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