Built up Fuselages

[Mike Griffin]

Here is something that I have wondered about in constructing a full fuselage.  Assuming it is a kit..you punch out the formers and build the fuselage by whatever method you use, (ie upside down, on a jig, or whatever)  when you finish you sight down the fuselage and discover that one side curves a little more than the other one.  What is the cause or causes for this happening?

Thankd

Mike

[Bill Little]

The problem is likely caused by different stresses in each sheet of balsa.........

BIG Bear
RNMM/AMM

[Tim Wescott]

Not putting in structure that holds things in place while it's still in the jig!

Unless you're hand-selecting (or hand-tuning, with a sanding board) the fuselage sides after you cut them, you're never going to get this absolutely perfect.  You'll probably often come close by hand-selecting the sheets from which you cut the fuselage sides, though.

[Mike Griffin]

I got the problem solved at least for this fuselage.  I removed formers F3 thru F7, because the bowing problem was from there back, not the crutch.  I went to the very end of the tail ofthe fuselage where they come together and while sighting down the fuslage sides, I used the fingers on my right hand to slide the fuselage sides slight back and forth until the curvature in the fuselage sides matched and then I clamped the very end of the fuselage sides back together.  I then reinserted the formers and glued them back and now the curve on both sides match.  Remember, this is a kit cut from contest balsa and the side that was curved or bowed too much was softer balsa and I am sure that had something to do with it also....I think I got it solved.

Mike

[Allen Brickhaus]

Purchase a C.F. Slattery fuselage jig.  Problem solved.

[john e. holliday]

Even with a jig sometimes a fuse will come out slightly bowed unless you put in diagonal braces between the formers top and bottom.  Go look at Doug Moon's construction pics.