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Author Topic: final covering of foam wings  (Read 1560 times)

Offline Gordon Tarbell

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final covering of foam wings
« on: November 14, 2009, 08:53:35 AM »
I am doing the foam wing cores of a Buccaneer 746. The sheeting was applied with foam safe CYO , is it recomended to cover with one of three thickness of silkspan before I paint them. I was thinking of applying several coats of nitrate, then putting on silkspan to add stiffness and to need less filling before using duplicolor rattle can paint.  I hope to use this mule to finally learn the real pattern (not beginner). Appearance is important but durability and keeping total weight down is paramount engine is MVVS 49 rear exh so I don't want to make finish too heavy. I considered monocoat breifly (very breifly). Just trying to get a handle on sieries of steps for finishing up this wing.
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Gordon Tarbell AMA 15019

Offline Ralph Wenzel (d)

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Re: final covering of foam wings
« Reply #1 on: November 14, 2009, 12:06:09 PM »
I'd suggest: sand to 220. Brush on one coat of unthinned Nitrate. Sand to 320, starting with 220. Apply .2 oz. Carbon tissue (veil) with Nitrate. Apply two more coats of Nitrate and sand to 400, starting with 220. One more coat of Nitrate. Then color.

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(Too many irons; not enough fire)

Ralph Wenzel
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Offline Gordon Tarbell

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Re: final covering of foam wings
« Reply #2 on: November 14, 2009, 04:12:21 PM »
Thanks Ralph, so the best thing to use is the carbon veil instead of silkspan. Is this for better strength with similar weight? Then I take it I should let the dope gas off for a few wks. then I can use duplicolor and clear for fuel proofing?
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Gordon Tarbell AMA 15019

Offline phil c

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Re: final covering of foam wings
« Reply #3 on: November 14, 2009, 05:30:11 PM »
Gordon, hope that the sheeting was properly glued together so no dope can leak through the seams and melt the foam.  That is one reason a lot of guys paint the INSIDE surface of the sheeting with a coat or two of dope before gluing it in place. 
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phil Cartier

Offline Gordon Tarbell

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Re: final covering of foam wings
« Reply #4 on: November 14, 2009, 11:40:41 PM »
I sure hope so too! I sanded the edges for a good fit before glueing . I guess time will tell after it is painted. or maybe after it is rekitted while learning the real pattern. Of course I could skip the carbon veil or silkspan and just primmer the sheeting and start shooting rattle can duplicolor and clear. Bruce Malm used to prime and paint his pattern ships , some were 1/64 ply and some were 1/16 balsa sheeting , they still look good after many yrs. of screaming around pulling high G's.  Just trying to shorten my learning curve.
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Gordon Tarbell AMA 15019

Offline Leester

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Re: final covering of foam wings
« Reply #5 on: November 15, 2009, 07:54:29 AM »
Gordon I wanted to use dope on my Buc 746 wing also but am having secound thoughts about dope eating the foam. The wing is an easy one to cover so am seriously thinking about Ultrakote. It's alot easier than Monokote IMHO.
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Leester
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Offline Gordon Tarbell

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Re: final covering of foam wings
« Reply #6 on: November 15, 2009, 08:35:39 AM »
Did you set the controls up as per the instructions? And use the stuff in the kit?
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Gordon Tarbell AMA 15019

Offline Leester

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Re: final covering of foam wings
« Reply #7 on: November 15, 2009, 09:44:14 AM »
Gordon, I built mine from scratch, mine is the 746 P profile so I went with the plans. BTW my wing was from Crist Rigotti and he cut the core so the tips would be flat 1/8" balsa no block.
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Leester
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Offline Balsa Butcher

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Re: final covering of foam wings
« Reply #8 on: November 17, 2009, 08:13:18 AM »
Hey Gordon, my "Smokin" Bucaneer is being finished right now. As usual, all dope, light silkspan over wood 1/2' fiberglass on the nose applied with Z-poxy. Only CF is on the flaps, not necessary on a foam wing. Why smokin'?, it's got a pipe.

