I just herd that some guys are setting up their clunk so it can flip to the front of the tank on purpose to prevent the engine from stalling on down lines. I have always made my clunk lines on my glow planes so it could not flip forward and cause a pinch in the line. Are any of you allowing the clunk to go forward like this? I set up my edge so it wouldn't go forward figuring that with almost 2 feet of fuel line it would take a very long down line to run out of gas and cause a flame out. Is there any reason I should rethink that logic?

i would say the question is, whether or not the clunk really will get stuck when it comes forward... if it can or has potential too, than that would be more dangerous it would seem to me... anybody want to rip a fuel tank out and play with it?

I would not rethink your logic. Been there - done that 8 or 9 years ago. I keep the clunk toward the rear of the tank. From what I understand there will always be fuel in the rear of the tank even in downlines but I can't prove it. No one at the 2 fields I fly at let the clunk go forward. If the guys at your field want to try this just be a good observer. Bill

I didn't think it made much sense just because I don't believe there is a fuel line on the market that is so flexible in gas that you could rely on it to allow the clunk to return to the rear of the tank when you returned to level flight.

About the best way I can think of to run out of gas with half a tank remaining would be to have the line flop to the front of the tank. If it didn't stick it would probably kink and cut off fuel anyway.

I had that happen on my EDGE! So I sliped a length of brass tube inside the tygon between the tank plug and clunk.

One of the guys about 5 years ago claimed that he had a very flexable line on the clunk and the clunk actually tied itself into a knot after doing some violent menuvers. He could still hear the clunk when he shook the plane but continued having problems. He finally took the tank apart after seveal dead sticks and couldn't believe his eyes at what he saw. I never really believed what he told me, but........
Bill

On the subject of clunks and gas fuel lines, I saw first hand yesterday a tygon fuel line that had been left in a tank for about 1 year.
The flyer had a DA-50 on a 28% plane. The engine almost stalled out a couple of times and would have been potentially fatal.
When we examined the fuel tank, you could not hear the clunk when shaking the tank. Upon opening the tank and examining the tygon tubing, the fuel pick up line was so rigid it would not move.

Can anyone comment on the length of time that tygon tubing should be replaced and/or a better type of fuel tubing to use inside the gas tank?

Jaketab

Some people swear by the blue areotrend tubing. Make sure its the gas safe verssion. Ive heard of people using the black neopreen tubing as well. I replace my Tygon every other year...just to be safe.