Hi Doug,

To be honest, the firewall strength doesn't concern me. You can beef it up if you wish; won't hurt. The basic structure of the wing and fuselage is up to the task.

The first change I would consider is adding tail brace wires, for a couple of reasons. The extra power can result in extra speed, so the braces will help stiffen those surfaces. And, if you run the wires clear up to the top of the fin, they will help guide the towline over the fin.

I would also be concerned about the flap linkage and would consider skipping the torque rod arrangement and going to two separate servos for a stiffer linkage.

I would also consider either replacing the balsa pushrods with glass/carbon rods for extra stiffness, or building in guides about halfway back to guide the balsa rods to keep them from flexing.

Note that my concern is with the extra speed that you might encounter with your extra power. Might not be a problem depending on the skill in your left thumb!

Bruce