I have just got down to putting together a GP Reactor Bipe. I was quite dissapointed when I looked at the fuse structure. The thing is essentially a 2mm ply frame with holes that have been sheeted over with balsa. There is almost no tristock anywhere, no stiffning balsa, nothing! Everything is just interlocking ply, even the bulkheads are not reinforced in place. Even the LG block is just a ply former. Its likely to break soon on our rough field and I will need to reinforce before I do anything else.

Now, I am planning to convert the fuse side into a box structure by gluing balsa strips (1/4"x1/4") on the inside to form a truss like structure and then sheeting over with balsa ply for additional strength to form a box frame. Te balsa strips will be applied in the direction in which force runs in the fuse in case of a hard landing i.e. going from the TE on the LG towards the next bulkhead. Then I will use tristock on all bulk heads. Will add birch blocks with the LG block and tristock the inside to hold it in place. Will also fibreglass the firewall from both sides. I believe all this wont add too much weight, will be using a FS110A anyway.

My question is

1) Is this a good way to go about strengthening?

2) Should I use CF instead of the 1/4" x 1/4" balsa strip or will it just punch through in a hard landing? Also, there is a step between the balsa frame and sheeting which I will need to fillup on the inside with some ply to provide the balsa strip more bearing area. Should I just add the ply under the balsa strip or fill up the entire bay with ply?

3) Anything else you suggest?

Ameyam