RCU Forums - Clunk Question

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RE: Clunk Question

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Even at low RPM (engine at idle when diving) you will probably not notice anything special because the air bubble will be a lot smaller (less fuel consumed at low RPM) and also the inertia of the rotating propeller together with the windmill effect on the propeller will tend to keep the engine running during the brief time it takes for the air bubble to be 'sucked' through the carburettor.

Don't get me wrong, I agree with most of what you're saying. However, I think it's doubtful that propeller inertia and windmill effect will keep the engine turning through compression should there be a flameout. Even if by some chance it did, and a flameout occurred, no turning of the engine will restart it.

RE: Clunk Question

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ORIGINAL: DBCherry

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IMO, the only "abrupt stop" with enough force to get your (unstiffened) clunk up front while flying is called a crash.

Guess that depends on your definition of a crash.

I've had my clunk wind up at the front of the tank after hitting the tall grass at the end of the runway when I landed too fast. :D
Dennis-

Very true. Well I define crash as the sudden and violent interaction of your plane with the earth or anything on it, FROM FLIGHT or a semblance of it, consequently requiring major repairs or a trip to the trash bin. Hitting something (e.g. tall grass, cars, your girlfriend, etc.) when you've already landed (i.e. wheels already rolling on the ground) is called differently... collision perhaps??. I'm sorry, I may be wrong, I'm not from an English speaking country.

On stiffening the clunk tubing, I guess it doesn't hurt. You can never be too careful, especially on planes with very large fuel tanks which requires long clunk tubing (say, 30 cms or so). Now on necessity... getting your clunk forward of the tank after a COLLISION doesn't affect flight or engine performance because the plane is already on the ground and the engine is dead anyway. It really doesn't matter because you can always shake the clunk to its original position before your next flight. Likewise, after a CRASH, where your clunk ends up will be the least of your concerns.[sm=biggrin.gif]
But still I have a question and I need enlightenment... is there a maneuver with enough inertia to cause the clunk (at the end of a 6 cm silicone tubing) to go forward IN FLIGHT? If there is, I really have to get one of those stiff tubings in my tank or avoid that maneuver.[sm=confused.gif]

RE: Clunk Question

how about to make both of the persons right how about putting a T fitting or vacuum Tee in the tank to face the front and one in the back. lol

RE: Clunk Question

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ORIGINAL: 26C4U

IMO, the only "abrupt stop" with enough force to get your (unstiffened) clunk up front while flying is called a crash.:D

You might think that, but I have seen it several times, and many years ago it happened to me.

I was landing a CGM Chipmunk on a grassy field, the grass was "Clumpy" and shortly after touchdown, the gear hit a clump and the plane nosed over. No damage done, but the abrupt stop caused the clunk to swing forward. I couldn't figure out why the next 2 flights deadsticked, until and older and wiser clubmember suggested what might be the problem.

Removed the tank, and there it was! The clunk was stuck up in the neck.

RE: Clunk Question

But I said getting the clunk up front due to an "abrupt stop" or an adverse maneuver WHILE IN FLIGHT, not on the ground. Anyway, good enough. I'm getting one of those stiff tubings (darn, I hate repairs). Saves the hassle of having to shake the plane every flight just to make sure the clunk is suppose to be where it is. Thanks.