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Fixing the starved horse look

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Old 12-17-2012, 03:20 PM
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LA7flier
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Default Fixing the starved horse look

I'm currently working on a model and the underside of the fuselage has developed the " starved horse look". Other than tearing out the sheeting and re-sheeting the fuselage all over again, is there a relatively painless fix for this? Thanks in advance
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Old 12-17-2012, 03:28 PM
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All Day Dan
 
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Default RE: Fixing the starved horse look

Post an image of the bottom so we can see what the problem is. Dan.
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Old 12-17-2012, 04:06 PM
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Chad Veich
 
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Default RE: Fixing the starved horse look

The only thing I can think of that wouldn't build up excessive weight would be to fill in the affected areas with some lighweight foam and then re-glass.
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Old 12-17-2012, 07:12 PM
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Default RE: Fixing the starved horse look

Maybe a coat of Model Magic, or some LIGHT weight spackle filler, than sand down carefully ..so as not to "Re-starve the horse"
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Old 12-17-2012, 10:13 PM
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Default RE: Fixing the starved horse look

How bad does the plane look once it gets airborne..?
There will always be another plane.
I'd just think of ways to avoid the same situation in the future.
Thicker sheeting, more stringers, etc.
On the relatively small scale that I build I almost never use 1/16" sheet [or less] unless the surface is supposed to be absolutely flat. I always go with 3/32" or even 1/8" balsa to sheet curved areas.
By the time I'm done sanding the rough carpentry...some areas are probably only 1/16" thick afterwards.
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Old 12-18-2012, 03:44 AM
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Default RE: Fixing the starved horse look

Without an image of the his problem, how can one begin to assess a proper course of action...

Bob
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Old 12-18-2012, 06:03 AM
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Default RE: Fixing the starved horse look

I can only guess what a starving horse looks like.
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Old 12-18-2012, 07:17 AM
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Default RE: Fixing the starved horse look

I built a "starved" wing once. I used too much glue on the sheeting where it joined the ribs and spars. When you get a web of glue that shrinks as it drys, it tends to pull the balsa into a slightly acute angle (if the parts were perpendicular to start with). A couple hours later and you have the look. The excess glue does not add strength to the joint, just weight. And if the sheeting is thin and low density (all good for light weight), it sucks in (general).
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Old 12-18-2012, 07:44 AM
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Default RE: Fixing the starved horse look

"Other than tearing out the sheeting and re-sheeting the fuselage all over again, is there a relatively painless fix for this?"

No.

Les
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Old 12-18-2012, 01:41 PM
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Default RE: Fixing the starved horse look

Thanks guys for the thoughts...sorry I didn't think to add a photo. The plane is in bare wood, currently under construction. I made the mistake of strip planking the bottom of the fuselage and with all the seams, didn't use thick enough wood so now paying the price.
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Old 12-18-2012, 04:10 PM
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Default RE: Fixing the starved horse look

I don't know what your weight budget is but there are 2 part polyester glazing putties out now that sand very easily by starting out with 80 grit and they can be feathered right into balsa with 220 then finish with 320 before primer or film covering. If you're just talking about some minor flat spots on the plane, then I doubt the filler will add too much weight...especially if the plane is already on target to finish at the desired weight.

The filler I'm using now is called, "Split Second" made by USChemical. Similar to Bondo but much easier to apply and sand to a feather edge.
BTW, some "real" planes have pretty flawed contours when you see the sheetmetal up close.
You could try doctoring one or two of your flat spots by gluing strips of balsa on top with white glue and seeing if that idea is something that you want to do to level the entire area. Even if the balsa patches don't feather 100% perfectly they would cut down on the amount of plastic filler.
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Old 12-18-2012, 04:41 PM
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Default RE: Fixing the starved horse look

I used Elmer's Wood Putty or some such name to alter the profile for this Super Cruiser's nose so a cowl would butt flush to separation line. Everything was glassed afterwards with 0.75 oz cloth and epoxy finishing resin. You can see the filler transition into the wood. This is a process that is applicable for your scenario.
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