I just completed the wing of the MM Hellcat and realize that the outer underside 1/3 of each wing tip is open exposed foam. How am I to finish this? I'm sure that paint will either not adhere to the foam, or eat it up. I notice now that in any video you see of this model finished and painted, the underside of the plane is never shown. Maybe this is why. Would it be advisable to build up the open area with scrap foam, or at least cover the exposed foam with paper so it can be painted? Im afraid adding a complete piece of foam out on the wing tip might mess up the aerodynamics of the wing. (it has a pretty good undercamber going on right now. Like a washout built in? Any ideas here would be appreciated.
f6f Mighty Mini Hellcat.... what to do with the underside of wing tips?
- Thread starter Danno66
- Start date
Foamforce
Well-known member
Yeah, the undercamber wingtip is an intentional part of the design, so don’t change that.
It‘s the propellant in spray paint that eats foam. I’ve heard that if you spray from far enough away, then the propellant doesn’t hurt it. I spray using an airbrush and it doesn’t affect the foam at all. So far the only exposed foam that I’ve painted are the edges, but the paint seems to stick fine. Covering it with paper would look nice too, at the expense of a little weight. Rough cut the paper to size, spray 3m 77 on the paper (not on the foam, the propellent again…), lay it onto the foam, and work out the wrinkles with a credit card. Then trim the edges in place. I think most people around here would just paint the foam though.
It‘s the propellant in spray paint that eats foam. I’ve heard that if you spray from far enough away, then the propellant doesn’t hurt it. I spray using an airbrush and it doesn’t affect the foam at all. So far the only exposed foam that I’ve painted are the edges, but the paint seems to stick fine. Covering it with paper would look nice too, at the expense of a little weight. Rough cut the paper to size, spray 3m 77 on the paper (not on the foam, the propellent again…), lay it onto the foam, and work out the wrinkles with a credit card. Then trim the edges in place. I think most people around here would just paint the foam though.
Aslansmonkey
Well-known member
You can either use light coats there or cover it with paper again. On builds like this I save the paper I tear off before curving the wings and glue that section back in again after the wing is done.
danskis
Master member
I haven't built the new MM series. On my swappable Spitfire I fill in that area with foam. I trace the wingtip and glue the piece of foam in the wingtip. I don't try to make it flush with the root of the wing. I place it at an angle so the front is higher than the back. This retains the undercamber/washout effect and works well. I can take a pic if anyone is interested.
The Fopster
Master member
Watered down PVA glue painted on the foam surface makes it paint-safe for me, even using a rattle can at close range. Almost zero weight penalty. Maybe test on a scrap piece tone sure?
Man it was late when I posted this. I was obviously done thinking for the day. Went out to the bench this morning and found the paper pieces that I had removed from those tips perfectly intact. I'll hit them with the 3m 7 contact cement. Glad you suggested spraying the paper and not the foam. I would have done that wrong. Although I never really noticed 3m 7 damaging the open cell styrofoam in my wing sheeting days. Maybe it did a little. Thanks for the suggestions. This material is so different than traditional model building. This is my first go. Hoping this goes well as I have the Master build F4U on deck. Thank you.
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