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Rob, et al,
Yep and a certain aileron that contains a trim tab and actuator
require even more balance weight.
Grayhawk
In a message dated 4/22/2009 8:27:23 A.M. Central Daylight Time,
rwolf99@aol.com writes:
I, too,
was surprised at how much lead I needed to balance my 360 ailerons. In
fact, I have those lead half-rounds going nearly full-span (two of them, flat
surface to flat surface). But let's stop to think about it. We
need as much "moment" (mass x distance) in front of the hinge line as
behind it. In practice, we have more weight (balance weight) forward of
the hinge line than we do behind it (the control surface itself) since the CG
of the control surface is generally much further behind the hinge line than
the balance weights are forward of it. This is certainly the case with
the ailerons, but less so for the rudder and elevators, since they have those
forward overhangs for aerodynamic balance.
For preliminary design
purposes, my airplane design group assumes that the balance weights weigh 1.5
times the weight of the control surface alone.
Bottom line -- your
balance weights need to be at least as heavy as the control surface, and up to
50% more.
Yup, it's a lot.
- Rob Wolf
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