As far as your's goes, I'd contact the designer, Alan Brickhaus regarding his finishing technique. He uses plastic film on the wings and stab, rust oleum on the fuselage. His technique has been posted and published and works well.

My technique is old school however I've got away from nitrate but using rustoleum that would be a good base. A couple of coats of nitrate, apply light or med silkspan, a couple more coats of dope then switch to the rustoleum primer and paint ought to do it. Good Luck!  8)
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Pete Cunha
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Offline Gordon Tarbell

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Re: final covering of foam wings
« Reply #9 on: November 20, 2009, 09:19:49 PM »
Ok , I got the cores sheeted now with the leading edge attached and sanded to shape. Small problem, I put a series of shallow dents in the suface while sanding (shoe shine style) the leading edge. Should I fill and sand these or try to steam them out like dents in an old gunstock. If it makes a difference I used foam safe CA glue for application of the sheeting.
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Gordon Tarbell AMA 15019

Offline Gordon Tarbell

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Re: final covering of foam wings
« Reply #10 on: November 20, 2009, 09:23:19 PM »
Hey Pete , mine will have a pipe also ,sorta.  Rear exhaust MVVS49 with short homemade muffler pipe.  I make a point to work on some part of this plane every night . tired of the beginner pattern and ARF's
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Gordon Tarbell AMA 15019

Offline Balsa Butcher

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Re: final covering of foam wings
« Reply #11 on: November 21, 2009, 11:54:45 AM »
Hey Gordon, glad to hear that your'e through "sandbaggin'" and gonna mix it up with the big boys. As far as your leading edge goes, "shoeshine" sanding is usually not a good thing. Get a long (12 or 18") Du-Bro or Great Planes sanding bar over the local HS. Use 220 grit (comes in an adhesive roll especially for the sanding bar) and go back and forth lengthwise along the length of the LE. Use a gentle touch and let the grit do the work, not pressure. Chances are your "dents" aren't too deep and can be sanded out without compromising the strength of the LE.

Roll the bar as you sand to maintain a nice rounded shape. Rounded but blunt leading edges are fine but you might want to make a pattern and hold it up to the LE as you shape it in order to maintain a consistent shape throughout the wingspan. This would be a better plan than using filler to regain the contour.  Another more extreme measure would be to razor plane the leading edge flat then gluing on a piece to the front of the LE and re-shaping it. This would be a last resort but IMHO would still be better than using putty.  8)

Added: If they are just "dings" then the water (best) or wood filler (OK) fix should work. If the sanding anomalies and irregularities are extensive then you might have to resort to the options above.  HB~>
« Last Edit: November 21, 2009, 02:46:28 PM by Pete Cunha »
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Offline Serge_Krauss

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Re: final covering of foam wings
« Reply #12 on: November 21, 2009, 02:00:14 PM »
Quote from: gordon tarbell on November 20, 2009, 09:19:49 PM
...I put a series of shallow dents in the suface while sanding (shoe shine style) the leading edge. Should I fill and sand these or try to steam them out like dents in an old gunstock.

Gordon-

If they are actually dents, try an eye-dropper with white vinegar or even just water locally at the dent. This often expands the wood and removes the dent. If these are really abrasions, then this technique might help some, but not restore what is no longer there. Yes, steam - as in dampening and then heating with an iron - works , but you do have to be careful to avoid scorching or warping. These are easy things to try, before getting extreme and labor intensive. They are sort of a matter of course as I build and bump things.

SK
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Offline Gordon Tarbell

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Re: final covering of foam wings
« Reply #13 on: November 21, 2009, 04:48:51 PM »
yes they are dents not abrasions. I was a little careless with my shoe shine antics while shapping the leading edge. I have done the steam dents out of gun stocks with a damp cloth and iron(very localized spot). Wasn't sure it wouldn't damage the glue down of the sheeting.
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Gordon Tarbell AMA 15019

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