A while back, I put my favorite scracth-built stick-type plane into a beautiful flat spin. I left it in the spin a little too long and didn't have enough altitude to pull it out of the spin resulting in a crash. The wing and the empennage were basically untouched, but the forward 2/3 of the fuse was destroyed. I finally got around to fixing it and built a new front 2/3 of a fuse. However, due to a slight miscalculation on my part, when I went to graft the empennage back onto the new fuse, I noticed that in order to get the top bottom and sides to align correctly, I will have to add 1.625" to the length of the tail boom of the new fuse.

When I go to balance the airplane, should I leave the CG in the original spot and adjust weight due to the longer tail boom? or should I shift the CG forward or aft a little bit to account for the increased length?

Also, since the tail boom is longer, the moment arm of the elevator and rudder is longer so the corresponding moments should also be larger. Should I expect these control surfaces to be more responsive (as if they were larger)?

Keep the C-of-G where it is supposed to be (add weight as required). You may find that the plane flies more easily with the longer tail -- it will likely be more damped in pitch.

@ 1.62" you will barely be able to notice the difference. What you may feel is a little more tail authority and stability------I think you'll like it---------IF you can tell the difference at all.

Do keep the CG at the same position as before and change it only to gain the flight characteristics you want.

All the foregoing is based upon the assumption that all else has remained 'as before'.

Thanks.....

This rebuild is going to be an interesting experiment. First off, the plane is a .40 sized "stick" that has a narrow fuse width and a very slender tail boom and was intended to be used with a .40 2-stroke. From the beginning, my intension was to build an almost rediculously overpowered sportster that would easily power itself through high winds (which we tend to have a lot of at our flying feild). I built the plane according to the plans (all balsa except for one former, the firewall and the landing gear plate) so the plane was pretty light. I mounted a Saito .65 4-stroke to the firewall which made it pretty nose heavy (duh!!), so I had to move the rudder and elevator servos back into the tail boom, I had to used a Hayes slimline tank and mounted it under the wing centered over the CG, and the battery and receiver were mounted aft of the trailing edge of the wing just to get it to balance.

Now for the rebuild... the original narrow, slender, all balsa fuse turned out to be pretty delicate, especially since I had to cut part of the structure away to mount the servos in the tail boom. This time around, I built the forward 2/3 of the fuse out of 1/8" lite-ply, so to compensate for adding all that weight to the front of the plane, I shortened the nose up a little and moved the firewall aft about 7/8". Then, as stated above, I had to lengthen the tail boom about 1 5/8" to get the empennage to line up correctly with the new fuse. The net result is an overall increase of 3/4" in the length of the fuse. The empennage was attached last night, so it's "game on".... I'm curious to find out how she flies. I hope it's as good or better than the original flew.