Model Forum / Radio Controlled / Helicopters / November 2008

Starting with a couple of assumptions:

You are using the recommended engine and blade size for this heli.
You have the correct gearing for this heli (note that the 30 and 50 size
Hawk have different intermediate gear ratios)
You have assembled with the engine pushed upward enough for the clutch to be
completely captured by the clutch bell.

If above is correct, it is unlikely that the clutch is slipping. That Hawk
clutch will easily hold a 60 size engine. However, the clutch, or some part
thereof, could be broken. Common failures are a clutch shoe breaking off
(usually due to too much clearance between clutch and clutch bell lining) or
the clutch bell lining coming loose from the clutch bell (usually due to too
much heat - engine running after a crash for example - which will destroy
the bond between clutch lining and clutch bell).

If all the above is correct, then not getting enough head speed will be due
to improper control system assembly/set up or improper transmitter set
up...not a bad clutch.

BTW, all of the above does not apply if you have an older model with a
plastic clutch bell. If so, toss the plastic bell and get the aluminum bell.