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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

Easy non-electronic parachute deployment

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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CheesyIceCream
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Easy non-electronic parachute deployment

Post by CheesyIceCream » Sat Nov 12, 2016 2:26 pm

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



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anoymous
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Re: Easy non-electronic parachute deployment

Post by anoymous » Wed Dec 14, 2016 9:16 am

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?


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skysaber89
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Re: Easy non-electronic parachute deployment

Post by skysaber89 » Thu Dec 15, 2016 10:07 am

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



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Blenderite
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Re: Easy non-electronic parachute deployment

Post by Blenderite » Fri Dec 16, 2016 9:42 am

: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!


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anachronist
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Re: Easy non-electronic parachute deployment

Post by anachronist » Tue May 23, 2017 8:22 pm

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).



addstogether
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Re: Easy non-electronic parachute deployment

Post by addstogether » Wed May 24, 2017 9:39 pm

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



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anachronist
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Re: Easy non-electronic parachute deployment

Post by anachronist » Thu Jul 06, 2017 3:15 am

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.



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addstogether2
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Re: Easy non-electronic parachute deployment

Post by addstogether2 » Sun Aug 06, 2017 5:42 pm

If you get it to work consistently please let us all know.

Looking forward to seeing more in this space.

Al


Life is like riding a bicycle. To keep your balance you must keep moving.
"Albert Einstein"

mattew
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Re: Easy non-electronic parachute deployment

Post by mattew » Thu Oct 26, 2017 2:02 pm

you can use a weighted nosecone that will fall off at apogy



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anachronist
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Re: Easy non-electronic parachute deployment

Post by anachronist » Thu Oct 26, 2017 4:53 pm

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.



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