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Regulator flow rates

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
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Unread postAuthor: kjjohn » Tue Dec 15, 2009 7:05 pm

Would perhaps an alloy steel be stronger and safer?
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Unread postAuthor: POLAND_SPUD » Tue Dec 15, 2009 7:50 pm

a welding reg would have a flow rate capable of continually filling my chamber in a fraction of a second

IDK much about regs but normally you can find such informations in data sheets... just use google
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Unread postAuthor: kjjohn » Tue Dec 15, 2009 7:56 pm

I'll check with welding reg specs. What about the pressure/temp problem? I suppose this is getting off topic, but I posted the specs in one of my previous posts. Tech might be able to answer this.
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Unread postAuthor: Larda » Wed Dec 16, 2009 1:47 am

A quick calculation, dont know if its even close....

10cu chamber= 164.9cc

and a 20 mix-- ~0.75l of gas per shoot

5 shoot per second= 0.75x5=3.75 l per second

3.75x60=225 l/min

225x60=1350 l/h

So with a oxy/mapp consumption of around 225 l/min its going to get HOT really fast.
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Unread postAuthor: kjjohn » Wed Dec 16, 2009 9:43 am

Would a cooling system help?
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Unread postAuthor: kenbo0422 » Wed Dec 16, 2009 11:52 am

Cooling would be a great help.

Concerning the Browning models, the first of which was water cooled:

The AN/M2 aircraft gun has a cyclic rate of 750-850 rpm; this increases to 1,200 rpm or more for AN/M3 aircraft guns fitted with electric or mechanical feed boost mechanisms. These maximum rates of fire are generally not achieved in use, as sustained fire at that rate will wear out the bore within a few thousand rounds, necessitating replacement.


If you achieve a relatively high rate of fire, the heating will soften your metal up to and including the point to where your rifling (if you have it) starts to smooth out. The metal alloy of the barrel is chosen to give a greater amount of consistency throughout the heating process of sustained firing. Even then, cooling eventually comes into play.

Unless you're going for some of the above quoted rates of fire, I would only consider an air cooled system with shrouded fins.
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Unread postAuthor: Larda » Wed Dec 16, 2009 12:57 pm

I am mostly worried about the valves and sealing surfaces.
What type of valve are you planing to use?
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Unread postAuthor: kjjohn » Wed Dec 16, 2009 5:42 pm

I will be using a piston valve, since this is a hybrid, and it will be sealed obviously by orings. That brings to mind the possibility that the rings might melt. I am planning on making the whole gun out of a high tensile strength steel alloy, possibly p20 or 8620. There will also be a high pressure check valve for fuel intake. And yes, if the bolt I designed works, it will be full auto.

By the way, this is all just in my head right now, I haven't actually started building. In fact, if this proves to be too impractical, I may not even build it at all.
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Unread postAuthor: kjjohn » Thu Dec 17, 2009 8:48 am

Would a p20 alloy be strong enough to hold in repeated blasts of 3000 psi?
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Unread postAuthor: Larda » Thu Dec 17, 2009 1:44 pm

Its impossible to say in your case, it depends of what dimensions and how its constructed. You could possibly even make the chamber out of wood and epoxy if you just use enough of it.....
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Unread postAuthor: kjjohn » Thu Dec 17, 2009 5:11 pm

I am thinking of having the chamber be 1.5" od with a .25 wall. What about the piston and check valve? Basically, will I be able to pull this off with the high temps involved?
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Unread postAuthor: psycix » Thu Dec 17, 2009 5:17 pm

You could possibly even make the chamber out of wood and epoxy if you just use enough of it.....

I even recall people saying that you could build a hybrid chamber out of cheese if you simply used thick enough walls. :D
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Unread postAuthor: kjjohn » Thu Dec 17, 2009 8:48 pm

Basically what I'm asking is will this work without blowing up or melting. I will be attempting the high rate of fire listed above. I may use a more complex water cooling system if that would help.
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Unread postAuthor: psycix » Thu Dec 17, 2009 8:58 pm

For endured periods with a high rate of fire, a cooling system is a must-have.
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Unread postAuthor: kjjohn » Thu Dec 17, 2009 9:01 pm

What about the o-rings on the piston and the check valve? The check valve will be rated for high pressure. Since the cooling system will be large, I will probably mount this on a turret. Just to clear things up, this will be a using a 20x MAPP/Oxy mix.
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