109 lines
3.8 KiB
Markdown
Executable File
109 lines
3.8 KiB
Markdown
Executable File
## Flight Summary
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Flight date: 8/21/10
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Time of liftoff: 10:47 (All times are GMT-5)
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Time of touchdown: 11:49
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Time of recovery: 12:20
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Total flight time: 1:02 (62 minutes)
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Liftoff to recovery time: 1:33 (93 minutes)
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Touchdown to recovery time: 0:31 (31 minutes)
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Weight of payload/chute: 1lb 13oz
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Total cost of launch: \$320
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## Airframe & Rigging
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Balloon: 800g Kaymont/Totex latex weather balloon cost: \$69
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Parachute Cord: 250-lb test Dacron line
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Balloon Cord: 50-lb test Dacron line
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Fill: 190 cubic-feet Helium - cost: \$95 (~10# nozzle lift, gas @
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\$0.50/Cu-ft)
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Chute: Rocketchutes flat 24" - cost: \$9
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Capsule: Insulated lunch pail (free, valued at ~\$7)
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## Payload
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Canon model PowerShot SD300 running CHDK (Canon Hack Development Kit)
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intervalometer script - cost: \$20
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Canon Li battery cost: \$3.25
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Canon 2GB SD card: \$6
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Falcom (uBlox based) GPS receiver + Serantel Antenna module - cost \$47
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Radiometrix VHF Narrow Band 300mW transmitter - cost \$38
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Ultralife U9VL-X Lithium-Manganese Dioxide non-rechargable battery cost:
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\$7
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Flight computer/Terminal Node Controller (TNC) - cost \$19
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[HacDC Spaceblimp Flickr Group
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Pool](http://www.flickr.com/groups/spaceblimp/pool/with/4922202931/)
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[aprs.fi Flight
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Map](http://aprs.fi/?call=w3hac-11&dt=1282348800&mt=roadmap&z=11&timerange=3600)
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## Some details on the avionics
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Our balloon carried a minimalist avionics package consisting of a custom
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built APRS tracker and a Canon PowerShot SD300 digital camera.
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The camera is configured to take pictures every 20 seconds using CHDK
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(http://chdk.wikia.com/wiki/CHDK) and one of the stock intervalometer
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scripts. It is powered by its own rechargeable lithium battery and
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operates independently of the tracker.
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The tracker is based around an atmega328p AVR microcontroller, running
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code derived from an open source AVR based APRS tracker called the
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WhereAVR (http://garydion.com/projects/whereavr/). By updating the sine
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wave generation code to use filtered 7-bit pulse width modulation in
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place of the 4-bit resistor network, we were able to improve tone
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quality with a reduced part count. A few additional components were
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added, including an I2C eeprom for local backup of flight data, external
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and internal I2C temperature sensors, and a cutdown MOSFET for switching
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power to a short strip of nichrome wire coiled around the balloon line
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(the cutdown system was not used in our final flight because we were
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apprehensive about the complications it added to the balloon rigging).
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To keep things light, compact, and simple, we designed a surface mount
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circuit board to integrate all of the trackers components with a Falcom
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FSA03 GPS module and a 300mW Radiometrix HX-1 144.39 MHz transmitter.
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The board was fabricated using the toner transfer method and hand
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soldered.
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For an antenna we used the common 300 ohm twinlead j-pole design
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(http://www.qsl.net/wb3gck/jpole.htm), tuned as close as possible for
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use on our frequency (144.39 MHz) and fed with a short length of 50 ohm
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coax cable for routing/strain relief.
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The tracker is powered by a single lithium 9v battery, and regulated
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down to 5v and 3.3v by linear regulators on the board. The typically
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undesirable loss of power to heat with these regulators is useful in
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this case for warming the electronics in the extreme cold temperatures
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encountered during the flight.
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Each chase vehicle had a radio tuned to 146.415 for simplex
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communication between the vehicles, and another radio tuned to 144.390
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for receiving packets from the balloon. For packet decoding we used
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radios with built in TNCs or laptops with external modems/soundcard
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modems and TNC software (Soundmodem and Xastir for Linux, AGWPE and
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UI-View for Windows).
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## Data
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The onboard data recorder from SB2 returned: [Media:
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blimp2_eeprom_log.txt](Media:_blimp2_eeprom_log.txt "wikilink") |