Auto Combustion Discussion

[Rambo]

When the fuel combusts it's tempreture gets to about 1000 and the presure rises 3 times.2/3 of the gases leave the chamber and the other one third is quikly colled=> the gun suck air.Now in the chamber is a mix of 2 parts air and 1 part of useless gases...But it doesent matter because the air from the bottle quikly take the plase of this durty air.I don't need to inject fuel all the time.30ml is enough for many shots.You are right that in fast succesion the shoots get weaker.But one for a socond and no problem.

[Brian the brain]

The fuel is already inside pimp.It's the alcohol he keeps talking about.There is a pool of it at the bottom of his chamber.But only the vapours can be ignited.He adds oxigen and keeps the ignition running till it fires.Then some more alcohol vaporises and because the oxigen is still streaming in the process will continue till there's no more vapor or when he stops the ignition.

Its very simple!!
You don't need to know about mixtures..just keep the oxigen flowing and the ignition on.It will fire when the mix is right.

[Rambo]

Yeah that's right. But it is more effective for semi auto(I mean when useing O2 riched air)

[CS]

What would you recomend for a full auto?

Alchol doesnt seem logical in a 4" chamber. That is why I was wondering about propane. I could have both the propane and oxygen hooked to 3 way valves. The first leg of the valve would be the tank, then on the second leg would be the metering pipe, and on the third leg it would run to the chamber.

As soon as BLB gets on Ill ask him if he knows the ratios I need. Ill draw up a ruff picture of how it will look... (drawing up right now and will edit post when finished)

[Rambo]

If you use H2 no comprest air is needed.You didn't tell me how many shots do you want for second?

[CS]

Oxygen would be preffered because I can get in little disposable contianers. How many shots per second? lol I wasnt expecting it to shoot that fast, but I suppose a shot a second would be fast enough. If I could even acheive that speed, couldnt I just speed up the process to get a faster ROF? Thanks for all the help so far.

In reference to picture below:
Im not sure on the ratio, but the amount can easily be changed. Via pressure being realesed into 3 way and/ or metering pipe size coming out of 2nd leg of 3 way. Now that I think about it, you will only need one 3 way and just regulate amounts by adjusting pressure regulators. Now the question is what are the ratios...

[boilingleadbath]

To produce the same mixture used in a normal combustion:
5 O2 : 1 C3H8 (~4% propane, 20% oxygen, 75% exaust gasses (unless the opperation of the launcher pulls in some fresh air, in which case you'll have to essentialy re-create latke's research on the fuel-air mix.
I personaly would mix the fuel and the air in the chamber, though...

I'd opt for a distributed injection system so that the gasses are already spread over the entire chamber fairly well imediatly following injection. It could allow for much faster shots.
Maybe one could take a small-diameter pipe and drill many very small holes along it's length, kindof like a sparkstrip. These holes would be angled to face tangital to the inside of the pipe, if placed on the side.

However, I'm not really a big fan of this O2 injection - it's not the cheapest substance in existance, and will end up costing nearly .1$/shot, if I remember the prices correctly.
A forced-air venting system probably wouldn't be too difficult to automate, and if you injected the air with a (previously described) "injection strip", the tornado-like whirl of air would be usefull for mixing in the propane.
This would require that you load the ammo after you inject the propane, although at high ROFs, the time lag between propane injection and the ammo sealing the chamber shouldn't be too much of a problem.

[Rambo]

Where I live 1L of H2O2 30% is for less the 3lv=2$. From 1L H2O2 30% I can get more the 150L of O2.=> 2$ per 150 incredible shots. The ratio betwen the O2 and C3H8 isn't criticle but no way it is going to work with out a one way valve.You will just have a torch in your gun.I think that the best you can do is to use a motor wich drives a valve and just when the valve is closed, it turns the spark.That way it can be very fast shooting. When the nossle is in angle to the bottom of the chamber it sprayes the alcohol everywhere and it is ready to be ignited quicer and less air loses.

[rna_duelers]

Well i want to no how it works aswell,and where is the chamber??or is the soda bottle it?sorry being noobish here

[Rambo]

Better read here http://www.spudfiles.com/forums/viewtopic.php?t=1278& .This should inspire us http://tinypic.com/view/?pic=rkq3jn