Comment by Ellison Chan on May 21, 2012 at 11:12am

What shoot deployment system is used for drag racing cars?

Comment by Bradley J Carr on May 21, 2012 at 11:17am

Ellison,  They use a pin and spring. With the cable attached to a lever in the car and also to the pressure release on the blower.

Comment by Ellison Chan on May 21, 2012 at 11:25am

Wouldn't such a system work for a plane, if the pin was operated by a servo or solenoid?

Comment by Bradley J Carr on May 21, 2012 at 11:32am

10-4.  I think it would be simpler to do.  Rather than a rocket engine.  How I would make it would be with a cloth small bag.  Then I would make like flaps and put something in the bottom for the spring to push on.  so when it was all packed nice and neat into the little bag.  Then you would have to make it so that a pin would hold the two flaps together.  Then hit the button and pulls the pin and pushes the chute out.

Comment by Alex Hills on May 21, 2012 at 2:31pm

I think the best solution would be to use a blast cap like at the bottom of this link: https://publicmissiles.com/secure/components.asp?groupid=26

and epoxy that to a wood bulkhead that you can epoxy to your rocket body tube.  I drew a picture of the setup I have in mind.  It uses estes parts and that blast cap.  You would need a little black powder or equivalent as a charge.  This is what they do in sport rocketry and the same thing used in the estes engines.

Comment by Alex Hills on May 21, 2012 at 2:34pm

If you wanted to do the same setup you had before I'd say use a nylon parachute ($12) and a stronger, fire resistant shock cord.  Also cover the bottom of the plane near the motor with a layer of aluminum foil.

Comment by Ellison Chan on May 21, 2012 at 2:42pm

Ok guys, just some additional comments.  I believe there are existing model rocketry regulations that prohibit the mounting and firing of rockets in horizontal position.  This prevents model rockets from being used as small missiles.  Also I'm not sure that bringing up of explosives, like blasting caps into the air is allowed.

Comment by Jack Crossfire on May 21, 2012 at 11:04pm

Definitely 1 of the funnier parachute failure videos.  Any proper Rube Goldberg machine has a toaster somewhere, to go with the rocket engine.

Comment by Mike Bristol on May 21, 2012 at 11:16pm

I second the traditional method.  Try using a spring loaded pilot chute.  Much simpler than a ballistic system.  I should know, I've got a few thousand skydives.  The spring loaded pilot chute is used on sport parachute reserve systems and emergency pilot rigs and are extremely reliable (I've had 8 reserve rides and witnessed countless others).  The idea is the spring inside the pilot chute is compressed and packed on top of the canopy and held in place by flaps, a loop and a pin connected to a rip cord.  The pin is pulled (or the loop is cut) and the spring fires out, catches clean air and drags the canopy with it.  Super simple :)

Moderator Comment by Brian on May 21, 2012 at 11:35pm

From my experience dabbling with a parachute recovery system it's easy to arrest the flight too quickly and cause damage to the air frame.  I had used a method similar to one listed above where a servo triggered released a rubber band holding my parachute.  I used a longer band that was wrapped around  the chute in such a way that it would flip the parachute out to the side to ensure it deployed correctly.  It was anchored using several larger sized rubber bands to the boom of my SkyFly Max.  It worked well to stop/drop the plane but did cause the eventual failure of the platform.  The stress from the arrest caused the fuse to crack where the boom was attached into the body.

It was fun but my caution would be to not anchor it too rigidly.  Use some thing that can absorb the shock of the  chute deploying but not too tight to cause damage like mine did...  Good luck and btw... foam and fire not a good combo...

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