Sunday, August 2, 2009

Rocket Chute Deployment

I have a friend who does model rockets as a hobby. He was looking at getting an off-the-shelf deployment module for adding a parachute to his project. I mentioned that we could do it with an arduino and some sensors.
I had him check digikey.com for a cheap altimeter, and we found one for $7, but the lead time was too long. He's moving pretty soon, so we needed an immediate solution. I decided that we could use an accelerometer, and when it reads 0-Gs on the vertical axis, we'd know it was free-falling. (or had ended acceleration)

We set up a timer that would deploy the parachute a given time after the acceleration ends.


The red and blue wires arm the device. These get twisted together after you get the rocket set up. so it won't go off unexpectedly. The device also monitors the nichrome ignition wires. If one of the wires gets broken, you can tell from the LED indicators on the bottom.

Here's the underside of the board. I drew it up in EAGLE and etched it in the shop at work. You can see it's a little on the hablich side, needs a dose of alcohol and it could also use a small redesign. I noticed after I got the software running that a couple of the outputs were configured wrong in the hardware. If I ever make a V2.0, it'll be a little more attractive.

Hopefully we'll be able to test it out next week after I get back from Mexico.

4 comments:

Aaron, Vicki Tunell said...

I think I'm the only one who knows what hablich means :) Great job on the rocket, you are so dang smart babe.

Vicki

Chris said...

So much technical information makes my brain scramble!!! Maybe it started out scrambled. Good luck in your travels and BE SAFE!!
You are too smart(epants)!
Mommy

Pryankster said...

Hey! I think I have your boards... My BatchPCB order came in, and I thought I got a huge overrun of 20 boards (I ordered 2 boards ... ) but when I looked at them, they were not mine. The boards are marked "FreePoint", with a foot print for an AVR and an XBee module ... drop me a line at pryanksterNN at gmail.com (where NN is 69 :-)

-- pryankster

dad said...

Is this like hässlich?
I don't think it is so ugly, perhaps a little flat blak paint?
xo