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PostPosted: Sun Dec 31, 2006 2:15 am
by utcpyro
Reminds me of the VERRY FIRST hybrid where a guy has a stun gun at the back of his barrel and was using some sort of air fule mix in his Pneumatic... The post about it is some where around here.

In my opinion, it probably wont work any better then a normal one, and getting the mix right is going to be a B.

PostPosted: Sun Dec 31, 2006 1:05 pm
by Velocity
In terms of increasing power, I do not really see a use. But for ease of firing, it could definitely work. Using a piston valve instead of a burst disk, along with a generation II hybrid fueling system could prove to make things a lot easier

This is just a rough, somewhat inaccurate image, but

<img src="http://www.spudfiles.com/uploader/uploadFiles/PistonValveHybrid.JPG">

PostPosted: Sun Dec 31, 2006 3:18 pm
by An Apple Pie
Gen III launcher possibly? I do not know if this is a big enough change to call it that. What do you guys think?(talking about this combined with the Gen II fueling system, like rmich's diagram)

PostPosted: Sun Dec 31, 2006 3:36 pm
by clide
The pressure created by ignition would trigger a piston valve just fine, so it is still rather pointless to put the ignition after the valve.

PostPosted: Sun Dec 31, 2006 3:41 pm
by An Apple Pie
How would it trigger the valve. A piston valve is ment to hold back the pressure. The only way to "trigger" a piston valve is through the pilot, and that is putting a partial vaccume on it, not putting pressure on it.

Unless you are talking about a chamber sealer. In this case I can kinda see what you are saying, but for some reason I feel that the heat would destroy the O-rings. Therefore you would have to use a barrel sealer. That would force you to ignite it afterward, and now you are back to the original plan.

PostPosted: Mon Jan 01, 2007 1:52 am
by spuzi14
I knew the chamber wasnt't getting smaller, what was I thinking?!

I do think I'm right about how to mix the propane though.

I was imagining a different idea that I think could very well give you more power. I was thinking putting a burstdisk then check valve (I think) between these two chambers. Maybe there's a different single valve I could use but I don't know. More importantly you would do propane first and it would be the amount for chamber 2. Then add air. The burst disk would break and then the mix would go through the check valve then be ignited. You might need a valve after that, I'm not sure.

That's what I thought he was going after.

PostPosted: Mon Jan 01, 2007 10:51 am
by LukeSkyRocket
There was a similar discussion on spudfiles, (I think that's where it was) about using something like a carburator to inject fuel into the breach of a pneumatic's barrel, along with a stun-gun spark to keep it ignited. The idea of mixing the fuel into the air in the pneumatic tank came up, and was rejected because of the possibility of the flame flashing back into the chamber and blowing the gun up.

I think spuzi said this, but if you ignite the fuel-air mix in the barrel-breach/small-chamber/whatever, the expansion will probably stop the flow from the tank, since there will be higher pressure where the ignition is. Or at least if it doesn't stop the flow, it will slow it. And that could allow the flame from to travel back to the tank. So then the tank would need to be able to hold full pressure. So then you might as well go with galfisk's valved hybrid. I don't care if his design requires lathe work, it's still awesome.

(A little bit of background: Galfisk's valve is a barrel-sealing piston valve. The ignition of the mix in the chamber causes a pressure rise in the gas on the chamber side of the piston, but the pilot volume doesn't ignite, and so the pressure remains lower. This has the same effect as venting the pilot area a bit: triggers the piston. So the piston starts to open, and as it does it causes a valve in the pilot area to actually vent the pilot. Then it's all downhill.)

I have a thought: could one make a hybrid valve like Galfisk's, but leave out the valve that vents the pilot area? This would likely mean that as the pressure in the chamber dropped during the shot, the valve would start to come closed prematurely, harming preformance. However, that all depends on what happens to the pressure; it may stay high enough for the shot to be successfully completed. I've had thoughts about a coax built like that.

PostPosted: Mon Jan 01, 2007 11:34 am
by BewareOfDog
<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote"><b>Originally posted by An Apple Pie</b>
The main difference between this and a normal hybrid would be that the gases are accelerated before they are ignited.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

And why would accelerating the gases before they are ignited lead to a significant increase in power?

PostPosted: Mon Jan 01, 2007 12:12 pm
by An Apple Pie
<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by DR
And why would accelerating the gases before they are ignited lead to a significant increase in power?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Obviously I am not an expert at this stuff, but when the gases are just sitting there and then ignited they only get the energy from the propane. In something where the gases are accelerated first, the gases start with more energy, and then it also receives the energy from the propane.

x=energy from propane
y=energy from the speed of the gases (not sure how to word that, but you know what I mean)

x+y>x

PostPosted: Mon Jan 01, 2007 12:36 pm
by LukeSkyRocket
Not really, applepie. I think DR's right. From a thermodynamics standpoint, the kinetic energy 'y' from the moving gas is already present as potential energy in the pressurized chamber, so there's not any difference in those terms.