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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.

Parachute deployment Idea

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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Alex
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Parachute deployment Idea

Post by Alex » Fri Nov 28, 2008 9:11 pm

Ok, we all know that after Apogee the rocket will turn upside down and just plummet if there's no wind and such, But the parachute seems to deploy to early with all these ''Flight Computers, Depoloyment stuff etc.''

How bout this,
You see, when the rocket is upside down, a small pair of wheels on the side go up a rail,m then a parachute, thanks to gravity, the cube rolls down, opens up, parachute comes up, and to make sure the cube does't come back up, there's a a bunch of pins that will jam into the side after it is done it's roll out of the cone. thus, when the parachute has unfolded and the rocket resets back on end, the cube, pinned into the cone (made out of foam most likely) she flutters down like a bird...

Eh?


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rockets-in-brighton
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Re: Parachute deployment Idea

Post by rockets-in-brighton » Sat Nov 29, 2008 11:21 am

Sorry, Alex, it is unlikely to work as you describe it. You can't depend on any mechanism that uses just gravity to deploy, because the rocket is in freefall and all of its parts are moving together. That's why you see so many active deployment mechanisms that use timers and springs/elastic bands.

The trouble is these things work OK when you test them on the ground, but conditions during a proper flight are not the same as just tossing a rocket into the air.

Try making a payload section that can hold experiments, and see if you can set up a small gravity-powered mechanism in it to try out under real flight conditions.


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Re: Parachute deployment Idea

Post by Andromeda » Sat Nov 29, 2008 11:32 am

rockets-in-brighton wrote:Sorry, Alex, it is unlikely to work as you describe it. You can't depend on any mechanism that uses just gravity to deploy, because the rocket is in freefall and all of its parts are moving together. That's why you see so many active deployment mechanisms that use timers and springs/elastic bands.

The trouble is these things work OK when you test them on the ground, but conditions during a proper flight are not the same as just tossing a rocket into the air.

Try making a payload section that can hold experiments, and see if you can set up a small gravity-powered mechanism in it to try out under real flight conditions.
My theory is that even in free fall that there is enough small force of gravity that you can set up a way to trigger that would deploy a parachute but the difficulty in this is that a sensitive trigger good enough to sense the small gravity would be impossible to build in a way that would ignore the huge forces of launch. It is a huge thing to ask it to do.


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rockets-in-brighton
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Re: Parachute deployment Idea

Post by rockets-in-brighton » Sat Nov 29, 2008 2:36 pm

Andromeda wrote: My theory is that even in free fall that there is enough small force of gravity that you can set up a way to trigger that would deploy a parachute but the difficulty in this is that a sensitive trigger good enough to sense the small gravity would be impossible to build in a way that would ignore the huge forces of launch. It is a huge thing to ask it to do.
Sure, that must be how the nose-falls-off-at-apogee method works, exploiting the tiny difference in forces on different parts of the rocket. As they are not attached to each other, they can go in different directions under the different forces.

You could maybe detect the "jostling" forces using an accelerometer, rigged to ignore the first set of jostling from launch. Still sensitive to being blown about during the4 flight though.


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Alex
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Re: Parachute deployment Idea

Post by Alex » Sat Nov 29, 2008 5:11 pm

rockets-in-brighton wrote:Sorry, Alex, it is unlikely to work as you describe it. You can't depend on any mechanism that uses just gravity to deploy, because the rocket is in freefall and all of its parts are moving together. That's why you see so many active deployment mechanisms that use timers and springs/elastic bands.

The trouble is these things work OK when you test them on the ground, but conditions during a proper flight are not the same as just tossing a rocket into the air.

Try making a payload section that can hold experiments, and see if you can set up a small gravity-powered mechanism in it to try out under real flight conditions.
nuts, oh well...I have other ideas....Some due from Australia did a test with smarties and when the rocket is in free fall, it's basically like space in there, no gravity and all....Though I think my idea could work with some Elbow grease, tests etc.


And in othe news, I found 4 good 2 Litre bottles in my fridge....Now I just need my family to drink all the contents and constrruction can start....P.S wat is the max PSI of a 2 litre bottle?


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Re: Parachute deployment Idea

Post by RaZias » Sat Nov 29, 2008 5:25 pm

Alex wrote:
rockets-in-brighton wrote:Sorry, Alex, it is unlikely to work as you describe it. You can't depend on any mechanism that uses just gravity to deploy, because the rocket is in freefall and all of its parts are moving together. That's why you see so many active deployment mechanisms that use timers and springs/elastic bands.

The trouble is these things work OK when you test them on the ground, but conditions during a proper flight are not the same as just tossing a rocket into the air.

Try making a payload section that can hold experiments, and see if you can set up a small gravity-powered mechanism in it to try out under real flight conditions.
nuts, oh well...I have other ideas....Some due from Australia did a test with smarties and when the rocket is in free fall, it's basically like space in there, no gravity and all....Though I think my idea could work with some Elbow grease, tests etc.


And in othe news, I found 4 good 2 Litre bottles in my fridge....Now I just need my family to drink all the contents and constrruction can start....P.S wat is the max PSI of a 2 litre bottle?
If the bottle is transparent, the max is 120 psi. If green, it´s 130 psi.
Beyond that they will get irreversible deformation and explode.
So they can explode after 120. Above 150 all of them explode.

