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Easy non-electronic parachute deployment

Posted: Sat Nov 12, 2016 2:26 pm
by CheesyIceCream
I'm working on a rocket, and I would like it to have a parachute deployment system, but I want to see if there is any simple way to get a parachute to deploy in-flight without electronics packages.

help plz

Re: Easy non-electronic parachute deployment

Posted: Wed Dec 14, 2016 9:16 am
by anoymous
i searched for that too, but in the end we just used one with an altimeter based one (an arduino version of USWR's LaunchPad alTImeter).
That was more reliable and we couldn't get timers.
If you can get a tomy timer, you could try that?

Re: Easy non-electronic parachute deployment

Posted: Thu Dec 15, 2016 10:07 am
by skysaber89
Your best, and most reliable, choice would honestly be to go with electronics. Mechanical timers can get to be a bit hairy as far as reliability is concerned. Tomy timers are the way to go if you really don't want to splurge on electronics, though. Good luck

Re: Easy non-electronic parachute deployment

Posted: Fri Dec 16, 2016 9:42 am
by Blenderite
:W WELCOME TO THE FORUM!!!! :W

I will echo everyone else and recommend that you go with an electric system, such as USWR's Launchpad AlTImeter 2 (http://www.uswaterrockets.com/documents ... manual.htm).

However if you are trying to steer away from electronics, tomy timer is definitely the way to go. There are other ways (air flap, chemical reactions, etc), but those are horribly unreliable. I have tried them and I can't recommend them.

Here is a very good article on how to construct and source a Tomy Timer system: http://waterrocket.uh-lab.de/tomytimers.htm

If you have more questions, don't hesitate to ask!

Re: Easy non-electronic parachute deployment

Posted: Tue May 23, 2017 8:22 pm
by anachronist
I'm working on a design of a purely mechanical deployment system that doesn't rely on timers or external vanes; rather it senses gravity changing when the rocket has started to descend and releases a catch. It won't work for all rockets, but the single soda bottle kind should work.

I've done some physics-based simulations of flights, and observed that a soda bottle rocket never actually experiences "free fall" in the sense of weightlessness, except right at the instant of apogee. Otherwise, objects inside the rocket are always experiencing a force toward the nose or toward the tail, due to thrust and air resistance. My mechanism takes advantage of that. It'll be a complicated collection of 3D printed parts when I finish it over the next few months (spare time project).

Re: Easy non-electronic parachute deployment

Posted: Wed May 24, 2017 9:39 pm
by addstogether
It's good to see your doing your own thing. I have tried the chemical deploy, gravity deploy, tommy timer methods and are now moving to electronic deployment.

This is purely for reliability and consistency. The only one that did work ok was the tommy timer.

Regards Al

Re: Easy non-electronic parachute deployment

Posted: Thu Jul 06, 2017 3:15 am
by anachronist
addstogether wrote:It's good to see your doing your own thing. I have tried the chemical deploy, gravity deploy, tommy timer methods and are now moving to electronic deployment.

This is purely for reliability and consistency. The only one that did work ok was the tommy timer.
Another reliable thing pointed out to me (mentioned in this thread) is to use some electronic fuse wire that the electronic deploy signal melts away, to release a latch. I haven't figured out yet how this would work while keeping everything internal. But it would be really light weight, if you already have the power available... and I believe the power would be less than what's needed for a pyro rocket igniter, which is what those altimeter deployment signals are designed for. A 40-gauge copper wire will melt at less than 2 amps, which a deployment signal should be able to supply.

Re: Easy non-electronic parachute deployment

Posted: Sun Aug 06, 2017 5:42 pm
by addstogether2
If you get it to work consistently please let us all know.

Looking forward to seeing more in this space.

Al

Re: Easy non-electronic parachute deployment

Posted: Thu Oct 26, 2017 2:02 pm
by mattew
you can use a weighted nosecone that will fall off at apogy

Re: Easy non-electronic parachute deployment

Posted: Thu Oct 26, 2017 4:53 pm
by anachronist
mattew wrote:
Thu Oct 26, 2017 2:02 pm
you can use a weighted nosecone that will fall off at apogy
Not really. Sometimes.

If the drag of the nosecone is greater than the rest of the rocket, the nosecone will stay on the rocket body. At apogee, both nose cone and body are weightless, so there's no reason why any part with extra mass would fall off. It might fall off due to the inertia resisting the rotation of the rocket at apogee, though.

If the drag of the nosecone is less than the rest of the rocket, it will likely fall off when the water is exhausted. The body will want to slow down while the nose will want to keep going. This would be undesirable considering that the water is exhausted in about 0.1 second.

Re: Easy non-electronic parachute deployment

Posted: Mon Apr 29, 2019 10:44 am
by superrealitykid
Take a look at my pneumatic parachute deployment system.

Re: Easy non-electronic parachute deployment

Posted: Mon Apr 29, 2019 3:52 pm
by anachronist
Ingenious. I'm curious how you control the delay of the pin retracting. It would be nice if the delay could be adjusted so that the deployment happens after the rocket starts on its way back down.

Do you think it's possible to build this mechanism from non-metallic parts?

I also envy your launch field that looks relatively clear of trees for a good distance around. That's hard to find in the area where I live.

Re: Easy non-electronic parachute deployment

Posted: Sat May 11, 2019 5:05 pm
by Willy
If you installed a small restriction in the line going to the cylinder, this would slow the release of the air pressure and delay pin retraction. To add some adjustment, you might try a small needle valve instead of the restriction. Most likely you would not be able to achieve enough adjustment using a valve?

Cheers
Willy