This mission will use a military surplus ML-541A/AM balloon, and try to achieve 100,000 ft. It will include a Peach1 tracker as well as a newer model Peach3 tracker, which we will test in harsher conditions outside of the insulated payload package. The trackers will each be beaconing once per minute, 30 seconds apart. We'll again include an 808 Key Fob camera.
The balloon burst at approximately 83,000 feet. It was recovered successfully. Unfortunately, the 808 camera did not work. The SD card was faulty, so we did not get in-flight video.
|Balloon||ML-541A/AM military surplus balloon, readily available on ebay|
|Payload||Peach1 Tracker, Peach3 Tracker, Micro camera|
|Payload container||Plastic bottle and bubble wrap|
|Max Payoad Weight||150g|
|Flight Time||130 min|
|Tracking||Peach1 HAB tracker, Peach3 HAB tracker|
|Telemetry||GPS and temperature data.|
|Tracker1 + Counterpoise||19|
|Tracker1 Battery - (1) AAA Ultimate Lithium||8|
|808 Camera 1||19|
|Camera Battery - (1) 600ma LiPo||16|
|Parachute + guyline||17|
|Peach3 Tracker, antenna, battery, packaging||46|
|Buzzer + CR2032 Battery||8|
|Balloon attachment (tape)||10|
|Total (goal: 1550)||1560|
|ML-541A/AM military surplus balloon||$40|
|Helium or Hydrogen (80 cu ft cylinder)||$66|
|Mini camera & SD card||$30|
|Balloon Mass||1200g Kaymont|
|Target Ascent Rate||4.5 m/s|
|Descent Rate||8.5 m/s|
|Start Location||Lyons, New York|
|Burst Altitude||30157 m|
|Ascent Rate||4.83 m/s|
|Neck Lift||1089 g|
|Launch Volume||78.7 cu ft|
|Flight Range||84.3 km|
|Flight Time||131 min|
*Note: We're totally guessing on the burst diameter based on data from only two previous flights documented through links on eBay. This will be a learning experience.
Using volume of a sphere for 78.7 cu ft
We called it 16' 8 1/2“ circumference.
Expected pounds of gas to use:
PSI = volume / .0265 PSI = 78.7 / .0265 PSI = 2970 PSI drop in tank.
The 808 camera in the payload did not function. It is suspected that a bad SD card led to the camera crashing moments after being turned on. Unfortunately, the activity lights on this camera both go off when the camera is filming, so it's impossible to tell “filming” from “off”. That's an unfortunate design with these cheap cameras.
This is an overlay of the prediction (Yellow) with the actual (Red). Note the balloon did not go as high, so it did not carry as far west in flight.
This is a map view, with data from both trackers overlayed. Though they were both attached to the balloon, there were minor differences in positions reported, and they beaconed at different times within each minute of flight.
|Ascent Rate||4.83 m/s||4.31 m/s|
|Descent Rate||8.5 m/s||7.07 m/s|
|Flight Range||84.3 km||49.54 km|
|Flight Time||131min||157 min|
Note, given that the balloon was overfilled at launch to nearly 6' in diameter (113 cu ft), the predictor indicates that the ascent rate should have been about 8.66m/s. This very closely matches our observed ascent rate of 8.57m/s. Let's hear it for science!
We had two temperature sensors on the launch. One tracker was inside the insulated plastic bottle with bubble wrap. The other was in a “cozy”, but otherwise exposed to the elements.
The tracker in the bottle reached a minimum temp of -6c.
The tracker more exposed to the elements reached a minimum temp of -50c.
Both trackers reached minimum temperatures on descent, after the balloon popped.
The 808 camera did not work on this flight. Subsequent testing after launch indicated that the SD card had a format error that was not immediately obvious with short tests. In subsequent launches we should do a full duration test of the camera / SD card prior to launch.
The balloon landed, of course, in a tree just a few feet from the edge of an open field. It was about 40-50 feet up.
After some searching, we found the land owner and got permission to cut the tree down and recover the payload. The land owner even provided the chainsaw!