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A suggestion,
I did this on my 360 on the vertidal
stabilizer. The couterweights were placed on the leading edge of the
rudder and in the counterweight overhang on top of the rudder. The moment
arm on the leadig edge was about 2 inches verses about 6 inches thus you need
only about 1/3rd the weight on the top of the rudder. My solution was to
add 1.5 inches to the height of the rudder and vertical stab. More room
for more lead. overall weight was reduced.
An addditional benefit I received was I increased
the demonstrated cross wind component for landing. I landed in a 24 knot
crosswind at Jackson Hole Wyoming one time.
Bob Smiley
----- Original Message -----
Sent: Wednesday, April 22, 2009 6:26
AM
Subject: [LML] Re: Balancing MkII
Elevators
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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