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Old Apr 07, 2009, 06:05 PM
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EricClark's Avatar
United States, MT, Butte
Joined Mar 2007
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Idea
Pressurized fuel tank

I have a small glow engine that doesn't have a muffler (cox .049 I believe) and it runs great. However, it has been difficult to keep the fuel flowing into the engine consistently (at least for me). I like scale aircraft with little room inside to position things like fuel tanks easily, its lucky to get one to fit inside at all. Therefore obviously causing issues with fuel flow cause the little bugger cant suck the fuel in very well. I came up with this idea.

Basically, its a mini electric pump/vacuum that runs on 4-12V (roughly) and the pressure can be regulated by the voltage. I found that a 4.8V rx battery will make it hum nicely and have a little pressure (have not actually ran the engine with it yet) so I'll play around with the voltages and whatnot. The point is, I figure that with a simulated muffler pressure line, the engine will have a consistent fuel flow and if an electric switch is implemented, the flow can be cut by cutting the pressure remotely and therefore killing the engine. There may be no throttle control but there can be an emergency cutoff.

I don't know, what do you think?

Eric
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Old Apr 07, 2009, 06:38 PM
Übung macht den Meister..
Deuce's Avatar
United States, OR, Fairview
Joined Jul 2006
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Quote:
Originally Posted by EricClark
I have a small glow engine that doesn't have a muffler (cox .049 I believe) and it runs great. However, it has been difficult to keep the fuel flowing into the engine consistently (at least for me). I like scale aircraft with little room inside to position things like fuel tanks easily, its lucky to get one to fit inside at all. Therefore obviously causing issues with fuel flow cause the little bugger cant suck the fuel in very well. I came up with this idea.

Basically, its a mini electric pump/vacuum that runs on 4-12V (roughly) and the pressure can be regulated by the voltage. I found that a 4.8V rx battery will make it hum nicely and have a little pressure (have not actually ran the engine with it yet) so I'll play around with the voltages and whatnot. The point is, I figure that with a simulated muffler pressure line, the engine will have a consistent fuel flow and if an electric switch is implemented, the flow can be cut by cutting the pressure remotely and therefore killing the engine. There may be no throttle control but there can be an emergency cutoff.

I don't know, what do you think?

Eric
Will this little gizmo work as a fuel pump as well, or only with gaseous fluids? It's a pretty cool idea...

James
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Old Apr 07, 2009, 06:46 PM
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I like this idea some myself. What, where, how much, how big?

It would be nice to show something to scale it with. A ruler or some coinage perhaps. Would that be a one ounce tank?
LT
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Old Apr 07, 2009, 09:34 PM
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EricClark's Avatar
United States, MT, Butte
Joined Mar 2007
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Quote:
Originally Posted by Deuce
Will this little gizmo work as a fuel pump as well, or only with gaseous fluids? It's a pretty cool idea...

James
Not sure. I know it works for air, liquids... idk. I'll try and find out.

Quote:
Originally Posted by lightthings
I like this idea some myself. What, where, how much, how big?

It would be nice to show something to scale it with. A ruler or some coinage perhaps. Would that be a one ounce tank?
LT
Its a one oz tank. I'll get some more pics later. Its a very small pump considering.

Eric
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Old Apr 15, 2009, 01:20 PM
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Nice idea. With a little extra work and an intake throttle it could also be the basis for a very good speed control. Perhaps by having an air pressure chamber and controlling the stroke rate of the pump the fuel pressure would be varied and the flow altered to synchronize with the setting on the intake throttle.

If your pump is driven by a brushed motor the pressure control would be a speed control using PWM (pulse width modulation) instead of a diaphragm pump driven by pulse rate.
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Old Apr 15, 2009, 02:20 PM
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Speed control and fuel consistency is indeed the main reason I came up with this.
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Old Apr 15, 2009, 09:58 PM
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This would work great for control line combat planes or any other that requires a pressurized system. I get tired of pacifiers for tanks.
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Old Apr 20, 2009, 04:34 PM
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Eric, Do you have a link to the pump?
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Old Apr 20, 2009, 05:39 PM
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So have you run it? How does it work?

How much does the setup weigh?
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Old Apr 20, 2009, 09:35 PM
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Need more info please!
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Old Apr 20, 2009, 10:10 PM
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just put a tap of the crank thats how thay do it on the cox .049 td's
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Old Apr 20, 2009, 11:26 PM
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Yeah, sorry I never got back on more info... I've been busy. Nope, haven't tested it yet so idk how well it works, if at all, but I have a plane I'm building to try it out in so there will be progress (hopefully) soon.

Link to site where I found/bought it here.

Eric
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Old Apr 21, 2009, 09:13 PM
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Pacifiers for tanks

Quote:
Originally Posted by Rodl
This would work great for control line combat planes or any other that requires a pressurized system. I get tired of pacifiers for tanks.
I'm going to hijack the thread and ask you how in the world you use a pacifier for a pressure tank. I can see filling the "binkie" with fuel, but how do you pressurize the darn thing ? I'm sure there are more here that would like to know. Can you refer us to a link, or describe the procedure briefly, here?

Thanks, Jim S.
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Old Apr 21, 2009, 09:20 PM
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Indeed. I too am curious.
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Old Apr 21, 2009, 09:57 PM
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In a combat control line plane size .35 motor, you have an opening in the wing for a pressurized tank. Some use 1/4 id surgical tubing sealed on one end and the other has a plastic fitting going to the fuel line which in turn goes to the motor. You use a syringe filled with fuel to fill the tubing and you put a "clip" on the line to keep fuel from rushing out. Pacifiers that we use are the old style that are hollow, and serve the same purpose. Prime the engine get it running "unclip" the fuel line, let the plane go and it runs off of the pressure in whatever you use for a fuel bladder in the pocket in the wing. What comes from the tubing or pacifier to the fuel line can be reduced to limit the amount of fuel going into the engine. I hope this helps, if not just look at some plans for control line combat and you will see the compartment for this "tank". Thanks rodl
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