High Quality Plan Sets for Radio Control Aircraft
Henry Struck's 1937 Benny Boxcar
Scaled to 108 inch span
Page 22
6-32 screws with self locking nuts retain the mount to the firewall and add strength to the mount.
The Boxcar was assembled and weighed at both main gear legs and at the tail post. A before covering CG point was calculated. It weighed 70.3 ounces at this point. The CG is at 12.01.
As usual all positionable components will need to be mounted as far forward as possible, and ballast will be required.
Control surface arms were made from 1/16 G10/FR4, circuit board material. Carbon fiber would be good but it is much harder to machine.
The arms should be installed centered on the pivot points and with the holes aligned with the pivot points. That will insure that the attach points describe
equal arcs around the pivot and are diametrically opposite. The tension on the cords then should remain very nearly constant at any control deflection.
Some time was spent determining the best routings for the control runs. 64 pound bonded Kevlar cord is used. I buy the cord from The Thread Exchange.
Here is the page for this cord: Thread Exchange 207 Kevlar 64 pound cord Once the locations were determined the servos were installed.
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