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I am in the process of helping my son design a sort of model of the Bloodhound SSC car for his school project, using balsa wood, model aircraft wheels, etc... It doesn't have to a like of like, but vaguely resemblant so that you can tell what it is just by looking at it. It would also be nice if the car could move and I was thinking of using on this small CO2 gas canisters as a means of propulsion:

enter image description here

You can get some which are threaded, as above, or some which are just plain. What I haven't been able to find is a way to quickly release the pressure from the canister to propel the car. Are there any small on/off manual valves that would fit this type of gas canister? I haven't been able to find any, the only ones apparently in existence are for fitting onto bike tyres to (re)inflate them.

The only method I have come across is people using some sort of puncturing device (e.g. with a nail) that is generally sprung-loaded to pierce the gas canister when launching the model car. This puncturing device can be made part of the car, but more generally tends to be part of the "launching pad" as it adds weight and unnecessary complexity to the car. I would like to avoid this if I can.

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  • $\begingroup$ I've never seen such a device. Only the screw-on types with a hollow cylindrical nail and a face seal to open the canister and seal it. Maybe you need to piggy back onto that device with a gate valve for fast actuation. Or try to simplify and/or improve the "launch pad" $\endgroup$ – GisMofx Oct 1 '15 at 13:11
  • $\begingroup$ @GisMofx Thanks for the suggestion. Can you point me towards an example of the screw-on type you mention? $\endgroup$ – am304 Oct 1 '15 at 13:14
  • $\begingroup$ Search google for "paintball co2 cartridge" or also search for "Co2 cracker" you'll see exactly what I'm talking about. Do you have a 12gram or 25gram cartridge? $\endgroup$ – GisMofx Oct 1 '15 at 13:26
  • $\begingroup$ Thanks, I see what you mean now. Not exactly an instantaneous release then... Probably will end up using the smaller cartridge (12g) $\endgroup$ – am304 Oct 1 '15 at 14:04
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    $\begingroup$ Yea, you would need to modify one of those devices or build your own around that same concept. My concern is that as soon as you puncture it, you loose some pressure by increasing the volume..if you attach a valve to it. $\endgroup$ – GisMofx Oct 1 '15 at 14:08
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In the end, I decided to use an Estes 1/4A3-3T rocket engine (the smallest one they do):

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We'll see how it goes!!

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  • $\begingroup$ Test fired it this week-end, seems to work although not powerful enough. Am getting the next size up of rocket engine. $\endgroup$ – am304 Nov 10 '15 at 21:21

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