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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.

Put a high pressure in a rocket without reinforcing it

Discussion about Compressors, hose, pipes, fittings, launchers, release mechanisms, and launch tubes.
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RaZias
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Put a high pressure in a rocket without reinforcing it

Post by RaZias » Sun Aug 30, 2009 9:36 am

Anyway, one day I will post a diagram of a launcher that allows to put a big pressure inside the rocket without the need of reinforcing the rocket.

I am not talking about a stomp rocket neither any high air pressure injection in the first miliseconds after the release of rocket by the tube that is inside of it.

Maybe in one to two months I will make a diagram.

It´s a theorical launcher (but not too hard to build and even is funny), imagine the amount of weight you could remove from the reinforcement.

----So how does it works ?

It´s a launcher with a box (plastic or metal...those box for fresh food in the beach would do).

Inside the box you will put the rocket and you will fill the box of water. Then you will close the box.
Needless to say that the rocket connector to the air hose is glued in the bottom of the box.

You could put any pressure and the rocket wouldn´t blow out since water is uncompressable. If you do this in a pool the water will deplace and the rocket will blast, but in a closed box the water cannot be deplaced and it will avoid the explosion.

For the launching you would need to action the quick-release and after open the box in the top.
If you open the box before, the water will be deplaced and the rocket will blast.
There must be a very low friction quick-release system because any delay during the launching after opening the box would explode the bottle.

So where does it fails ? I think that depends if the 22mm of the bottle (or a 9mm in a gardena) is enough to allow the pressure release during the flight without blasting the bottle halls.


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Re: Put a high pressure in a rocket without reinforcing it

Post by U.S. Water Rockets1 » Sat Sep 05, 2009 10:05 pm

The idea sounds logical, but the timing of the release will be a challenge. Keep us posted how it works!


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Re: Put a high pressure in a rocket without reinforcing it

Post by castle-bravo » Sun Sep 06, 2009 4:23 am

nice



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Re: Put a high pressure in a rocket without reinforcing it

Post by RaZias » Sun Sep 06, 2009 8:18 am

U.S. Water Rockets1 wrote:The idea sounds logical, but the timing of the release will be a challenge. Keep us posted how it works!
There is a solution for the release. The bottle will connect to the quick-release but the quick-release won´t hold the bottle (you must modify the quick-release to disable the holding system).

So what will maintaing the bottle connect to the quick-release ?

Well...if the upper wall of the box (the one that when oppened will release the rocket) will be touching the part of the bottle (the oposed to the one that has the nozzle) it will create a force that will compress the nozzle against the quick-release...so it will hold the nozzle in the quick-release.

When you open the box there will be notingh holding the bottle and it will be fired up.


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Re: Put a high pressure in a rocket without reinforcing it

Post by Tim Chen » Fri Sep 11, 2009 1:40 pm

RaZias wrote:
U.S. Water Rockets1 wrote:The idea sounds logical, but the timing of the release will be a challenge. Keep us posted how it works!
There is a solution for the release. The bottle will connect to the quick-release but the quick-release won´t hold the bottle (you must modify the quick-release to disable the holding system).

So what will maintaing the bottle connect to the quick-release ?

Well...if the upper wall of the box (the one that when oppened will release the rocket) will be touching the part of the bottle (the oposed to the one that has the nozzle) it will create a force that will compress the nozzle against the quick-release...so it will hold the nozzle in the quick-release.

When you open the box there will be notingh holding the bottle and it will be fired up.
Will the water shoot up out of the box once you open it?


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Re: Put a high pressure in a rocket without reinforcing it

Post by SaskAlex » Fri Sep 11, 2009 3:36 pm

Here is one thing to think about. If you want to put, for example, 500 psi in your rocket then your rocket could exert up to 500 psi on the water. Since the pressure will be the same throughout the water, it will exert up to 500 psi on your box. I'm not saying you can't make it work, but you will need a strong box.

Are you planning on competing with this? I can't see any rules that it breaks, but if you weren't going to compete seriously I think I would just make a stomp rocket. It would be easier. And if you got the rocket part all figured out, you could make the launcher later. Then you could use the same rocket, and you would be eligible to compete.



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Re: Put a high pressure in a rocket without reinforcing it

Post by RaZias » Fri Sep 11, 2009 4:50 pm

Tim Chen wrote:
RaZias wrote:
U.S. Water Rockets1 wrote:The idea sounds logical, but the timing of the release will be a challenge. Keep us posted how it works!
There is a solution for the release. The bottle will connect to the quick-release but the quick-release won´t hold the bottle (you must modify the quick-release to disable the holding system).

So what will maintaing the bottle connect to the quick-release ?

Well...if the upper wall of the box (the one that when oppened will release the rocket) will be touching the part of the bottle (the oposed to the one that has the nozzle) it will create a force that will compress the nozzle against the quick-release...so it will hold the nozzle in the quick-release.

When you open the box there will be notingh holding the bottle and it will be fired up.
Will the water shoot up out of the box once you open it?
If the rocket can get out vertically it´s what it matters, I don´t water getting out as a problem, specially in a beach.


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Re: Put a high pressure in a rocket without reinforcing it

Post by RaZias » Fri Sep 11, 2009 4:59 pm

SaskAlex wrote:Here is one thing to think about. If you want to put, for example, 500 psi in your rocket then your rocket could exert up to 500 psi on the water. Since the pressure will be the same throughout the water, it will exert up to 500 psi on your box. I'm not saying you can't make it work, but you will need a strong box.

Are you planning on competing with this? I can't see any rules that it breaks, but if you weren't going to compete seriously I think I would just make a stomp rocket. It would be easier. And if you got the rocket part all figured out, you could make the launcher later. Then you could use the same rocket, and you would be eligible to compete.
I already knew the effect on the box, and it can be made of steel or a plastic box (for sandwichs in summer) reinforced by carbon so the weight of the reinforcement would be transfered to the launcher.

