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All Forums >> RC Airplanes >> Golden Age, Vintage & Antique RC >> Covering undercamber secrets ? Page: [1]

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Covering undercamber secrets ? - 11/19/2009 10:17 PM   
Ed


 

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From: Bemis, NM, USA
Status: offline 		I'll be using Ultracote Lite transparent film for covering. Has anyone ever heard about using Hair Spray to assist sticking to undercamber ?

What's the secret for doing undercamber ? ? ?

Ed

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RE: Covering undercamber secrets ? - 11/19/2009 10:27 PM   
foodstick



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Status: offline 		Well I am doing a big pup, and I used a balsa surface glue prep..Sig stixit, red baron also makes a product. It sounds like you are building smaller and light..both of the products I mentioned will add some weight...

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RE: Covering undercamber secrets ? - 11/20/2009 12:07 AM   
N1EDM



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Status: offline 		Hi Ed,

I've only heard of using hairspray to semi-cover bare balsa before covering it with fiberglass and epoxy for a painted finish. The hairspray is supposed to keep the epoxy from soaking too far into the wood and creating unneeded weight.

Never heard of it for covering undercambered wings. If there's a reason, I want to hear about it. I may be doing that myself soon,

Bob

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RE: Covering undercamber secrets ? - 11/20/2009 1:24 AM   
AH1G


 

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Status: offline 		While I am a monokote fan, the technique I use is, cut an oversize piece the length of the span. Tack a both the outboard and inboard end in the deepest part of the undercamber; stretching the cover as tight as possible. Then tack each rib at the deepest point. Work toward the leading edge tacking about 1-1 1/2" at each rib as you work out from the center; then do the same out to the trailing edge. Seal the LE and TE last. Use the tip of the iron as you do your tacking. Cover the top of the wing as normal but do not shrink until you go back the underside and using the tip of the iron fully seal the covering to each rib trying to avoid shrinking between the bays until finished.
I have covered about 30 planes this way.

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RE: Covering undercamber secrets ? - 11/20/2009 1:35 AM   
Dsegal


 

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Status: offline 		You can apply an adhesive such as Balsaloc or Balsarite to the deepest part of the undercamber on each rib.

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RE: Covering undercamber secrets ? - 11/20/2009 2:48 AM   
safeTwire


 

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Status: offline 		AH1G 's method is exactly how I covered the undercambered wing on a Buzzard Bombshell using silk and dope. Same procedure, except pre-coating the airframe with several coats of thinned dope, then securing the covering in place by brushing through the covering with thinned dope again. Wait for it to dry, then move along as described. After the covering was all in place and the dope completely dry, I shrunk it with atomized water, then filled in the weave.

The products available (mentioned above) to help adhere current iron on coverings do work! These products will add some weight, but it will be worth it if you can accept the extra weight. For interest or future information, weigh the frame before and after you apply the bonding agent.



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RE: Covering undercamber secrets ? - 11/20/2009 12:48 PM   
Strat2003


 

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Status: offline 		If your wing has spars exposed on the bottom be sure to stick the covering to those.
Also, a small detail iron is good for sticking covering to the ribs and spars without shrinking too much material in the open bays, and is good for shrinking without heating the tacked areas once the covering is all attached.

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RE: Covering undercamber secrets ? - 11/20/2009 3:09 PM   
Walt Thyng


 

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Status: offline 		I hope you noticed that nobody recommended using a heat gun. It simply won't work (unless you are truly and expert) on either surface. Especially on the undercamber surface use the absolute minimum heat to get an acceptable tautness.
Walt

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RE: Covering undercamber secrets ? - 12/12/2009 6:01 PM   
EyeflyRC



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Status: offline 		I have a Super Buccaneer with an under camber wing covered in Monocote that I bought from an estate. The Monocote has come loose on a couple of ribs on the under camber side of the wing. Any ideas of how to stick it back onto those ribs if an iron won't do the job?

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RE: Covering undercamber secrets ? - 12/12/2009 9:36 PM   
jay mendoza


 

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Status: offline 		The original Hobie Hawk assembly manual had excellent instructions on how to do this. They have you use a MonoKote iron with an ordinary tube sock over it, this aides in controlling the heat and leaving dents in the frame where you are adhering the covering to the undercambered surfaces. The technique is to start tacking the covering to the center(mid chord) of each rib, working from the middle of the wing towards each tip. There is no need to adhere the covering to sheeted areas as long as they are not convex(undercambered). After the covering is tacked, you follow up by seaming it at a higher heat along the tip, LE, TE, and root. The top of the wing has already been covered, but not shrunk. Pin holes are poked in each rib bay so the air can escape while the covering is shrunk, as the heated air expands and tends to pop the covering off the undercambered frames and ribs. Using a chordwise motion, the iron is moved back and forth towards the leading edge, then trailing edge, applying light pressure to assure the covering is held against the undercambered surfaces. The iron is oriented spanwise during this step, and you only move it side to side(chord wise) enough to shrink the covering in the middle of the wing at first. It works better to do light passes, and then move from the center towards the tip and root of the wing, allowing the areas that have been shrunk to cool. Then you can come back and shrink the remainder of the covering near the leading and trailing edges. This method assures the undercambered areas are adhered and cooled before full tension is applied by shrinking all the covering. The pin holes are important too, or else each rib bay will deleope pressure and pop the covering loose.

With coverings other than MonoKote that require the wood be primed with something like Balsa-rite, be sure to follow the manufacturers directions.

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RE: Covering undercamber secrets ? - 12/13/2009 9:53 AM   
EyeflyRC



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Status: offline 		The Hobie Hawk method sounds good for a new covering. My wing is already covered and it is in good condition other than for a couple of ribs near the middle of the wing where the Mononcote has separated from the undercamber. I am considering using a syringe and injecting some CA or glue or dope onto the edge of the ribs and then pressing down on the raised Monocote to adhere it. If I use a small needle on the syringe, the hole in the Monocote should not be much bigger than a pin ****. Think that would work? What would be the best material with which to glue the Monocote if I use this method?

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RE: Covering undercamber secrets ? - 12/14/2009 4:05 PM   
jaymen


 

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Status: offline 		Try this:
Many of my old Hobie Hawks needed recovering, and the problem of the covering pulling away sometimes was an issue.

If your covering is solid color(non transparent) then your job is easy. Remove the bad areas and replace the covering using the techniques above. You can do just one rib bay, or a partial, or complete panel. If the old covering is not adhering, it's better to take it off and put on new, as any glue you use will release when the covering is shrunk, due to it changing size dimensionally. I've tried what you are proposing, but the results were less than satisfactory2, it's actually less work to just re-cover the bad sections.

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RE: Covering undercamber secrets ? - 12/14/2009 4:38 PM   
EyeflyRC



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Status: offline 		Thanks for the heads-up on the syringe approach. Think I will ignore the problem with the couple of ribs for now and recoverl when flight characteristics are negatively affected.

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