EXPERIMENTS IN HIGH ALTITUDE BALLOONING

Transcription

1 EXPERIMENTS IN HIGH ALTITUDE BALLOONING 08/28/2014 Andrew Donelick Harvey Mudd College

2 Overview My whole summer! Launch and tracking improvements Implementation of radio system Additional side projects: Zero pressure balloon development Wind tracing experiment Ascent rate modification

3 Basic Balloon Train

4 The Old System Copy of Moscow High School setup Balloons: gram latex Lifting gas: helium Payloads: passive, uncontrollable Tracking: APRS radio transmitters

5 The Old System Drawbacks: Expensive to launch Uncontrollable once released Data recovery dependent on module recovery Finding landing location difficult How to solve these problems?

6 Ground Improvements Changing the lifting gas Add car tracking GPS system Change launch time procedure

7 Hydrogen Lifting Gas First modification to the original setup Benefits: Much cheaper than helium Renewable Greater lift Drawbacks: Highly flammable

8 Hydrogen Results Completely satisfied Record high altitude achievements Max altitude: 118,000 feet MSL Monetary savings: $425

9 Improved Tracking Same APRS setup for payload Attached GPS to chase vehicle Easily integrated into APRS Point

10 Tracking Example

11 Launch According to Weather Not a new idea Ideal launch: Low winds Clear skies The balloon fills itself!

12 Flight Systems Improvement Test new sensors, flight computer Construct long range radio system Receive data from balloon Transmit commands to balloon

13 Module Design General design Designed around Arduino Mega 4 UARTs 54 digital I/O pins 16 analog I/O pins Module name: Sparky

14 Instrumentation Instruments chosen to collect general flight data Sampling rate: ~10 Hz Data logged onto onboard MicroSD card

15 Internal Temperature 3 sensors 2 analog sensors, different locations 1 digital sensor (integrated with pressure)

16 Atmospheric Pressure 1 digital sensor, internally mounted Also provided an internal temperature measurement

17 Humidity 1 analog sensor, internally mounted

18 External Temperature 1 digital sensor, externally mounted 12 bit precision Accurate measurements down to -55 C

19 Attitude Pitch, roll and yaw IMU composed of three sensors: 3 axis accelerometer 3-axis gyroscope 3-axis magnetometer

20 Altitude (GPS) GPS4 Byonics GPS receiver TinyGPS++ software package

21 Relays 4 reed relays Allows for heater control, cutdown

22 Electronic Heater Five 30 Ω power resistors in parallel One 9 volt battery 13.5 watts of power Continuous operation for 2 hours

23 Radio Communication Most difficult portion of the project! Custom designed for ballooning Packet scheme Software implementation Hardware implementation Enables two way communication between ground and the balloon

24 Radio System Overview Requirements: Direct communication Cheap Flexible

25 Packet Scheme Composed of 16 bit unsigned integers Packet contains: Source Packet type Commands (if any) Data Values Checksum

26 Software Implementation Developed new Arduino library: PacketRadio All complex operations handled in library

27 To Send a Packet Initialize the radio, packet Send the packet

28 To Receive a Packet Receive the packet:

29 To Receive a Packet Check packet type Data report: decode sensor readings Command: execute command Command response: check for errors

30 Hardware Implementation Complete system (receiver and transmitter) requires: Two 2-meter transceivers Two radio modems Two microcontrollers

31 Hardware Implementation

32 Ground Control/Monitoring

33 Live Instrument Monitoring

34 Error Monitoring

35 Control

36 Control Possible commands: Change transmission rate Toggle manual heater control Toggle heater Cutdown module from the balloon Toggle relays

37 Instrument History

38 Packet Logging

39 Problems Encountered Three flights: Sparky 1 & 2 Lost contact halfway through flight Sparky 3 Lost contact immediately after launch All flights: Abnormal data readings

40 Possible Causes User error Instrument Readings Radio interference Unknown software problems

41 Future Work Isolate code that fails Fix any problems Extract GPS position Move data logging to separate processor?

42 Other Experiments/Projects Custom constructed zero-pressure balloon Upper atmospheric wind tracing experiment Ascent rate modification

43 Zero Pressure Balloon Different balloon construction Unstretchable polyethylene Balloon pressure = ambient pressure Constant altitude Longer flights

44 ZP Balloon Design

45 ZP Balloon Construction

46 Ascent Rate Modification Use small thrusters to decrease balloon s effective weight Temporarily increase ascent rate Generate exhaust contrail Trace upper atmospheric winds?

47 Ascent Rate Modification One test flight (Sparky 2) Ignition of propellant failed Possible problems: Low temperature Low pressure

48 Future Work: ZP Balloon Prototype: Finish construction Test for leaks Fly small payload Other: Improve sealing technique Scale to larger balloon sizes

49 Future Work: Tracing/Thrust Achieve high altitude ignition New propellant type New ignition method Develop better heat resistant casing

50 Conclusion Successfully improved launch cost, recovery time, and altitude achievements

51 Conclusion Constructed and tested a new two-way radio communication system Mostly successful Almost ready for general use

52 Conclusion Significant progress made on new zero pressure balloon design/construction More work needed to test prototype Faster construction would help More people?

53 Conclusion Ascent rate modification/wind tracing still in experimental development stage

54 Acknowledgements Pat Blount Dr. David Atkinson Margaret Donelick

55 Questions?