I am not planning competing, it is a theoretical design for now.
The real aim for me in WR is not competition but the "R and D" (research and development) and RD is the soul of WR.

I have a bounch of theorical stuff and I will work them over the week-ends, but I aiming to do this launcher next year.
I only need to put 200 psi in a bottle to prove it (or not) so I don´t need a heavy box.

If this works then we can talk of bigger pressures later, the problem will be to seal the box...maybe I will put ruber below the box´s cap like they did to seal the Apollo´s doors for space.


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Re: Put a high pressure in a rocket without reinforcing it

Post by eljose707 » Sun Oct 25, 2009 5:10 pm

interesting



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Re: Put a high pressure in a rocket without reinforcing it

Post by RaZias » Sat Apr 03, 2010 5:34 pm

Here is the diagram of a Reinforced Box-Launcher to launch a Non-Reinforced Water Rocket.

The 400 psi pressure of the air in rocket are transmitted to the water, and since water is uncomprensible and the box is reinforced, the rocket won´t blast (altough it can only stand 120psi).

This way the weight of the reinforcement goes to the box and not to the rocket.

Note that since the cone of the rocket is reinforced so it can stand the pressure, because it´s the box cover.

The big problem is to find a big o-ring to put between the box and rocket cone.
Unless there is another sealing rubber that is sold. (like those to seal submarine doors lol)

When the holders are realesed the rocket will fly out, the clark-tie are not needed.
rocket-box1.jpg
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Re: Put a high pressure in a rocket without reinforcing it

Post by RaZias » Sat Apr 03, 2010 5:36 pm

Here is the diagram of a Reinforced Box-Launcher to launch a Non-Reinforced Water Rocket.

The 400 psi pressure of the air in rocket are transmitted to the water, and since water is uncomprensible and the box is reinforced, the rocket won´t blast (altough it can only stand 120psi).

This way the weight of the reinforcement goes to the box and not to the rocket.

Note that since the cone of the rocket is reinforced so it can stand the pressure, because it´s the box cover.

The big problem is to find a big o-ring to put between the box and rocket cone.
Unless there is another sealing rubber that is sold. (like those to seal submarine doors lol)

When the holders are realesed the rocket will fly out, the clark-tie are not needed.
rocket-box1.jpg
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Re: Put a high pressure in a rocket without reinforcing it

Post by air.command » Sat Apr 03, 2010 7:54 pm

RaZias wrote:Here is the diagram of a Reinforced Box-Launcher to launch a Non-Reinforced Water Rocket.

The 400 psi pressure of the air in rocket are transmitted to the water, and since water is uncomprensible and the box is reinforced, the rocket won´t blast (altough it can only stand 120psi).

This way the weight of the reinforcement goes to the box and not to the rocket.

Note that since the cone of the rocket is reinforced so it can stand the pressure, because it´s the box cover.

The big problem is to find a big o-ring to put between the box and rocket cone.
Unless there is another sealing rubber that is sold. (like those to seal submarine doors lol)

When the holders are realesed the rocket will fly out, the clark-tie are not needed.
Hi Razias,

It's an interesting concept. The one major problem you will find is that during launch as soon as you break the seal around the nose cone, the water around the outside will depressurise rapidly. This will cause the rocket to overpressurise and explode before it makes it off the end of the launch tube. If you still wanted to give it a go, build the rocket small and skinny so that you don't need a big o-ring. With a smaller diameter box/tube it would be easier to contain the pressure as well.


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Re: Put a high pressure in a rocket without reinforcing it

Post by U.S. Water Rockets1 » Sat Apr 03, 2010 10:19 pm

Hi RaZias,

It's likely that what George said is going to be the outcome of your experiment. The water will displace when you open the top and the rapid drop in pressure will be much like an explosion inside the bottle and that instantaneous pressure will burst the bottle before it can get out of the tube.

Of course, there's a chance that the reality of the test will unveil some counter intuitive effect that we don't predict and it would without bursting, but it doesn't seem like it would if taken as a thought experiment.

If you do try it, it would be great to be proven wrong!


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Re: Put a high pressure in a rocket without reinforcing it

Post by RaZias » Sun Apr 04, 2010 5:23 pm

I had already tought on the water displacement and even I have my "if this / if that" about it.

When the seals is broked the pressure will act in all directions, so when at the same time is trying to blast the bottle at same time is trying to eject the bottle.
Will the 22mm nozzle be able to drop the pressure before it bursts ?
Because one thing is bursting a closed bottle...the other is bursting a bottle with a 22mm on it.

And also the ejection time might be same to the bursting time because both are the same thing (both are the result of force by the pressure over surfaces).

Will it might be possible to eject before it bursts ??? The ejection time takeslike 0.01 sec or less (i hope).


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Re: Put a high pressure in a rocket without reinforcing it

Post by SaskAlex » Sun Apr 04, 2010 11:26 pm

Well I know people have used hydrogen to pressurize bottles to a greater pressure than they can normally withstand. I've never heard of anyone going anywhere near 400 psi though.

Another thing to think about in your design is the release mechanism. If you make the seal with the nose cone, you will have the pressure x the full cross-sectional area of the bottle to hold down. Let's err on the small side, and say your 2L bottle has a 9 square inch cross section. Then your release mechanism will have to handle 3600 pounds.

All in all, it might be possible to use this method and get marginal gains. But I think you could get the same effect for less effort from some type of stomp rocket. Either use a launch tube with a large valve that quickly lets air enter the rocket, or if you really know your stuff, try igniting a hydrogen-oxygen mixture.

Good luck if you get around to some experimenting.

Alex



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