Hybrid Charger - Not a cannon

Just build a cannon and want to show it off? Post it in here.

Postby Freefall » Wed Feb 14, 2007 11:20 am

I guess I'm not getting it either.
The premixed gases enter the hybrid <b><i>how</i></b>?
How are you accounting for air already <i>in</i> the hybrid?

Is this some variation on the GenII theme?
Freefall
 
Posts: 3252
Joined: Tue Jul 29, 2003 4:46 pm
Location: USA
 

Postby Duodec » Wed Feb 14, 2007 1:35 pm

Notice the quick disconnect at the one end? Hook up a regulator to that with a hose to the cannon. Then you can inject pre-mixed gasses into your hybrid. The pressure set by the regulator determines the mix, so it will work with any size chamber, and provide many quick refuels with one big chamber of gas.

Freefall I think you got me there. I did forgot to account for air already in the hybrid. I think it can be solved by adding a larger percentage of propane.

Assume a 4x mix, the air already in the chamber will give the first 14.7psia. So that would mean regardless of the chamber size, a 25% increase in propane mix would be required in the pre-mix to account for the dilution of the propane.

To use round figures, say I want 80psig when the pre-mix chamber is charged. I should be able to increase the pressure of the propane 25% to 100psi when metering thus giving me 25% more, right?

If my figuring is correct, that should allow it to work regardless of chamber size.
Duodec
 
Posts: 45
Joined: Wed Jun 14, 2006 1:00 am
Location: USA
 

Postby Freefall » Wed Feb 14, 2007 2:50 pm

So...what? You use a pre-pressurized mix in this chamber, hook it up to your hybrid, open the valve, and let it equalize? That'll get you one shot at your chosen pressure. Where are you getting many quick refuels?

or, I ask again: Is this a variation on a GenII design, where premix gas is displaced into the hybrid?
Freefall
 
Posts: 3252
Joined: Tue Jul 29, 2003 4:46 pm
Location: USA
 

Postby Duodec » Wed Feb 14, 2007 3:58 pm

No, its not a genII variant.

Its supposed to be pressurized up to 100psi. Using a regulator you can then set the pressure in your gun to whatever you want. For example, 14.7 psig into your cannon for a 2x mix. You would have to have a very large cannon to not get several shots out of it before it is below a usable pressure.
Duodec
 
Posts: 45
Joined: Wed Jun 14, 2006 1:00 am
Location: USA
 

Sponsored

Sponsor
 
 

Postby aturner » Wed Feb 14, 2007 4:14 pm

Freefall, at first I was wondering if it was a GenII fueling device, but then I remembered it has a fan inside.

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Duodec
[br]Notice the quick disconnect at the one end? <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Actually, I see a quick disconnect at both ends! ;) And to be honest, at first I wasn't 100% sure which one would be hooked up to the hybrid chamber. But now I think you're talking about the q.d. on the left in your first picture? Correct?

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">
Hook up a regulator to that with a hose to the cannon. Then you can inject pre-mixed gasses into your hybrid. The pressure set by the regulator determines the mix.....<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
Okay, so you will use a second regulator to control the flow of mixed air and gas from the meter to the hybrid chamber? That is a key detail, which had escaped me until now. This addresses the issue Freefall raised about the pressure equalizing between the meter and hybrid.

I'm not sure if you can just say a 25% increase in propane will do the trick, but you have the right idea. The issue of air in the chamber has to be dealt with in any hybrid fueling, regardless of the meter device. I recommend you play around with BigBang's prometer. He's designed a hybrid fuel calculator that can account for air in the chamber, as well as increase in pressure over multiple fueling steps. When you do this, I think you'll need to first calculate how to fuel your 4" pipe on your metering device (multiple injections, correct?), and then separately calculate a 1 step fueling for your hybrid chamber. Make sense?

Just try to avoid a lean mix.
aturner
 
Posts: 1470
Joined: Thu May 27, 2004 1:50 pm
Location: USA
 

Postby SPG » Thu Feb 15, 2007 8:34 am

Clever, nice and simple, I can see how it works easily. It's a big cylinder full of HIGH PRESSURE premixed fuel and air.

You connect it up through a regulator to a small chambered hybrid.

You dial in the pressure on the regulator to suit the desired chamber pressure in your hybrid (we often talk about 2X, 3X, 4X mixes, all we're refering to is the gas ressure in the chamber, with this you could have a 2.76589X mix if you wanted).

You open a single valve and the high pressure gas flows out of the BIG cylinder into the SMALL chambered hybrid till the chamber pressure in the hybrid reaches the pressure set on the regulator (NOT till pressure in BIG cylinder and SMALL chamber equalise).

You fire the gun.

Repeat till your BIG cylinder pressure is less than you regulator pressure.

Refill BIG cylinder.

Repeat.

One thought, if this is for very small chambered hybrids, then why not "wash out" the chamber of exhaust gases with a short burst of propane/air mix from your BIG cylinder, before putting in a new burst disc. That way the chances are you won't have to worry about the air problem that Freefall brings up.
SPG
 
Posts: 983
Joined: Mon Jan 12, 2004 4:51 am
Location: France
 

Postby Duodec » Thu Feb 15, 2007 8:46 am

I thought of that SPG, but the 'washing out' might use too much air, lemme get some time using it and I'll figure it out.

I am just glad that somebody finally gets it!

I know you guys aren't idiots, so you had me wondering if I was being coherent enough to understand.
Duodec
 
Posts: 45
Joined: Wed Jun 14, 2006 1:00 am
Location: USA
 

Postby SPG » Fri Feb 16, 2007 7:24 am

Duodec, it would I guess depend on what size chamber you're using in relation to the size of your BIG cylinder (technical term there), but as an example, let's say you're going to use the equivalent of a 4x mix.

Your regulator's set for 4ATM, but to replace the air or spent combustion gases in your chamber you'll only need 1/4 of your chamber volume, because of course all you need is a chamber full of propane/air mix at 1ATM.

So if you really are using a small chamber in relation to the BIG cylinder, you should still get plenty of shots out of it.

Another thought would be to have some of plunger (think syringe) inside your chamber, to push out the air/spent combustion gasses, before refuelling. Imagine you fire the spudgun, then push the plunger forward, then insert a burst disc, now refuel, as you do so the plunger is pushed backwards by the propane/air mix. This plunger could even be spring mounted inside the chamber so that it automatically moved forward as soon as chamber pressure (on firing) had reduced enough. Only problem is locating your spark gap in such a way that either it is on the inside face of the piston or the piston clears is as it moves past.

The only thing you'd need is your refuelling port located at the front of the chamber.
SPG
 
Posts: 983
Joined: Mon Jan 12, 2004 4:51 am
Location: France
 

Postby BewareOfDog » Sat Feb 17, 2007 1:01 am

Two problems I see with this are:

1.) Charging your BIG chamber to an EXACT high pressure, while trying to compensate for a larger percentage of propane, will be very tricky.

2.) Your fan is gonna be hatin' life as it feebly attempts to run in a compressed environment.

I'm not shooting down your idea, but there are much simpler ways to charge any given hybrid.
BewareOfDog
 
Posts: 4306
Joined: Fri Sep 19, 2003 12:37 am
Location: USA
 
 
Previous

Return to Finished Cannons

cron