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Building Tips and technical articles. => Building techniques => Topic started by: Leester on July 16, 2006, 06:29:33 AM

Title: Profile Fusalage Repair
Post by: Leester on July 16, 2006, 06:29:33 AM

I have a profile fusalage that is damaged, the last 6" are messed up. I would like to save the foward part.wing cut out and forward. I believe the F. Twister you extend the fusalage by cuting on an angle adding desired amount. I was thinking if doing this just replacing the damaged section with new. I was wondering if the following would work.
 Cut off damaged area at an angle.
 epoxy new in place
 put 05-07 carbon mat on both sides of the new section and extend onto old up to wing cut out? or up to fusalage doublers?
 then cover carbon mat with 1/64th ply, using epoxy.
 It sounds like a lot to do but I would like to at least give it a shot. Any suggestions?  Thanks

Title: Re: Profile Fusalage Repair
Post by: Jim Oliver on July 16, 2006, 07:23:24 AM

Hi,

I like the idea of cutting at an angle; I would probably then cut a couple of 1/8 x 2 inch slots in the two pieces and use 1/8 lite ply to make a couple of joiners to fit into the slots.

Good tight joints with the minimum amount of epoxy needed to get good coverage will produce a repair that will be stronger than the rest of the fuse.

I would not use the 1/64 ply--I have done that and found it to be just too heavy.  Light weight carbon veil over the joint if you feel the need, but I doubt if it will help much.

Cheers,

Jim

Title: Re: Profile Fusalage Repair
Post by: Bill Little on July 16, 2006, 05:14:03 PM

HI Lee,

I go with what Jim said.  Angle cut, some "biscuits" for joiners.  Use at least 30 min epoxy, maybe the Sig 2 part, 2 hour.  No more glue than necessary (which ain't much).  I would use some .2 oz. CF veil about 1" wide to cover the joint and CA it on.  This would stop the crease in the finish from coming through later.

Title: Re: Profile Fusalage Repair
Post by: Ralph Wenzel (d) on July 17, 2006, 03:41:38 AM

FWIW, the fuselage of my first Cardinal arrived cracked just about the high-point of the wing. I braced it into correct alignment and drilled for 1/4" CF Arrowshafts aboupt 4" long, angled, top and bottom. After re-assembly, I added a couple of soft balsa plugs.

It flew quite well, until it's final appearance as a lawn dart. Inboard wing broke off at the fuselage, fuselage front end broke off (NOT at the site of the original fix), smithereened the Rev-Up (sob!) and the CG spinner and split the Tettra tank shell (repairable, I think).

Anyhow, the point of all this was to suggest arrowshafts as a repair medium.

Title: Re: Profile Fusalage Repair
Post by: Bill Little on July 17, 2006, 05:59:20 PM

Hi Ralph,

I did something similar to a Profile I had.  I made an Impact Profile at about 80% (~50" wingspan) but the rear end of it would wiggle better than ANY hula dancer in the South Pacific!!!!  **)

I cut grooves in the top and bottom of the fuselage deep enough to sink CF rods ~ 3/8" dia.   That cured the tail wiggles!  y1

Bill <><