Water Rocket Mortar

[Jakal444]

This is just an idea a had whilst reading up on burst discs. Just thought I would post it for fun. Maybe someone will draw some inspiration from it.

This design is in no way perfect, its just a thought. So there is no need to tell me how stupid I am ... I know.

Click on the pic for better quality.

[saladtossser]

thats pretty cleaver, reminds me of this

oh, and howdy doodle made this

[Jakal444]

Similar concept. But I think my idea is slightly safer, the parts are cheaper and it is almost infinitely reusable (until you break off something on landing).

However I foresee some problems:

- Thrust to weight ratio might be a bit high.
- I think the rubber will burst even before punctured (Maybe rubber glove rubber instead?).
-Rocket wont fall down tube "hard" enough to pierce itself.

Other than those minor nags it seems like an idea that would be fun for all ages!

[jrrdw]

I had a water rocket when i was a kid. It came with a little plastic version of a bike pump, and a little measureing cup to add the water. Put in the water, screw the nose cone back on, give it 10 pumps, pull the trigger and watch it fly.

Nice plan! I have allways liked water rockets.

If you get the rite shape discharge nozzel, the weight ratio won't effect it to bad.

Try aluminum foil for your burst disk.

Use a skinnier sharper nail to break the disk.

Put fins up top just below the nose cone, you will need a longer launch tube, but the top fins will stableize the rocket to a better center, thus, makeing the rocket slide much better.

Hope my thoughts help you.

Keep us posted.

[Atlantis]

This is brilliant, I might build one of these my self. Would it be possible to pressurize pop bottles with a valve threaded onto the cap?

[Jakal444]

Jrrdw: Regards the foil, how will it be attached to the endcap, wont it tear when you try to thread it?

Also in my design there is meant to be a smaller set of fins at the top like you suggested, they are not included in the above diagram because its the wrong picture.


Atlantis : Im not sure, probably, you might need to find a way to stabilise it though. If you do build one let me know how it goes.

Tomorrow I am going to buy the parts and it should be finished quite quickly since I am going to use PTFE tape rather than glue to hold everything togheter.

[jrrdw]

Just cut it to the diameter of the end cap and screw it on carefully, it should be fine, use mutiable layers of foil, like try three if you have thin stuff.


If you use plastic bottles, PCGUY just put a cannon on recently useing 3 of them for chambers, look at his post for this month, it will be easy to find, i think it's called 3D, or Trident, something like that.

[Jakal444]

What sort of pressure does foil burst at?

And that cannon is called Trident.

[taz22]

i'v disigne a animation for this (all the text are dutch) the ammo would be just a cheap 1.5L soda botle. the thing that holds the compressed air and water insider would be a part of a medical gvlove (those gloves of rubber) the thin that would punch the rubber glove will be a screw.

the design is verry easy and cheap, becaus i don't like to build expencive things:D

1 thing i'v forgot to put in it is a smal tire valve

[jrrdw]

Different amount of layers will give different bursting presures. Fun to experiment with. Let us know how they turn out.

How much presure does the rubber gloves hold? How far do they go?

[taz22]

duno must make 1 first. i think i will start tomorow (over 10hrs) first i will chek that for you. as soon as i know it i'll let you know

[taz22]

i'v got a new idee, instead of water use cola with a bit of sugar in it:D than olso try to add some more presure on it:D the bee's would love it:D

[dragon finder]

Well the pressure cap needs to hold alot of pressure about 80 to 90 psi. So if there were a bunch of layers of rubber ither balloon/rubber glove the pressure would put alot of stress on the rubber so the nail would easly go through the rubber. Even better if the nail was filed to a very sharp point. Also the end cap could be the bottle cap with a hole in it so the rubber will stay in the bottle and you should leave a lip in the cap so it will hold the rubber even better.

[saladtossser]

if would also work if you have a flame in the tube, or a red hot wire, or a soldering iron

[dragon finder]

That is to complicated a nail would work fine. Or four nails clumped together for a better chance of the hole expanding.