Mini N2O gas canisters?

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fastnova
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Mini N2O gas canisters?

Post by fastnova » Mon Sep 15, 2008 8:36 pm

Hi
This may be subject already well covered but being new here and without spending several hours going threw the forums its hard to tell.

Basically I was talking to a friend of mine today who mentioned something that gave me an idea. You can get these little 8 gram bottles of gas that are used to whip cream strait out of a dispenser, what I found out today was that the gas in these bottles was N2O, you can buy them off ebay for about £30 for 100, there in the restaurant & catering section, just search for NOS.

My idea is would you be able to use these as the oxidiser in some kind of small hybrid rocket motor, a kind of single use replaceable fuel cartridge. They hold a surprising amount of gas as I have used them before when I was working in a pub, without even knowing what they were. I also remember using identical bottles but I think filled with CO2 to power a bb gun when I was a kid.
Surely these things hold loads of potential for cheep replaceable fuel canisters. You could use a CO2 one to pressurise a liquid fuel and an N2O one as the oxidiser.

This all just goes back to my dream of creating the fastest RC car on the planet.

Have I found something interesting here or am I just p*****g up the wrong gas canister?
I don’t see problems, only opportunities.

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Re: Mini N2O gas canisters?

Post by metiz » Mon Sep 15, 2008 9:00 pm

Ha! I actually have one of those, found it some time ago - empty tho. thanks for clearing that up for me. I don't know it it is any use as is (ill provide a picure if needed) but if you want it and you're willing to pay for shipping, it's yours.
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fastnova
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Re: Mini N2O gas canisters?

Post by fastnova » Mon Sep 15, 2008 9:05 pm

I dont get it?...
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Re: Mini N2O gas canisters?

Post by metiz » Mon Sep 15, 2008 9:20 pm

hmm maybe i did not read correctly. I do not know anything about what you are proposing, I do however, have one of those canisters. if you need it, it's yours. After reading your post again, tho, you're probably drowning in em.
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fastnova
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Re: Mini N2O gas canisters?

Post by fastnova » Mon Sep 15, 2008 9:51 pm

Ok then?
My point was has anyone tried to use these before? Seeing as they are quite cheep and easy to get hold of I thought they might make a good source of N20 for testing of an idea or something along those lines. Or perhaps should anyone one day attempt to send something skywards, an easy compact, pre bottled source.
Maybe my idea got a little lost, I hope this clears things up for you.

And no I have no use for your empty canister, seeing as I am new here I am just trying to build up some knowledge and express a few ideas to save myself the disappointment of failure in the event that what I am suggesting has already been proven not to work, I have no desire to repeat another’s mistakes.

Maybe a scrap man will give you a couple of pence for it though.
I don’t see problems, only opportunities.

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Re: Mini N2O gas canisters?

Post by Ray » Mon Sep 15, 2008 10:17 pm

Your idea works and is available for purchase.

Seems pretty complex for only 11 N of total impulse.

http://www.aeroconsystems.com/motors/Sc ... reamer.htm

Enjoy

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Re: Mini N2O gas canisters?

Post by larry cottrill » Tue Sep 16, 2008 5:26 pm

fastnova & Ray -

I have a better idea -- but, unfortunately, it doesn't belong on the Rocket Forum (unless you'd want to use it as a low-altitude booster or something). Anyway:

Rig the little cannister so that when pierced, it blows into the front end of an eductor, so it will drag in a bunch of air with it. At the same time, set up a liquid fuel nozzle in the eductor throat so the stream from the cylinder blows right across it. You now have a carburetor with terrific fuel suction and a central forced draft of N2O. Put a reasonable size combustion/expansion chamber behind the eductor (with spark plug) and add a decent nozzle at the very end. You now have a limited duration pressure jet that eats liquid fuel.

Some experimentation required. Ha.

Remember, you saw it here first ...

L Cottrill

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Re: Mini N2O gas canisters?

Post by Ray » Tue Sep 16, 2008 6:21 pm

larry cottrill wrote:fastnova & Ray -

I have a better idea -- but, unfortunately, it doesn't belong on the Rocket Forum (unless you'd want to use it as a low-altitude booster or something). Anyway:

Rig the little cannister so that when pierced, it blows into the front end of an eductor, so it will drag in a bunch of air with it. At the same time, set up a liquid fuel nozzle in the eductor throat so the stream from the cylinder blows right across it. You now have a carburetor with terrific fuel suction and a central forced draft of N2O. Put a reasonable size combustion/expansion chamber behind the eductor (with spark plug) and add a decent nozzle at the very end. You now have a limited duration pressure jet that eats liquid fuel.

Some experimentation required. Ha.

Remember, you saw it here first ...

L Cottrill
Errr, why would you do this? You have a great oxidizer in Nitrous Oxide...why pull in a less dense, less efficient oxidizer? Then mix it with fuel from a venturi? It just doesn't make any sense to me.

The little Nitrous oxide canisters work, but they just don't have enough nitrous in them to really be useful. Once you want to make something that actually has some total impulse you'll quickly want a tank like they put in a car...There are lots of people out there using the tanks from cars to fill either custom machined motors or CO2 tanks from paint guns. Then there are the guys that use multiple K tanks from a welding shop to fill their N2O motors.

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Re: Mini N2O gas canisters?

