Thread: Build Log MK Skymaster 20 build
View Single Post
Old Sep 06, 2012, 11:34 AM
doxilia is online now
Find More Posts by doxilia
Registered User
doxilia's Avatar
Montreal, Canada
Joined Mar 2008
2,460 Posts
Originally Posted by Generic Member View Post
I'm in un-charted waters with the finishing of my Skymaster.

I've thought about thinning the stab structure and laminating 1/64" balsa top/bottom then glassing.

Mmm... 1/64" balsa sounds paper thin and if memory serves the stab doesn't have a numerous rib structure. When I put the model into CAD I thought about that and decided to instead thin out the frame by using thinner wood and cover the top and bottom with 1/32" which should hold up better. Heck, even if the stab winds up a little thicker overall, it shouldn't be a big deal. I believe it is designed at the equivalent of 3/16" in metric which allows a 1/8" frame to be built and sheeted with 1/32" top and bottom.

Given that you've already built the stab you could go the 1/64" route but another option would be to cover with transparent MK, then cutout the area where it is to be glued to the fuse leaving an extra 3/16" of bare wood on either side of the fuse where you will create the fillet prior to lightly sanding the MK and priming the entire frame. I suspect this will be lighter than the sheeting and glassing process. At that point, covering the wing in transparent might seem like an attractive idea as well as you'd wind up with a completely painted model.

I've painted MK with good success although apparently UC is the better way to go - both for trim MK colors atop as well as for paint. One thing that doesn't happen is that you don't wind up with wrinkled MK under the paint - the paint prevents this from happening. Wrinkles can develop in MK elsewhere if not painted. I have never painted an entirely covered transparent MK structure so I don't know how it holds up in the long run but before the super lightweight coverings, transparent MK was often suggested as a way to finish warbirds. The HOB kits in particular used this approach and being 10-15 size birds or smaller, it must have been a viable approach in terms of weight. Transparent MK is a fair bit thinner than colored MK and correspondingly lighter.

I finished a Tipo last fall in a combination of MK surfaces and painted glass fuse/fin. I painted the base white/red and then covered the wing and stab in red/white prior to adding trim colors. I made the fillet between the glass fuse and the foam core sheeted stab prior to primer so that the fillet was painted entirely and the MK only had to extend up to the fillet. This requires a little fairing in of the paint into the wood prior to covering but nothing too complex. The CC was applied over the paint once everything was painted and covered overlapping the MK edge to seal it down. I think this is an often used approach.

Looking forward Jeff.

doxilia is online now Find More Posts by doxilia
Reply With Quote