PS: blue pepsi bottle can handle better the impact than the transparent cola bottle.
If they get deformated in impact and you try to fix the shape with pressure, the pepsi won´t explode.

But the pepsi is more irregular and more difficult to joint to others bottles.


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Alex
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Re: Parachute deployment Idea

Post by Alex » Sat Nov 29, 2008 5:31 pm

RaZias wrote:
Alex wrote:
rockets-in-brighton wrote:Sorry, Alex, it is unlikely to work as you describe it. You can't depend on any mechanism that uses just gravity to deploy, because the rocket is in freefall and all of its parts are moving together. That's why you see so many active deployment mechanisms that use timers and springs/elastic bands.

The trouble is these things work OK when you test them on the ground, but conditions during a proper flight are not the same as just tossing a rocket into the air.

Try making a payload section that can hold experiments, and see if you can set up a small gravity-powered mechanism in it to try out under real flight conditions.
nuts, oh well...I have other ideas....Some due from Australia did a test with smarties and when the rocket is in free fall, it's basically like space in there, no gravity and all....Though I think my idea could work with some Elbow grease, tests etc.


And in othe news, I found 4 good 2 Litre bottles in my fridge....Now I just need my family to drink all the contents and constrruction can start....P.S wat is the max PSI of a 2 litre bottle?
If the bottle is transparent, the max is 120 psi. If green, it´s 130 psi.
Beyond that they will get irreversible deformation and explode.
So they can explode after 120. Above 150 all of them explode.

PS: blue pepsi bottle can handle better the impact than the transparent cola bottle.
If they get deformated in impact and you try to fix the shape with pressure, the pepsi won´t explode.

But the pepsi is more irregular and more difficult to joint to others bottles.
K thanks. I have 1 Coke Bottle (dark black hue), 1 Sprite (green) and 2 others that are clear and stuff......So thanks for that.....


Now, to Microsoft Paint do design a rocket because i'm bored. And also contemplate a Parachute deployment thingy.....ugh...that's the tough part. toughest next to make a nozzle, good pump and launch pad....


Water Rockets are amazing things, One second there sitting on the launch pad, the next, splattered all over your shirt.

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Re: Parachute deployment Idea

Post by andicirk » Sat Nov 29, 2008 7:39 pm

i dont know if you can access them were you live but try perrier 1.5 ltr bottles, ive been using them at 11 to 13bar wit no problems , they are green plastic with a very long taper so i think for some reason they are a little stronger



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Re: Parachute deployment Idea

Post by andicirk » Sat Nov 29, 2008 7:45 pm

andicirk wrote:i dont know if you can access them were you live but try perrier 1.5 ltr bottles, ive been using them at 11 to 13bar with no problems , they are green plastic with a very long taper so i think for some reason they are a little stronger


forgot to add that thats 160 -190 psi ,

as always stay safe and test your bottles first before mounting to these pressures,

i would like to test them until destruction but i still dont have a pump that goes above 13bar (190 psi)



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Re: Parachute deployment Idea

Post by U.S. Water Rockets1 » Sat Nov 29, 2008 9:34 pm

andicirk wrote:
andicirk wrote:i dont know if you can access them were you live but try perrier 1.5 ltr bottles, ive been using them at 11 to 13bar with no problems , they are green plastic with a very long taper so i think for some reason they are a little stronger


forgot to add that thats 160 -190 psi ,

as always stay safe and test your bottles first before mounting to these pressures,

i would like to test them until destruction but i still dont have a pump that goes above 13bar (190 psi)
There are numerous small compressors on the market for $10 to $20 that can reach 250PSI to 300PSI in short durations. If you're hydro testing a bottle it should be completely filled with water and so a compressor like this should not overheat because the air volume will be very small and take no time at all to fill. You shouldn't have a breakdown if you only run it for a brief period at such high pressures.


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Alex
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Re: Parachute deployment Idea

Post by Alex » Sun Nov 30, 2008 2:31 pm

HAHA! I was doing a few tests (just kinda shoved a piece of toilet paper with tape on it into a small bottle)and i threw it into the air....and....It works! kinda....You see, RIGHT after Apogee, the rocket is just sitting there before gravity does it's thing and the rocket falls....And, the paper/tape fell out, ONly if the rocket falls either Upside down or just vertically with the nozzle facing down....It pops out and such....So....with some elbow grease, brains and sturf, I could get this to work....


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Re: Parachute deployment Idea

Post by Brian » Fri Dec 05, 2008 8:12 pm

The way gravity deployment systems work is
1 has a nose cone twice as heavy as the rocket and aerodynamics holds it on during flight.
and 2 is a small weight on a locking pin, but thats for small nozzled rockets because have a small Negative G stage of flight.
Negative G's are when fuel runs out and the rocket deaccelerates and this would deploy your system mid-flight.
so if your trying to make a light gravity deployment systems with a large nozzle maby work on defying the Negative G stage of flight.

My gravity deployment system is desined to defy the Negative G stage of flight and be light. will launch today or tomorrow.


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Re: Parachute deployment Idea

Post by Alex » Sat Dec 06, 2008 5:07 pm

What he said


Water Rockets are amazing things, One second there sitting on the launch pad, the next, splattered all over your shirt.

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