This mission will use a military surplus ML-541A/AM balloon, further refining our estimate of that envelope's burst diameter and characteristics. It will include a Peach3 tracker and two 808 #16 cameras. One will point to the horizon and the other up toward the balloon. We will add some stabilizing bars to the payload to attempt to improve video quality.
The balloon burst early in turbulence, after the payload bounced up and struck it. The moment was captured on video. The stabilizing bars worked nicely to clean up the video.
|Balloon||ML-541A/AM military surplus balloon, readily available on ebay|
|Payload||Peach3 Tracker, 808 #16 Micro camera|
|Payload container||Foam box with stabilizing bars extending from it.|
|Max Payoad Weight||200g|
|Flight Time||Under 180 min|
|Recovery||Small drogue chute|
|Tracking||Peach3 HAB tracker|
|Telemetry||GPS and temperature data.|
|Tracker + Counterpoise||12|
|Tracker Battery - (1) L92 AAA Ultimate Lithium||9|
|#16 808 Camera w/SanDisk 16G SDHC I, Class 4||10|
|#16 808 Camera w/SanDisk 16G SDHC I, Class 10||10|
|Camera Battery - (2) L9 AAA Ultimate Lithium||33|
|Guylines + Chute||14|
|Beeper + Battery||8|
|Balloon attachment (Final string and tape)||40|
|Total (goal: 1400)||1461|
This is the tracker plus AAA battery weight. Note this was actually from a different launch configuration, but the same idea. For THIS launch, we did not secure the battery to the tracker, and the string was not present.
This image is the internals of the payload before we chose to add the second camera. It shows the general placement of the tracker and first camera.
|(2) Mini camera & SD card||$100|
|ML-541A/AM military surplus balloon||$40|
|Helium (80 cu ft cylinder)||$71|
|Balloon Mass||1200g Kaymont|
|Target Ascent Rate||5.0 m/s|
|Descent Rate||9.8 m/s|
|Start Location||Seneca Castle, New York|
|Ascent Rate||5.52 m/s|
|Neck Lift||1280 g|
|Launch Volume||85.3 cu ft|
|Flight Range||65.2 km|
|Time to burst||82 min|
|Flight Time||102 min|
Using volume of a sphere for 76.3 cu ft
We called it 17' 1 7/8“ circumference.
Expected pounds of gas to use:
PSI = volume / .0265 PSI = 85.3 / .0265 PSI = 3218 PSI drop in tank.
|Ascent Rate||5.52 m/s||4.9 m/s|
|Time to burst||01:22:00||00:57:00|
|Descent Rate||9.8 m/s||9.3 m/s|
|Time to descend (predictor)||00:20:00||00:29:54|
|Time to descend (altitude / descent rate)||00:50:11||00:29:54|
|Flight Range||65.2 km||85.7 km|
Balloon burst early after striking the payload in turbulence.
Given that the payload bounced and hit the payload, it seems the tether was too short. For this launch we had:
|Balloon to chute top||7' 10”|
|Chute top to chute gather||1' 10“|
|Chute gather to payload gather||3' 8”|
Lowest observed temperature was -27.6c on the descent at 9774 meters (32,066 ft).
Temperature at apogee (16,707m = 54,819 ft) was -18.4c.
The upward facing camera failed shortly before landing. I believe it was a thermal problem that we observed in ground testing. It most likely overheated as the payload got to near normal external temperatures. The horizontal camera worked flawlessly through the launch and landing.
Recovery was trivial. It was on the ground beside a driveway. Once getting a beacon from the payload as we drove by it, we were able to drive right to it, and heard the beeper on the payload as we approached.