So whats the trick to keeping fuel in your engine when flying upside down?

What do you mean? Most of us keep our fuel in the fuel tank and pressurize it with a line from the muffler on the engine. Suction moves the fuel through the carb and into the engine.

just got into gas. Seems when I do a loop or upside down flying my plane boggs out on me.

No trick; the clunk inside the tank keeps the fuel line in fuel, and muffler pressure (or carb pump on a gas engine) keeps positive fuel pressure. The engine itself doesn't care which way it's pointed, it will run as long as fuel can get to the carb.

Just saw your return post. Sounds like you might have a mixture issue. What engine, and have you played with the needles yet?

I have a brass tubing going into my tank should I connect a rubber tubing and a clunker to it?

Two words, "header tank".

The best one is sold at bvmjets.com called a UAT.

looks pretty cool. question is it worth 60 bucks?

How many airplanes do you have? I have 6 and they are all Turbine Jets. Each of them has one. 6 jets, call it $5,000 a jet, even though they are more like $8, and then 6 times 60 is a measley 360 clams.

Ya, they are are worth it

For a prop plane, you could get away with what we used to do in Ducted Fan, which is basically a four ounce tank plumbed the way a normal tank is. Just plumb it between the main tank and the engine. That way the engine is always drawing from a full tank. The clunk will never be suspended in air.

FWIW.

Install the engine upside down so when the model is inverted it's running right side up. ;-)

Header tank is a nice idea but my glow engines have muffler pressure while my gassers have diaphram pumps. I generally don't fly-'em-dry and land before the klunk sucks air.

Keep enough forward motion up so the fuel all sloshes back to where the tank is. Speed is life!

If you're talking about inside the tank, yes, you need tubing with a clunk on it inside the tank. If you don't, that's your problem.

Then that is my problem. Thank you.

$30.000 in Jets, Whew ! that come with a basement ? jk

Be sure to use only neporene lines. Silicone will quickly melt and Tygon hardens with age. I use a sintered bronze clunk in my tanks. Keep the end of the clunk about 3/8" away from the back wall of the tank.

Dr.1

put a cork in the carb throat!

I know he said, "Gas", but I am assuming that since he didn't realize that he needed a clunk, he is using Glow fuel, not Gasoline

The clunk for most gasoline engines is usually slightly larger and often differs from a nitro fueled engine by having a felt like covering over the clunk as well as a screen filter at the mouth of the clunk. This aids greatly in getting good fuel flow as the tank nears the empty mark. With the felt filter, you will get the last drop of gas out of the tank. Check with your local lawn mower shop for possible sources of fuel line suitable for gasoline as well as tanks and clunks at usually a lower price than the local hobby shop.

hey sean, just a Q for ya, since glow engines don't use pumps like the jet guys do (most don't, yes i know about perry pumps and things like that but it isn't the slandered)

wouldnt one of those UAT's just give you problems with restriction..?

Just a thought..

Steven