Water Rocket/Jet Board

[Acdcmonkey1991]

Ok so here is the equation Me+ $20 + Boredom+ old skateboard+Lowe's=JETBOARD!!!
What I did today was I went to Lowes and bought 5 feet of 2in. pipe, a cap, a 2in.-1/2in. bushing and a 1/2in. steel ball valve. What I want to know is if I attached it to my skateboard, would it give me any propulsion at all? Or would it just shoot a stream of water. The pressure would be at 100 psi, and another thing I want to know is the best amount of water to put in the tank. thank you,
Acdcmonkey1991

Edit: Yaaaaay!!! 250 posts and a red star! lol

[bigbob12345]

It would probably give of a little bit mabey enough to move 10 ft with you on it

[ShowNoMercy]

Since you already bought all the stuff, just build it and tell us what happens?

[octane89]

The mythbusters tried something similiar. They used two compressed air tanks (3000-4500psi) and tried to make a jet boat. I think it did 5mph. But there is less drag on land, but you will need a sufficent amount of power. If you built something that could get you moving fairly fast, it would have to be able to knock you off your feet as well. That is an example of newton's law: every action has an opposite and equal reaction.

[ShowNoMercy]

I think I am leaning to disagree.

[Novacastrian]

I think with bottle rockets the mythbusters concluded that 1/3 of the volume should be water. Who cares if it works it would look kick ass.
Just take it down a hill a press the nos button (or open the valve).

[bigbob12345]

Yea just make it and tell us what happens

[FordGtMan]

I definitely want to see this... when you test it out make sure you make a video! I want to see it not hear about it

[ShowNoMercy]

Fill it with coke and drop like 5 mentos in it and hold on

[schmanman]

worst comes to worst, put a barrel on it and use it as a potato gun

[psycix]

Since the water is heavier then the air the water will not reach the valve (assuming you have put in 1/3 water and the valve is in the mid)
So only air will flow out.
You should have your tank stand straight up with the valve on the end aimed to the side.

If you make the amount of water being put in (and thus the size of your tank) more in weight then the total construction+skatboard+you you may reach velocities that require a helmet and other protection to be weared.

[Acdcmonkey1991]

Wow, I just tried sitting on the contraption... not comfy.... so I think I am going to put it on a dolly cart at an angle.my first test should be this weekend, but the video wont be up until x-mas time because my friend has a camera...

[Ragnarok]

The optimal amount of water will vary hugely depending on your weight, friction, the surface etc.

At 100 psi, a 5' long piece of 2" pipe can contain no more than 650J. Assuming you and the contraption weigh 80 kilos together, even 100% efficiency would give you only 9 mph.

You will not get anywhere near that efficiency, and there will be less energy. Expect to get going at maybe a leisurely half mile an hour tops.
Don't get your hopes up, especially from a 1/2" nozzle.

Maybe with a much larger chamber (4" at least), 2" ball valve, a piston to separate the air and water, and a load more pressure... You might get a moderate pace for a couple of seconds.

[Maniac]

if it works i cant wait to see it that thing would be awsome i would have to build one if its uncomfortable attach 2 two the side with big cable ties or hose clamps

[boilingleadbath]

"efficiency"
WRONG way to think about rockets.

See <a href="http://www.spudfiles.com/forums/bicycle ... l">this</a> thread. Very similar subject matter, nice equations.