The best reason for using a 46 size engine is that no weight needs to be added to the nose in order to achieve balance. I have built 2 pitts now using a tower hobbies .46 in the first, and an OS .46 LA in the second one. Both planes balance out perfectly 3.1" back from the top L.E. Both times I mounted the engines at 90 degrees and used a PITTS style muffler to exhaust below the fuselage. As far as the structural problem is concerned, I have finally concluded that the R.H. strut broke at the lower lightening hole just above the lower wing attachment point due to high bending stresses in the region. With no strut to stabilize the upper wing, the wing oscillated violently destroying the ailerons on that side. Examining the L.H. strut, I see cracks in the same area. So all the beefing up of attachment points will do no good if the struts break. The solution I came up with was to remove all bending stresses by shimming the 1/2" difference between the strut attachment locations by using a nylon spacer I got at ACE hardware #6 screwhole in the center, and 1/2" Outside dia. This allows the struts to be perfectly straight. I received a damaged canopy from RAIDENTECH, and e-mailed them a pic of it. They have sent a new one. As soon as it is on, and the OS is purring, I will test fly it. The weather here on the Texas gulf coast has been crappy for a month now.