Installing side Aluminum Stringers

I am installing the 1/2 wide alum side stringers and not sure of proper way to install.
These stringers pass some tubes without attach points. Should I wrap the tube in
something like electrical tape and pull the stringer tight with safety wire? It requires
some tension on the stringer to pull into position, is this OK or should I try to cut
out a wedge to allow bending?

Thanks
Jim Miller

Wrap the tubes with friction tape to protect against chaffing. To attach the stringer to the tube, drill a hole large enough for two pieces of .041 safety wire and pull it tight. Afterwards, shellac the friction tape to keep it from coming apart.

Tape/wire seems the way to go. If the stringer does not follow an easy, natural bend along your tubes, it sounds like things are not as they should be. Any sharp(er) bends will stick out like a sore thumb when painted. Don't cut/bend the stringers! Maybe try some sort of spacer between the tube/stringer if just one or two have a gap. Pull stringer into place, sight along it & imagine it's covered/painted. Nice smooth curve??

Jim, This is how the factory did it. I do the same except like posted above I wrap the tube with friction tape and two coats of shellac. Oh, and I put a courtesy curl in that safety wire.

I welded some small tabs along a line like an older supercub fuselage I had to look at. Is tabs common
to all supercubs? Their are five tabs per side but none on the front two or three tubes the stringer
crosses.

Jim

Hi Jim,
Check out Darrel Starr's photo album. He welded in some 3/8" birdcage channel to his diagonals for the tabs that the aluminum stringer sits in. I think he drilled and saftied the stringers to the tabs/channel. This would only require some careful measuring to ensure that those channels are lined up so the stringer looks good. I thought that this was a clever idea if using the aluminum stringers. Hopefully, Darrel will comment on this process.

On my -12, I used wood stringers on mine and used those tabs that pinch the wood. These are the tabs that came from the factory. I would think that the factory used the same tabs on all the models just for an ease of production and not have to build new parts. I had to replace several tabs as they fell off when pinched or when they were opened up enough to insert the stinger. I was not a happy camper. The tabs are drilled so you can saftey wire the stringer.

I do the same with friction tape and safety wire...

and also usually have to notch it for the tube behind door or its too funky there.....

Like Kevin said, we cut short lengths of 3/8 wide channel to guide the stringers. Bob Eckstein had me safety wire the stringer to the most forward channel then with a small hole in the rear most part of the stringer web, we pulled the stringer tight and straight against the fuselage by twisting a lock wire attached to the stringer and anchored to the tail post. With the short channels already threaded onto the stringer we then made sure the straight stringer was exactly where we wanted it then tacked the channels to the fuselage tubing. A picture is in the following old thread.
http://www.supercub.org/forum/showthread.php?37394-Stringer-installation

mike mcs repair said:

I do the same with friction tape and safety wire...

and also usually have to notch it for the tube behind door or its too funky there.....

Click to expand...

Thanks all for the replies. Mike I am finding the same thing with the tube you mention.
On the tubes where I welded the tabs (Simple flat piece of .050 4130 about 5/8" by 1/2")
I predrilled #40 holes in these tabs and use SS #4 screws to attach fairing to the five
tabs per side. On the tubes without tabs I will do as suggested and use the friction tape
and wire.

Thanks
Jim Miller