Pneumatic Rocket for my school Project

[Thursto]

Hey all, well at school we have this thing where we have to do a personal project, which could be anything of our choice. I was going to build a pneumatic gun, but i doubt my school would let me bring that in, so i thought about making a pneumatic rocket. It wont just be one of those coke bottle type ones.

It will have 2 engines (pressurized cylinders with air+water) realised by 2 garden quick disconnect fittings (like you use on the coke bottle rockets etc). The 2 garden disconnect fittings will be set off at the same time, actuated by a pull cord.

I just need your help on a few things:

Once its in the air, and on its way down, i need a parachute to deploy (not using electronics either)

how do i connect the tire vale to the hose (which leads to the engines)

And how do i make a strong nose cone

Heres a few drawings i have done:

Rocket on launch pad


rocket and launch pad seperated


Approx dimensions:
Engines:
length: 20cm
Width: 2"
Main Section (middle area):
Length: 50cm
Width: 3" DWV

EDIT: Heres some pics of the garden disconnects:


Still attached to my garden connections but we have some spares in the shed, but yeah u get the point, the gold part will be attached to he bottem of the rocket, an will act as the nozle in witc the water sprays out of.


Here it is disconnected

[elitesniper]

neatly pack a parachute in the top put a nother half soda bottle of that so when it reaches its peak hight and begins to turn back to earth the force pushes the nose cone off and ur parachute depolys or u can do the back slider it has a really tall nose when it goes up its just rolls verly slowly down it can reach very high altitudes for a strong nose cone just wrap some big constuction paper into a big ice cream cone like thing and electrical tape it to ur bottle the areodynamic cone should be strong enough it dosent have to be really strong just areodynamic

[BigGrib]

should work you might be able to go to your local hobby sorte and get sheet plastic or maybe get some fiberglass epoxy to build your nose cone with.

[elitesniper]

that should work well but remember the lighter it is the better it will perform in the air

[Thursto]

Im not making it out of a soda bottle, all out of PVC, the engines will be pressure rated PVC and the main section out of DWV (so its lighter, less weight the better)i was thinking of using a vortex ball as a cone
but its not very pointy, but i justneed the parachute to deploy somehow

[elitesniper]

ohhh mabey u could put a small cut in half watter bottle and use epoxy and mold it over the top of the water bottle so then put the water bottle over the pvc attach a rope on to the nose cone to the para chute so that when the nose cone is pulled out by the force it pulls the parachute with it

[Thursto]

But when its going up, wouldnt it have the same forces applying on it on the way down (like air pushing against the cone when its going up, and when its going down, the air will still be pushing against it)? I might use my vortex as the nose cone, coz it doesnt have a tail fin (it broke) but its one o the ones with the whistles in it

[elitesniper]

but when its about to go down it turns so the turning makes the nose cone come off

[Thursto]

Mmmmm it could work, but i dont really wont to do it that way... but if its the only way i might have to

[elitesniper]

haha do back slider its pretty cool u can search back slider on google it needs no parachutes or deatchable nose cones

[SpudUke5]

It should work just like any other model rocket. At the peak of flight, it would deploy its parachute as the rocket is about to fly down. Except instead of having a discharge the engines give in a model rocket, the gravity acts as a discharge and it should allow the parachute to unfold. I have built model rockets and have done some research. This really inspires me to make what you are. I had make one of these one time, out if a soda bottle, and i did but never tested it and b.s.ed the project with assumptions for data. That my was my 6th grade science fair. I want to redeem myself. But i dont know where you are getting pneumatic cylinders from? could you tell me?

[jackssmirkingrevenge]

Instead of having the "rockets" on board, why not build something like this paper rocket where the rocket fits over the barrel of a pneumatic launcher?

[Novacastrian]

I think i may have a good idea to lighten the body. Make swiss cheese out of it with a hole saw (like someone has been at it with a .50 cal machine gun)
then wrap around the body with contact or similar. If you use clear stuff it would look hella cool. You could do the same with the fins.

[Insomniac]

It would work much better if made out of a coke bottle. Water rockets only have thrust for a very short time, and they need it to be effective. The pvc will simply be too heavy to work well. For a parachute deployment system, you could design somthing around the little mechanisms that you find in cheap $2 wind up toys. They are often used in water rockets, they are called tomy timers.

[ammosmoke]

Instead of having the "rockets" on board, why not build something like this paper rocket where the rocket fits over the barrel of a pneumatic launcher?

Nah, thats boring. Just use a model rocket nose cone. They are pretty cheap, and are perfectly uniform. Why don't you just use a cardboard tube? They are much lighter than pvc, and you don't need pressure there anyway. If you can manage to make a small chute that fits over the nose cone, you can tape it just barely there with tiny things of scotch tape. The rocket doesn't need a very big chute.

EDIT: Of course, secure it somehow though.

3/4" PVC can be pressurized to about 400psi I think, assuming its sch40, so you should be able to get a lot out of a fairly small package. You will need to create a nozzle somehow, and maybe some sort of puncturable burst disk. Like, the rocket goes on a stand, and you stomp on something to puncture it.

EditEDIT: Oh, I forgot the part about quick disconnect hose things. Depending on how large your rocket is, you may want to use something with a smaller hole.