EXPERIMENTS IN HIGH ALTITUDE BALLOONING 08/28/2014 Andrew Donelick Harvey Mudd College
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
Basic Balloon Train
The Old System Copy of Moscow High School setup Balloons: 1200 1600 gram latex Lifting gas: helium Payloads: passive, uncontrollable Tracking: APRS radio transmitters
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?
Ground Improvements Changing the lifting gas Add car tracking GPS system Change launch time procedure
Hydrogen Lifting Gas First modification to the original setup Benefits: Much cheaper than helium Renewable Greater lift Drawbacks: Highly flammable http://www.safetysupplywarehouse.com/dot_placard_1049_hydrogen_compressed_p/dot-1049.htm
Hydrogen Results Completely satisfied Record high altitude achievements Max altitude: 118,000 feet MSL Monetary savings: $425 http://www.safetysupplywarehouse.com/dot_placard_1049_hydrogen_compressed_p/dot-1049.htm
Improved Tracking Same APRS setup for payload Attached GPS to chase vehicle Easily integrated into APRS Point
Tracking Example
Launch According to Weather Not a new idea Ideal launch: Low winds Clear skies The balloon fills itself!
Flight Systems Improvement Test new sensors, flight computer Construct long range radio system Receive data from balloon Transmit commands to balloon
Module Design General design Designed around Arduino Mega 4 UARTs 54 digital I/O pins 16 analog I/O pins Module name: Sparky
Instrumentation Instruments chosen to collect general flight data Sampling rate: ~10 Hz Data logged onto onboard MicroSD card
Internal Temperature 3 sensors 2 analog sensors, different locations 1 digital sensor (integrated with pressure) https://www.sparkfun.com/products/10988
Atmospheric Pressure 1 digital sensor, internally mounted Also provided an internal temperature measurement https://www.sparkfun.com/products/retired/11282
Humidity 1 analog sensor, internally mounted https://www.sparkfun.com/products/9569
External Temperature 1 digital sensor, externally mounted 12 bit precision Accurate measurements down to -55 C https://www.sparkfun.com/products/245
Attitude Pitch, roll and yaw IMU composed of three sensors: 3 axis accelerometer 3-axis gyroscope 3-axis magnetometer https://www.sparkfun.com/products/10736
Altitude (GPS) GPS4 Byonics GPS receiver TinyGPS++ software package http://www.byonics.com/tinytrak/gps.php
Relays 4 reed relays Allows for heater control, cutdown http://www.amazon.com/sainsmart-4-ch-4-channel-relay-module/dp/b0057oc5o8
Electronic Heater Five 30 Ω power resistors in parallel One 9 volt battery 13.5 watts of power Continuous operation for 2 hours
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
Radio System Overview Requirements: Direct communication Cheap Flexible
Packet Scheme Composed of 16 bit unsigned integers Packet contains: Source Packet type Commands (if any) Data Values Checksum
Software Implementation Developed new Arduino library: PacketRadio All complex operations handled in library
To Send a Packet Initialize the radio, packet Send the packet
To Receive a Packet Receive the packet:
To Receive a Packet Check packet type Data report: decode sensor readings Command: execute command Command response: check for errors
Hardware Implementation Complete system (receiver and transmitter) requires: Two 2-meter transceivers Two radio modems Two microcontrollers
Hardware Implementation
Ground Control/Monitoring
Live Instrument Monitoring
Error Monitoring
Control
Control Possible commands: Change transmission rate Toggle manual heater control Toggle heater Cutdown module from the balloon Toggle relays
Instrument History
Packet Logging
Problems Encountered Three flights: Sparky 1 & 2 Lost contact halfway through flight Sparky 3 Lost contact immediately after launch All flights: Abnormal data readings
Possible Causes User error Instrument Readings Radio interference Unknown software problems
Future Work Isolate code that fails Fix any problems Extract GPS position Move data logging to separate processor?
Other Experiments/Projects Custom constructed zero-pressure balloon Upper atmospheric wind tracing experiment Ascent rate modification
Zero Pressure Balloon Different balloon construction Unstretchable polyethylene Balloon pressure = ambient pressure Constant altitude Longer flights
ZP Balloon Design
ZP Balloon Construction
Ascent Rate Modification Use small thrusters to decrease balloon s effective weight Temporarily increase ascent rate Generate exhaust contrail Trace upper atmospheric winds?
Ascent Rate Modification One test flight (Sparky 2) Ignition of propellant failed Possible problems: Low temperature Low pressure
Future Work: ZP Balloon Prototype: Finish construction Test for leaks Fly small payload Other: Improve sealing technique Scale to larger balloon sizes
Future Work: Tracing/Thrust Achieve high altitude ignition New propellant type New ignition method Develop better heat resistant casing
Conclusion Successfully improved launch cost, recovery time, and altitude achievements
Conclusion Constructed and tested a new two-way radio communication system Mostly successful Almost ready for general use
Conclusion Significant progress made on new zero pressure balloon design/construction More work needed to test prototype Faster construction would help More people?
Conclusion Ascent rate modification/wind tracing still in experimental development stage
Acknowledgements Pat Blount Dr. David Atkinson Margaret Donelick
Questions?