RE: Super Sportster 90/120
I am in the finishing phase of one of these kits. It will have an OS FS120 Surpass. Set up as a taildragger. I decided to use the hardwood engine mount (instead of a bolt on mount). Instead of the aileron torque rods, I'm using two mid-wing servos. I've had this kit for quite some time (since the 80s) and decided to build it now mostly so that I would have a something to carry an Eagle Tree Systems flight data recorder.
After I got the kit, I received a "WARNINGS AND REQUIRED MODIFICATIONS" (I don't see a date on this) kit from Great Planes to strengthen the stab/fuse joint. I also received (apparently a little later) a "SUPER SPORTSTER 90/120 UPDATE" from Great Planes dated May 24, 1988 regarding in-flight stabilizer/fuselage separation issues. There is also some mention of flutter in the original instructions.
Having the impression that flutter can be an issue with this plane (besides installing the modifications kit) I decided to counter weight the elevator and rudder surfaces. My modifications don't fully balance the surfaces at the hinge line but it does balance closer to the hinge line (maybe 1/2" closer) than the original surfaces. I also added triangle stock under the stab/fuse joint on the outside of the plane. I don't know how wise/worthwhile my modifications are, it's just something I wanted to try.
I'm looking forward to giving this thing a whirl this summer.