EdWalker
Posts: 3
Joined: Sun Feb 24, 2013 1:37 pm

Parachute release

Sun Mar 10, 2013 4:49 pm

Hello.

My team and I are sending a raspberry pi 24 km into the sky. I've programmed it so that once it reaches a certain descent speed, it will give the command to release the parachute. Problem is, once it receives the command to release the parachute, how would it actually release? Is there an item which I'll need to make this possible?

I'd be grateful if this question could be answered.

Ravenous
Posts: 1956
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK

Re: Parachute release

Mon Mar 11, 2013 9:28 am

Have a look at this post:

http://www.raspberrypi.org/phpBB3/viewt ... 45#p121445

That poster (daveake) is one of the balloonatics around this forum who knows a thing or two about falling from a great height. There have been other proposed projects too but I don't know how many have actually flown. It may be worth searching for those posts and following the projects to their blogs...

User avatar
daveake
Posts: 184
Joined: Thu Jul 12, 2012 12:07 am

Re: Parachute release

Mon Mar 11, 2013 10:59 am

Yeah, don't do it like that!

The rocket guys use releasable parachutes all the time, but if a deployment fails (and they do) the rocket destroys itself into the ground near the launch site. I've seen a video of this happening and it made a pretty big hole in the ground. With a balloon the landing spot could be anywhere, and a failed chute is going to see your payload meet the ground (or whoever/whatever happens to be in the way) quite quickly.

Failures can happen for lots of reasons - mechanism jamming, software error, problem with the Pi, or the GPS not reporting the altitude (you'll get this above 18km if you don't use the right type of GPS and in some cases if you don't put it into "flight mode").

Instead, do what everyone else does - use an inline chute. This will (no ifs, no buts, *will*) open automatically, within a few seconds of the balloon bursting. You can buy a specially made 'chutes from http://randomsolutions.co.uk/Random_Aer ... hutes.html, and these have a hole in the top with short lengths of tape sewn in. You tie the balloon to these, and you hang the payload below.

Dave

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Parachute release

Mon Mar 11, 2013 11:49 am

It is like the old parachuting joke its not jumping out of the plane that kills you its hitting the ground
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

LesTroyer
Posts: 14
Joined: Wed Aug 29, 2012 2:38 pm

Re: Parachute release

Tue Mar 12, 2013 7:08 pm

flash bulbs and black powder are very reliable for deploying a chute - what usually fails is the computer. Batteries come unplugged, things dislodge under high-G.

Les

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