Help designing/building High Altitude Balloon cut-away system

I am working with my kids to put together a High Altitude Balloon launch to take pictures.

I am stuck at building a system to cutaway the balloon in the event that it does not reach burst altitude.

Any help, or resources that would get me going would be appreciated.

I am leaning towards a system that can me initiated from the ground via ham radio, as well as timer based in the event of communication failure.

Thanks!

Make an arduino clone with arctic or mil-spec rated components that will survive close to -80C since that's about how cold it is at 36000ft at night. If you can do that, get it to listen for signals from your radio.

If not, try messing with some suitable 555 timers that trigger some fuse to light.

Or if there's no suitably rated parts, make the board with what you can and seal it in a brick of styrofoam insulation.
PKM5 years ago
You might learn a lot about how not to do it by reading the story of PARIS (paper aircraft released into space) over on The Register. They tried to invent a very clever but over-complicated altitude release mechanism, which failed to work (but thankfully the plane released when the balloon burst anyway).

An electronic timer, with the beeper wired to activate a simple electric release mechanism (a solenoid, perhaps, or an igniter and some pyrogen if you can get hold of them) has few potential points of failure.  Just make sure whatever you use can deal with low temperatures- it's cold up there!
Kiteman5 years ago
(Moved to Tech)

A long piece of slow-burning fuse, with the non-lit end taped to the balloon skin?