Model Forum / Radio Controlled / Air Models / March 2006

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.