Hi, I couldn't find this answer, maybe I need a little guidance.

I can do a pretty good monocote wingtip. My silk wingtips came out good. But this polyspan doesn't bend or go around corners very well. Even the directions say not to do wingtips. Does this mean...
A. carve wingtips from balsa rather than building them up?

Or

B. Don't use polyspan.

Or

C. If I get polyspan wet, will it wrap around and stick to a wingtip?

Or

What? I've heard about using CA on the edges of polyspan. Could I CA it to the wingtip, then shrink it?

Thanks

Da Shorts,

I just submitted a build article to our club newsletter last week that had a couple photos and some comments. Let me try to post them here.

People say don't use it on wingtips. To pre-cover these with silkspan. But I think that advice could be more specific. It works fine for some wingtips. In my example, I used it to cover a carved tip the same way I would have covered with tissue or silkspan--except for getting it wet and trying to stretch it. Since polyspan is a synthetic fiber material, getting it wet is not going to make it relax or shrink.

If you were going to use it on a Flight Streak-like tip, I would just make sure the gussets were wide enough, and strategically located that you could slit and attach the polyspan at each of these, as needed.

I don't know about using CyA. I found nitrate dope to be sticky and thick enough to hold over reasonable curves. Not sure if CyA might give you hard spots that would telegraph thru any finish?

Da Divot



(2394) People will say that polyspan doesn't go around curves real well and that you are better off pre-covering wingtips and other compound curves with tissue or silkspan. On this plane, since I was experimenting, I decided to go polyspan all the way. Here is the covering job you are faced with.

(2398) I used the same techniques I would have used on tissue, slitting and butting the covering as needed. The inboard tip is a bit more difficult as you must work around the leadout wires. It came out fine and wasn't really any more difficult than tissue. Just don't try to sand it until you have plenty of dope on it.

Robert has videos on just about every aspect of his techniques.....way up top is you tube link...the search box works well

https://www.youtube.com/results?search_query=polyspan

Hey David we all have that problem once in a while.  I use heat sensitive adhesive and use the heat to make the poly-span go around the surfaces.  Once in a while I may have to put a patch on.  When I was using dope, after a few coats you could hardly feel the seam or wrinkle.   The primer coats will take care of the rest. Keep us posted.

With practice, polyspan is no harder to use than anything else.  Heat, stretch, trim and repeat until complete.  It stretches a lot like Monokote, just takes practice.

if you´re talking about open structure covering, can be done
it´s a lot f work and you have to use multiple parts and direct the "grain" parallel to the longest area. this Stuka wigtip is polyspan in several directions.
i use undiluted dope on the borders to attach them. i use a brush and run dope under the new piece of polyspan, attach the polyspan and with a toilet paper i clean up the surplus which makes the polyspan to stick almost instantly on the edges
hope i could make in easy to understand

Fred has it right.  Any small anomalies will disappear with more dope, and a little heat if necessary.  Again, nitrate works better than butyrate for application but butyrate will work.

if you´re talking about open structure covering, can be done
it´s a lot f work and you have to use multiple parts and direct the "grain" parallel to the longest area. this Stuka wigtip is polyspan in several directions.
i use undiluted dope on the borders to attach them. i use a brush and run dope under the new piece of polyspan, attach the polyspan and with a toilet paper i clean up the surplus which makes the polyspan to stick almost instantly on the edges
hope i could make in easy to understand

Fred,

Is silk available in Brazil?

Charles

 

With practice, polyspan is no harder to use than anything else.  Heat, stretch, trim and repeat until complete.  It stretches a lot like Monokote, just takes practice.