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Help with OS 46 - sagging in hover

I have a os 46fx that is well broken in,runs great, but tends to want to sag while hovering my edge540 spad. I have made sure that is not lean while full throttle and pointed straight up (motor speeds up slightly when pointed up), and also have it set on the bottom end a little rich when horiz thinking that when it points straight up the low end will tend to lean out. Any tips on how to get this adjusted properly for 3D is appreciated. Maybe I just need to mount the plane straight up and tune it up that way, for both low end and high? Thanks

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Reply to
Mike
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Overheating?

Have you tried the speed-up-on-vertical test at the throttle setting that you need for hovering? Your mixture could be different at that setting than when you have the throttle pegged.

If you suspect a too-lean run, try richening it up a tick or two, and fly. Maybe do this two or three times until it's _really_ rich (do hover way up there, so you have time to recover from a dead-stick).

If it only needs a little bit of richening to be OK then it's probably too lean and you just need to diddle with the tank location or maybe find a pinhole in a tube.

If it needs a _lot_ of richening, and particularly if it takes a while to sag -- maybe it's getting too hot? I can't imagine that the engine is getting as much airflow in a hover as it does in level flight, and you're certainly going to have the throttle up there.

You could probably test for heat problems on the ground -- just keep it from moving, hold it at the hover throttle setting, and see if it sags after a while. If it does, shut it down and feel the engine or squirt some fuel on it -- if the fuel boils then it's too hot.

Reply to
Tim Wescott

Sounds like you answered it yourself ...''motor speeds up slightly when pointed up"... it's leaning out.

Reply to
chris-s

Also check to make sure the clunk is at least 1/4" away from the back of the tank when the plane is held vertical.

You could also be dealing with a cooling issue. Block off the cowl opening on the side opposite of the cylinder, then make sure you have 1.5 - 2 times that remaining opening size for exit air.

Reply to
Tom Minger

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