The rear end of the profile

flexes in flight. Very noticable. 2" maybe.
this is the fuselage from the TE of the wing back.
I can hold the engine, swing the plane back and forth, and the tail will flex left and right, up and down.
Need to fix it with out building a new plane.
Ideas?
Thanks!!
Bill

Wow, 2"!

My suggestion would be to refinish the aft portion of the fuselage with fiberglass and epoxy resin. Bill Melton did his profile carrier ships that way and they were stiff as a board.

Good luck. (What sort of ship is it?)

[photo not recovered: 3e69bb3870f12ad5.jpg]

"The trouble with being punctual is that no one is there to appreciate it."

Larry, THANKS! It is my "Original" (Ha, Ha) "IMPULSE".
I sorta, kinda, made a 48" span Impact profile. It could REALLY be a great flier if I can get the dog tail out of it. Great size for the OS 40FP. Won my first contest with my first one, all sheeted wing, now the new version has silkspan and a good bit lighter.
Thanks!
Bill

If cosmetics aren't too critical, just epoxy or epoxy/glass a carbon arrow shaft to the side(s) of the fuse from just fwd of the flap horn to aft under or above the stab.

Glassing or putting CF cloth over the aft fuse is good also and can be finished better.

The stiffest profile fuses I have seen are the versions of Larry's (Mo' Best) trussed core/64th ply built-ups. Lite and very stiff.

The arrow shaft solution will improve the bending problem but wont do much for twisting. Only an area cover will fix that.

Bottom line is how far do you want to go and what do you want it to look like in the end.

LAST EDITED ON Sep-30-03 AT 10:57 AM (CDT)
 
Thanks Curt! I just got a set of Mo Best plans, and I think I am going to cut the rear of the fuselage out and do it that way.
Cosmetics aren't real important since the profile class here doesn't have appearance judging. Going to have to do a couple of wing repairs, so will need to get the paint gun out. Might as well go with the braces, etc. I am afraid that the glass/epoxy might bring out a tail heavy condition. (??) Want to still keep it as light as is reasonable.
Bill

>Thanks Curt! I just got a set of Mo Best plans, and I think
>I am going to cut the rear of the fuselage out and do it
>that way.

Bill,

Mo'Best plans do not contain the latest incarnation of Larry's built-up profile approach. In the latest version, he uses 1/64th birch plywood. It is much stronger and lighter.

Hi Bill. What they said and I have seen on two Brodak Cardinals, a fillet that lead from the horizontal stab forward. LIke an extension of the stab. This made the fuselage stiffer. Nice thing about the old Magician is the fact that it was a two piece profile. If one piece is harder than the other, this will also help to stiffen it.

Hello Bill,
This is something that I learned from Tom Farmer of Forerunner fame and it is the same thing that Larry Cunningham talked about.
Core the rear of the fuse and install diagonal braces, then sheet each side with 1/64th plywood. I did this on a Forerunner and a stretched Twister and the tail will not flex at all.
When you get that "wiggle" you lose elevator deflection as well, and that can cause the re-kitting process to take place.
Best of luck, Gil

I had a profile that had the same problem.

Bene told me to open up some holes in the fuse and glue two 1/8" doublers, from the end oh the fuse till where the ply doublers start,

It really worked!!!

In Christ,