will not mistakenly trip if a launch rod snag or noisy motor burn causes a brief drop in the motor thrust It also won t mistake a stage separation charge from a motor ignition However very low impulse airstart motor may not trigger the burnout counter so this should only be used for motors that will increase the velocity by 40 feet second or greater Calibrating the accelerometer The Raven has a user calibration function for the accelerometer to ensure correct accelerometer operation and account for accelerometer drift over time If the average axial G reading in the live data is outside of 0 8 to 1 2 the accelerometer should be recalibrated To calibrate the accelerometer push the calibrate button in the cal test flight tab and place the Raven on a flat surface on its short edge Follow the FIP instructions to hold the Raven in each of the 4 positions shown Each position is a 90 degree rotation from the previous position cee e J eA ty Are Running a flight simulation The Raven has a flight simulation feature that allows a realistic flight simulation to be performed on the Raven using the Raven s own sensors the current deployment logic and real activation of the outputs This is useful for verifying the deployment settings as well as the compatibility of the Raven power source with the e matches or igniters used The
14. mage to wiring or the connectors at a lower current level than the 40 Amp capability of the Raven3 s FETs Any switch can be used as long as it can handle the deployment charge current Our customers love the Featherweight screw switch because of its reliability tiny size and convenient mounting terminals The screw head wipes and preloads the contacts with every operation The Featherweight magnetic switch is also a great option as no holes or alignment are required to use it and its solid state construction makes it very reliable High G flights For extra durability a dab of epoxy or silicone can be used under the Raven s hold up capacitor to secure it to the board The hold up capacitor is the component wrapped in shiny black plastic next to the USB connector Operation in the Field Although the Raven is designed as an advanced recording altimeter it can be installed and used indefinitely without ever being connected to a computer using the default settings for the outputs The following describes how the Raven is operated at the launch range Pre flight operation Turn on the Raven using an external arm switch The first set of beeps after power up is the battery voltage rounded down to the nearest volt 9 7 Volts 9 beeps After power on the Raven goes into pre launch mode The Raven will beep a low single beep every 2 seconds if no charges are detected or if the accelerometer does not read a near vertical orientation
15. n increments of 32 feet For the rest of the main deployment settings other conditions need to be checked since this condition will be true from liftoff until the rocket gets above the main deployment altitude Velocity lt Vel1 used for the default main deployment channel and backup channels This condition is true when the accelerometer based estimate of upward velocity is lower than Vell This trigger is useful in combination with the pressure increasing trigger to ensure that the rocket is out of the transonic region before using the pressure increasing check The velocity check is also a useful trigger for a stage ignition Optimal altitude can be achieved by allowing the rocket to slow down before 2s stage ignition while maintaining enough speed so that the flight path stays nearly vertical This trigger can be used to ignite a ore stage at the desired velocity even in the event of unexpected drag or motor performance Velocity gt Vel2 This condition is true when the accelerometer based estimate of upward velocity is higher than the Vel2 value Vel2 can be set between 48 feet second and 1998 feet second in 2 f t second increments This setting is one way to check to make sure that the rocket is flying as expected before performing a high speed sustainer ignition If the rocket is in the middle of a tumbling breakup the velocity will be lower than expected Acceleration gt Accel1 and Acceleration lt Accel2 This conditio
16. n is true when the accelerometer s reading is greater than the Accl value or less than the Acc2 value respectively Accl and Acc2 can be set in the range from 50Gs to 50Gs in increments of 0 1 Gs These triggers are useful for detecting staging charges deployment charges motor burns and landing events Note that there are lots of different flight events that can cause changes in the acceleration values so it s important to combine this trigger with other conditions if used For example you could use this trigger to detect landing for a chute disconnect device by looking for acceleration greater than 3 Gs For this application you would also need to prevent a premature deployment by setting the following additional conditions for the trigger the altitude lt AGLI pressure increasing velocity lt Vell to avoid a premature deployment New for the Raven2 not available with the original Raven is a third altitude trigger that makes it easier to set up the landing detection and the main deployment using the same altimeter See Height Above Pad lt AGL3 Time lt user timer value and Time gt user timer value This condition is true when the elapsed time from liftoff detection is less than or greater than the user settable timer threshold TVal TVal can be set from 0 to 51 2 seconds in 0 02 second increments The time gt Tval setting can be used as a simple timer or in combination with other conditions to make sure that the rock
17. of a landing detection To detect landing set AGL3 well below the main deployment altitude but higher than the highest terrain that the rocket might land on Set the velocity lt 0 check so that it won t happen on the way up and set the accelerometer check consistent with the direction of the landing impulse For a typical setup with the rocket s main chute attached above the av bay look for a positive acceleration and use a value that is higher than the rocket might get on the main chute gt 1 5 2 Gs but lower than the landing impulse typically 5 20 Gs Note that the default settings in the FIP for landing detection assume that the av bay will land in the same orientation as it has on the pad If your rocket configuration leads to a nose down landing the landing detection should be set up to look for accel lt Accel2 and Accel2 should be set to a negative number Burnout counter default of 1 for all outputs This condition is the count of the motor burnouts detected by the Raven It is settable between O don t wait for any burnout indication and 1023 not that anyone can make a 1024 stage rocket and the burnout count can be set individually for each output The Raven watches for a change in velocity of at least 40 ft sec and then waits for the velocity to drop by at least 5 feet second before adding to the burnout count When the burnout counter is greater than or equal to the user burnout count for that output channel t
