High Altitude Balloon project

So we've started a new project at the shop: a high altitude balloon. This started when we acquired an 80ft^3 Helium tank when we bought out at an estate full of old tools and supplies. The eventual goal would be to be able to send a package of instruments and a camera up to 100,000' and recover it at will. Rather than risk $100s in electronics right off the bat, we've decided to use a "progressive" approach to gain experience and test systems. Here is what we've done so far:

1. The $1 flight: We bought some 17" "jumbo" party balloons from the balloon wholesaler down the street. (Funtastic on Lemon/Raymond). Some testing shows that this balloon will burst at 24-25" and has a gross lift of just over 35gm. Based on this, we flew one with 22.5gm of payload (sand) and got around 150m/min in climb (estimated). Using the balloon burst calculator, we estimate that this balloon could go to 20-25K feet.

Status: Successful

2. The $10 flight: We launched the same balloon, but added the following:

• A parachute of 20cm, made from a black trash bag, some 6lb test fishing line and a bit of Scotch tape and a fishing swivel.
• A small radio beacon, made from leftover parts. Used a 23A battery and a 6" piece of 30ga wire for the antenna. We had trouble getting it to oscillate with a bigger antenna attached, probably due to capacitance issues.
• 3m of 10lb test fishing line to hold it all together.
• A 10K thermistor from Sparkfun.com, to change the beacon's tone in response to temperature.
  

This package got flown last weekend in the Mojave desert. What we learned:

1. This balloon/weight combination has plenty of lift to send the package much farther away than you can see even with binoculars.
2. The tiny radio transmitter, with its inefficient antenna and <20mw output could not be tracked after about 30seconds, even with a good directional antenna and receiver.
3. The white styrofoam package with clear tape and the black 'chute were very visible, even at several miles.
4. Testing the parachute from the roof of the shop shows that it deploys 100% of the time. 60gm of weight could be brought down nicely with a 30cm chute.

We did not get this package back, due to the wind picking up and sending it over a mountain.

Status: Partially successful


Arclight