Gee, those Robart 550s look like they leave the wheel sticking out quite a bit. Did you use the 85 degree or the 90 degree retracts? Theoretically (with dihedral) the 85s should work but the 90s should bring the wheel up into the wing a little more.

Perhaps another theory on the stab failures: I don't think it's the carbon tubes or broken ribs at all. If the tubes are too long they will break the outboard ribs which don't contribute much to overall strength. Not using enough glue (on the tubes ) shouldn't make any difference, either, since we fly 160-180mph racers with plug-in stabs that are only held on with tape (!). I believe that the extra trim load on the elevator (required to overcome the 3.5 degrees of downthrust at high speed), probably made worse by overpowering the aircraft, might have caused the stab to fail by breaking downward near the root (probably just outside the attachment point).

I haven't seen any of the photos but having read about the tubes being too long and a few broken ribs just doesn't make much sense to me. I heard of a TT RB stab failure locally (Phoenix) before even reading this forum so it appears to be more than just an isolated incident. From what I understand the local failure involved a YS 1.10 and substantial airspeed. I'll check the tube lengths when building mine but I'll bet that removing most of the downthrust before installing a YS 1.20 will probably keep mine safe.