Icepoint problem
Just finished my Icepoint which has been under construction for the last year or so. I know, I'm a slow builder. Actually, it got bumped off the assembly line for quite a while.
Anyway, finally made the first test run today on the new YS160DZ which is mounted with an MK soft beam mount and a nose ring. Engine started reluctantly but got it running ok. A brute, to say the least. With an APC 17x12 and Cool Power 30%, about 8000 rpm. But it shakes like crazy, not just at idle, but even above 7000 rpm. Transmits a huge amount of energy into the airframe. Yes, the prop's balanced. Am I using the wrong engine mount?
The resulting problem is that the horizontal stab, which is mounted on a 1/2" diameter carbon tube, with incidence adjusters at the front of the stab, is now so loose that the tips can move up and down about 3/8". The rod for the incidence adjusters is also loose. The fuselage is only about 1" thick where the tube goes through, and the fiberglass sleeve in the fuselage just doesn't have enough length to handle the torsional vibration.
Has anyone else encountered this problem? Seems it will occur sooner or later, even with a smoother running engine. I can replace the worn sleeve with a new one, but I expect the problem will return rather quickly. I guess I could install flying wires like a Pitts, but somehow that just doesn't seem appropriate for a pattern plane.
Comments appreciated.
Jack