Covering a Convex / Under-cambered wing

[brian caven]

Are there any special things to watch out for while covering the underside of a convex wing? I am going to cover the small Polecat hlg wing and was just going to start from the center of ribs/airfoil and work my way out, tacking down to the ribs before covering the top and shrinking. Any tips would be very much appreciated.

Brian C

[Steve Moskal]

Brian:

Since oldtimers and some scale models often have undercambered wings, I've evolved one two more "wrinkles" to your planned method. I brushed Coverite Balsarite thinned 50% on the undercamber of each rib. Starting from the center and moving chordwise and spanwise - as in your plan - tack them down before the full temp shrink. But the second wrinkle is as follows.

As you can see in the photo of a deeply undercambered wing of my 1912 Blackburn Monoplane,  I use fine pins (My set of Profi pins is what you see but no longer sold by Hobby Express. A good substitute is found here http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRRG8 and I use mine in every project because they don't split balsa when pinning.) to hold the covering in place. That way I can get all the big wrinkles out and tack with the covering iron pulling the pins as I go. The covering remains in place as you proceed.

Hope this helps.

(You can use dressmakers fine pins but I love the plastic "barrels" that give you more grip and control than the conventional T-pins. In fact, I'm going to order a set from Tower now, since I find them so useful.)

Steve

[brian caven]

Thank You Steve. That definitely helps, did not think of using pins, but will probably use sewing pins because I have a tone of those. The ribs on this wing are very thin, so a test is in order before starting to make sure they do not split the balsa.

Brian

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[stan.j...@comcast.net]

Brian,

We have some very small diameter straight pins at Hobby Proz.  We stock them for the guys building the small stick and tissue models.  They are about 1/2 the diameter of a standard straight pin.  They are in the back corner on the west wall next to the balsa wood rack.

Stan

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From: "brian caven" <bcav...@gmail.com>
To: soa...@googlegroups.com
Sent: Monday, December 29, 2014 10:46:01 AM
Subject: Re: [ASA] Re: Covering a Convex / Under-cambered wing

[ROBERT J GALLER]

Sometimes if a very light model I put the stixit or balsa right just in the lowest or deepest part of the concavity and sometimes 2 coats. But then not on rest of the rib. Larger heavier model coat entire undercamber. I will try Steve's pins in future.

Bob

Sent from my Verizon Wireless 4G LTE smartphone

[Dan Tandberg]

If you go to a sewing store, ask for "satin pins".  Balsa rite unthinned works good too.

On Sunday, December 28, 2014 7:37:01 PM UTC-7, brian caven wrote:

[brian caven]

Thank You all for all the wisdom. Just picked up some of the tiny pins, and Balsarite from Hobby Proz and a Futaba servo for the Encore. Going to try to finish the Encore before the weekend and fly it! Cannot imagine doing all this stuff without the vast knowledge and years of experience from the club. 

Brian C

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[ezaf...@comcast.net]

What happened to the old way of following the iron with a tissue?

cz

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From: "brian caven" <bcav...@gmail.com>
To: "soarabq" <soa...@googlegroups.com>
Sent: Monday, December 29, 2014 7:36:23 PM

Subject: Re: [ASA] Re: Covering a Convex / Under-cambered wing