Stringers 'n clips

[Billy-250]

Hi,

Does anyone have any tips for installing aluminum stringers, are there any things to watch out for? I have fitted this type of clip:

http://univairparts.com/shopping/product_info.php?products_id=11379

They are of thinner gauge steel and shorter than the original Piper ones. I am beginning to think that they are meant for the wooden stringers. Has anyone used these with aluminum stringers, are they ok?
The turtle arch kit I had used 'U' shaped type clips, but I had to cut them out when I remodeled the supplied arches get to the plane's original shape. Are there any special techniques for clenching them up as they seem weaker than the stringers themselves.

Any advice appreciated.

Bill M

 

[iamcamper]

My TCOW kit has the thin metal tabs for the stringers and I used the aluminum stringers. TCOW said to use 4-40 screws. Only thing I noticed was that when the screws are tightened the tabs bend inwards and if they are tightened to much the screws will bend as well.

I played with the idea of putting a small piece of plastic in the channel of the stringer to support the tabs and this worked well, but I also determined it wasn't worth the effort. Just snug up the screws till the stringer is secure and the fabric should do the rest.

Hope that helps
Ted

 

[supercub]

I've seen safety wire used

 

[Steve's Aircraft (Brian)]

I straighten out the clips and drill for 3/32 cotter keys. Works real well and is light.

Brian.

 

[Steve Pierce]

I believe those clips are meant for the wooden stringers however I have done like Brian suggested when using aluminum. All the new fuselages I have worked on use a "U" shaped clip.

 

[Darrel Starr]

When we faced this issue on our Super Cub, N18SY, Bob Eckstein came up with the idea of cutting lengths of 3/8 in. channel to fit against each passing fuselage member -- each piece of channel being the correct length for that fuselage member depending on the fuselage member angle. We cut these channels and snapped them on to the stringers. Then we lock wired the forward end of the stringer to the fuselage. The rearward end of the stringer was left a little longer than needed, later to be trimmed to length. A hole was drilled in the rearward end and that hole was used to attach another piece of lock wire. That piece of lock wire was twisted to pull the stinger taut -- the important insight being to pull the stringer straight. Then with the stringer absolutely straight and taut and with the pieces of channel positioned against the fuselage members, Bob Tig welded the channels to the fuselage and so the stringers were positioned perfectly -- another great idea that Bob Eckstein added to this project.
regards, Darrel

 

[NimpoCub]

Where I had clips, I drilled & SS safety wired.
The side stringers are drilled & safety wired to all the diag. braces between the upper/lower longerons. A bit tricky keeping those straight, but they snugged up quite tight & never moved.

Pay attention to the U-channel where the stringers' ends meet the hard fuselage tho, those can be an ugly bump.

 

[Billy-250]

Thanks for the replies guys. Some good advice + I hadn't even begun to think about the side stringers!

I'll give some thought to Brian's suggestion with the clips I've fitted, seems though that they are the wrong type. Otherwise it's out with the grinder, again...

Thanks
Bill M

 

[Steve Pierce]

I posted some pictures in my Super Cub Production Pictures Gallery of stringer installation at Piper in the late 1970s.

http://www.supercub.org/photopost/showgallery.php?cat=754