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<< Lancair Builders' Mail List >>
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fixed rudder trim tabs are ugly.
the proper fix is to reshape your rudder surfaces to trail properly andor
correct any misallignment in the vertical stab and or differential rudder
spring pressure. I did a combination of both.
My plane was flying about 1/3 to 1/2 left ball off center. first I found the
vertical stab to be flat on one side thus added 1/4 inch of foam, shaped and
covered with one bid on the right side of the stab using templates spaced 3
inches apart from the left side for a pattern. 100 hours.
There was some improvement. about half the yaw was removed. Next I found
the left side of the rudder to be concave about 3/32 inch. I used
polyfiber, very light and covered with a lightweight glass after it was
shaped properly. That took out almost all of the yaw.
Finally I made two aluminum brackets to attach to the foot pedals (the
expensive accessory type) to which I used two wingnuts and two zinc plated
carriage bolts for adjusting the spring tension on the pedals.I ground off
the bolt heads and drilled a hole in the bolt rectangular portion to affix
one end of the spring. the bolt head is facing forward in the craft with the
wingnut aft for adjustment. I can adjust the system in flight for testing
(albeit difficult) and once it was adjusted that is all. The differential
tension in the cables is very minor about two lbs.
You may not have to be as drastic as I depending on your building technique
but be sure your flying surfaces are symetrical. Before you close out make
templates of your fixed side and make sure the final piece when glued in
matches the other side. I didn't and paid the price. Also I would suggest
you fly in primer for a year an work out all the bugs, tight tolerances,
repair all cracks that appear etc. before final paint.
In test flying, make sure your turn and bank coordinator is perfectly
horizontal and parallel with respect to the wings, not the fuselage
longerons. Any deviation from these dimensions will give you an imprecise
measurement in flight. I found out that my coordinator was two tenths of a
degree tilted to the left but my friend Dave Fase said "Bob, you're not
going to the moon, enjoy."
Good luck
Bob Smiley
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LML website: http://www.olsusa.com/Users/Mkaye/maillist.html
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Please send your photos and drawings to marvkaye@olsusa.com.
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