More info from Keith Shaw who you’ll remember has done some extensive scale detailing to one of our kits. Keith is an AMA Hall of Fame member. He’s tuning and trimming his bird and offers the following.
Now have 8 more flights on the Wright. Two improvements have GREATLY helped the directional control.
1) I found that the aileron cross pushrod was buckling. Increased wire thickness to 1/16th, helped a little. Rolled masking tape around pushrod ends and middle to get it up to the ID of 1/8th aluminum tube. Coated the tape with 5 minute epoxy and slipped the tube on. Wing warping is now very solid and uniform over flight speed range.
2) Mine had the few hertz rudder oscillation like yours. Carefully flexed everything back there and found that the vertical wire was wobbling all over the place at the bottom. The rudder pushrod was very solid in comparison, so side loads on the fins cause large distortion of the bottom inch of wire. Drilled out the boom bearings and plywood fin cross braces to use a 3/32″ wire instead. Rudder control is nice and solid and the oscillation is gone. Might have been able to get away with 1/16″ wire, but went for the 3/23″. Besides, I needed to move the CG back. 🙂
Now flying with CG about 7/8″ behind leading edge, still need to do some small tweaks on the motor thrust line. The plane now has a very solid feeling, with only a slight pitch bobble when it hits some turbulence. Flew it twice yesterday at an airshow in Detroit in 10 mph breeze with some minor turbulence. No problems. Before the mods this would not have been wise.
BTW, the crowd at the airshow LOVED it. More photos taken and questions asked than any other plane there.