Post by fastnova » Tue Sep 16, 2008 7:22 pm

I think there is a kind of dragster that is powered by something similar, from what I was told it basically has a tinfoil tube, at one end N2O is injected and mixed with old chip fat, then at the other end there is a specially shaped steal cone of some sort that stops the fiery bit advancing up the tube and provides the thrust, it doesn’t have a combustion chamber exactly, its something to do with the way the fuel burns and expands rapidly within the cone and provides thrust. From what I was told it could cover a quarter mile in under 4 seconds, giving the driver a rather nice nose bleed every time.
But then this is only what I have been told so have no idea at all how true/correct it is, I did try to search for it with google but without actually knowing what it is called is slightly tricky.

Has anyone here heard of anything of the like, the propulsion bit not the dragster that is.
I don’t see problems, only opportunities.

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Re: Mini N2O gas canisters?

Post by larry cottrill » Wed Sep 17, 2008 2:41 pm

Ray wrote:Errr, why would you do this? You have a great oxidizer in Nitrous Oxide...why pull in a less dense, less efficient oxidizer? Then mix it with fuel from a venturi? It just doesn't make any sense to me.
Ray -

Because in a jet, you don't carry all the thrown mass with you -- you pick it up as you go along. In all jets, we pick up "excess air" that isn't used for combustion, then heat it up to move it faster, so it all becomes part of the thrown mass. Consider: In a rocket, the fuel you carry comprises 100 percent of the ejected mass; in a quite ordinary turbojet, the fuel you carry makes up THREE percent of the ejected mass. I'm sure you realize that's why there are lots of jet airliners, but no rocket powered ones.

As I admitted earlier, the idea didn't really belong here. Apologies.

L Cottrill

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Re: Mini N2O gas canisters?

Post by Ray » Wed Sep 17, 2008 5:23 pm

Then wouldn't it make more sense to inject the fuel under pressure and rely on air as the oxidizer? I doubt that you'd really get much appreciable thrust from what you suggest. How are you going to entrain atmospheric pressure air into a chamber that is running at 68 atmospheres.

I've thought at times an augmenter may be useful on a rocket motor, but I suspect it doesn't do much...otherwise the military would use them on missiles...etc.

OH, and btw, there aren't any commercial passenger craft that are powered by rockets...and there pby never will be, but the rocket racing league is getting ready to compete.

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Re: Mini N2O gas canisters?

Post by Viv » Wed Sep 17, 2008 5:57 pm

Hi Ray

There are ducted rockets but I have not seen one actively after-burning as it were in the duct the entrained air, normally its just added as reaction mass, there was a nice peroxide ducted project on the web some were, I will see if I have the link around for it.
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fastnova
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Re: Mini N2O gas canisters?

Post by fastnova » Wed Sep 17, 2008 6:22 pm

I thought about this a little today and I wouldn’t be quite so quick to dismiss it.
What I am about to suggest is backed up with very little experience so correct me if I am wrong, but from what I can understand of a pressure jet and the idea you propose is,
It is the rapid expansion of a gaseous fuel in a liquid form travelling threw the diffuser that draws in and cools the air required for combustion to create thrust. A fuel that is liquid at room temperature could not be used in this way as it wont expand like a “liquid gas” would unless you heat it up, thus making the air less dense and eliminating vast amounts of power, and even then it would never expand as much as something like propane would.
So, if you replace the propane with N2O you get the rapid expansion and cooling properties of propane, plus some air and you can use a liquid fuel.

It wouldn’t produce as much thrust as it would if you were using pure N2O but it may produce a little less thrust for a much longer period of time as you are sucking in extra air and not relying completely on the N2O.
So it would be a kind of liquid fuelled, turbocharged pressure jet.
Ok, your never going to get liquid N2O out of one of those little canisters, but the idea is there, this aside a possible use would be something low-level that only requires thrust for a relatively short period of time, like launching a glider into the air from a runway, some of them use miniature diesel or nitro engines with a limited amount of fuel, but this would be far more fun.

As I said before, I don’t know very much about pressure jets so if I am wrong please put thing right.
I don’t see problems, only opportunities.

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Re: Mini N2O gas canisters?

Post by marksteamnz » Tue Sep 23, 2008 7:28 am

You were told fairy tales.
www.laffin-gas.com/ is the reality.

fastnova wrote:I think there is a kind of dragster that is powered by something similar, from what I was told it basically has a tinfoil tube, at one end N2O is injected and mixed with old chip fat, then at the other end there is a specially shaped steal cone of some sort that stops the fiery bit advancing up the tube and provides the thrust, it doesn’t have a combustion chamber exactly, its something to do with the way the fuel burns and expands rapidly within the cone and provides thrust. From what I was told it could cover a quarter mile in under 4 seconds, giving the driver a rather nice nose bleed every time.
But then this is only what I have been told so have no idea at all how true/correct it is, I did try to search for it with google but without actually knowing what it is called is slightly tricky.

Has anyone here heard of anything of the like, the propulsion bit not the dragster that is.
Cheers
Mark Stacey
www.cncprototyping.co.nz

fastnova
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Re: Mini N2O gas canisters?

Post by fastnova » Tue Sep 23, 2008 5:55 pm

Nope, it’s not that one; the one I was told about is a prototype thing.
Incidentally, I actually got to see that one in Farnbrough at an Engineering/Electronics show last year. Unfortunately it wasn’t whizzing up and down the runway, was just posing, hoping for inverters/sponsors I believe.
There was a rumour that it was going to do a run up the runway, but if it did I missed it. :( :x :cry:
I don’t see problems, only opportunities.

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