RE: GP Ultimate Bipe
The whole thing builds really easily. Turtle deck sheeting too.
Listen on that wing sheeting. Its already thin and light and gets thinner if more than final sanding is needed. Its so thin that CA can go right through the sheeting and glue you to the wing while you CA the sheeting into place so line it up well and straight. Make sure you join and sand your center sheeting and apply it as a unit, not in pieces (i think the instructions had the builder sheet the center section with small pieces butted up one at a time on the wing...sloppy way to build, maybe it was a different airplane).
The fuse is much stronger and heavier than necessary. Lighten wherever you can. I built mine 100% stock and flew it so hard than any other airplane would have split in two. Not this one. Blender after blender at high speed. I did break the forward cabane, but I never cracked the structure, even after a double cartwheel. A second aileron servo is a good idea. One per wing on the low and use interlinks between the ailerons. Make the interlinks with 4-40 rod and quality linkage on both ends. Quality clevises will work fine as long as the holes are not sloppy. Do not use the supplied 2-56 rod with one clevis and one z-bend. You will probably get a nice humming flutter if you do, although not usually catastrophic with an airplane of this size and strength.
It comes out nose heavy easily so a servo in the tail is perfect. If you can, frame it up and dry assemble it uncovered with everything but the last two servos for CG and then decide on the servo positions. You might decide to place both elevator and rudder servos in the tail.
Lastly, make sure you give every surface LOTS of throw potential. The surfaces are good sized, bevel for outrageous throw so its there if you want it.
Mark