The elegant and simple way to build straight fuselages

[jan brilman]

Since I have read several times about problems with building straight fuselages, I thougt may be it is a good idea to share the method I have 'contrived' (?).

The pictures speak for themselves, I think.

http://www.modelbouwforum.nl/threads/guillows-20-piper-140-cherokee.238939/page-2

Starts at post 33 . . .

(The vertical wooden blocks have magnets in the bottom.)


jan.

[Bill Gaylord]

Side keels almost inevitably will have some degree of pre-stress or imperfect fit, when installing by the half-fuse method. Sometimes you will lift the half shell from the board, and the center keels are no longer straight. LC kits with parts made from accurate CAD profiles shouldn't have much of this issue, but with die-cut kits you can sometimes get better results by installing the side keels in mid air, after both halves of the fuse formers are installed on the center keel structure. With this method, one can install the keels and glue them in place starting from either end, ensuring that the fuselage stays straight as they glue them in place.

[kittyfritters]

The problem that most die half shell type kits have in maintaining straight fuselages is the layout of the parts. It's difficult, if not impossible, to make two identical dies for former halves and side keels. The way it's done is to make one die for the half formers and side keels, then stamp it on two sheets of balsa. Now you have the problem of trying to get two sheets of balsa with identical grain structure and density...which is impossible. To build a die cut fuselage straight you need some kind of jigging fixture to hold the parts straight.

Laser cutting does not have this problem. The laser cutter, essentially a printer/plotter that cuts, will "draw" the same part every time. Parts for both sides of the fuselage can be laid out, interleaved, on the same sheet of wood, and being cut from "the same piece of real estate" will build a straighter fuselage. In low volume production, the parts can even be designed to interlock, Chinese puzzle style, to be self-jigging. This does slow the laser cutter down quite a bit and is not usually done for high volume kit production.

Howard