Overlap polyspan at wing center or not?

[Mike Scholtes]

Getting ready to polyspan the wing on  a 60-size stunter with built-up open bay construction, molded leading edges, center sheeting, typical design. I have used polyspan many times and it works very well for me. The wing is not yet mounted in the fuselage. Question is, is there a benefit to overlapping the covering at the center joint of the wing? I have heard it said that increases the wing strength but I have never done it that way before and never had a problem. On the other hand I am concerned that the epoxy will not seep into the wood fibers at the wing-fuse joint if the wing is already covered. In the past I have run the covering up to the edge of the fuselage so that the joint is wood to wood. Am I over-thinking this?

[Jim Hoffman]

Hi Mike - the short answer is "do it"

Running the polyspan past the centerline of the wing will add strength and stiffness w/ nearly zero weight penalty.  I go about 6" past the CL, or up to the first open bay panel on the other wing panel.

Jim Hoffman

[Gerald Arana]

Don't do it Mike.  

Instead use milled fiber and resin for your joint on bare wood, wing to fuse. (Sparingly of course)
There is no reason to have extra "strength" when you have spars going through the center. In the olden (well, a few years ago) when we butt jointed the two wing halves together it was necessary to run fiber glass across the joint which in turn transferred the load to the outside skin inside the fuse.
I've never been able to break one on an "air" load. I have however busted the wings/nose/tail off when the ground.............so it doesn't make much difference what you do!  

Later, Jerry

[Mike Scholtes]

Thanks everybody. This particular wing is strong with full-span spars and a second "helper" spar in the center section. The model is Claus Maikis' China Clipper. Trailing edge sheeting also overlaps. I think I would feel better having a good glue joint at wing-fuse junction, but I value everyone's insight into this issue.

Jerry, you building anything new for this season? Woodland will probably be a dust bowl this summer but its the only show in town.

[Balsa Butcher]

DUST BOWL!, Mike, we are bustin' our tails trying to keep it green. As we speak the sprinklers are on in the center circle, mowed the south circle last week, field looks GREAT! Come on out on the 27 and 28th for Stuntfest 2015 and you can see for yourself. Looking forward to seeing your new stunter.   

[Gerald Arana]

Jerry, you building anything new for this season? Woodland will probably be a dust bowl this summer but its the only show in town.
[/quote]



Hi Mike, Yes as a matter of fact I am working on something. It is the "Chisler" that Ted F. gave me. After I got it all stripped I had to take a while (long) to admire Ted's work. He is one great builder!

I fixed a few small damaged areas and used CF on the wings. Got it covered today with Polyspan. Now to start the finish............I'm using Brodak dope all the way.
I'm thinking of beige (piper crème) and orange (burnt) and a black or dark blue strip. But, that can all change in an instant! 

I'm hoping to go to Woodland. It'll be tight as I need to get ready to go fishing on Tues. Going just for the "halibut" and of course salmon.

Hope to see you on the 27 Th, Jerry

[Mike Scholtes]

Hi Pete:

Great to hear the field is in good shape! I have had a crash course in water law over the last year and figured the source would be "curtailed"  radically, leaving no water for a model plane field. Must be the landowner has historic rights to enough water. As always, a big THANKS! to you and the Davis-Woodland crew for your tireless efforts to provide the rest of us with a primo contest site.

I am chomping at the bit to get up there in June and see the guys. The China Clipper won't  be ready, but maybe by later this summer. You can see what it looks like on Claus' "Ukie" site (select English version).

Jerry, is that the same Chisler Ted has been flying for years? Dick Mathis design? Color scheme sounds interesting, will enjoy seeing it in person.

[Gerald Arana]

Hi Pete:

Great to hear the field is in good shape! I have had a crash course in water law over the last year and figured the source would be "curtailed"  radically, leaving no water for a model plane field. Must be the landowner has historic rights to enough water. As always, a big THANKS! to you and the Davis-Woodland crew for your tireless efforts to provide the rest of us with a primo contest site.

I am chomping at the bit to get up there in June and see the guys. The China Clipper won't  be ready, but maybe by later this summer. You can see what it looks like on Claus' "Ukie" site (select English version).

Jerry, is that the same Chisler Ted has been flying for years? Dick Mathis design? Color scheme sounds interesting, will enjoy seeing it in person.

That it is!