Some time back I suggested using a sailboat cam cleat, small line
and rubber band as roll trim by attaching the cleat to the bottom
of the stick with a bracket. I have since tried this and found
it awkward to use in that if one exceeds the needed roll trim
setting the line must be popped out of the cleat to start again.
It only took a one flight to decide this wasn't a convenient way
to do the job.
I then used some 64 mil aluminum to make an angle piece, 3/4 inch
sides by about 2 inches long -- just clears the seat at full aft
stick. This was bolted to the original bracket used for the cam
cleat at the base of the stick. A 1 inch diameter washer made of
1/16 inch rubber was inserted between them as a friction clutch
to allow pivoting the angle piece. A cord is tied through a hole
in the aft vertical part of the angle bracket; a rubber band is
tied to the end of this cord (Rube Goldberg would be proud). The
carefully calibrated :-) rubber band is passed over a 6-32 bolt
which protrudes from the forward inboard edge of the seat
support; a second bolt on the outboard forward edge of the seat
allows roll trim in the other direction -- with only the pilot on
board, right trim is all I've needed so far.
The vertical section of the aluminum angle is cut away on the
forward half in a pleasing curve to allow the horizontal forward
end to be rounded, this to ensure it doesn't bump the stick as it
is rotated to adjust trim. The remaining vertical part of the
angle section is used as the handle when setting trim.
The Europa's good basic balance is what allows this light duty
design to handle the job since only a couple of ounces of force
are needed even when applied only a few inches from the stick's
pivot point. There may be some slight coupling of roll trim into
pitch trim since the roll correction force has a back component
although I haven't noted this, perhaps because I generally set
roll trim first.
This simple gadget took about a half hour to build and install.
Works great, allowing roll trim to be adjusted quickly and
easily. Simpler and cheaper than my original cam cleat
inspiration.
John N44EU
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