Water bottle rocket launch mechanism

A simple and reliable release mechanism for water rockets can be built from PVC plumbing supplies and cable ties, as in the diagram. This will cope with pressures in excess of 100 p.s.i with safety.

Step 1: General principles

An easily controlled release mechanism is shown, whereby the forces trying to drive the bottle upwards are directed downwards along the length of the cable ties, with only a very small component, courtesy of the bevels on the tie terminations, directed outwards against the retaining sleeve. The coefficient of friction for plastic on plastic is low and the actual contact area is reduced, because of the internal curve on the sleeve, such that very little effort is required to pull it downwards, well within the amount of force that can be supplied by a radio control servo, for example.

Comments

[i make shooting things]

mythbusters used this i think. when they made the water bottle jet pack, lots of problems with simultaneous ignition.

[voxelator]

Have yet to crack a two-stage rocket....any suggestions?

[singhtarandeep15]

read the instructable of MK3 stager....That will definitely help you

[oscarthompson]

Yes- and theres a whole website with easy instructions on how to build it and its realy easy to build- a 10 year old could probably do it! i have posted the link below
http://home.people.net.au/~aircommand/howitworks_1.htm#DropAwayBoosters

[theinventormentor]

I have done 2 stage rockets with my science programs. I take a 2 liter bottle, add a cut off bottom to the top, such that it can carry payloads (best one is vegetable bags from produce isle of supermarket, with beans taped in 4 places to make a simple parachute) however, to make a second stage, i have kids make paper airplanes with unfolded paperclip in the mid section, such that you could launch it on a rubber band. then i attach a rubberband to the waterbottle rocket, add the paper airplanes, and launch. the rubber band stretches on accerleration, and launches to airplane or glider as the momentum from the stage one rocket fades. you can also just hook the paper airplane in the payload half top and see max time aloft of planes. I'll have some of this on my site in a few weeks. www.the-inventor-mentor.com terry murray

[skim1]

yah. i found this site, but havent gotten around to making it.<br/>here's the link: <a rel="nofollow" href="http://home.people.net.au/~aircommand/howitworks_2.htm">http://home.people.net.au/~aircommand/howitworks_2.htm</a> <br/>

[voxelator]

Hey, thanks for that! Ingenious to the max. Obviously works but still quite complex....and heavy. Will certainly give it a go tho'.

[tac135]

I have kinda an idea for multi stages, you could cut the bottle's bottom off then put another bottle inside, that and glue it so its airtight. Pressurize the top bottle first, then fill up the bottom bottle and pressurize that, but i dont have any ideas on how to get the second bottle going though. Or maybe you could have it so the only thing keeping the top bottles valve shut was the pressure from the bottom one, then when the bottom bottle is done the second one will go off, if you get what i'm saying. I dont know if it would work though. Good i'ble by the way.

[voxelator]

I think the answer will revolve around differential pressures somehow - as the pressure drops off in stage 1 it releases a valve in stage 2 which then accelerates on its own. Both stages will need to be independently pressurised tho'.

[singhtarandeep15]

Can this be used as a launch vehicle for MK3 Stager??

[ReelTym]

This looks nice all put together like this but would really be helped by having a parts list and assembly instructions.

[El Diablo97]

Can you show how to make this? I've tried this using the pictures as a guide but it never works no matter how I change it.

[hedgiehog]

very good, very clear. The first picture is very good. Ive seen this design before, but this is the best one

[voxelator]

Thanks. Any ideas on how it might be extended to more than 1 stage?

[El Diablo97]

Try searching "crushing sleeve water bottle rocket staging mechanism".

[voxelator]

Thanks for that

[hedgiehog]

well you need a second stage trigor of some sort, Then the top of the first stage bottle ( which will obviously be bigger) becoming the platform. So u have one launch mechanism on the ground and one on the first rocket. Then when its triggered, the second one flys off. Another way you could do it is to have a two chamber rocket, So the first chamber goes off and then you cud use sum sort of electronic trigger with a timer, to open up the second chamber which would be located above the first. ill find a link or a picture

[LarrySDonald]

Did this with the leg of a baby toy (long since in the crash pile) pvc pipe, a valve from an old bike innertube and some duct tape for the "inner sleeve" and some vulcanizing tape for the oring and the mouth of a milk carton for the outer sleeve. The milk carton was epic - fit perfect and tapered top to push the cable ties in. The nothing-but-duck-tape inner was less then optimal, hard to get a good seal but still working on it.

[Kryptonite]

Wow, that's brilliant! Slightly lacking in discription but totally made up in the pictures, 5/5 stars.

[Jahoovi]

dude anyone can make this. u can also use a 2liter bottle for it. any way this is more advanced 4*

[SurferGeek]

dUde... u roX Yo!

[voxelator]

Need to come up with a way of multi-staging the rocket tho'