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I am currently working on a small hybrid rocket as a summer project. I've decided on using nitrous oxide as the oxidizer, but large tanks are expensive and I don't have a lot of money (I'm in high school). Would it be possible to use the small nitrous tanks used in whipped cream makers as a source of oxidizer? You could make some sort of adapter and valve and pipe it into the engine no problem, but would this provide a high enough quality oxidizer for the engine to work (even if just for a few seconds)?

EDIT: I am NOT trying to get to space with this engine, nor anywhere close for that matter. It's merely a proof of concept and a predecessor to what I hope WILL fly.

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    $\begingroup$ you don't want to cheap out when working with nitrous oxide... can you buy an automotive grade/size tank or use oxygen instead? $\endgroup$ – costrom May 24 '16 at 21:38
  • $\begingroup$ @costrom as much as I would love to, it's just not realistic for my case due to money and ease of aquiring. From what I can tell, the stuff in these chargers is pretty pure (people use it to get high), so one could say I'm not going cheap, rather accessible and convenient $\endgroup$ – cylo78 May 24 '16 at 22:33
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    $\begingroup$ I'm not worried about the purity of the nitrous, I'm worried about safety. $\endgroup$ – costrom May 24 '16 at 23:03
  • $\begingroup$ These small canisters sold for food use (and sadly for other uses we won't go into) contain pressurised gas, not liquid. So be aware you might only get a tiny volume of usable gas out of a canister! (You should check.) You could empty several cans into a larger bag or other container, but I don't like the idea of a DIY container holding a large volume of nitrous, even at low pressure... $\endgroup$ – Andy May 25 '16 at 8:07
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What a fantastic question! Absolutely it's possible!

$N_2O$ is $N_2O$, whether you get it from an 8g whipped cream charger or a massive industrial tank, it oxidises just the same. The valve you'll need to buy/make for 8g canisters is called a pin valve. Here's an example; basically it is just a hollow needle that breaks the seal when the canister is pressed or screwed into it.

You're not the first to think of using 8g and 16g nitrous canisters in hybrids. There's a test fire of one motor on YouTube. Unfortunately there's very little detail on the design. However, there are complete motor kits (with cutaway diagrams) if you want to really cut corners. Apparently these motors usually get around 11Ns of impulse, the same as a class D solid motor, so a respectable amount of power for their size.

So go out and do it!

However, always exercise extreme caution when dealing with pressurised gasses. 8g of gas may not sound like much, but one of those little cylinders has enough energy to fire a needle-like pin valve through your eye and into your brain. Always wear eye protection when you're working with pressurised gasses, avoid situations where the gas could propel any object (including its own cylinder), and keep your work area well ventilated.

$N_2O$ is a particularly unpleasant gas to deal with, and has killed many people who thought they knew what they were doing. See SPL's safety PDF for a good summary of some of the often overlooked dangers of $N_2O$.

Finally, any rocket is always just one mistake or failure away from turning into a bomb, and amateur rockets are definitely no exception. Follow the same (or greater) safety precautions you would for a standard solid-fuel rocket when handling, firing, or launching.

Good luck. Fly safe.

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  • $\begingroup$ Do you know of any way that this idea could be done with raw materials? I am unaware of how to release the small amount of gas at the correct time? $\endgroup$ – Michael Joseph Sep 27 '17 at 12:27

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