View Full Version : Extending wings
Here's one for you engineering types. I intend to use a set of Tripacer wings for my experimental Supercub project. I will make the flaps and ailerons longer to match the longer wings, but here's the deal. The spar on a Tripacer is 5 1/2 inches across. I believe the PA 18 spar is 7 inches. To my mind. if you add roughly four feet of spar, to match the SC length, without beefing up the spar with a strap, you end up with a weaker wing. Am I thinking straight? Does anyone have any experience with this? I know that some guys have expended their Pacer wings, should be the same spar. Thanks Joe
10-14-2003, 07:07 PM
I must be missing something here. If you are going to attempt a spar splice, add ribs, add compression strut tubes and wires then try to beef it up and keep it square. then why not just rebuild both wings using new full length spars?
I stuck a ruler up inside of an inspection hole on a Cub and the spar looked like it measured 7". If they are the same size, I would just use new longer spars. Otherwise, I've got all these ribs and stuff that I want to try and use. I guess it's the homebuilder in me. Can someone give me the width of a Supercub spar?
10-14-2003, 08:07 PM
They are the same except for the length. I have built both. They just removed a set bay of drag/anti-drag wires. The front spar is taller than the rear spar.
10-15-2003, 02:11 AM
Yep they are the same spar material.
Change the complete spars instead of fooling around with the tripacer stuff. That way you will have all of the correct hole spacing for ribs, compression struts, lift strut attachments, etc. Your going to have every screw out of them anyway.
10-15-2003, 08:52 AM
The easiest way would be to buy a new set of Univair Super Cub spars. They are not to expensive, and will save you huge amounts of time and guess work. They come predrilled, so all you would have to do is screw and bolt everything on, using as much of the Pacer parts as will fit, then buying whatever is left. You can get either 13 or 16 rib wing spars, whatever you choose, and remember that there is a difference between right and left spars because the rib flanges all bend the same way. Try putting a spar from the wrong (left or right) wing in, and the ribs will not line up.
sounds good, that is what I wanted to do in the first place and couldn't believe there was that much difference in the spars. I am going to go back and look at what I was measuring. Thanks Joe
10-15-2003, 09:15 AM
Sorry, Forgot to include the measurements. Rear spar is 4" high, and front is 5 11/16".
7" is roughly the thickness of the wing at the front spar location, you were probably measuring the leading edge skin, which covers the spar and sticks up higher.
10-15-2003, 10:03 AM
Joe, Order your aluminum stringer material for the fuseage at the same time you order the spars cause they are both to long to be shipped UPS. Mark is right about the spars from Univair. Get the right part numbers and everything is drilled. You just bolt everything together. No guess work. I would be interested in your Pacer spars and any other Pacer stuff you have left over. Do you know Wilford. I met him a few years ago? I rebuilt the bottom end on his Bellanca 260B.
Powered by vBulletin® Version 4.2.0 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.