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Engine basics => Engine set up tips => Topic started by: Paul Allen on August 09, 2014, 08:26:35 PM
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Is there anything, other than angling the rear of the tank out, to promote a clean cutoff ?
thanks
Paul
In OZ
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Try reducing outward yaw first...move your LO's forward or reduce rudder offset if there is some. H^^ Steve
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Paul, what are your symptoms?
Making sure that your leadouts are in the right spot is a Really Good idea (go by Paul Walker's trim article, if you can find it). If you're still having trouble after that -- let us know what's happening, and we'll make suggestions. Some of them may even help your situation.
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Smaller diameter fuel tubing?
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Hi Paul,
I have had muffler pressure cure it completely.
Bill
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I took off muffler pressure and it cured completely:)
-correct tank position
-baffle in tank helps but if all is right, it's not completely necessary.
-good piston/ cylinder fitting that does not loosen up too much when engine goes lean.
-even better; a well made ringed setup.
-Fuel filter volume. Sometimes the transparent Sullivan filter (craptrap?) is too big for low consumption engines. Possible air bubbles won't get out easily. Try something with less volume. And, fuel filter, like anything else in fuel/air system, must not have any leaks.
L
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Paul,
Getting the fuse in proper alignment in yaw is the first step. If you are tight on fuse tank compartment to kick the tank out you can build or have built a tank that has the built in wedge shape where the front is a little narrower than the back. Make sure the uniflow is in the correct position from the end of the pickup tube. Last thing is learn to do the "Command Cut Off Loop". You can do a search on YouTube for Al Rabe Command Cut Off Maneuver. He shows how to bring the ship into a gradual climb then a bit of a tight loop. You need to learn the right point once the engine hits the off the uniflow then do the loop. Be careful, if you try it and it doesn't cut you can try it one more time the next lap. If it still doesn't cut just let it run out and adjust your timing next flight (I almost lose a ship doing this when I tried it to late, I didn't step back as I did the loop and it was going to slow, drifted in, just caught it before it hit the ground).
Best, DennisT
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To add to this: In my experience cut off loops do not work if one is using uniflow with muffler pressure. Nor are will they reliably work if the engine has already gone lean. At a contest when they do work, it looks good, bad when they don't. Often used as a desperation maneuver at around 7 minutes and 30 seconds into the pattern. And don't ever do one up wind...I learned that one the hard way. 8)
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Hi Paul,
I have had muffler pressure cure it completely.
Bill
or pressure can cause it !!!
Randy