18. ometer calibration offset it uses during the flight to maximize the accuracy of its apogee detection If the rocket is dropped a short distance the Raven will ignore the subsequent contact to avoid premature liftoff detection Despite these features it is possible for the Raven to misinterpret normal handling as a liftoff so do not arm and or turn on the Raven with charges connected until the rocket is installed in the launch rail or tower and the rocket is pointed in a safe direction The Raven will detect liftoff when accelerometer readings in excess of 3 Gs integrate to a 3 mph upward velocity Upon detection of liftoff a prelaunch data buffer of 0 352 to 0 704 seconds will be stored into flash memory and data recording continues from there In liftoff mode the Raven s red LED lights continuously and the following data is stored Periodic measurements e 400 Hz axial Accelerometer 70 Gs or 250 Gs for the 250G model e 200 Hz lateral Accelerometer 35 Gs battery current for the 250G model e 20 Hz Baro data 0 3 accuracy e 20 Hz voltage on each of 4 outputs e 40 Hz output current e 20 Hz high precision temperature sensor e 20 Hz for all flight events used for deployment logic Once per flight e Flight counter e All output program settings e Accel calibrations used during the flight e Pad altitude ASL After the first few minutes of flight the data recording changes to a lower rate and stores approximately 3
19. pyro battery for future use and or damage the FET switch Deployment triggers details and examples Pressure Increasing used for the default apogee main and main backup deployment channels This condition is true whenever the filtered baro pressure measurements are increasing Since pressure decreases with altitude this trigger corresponds to when the rocket is falling This trigger is used for the default main deployment channel so that the ascent is ignored for the main chute deployment Transitions to and from supersonic flight can cause this condition to become true temporarily during ascent That s why the main deployment channel looks for an additional condition the velocity check Velocity lt 0 feet second used for the backup apogee deployment channel This trigger is true when the upward velocity has stopped and the rocket is starting to fall The Raven senses the acceleration and subtracts off what it was reading when it was sitting on the pad about 1 G Then it adds up the accelerations continuously throughout the flight to calculate the velocity This method provides an apogee detection that 1s immune to pressure anomalies but off vertical flights or mis aligned altimeter can affect the apogee detection accuracy Height above pad lt AGL1 used for the default main deployment channel This condition is true when the measured altitude above the pad is below the AGLI setting AGLI can be set between 0 and 32736 feet i
20. scale pressure error over most conditions and less than 3 mbar pressure error 0 3 the temperature range from 40C to 85C and from 1 1 Atm 2500 feet below sea level to 0 3 Atm 30 000 feet above sea level Keep in mind that however accurately the Raven measures pressure converting pressure to altitude results in additional error The Raven uses the International Standard Atmosphere ISA model which uses 3 different formulas for different altitude ranges between sea level and 104 987 feet to compensate for the temperature behavior of different parts of the atmosphere The standard atmosphere model is implemented in the Raven with full ANSI C floating point calculations to avoid errors from numerical approximations The standard atmosphere model however is an approximation to typical conditions for mid latitude locations It assumes a temperature profile that is likely to be colder than typical rocketry conditions For example the standard atmosphere model assumes that the sea level temperature is 59 F and that the temperature at 5400 feet ASL is 40F Errors caused by the atmosphere being warmer than the standard atmosphere can result in reported altitudes that are low by 10 or more For the most accurate conversion between the pressure and altitude use the twice daily balloon sounding data measured by NOAA and conveniently available at http weather uwyo edu upperair sounding html Future versions of the FIP may include an option for autom
21. t your altimeter works for your application and that your rocket will fly safely Power An external battery and a switch are required A 9V battery is recommended but small lithium polymer batteries have also been used successfully The Raven can be powered by any DC power source between 3 8 and 16 V 9V batteries and single LiPoly cells are the most common choices A separate deployment charge battery up to 20V can be used in combination with a lower voltage battery for the electronics An aerogel ultracapacitor will keep the altimeter operational when the power is disconnected for 7 10 seconds The field effect transistor FET used to switch the Apogee and Main deployment outputs is rated for 9 Amps for pulses lt 5 seconds and has an Rds on of about 20 mOhms The Raven can be damaged by deployment currents in excess of 9 Amps or by connecting a 9V battery to the altimeter with the leads reversed Please carefully note the battery polarity before connecting it The 3 and 4 channels are recommended for airstarts because they are designed with larger output FETs that can handle higher current up to about 13 Amps in the case of the Raven and 2 models and 40Amps in the case of the Raven3 Motor airstarts typically result in short circuits as soon as the motor ignites so be sure to use batteries for airstarts that cannot exceed the FET rated current when shorted Currents in excess of 20 Amps have not been tested and may result in da
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