Covering a Manhattan Cabin

[Flyguy]

Hi - I'm building the Babyshark Manhattan Cabin available from J & H aero and have a question about covering the fuselage. For the wing, stab, and rudder, I just used 3m 77 spray and dropped it on to Harlan's superultrafilm attached to a frame, the usual approach. I'm also going to drop each side of the fuselage on the film attached to a frame. Question is about the spray. Let's say I spray the top, attach it, and cut it out (I use temperature controlled soldering iron just hot enough to cut the film). If I'm going to next spray another side, I'll have to cover the side with the film, from the inside if that side is now on the bottom (I usually use paper towels for this) to keep the spray from getting on the insider of the film. Seems a pain, there are 1/32" sq diagonals in the way and they break pretty easily. The alternative I'm considering is to instead use glue stick, lightly rubbed on the 1/16" sq. part of the frame, that should work but it's not as nice as the spray. Any comments welcome!

[Crabby]

Hi Larry long time.
Here's an idea before I ruin your 3m madness. Maybe generously with out being sloppy spray a sheet of wax paper with 3M then lay the side you want to cover down upon it before it dries out. Then peel the fuse from the wax paper. There should be enough adhesive stuck to the frame to do the trick. Its gonna be pick it up, move quick then lay it down on the film. There's going to be some choreography to rehearse and you are going to have to be a true ballet artist to move efficiently enough before the adhesive dries. Everything has to be in its proper place. Uncork the champagne and invite Beyonce over to celebrate if you succeed!

[ElDee]

Maybe spray the 3M into a container, and dilute it with a solvent. It could be brushed onto the fuselage framework so that the covering could be applied in a conventional manner, and not have to deal with overspray. I think some of the Science Olympiad folks use this technique with "veggie bag" covering.

I've also heard of rubber cement diluted with naphtha used in a similar manner to glue film covering onto balsa structures.

[Crabby]

Here’s another wet noodle to toss at the wall, stuff the fuse with tissue paper, just enough to catch most of the overspray. You aren’t going crazy with it anyway so the tissue on the inside will catch 90% of the overspray.  

In the end you will probably just slide strips of card stock in between the framing members: in through the top longerons and out through the bottoms. If you make em long enough you can suspend the whole apparatus between 2x4s or books.

[Flyguy]

Hi Larry long time.
Here's an idea before I ruin your 3m madness. Maybe generously with out being sloppy spray a sheet of wax paper with 3M then lay the side you want to cover down upon it before it dries out. Then peel the fuse from the wax paper. There should be enough adhesive stuck to the frame to do the trick. Its gonna be pick it up, move quick then lay it down on the film. There's going to be some choreography to rehearse and you are going to have to be a true ballet artist to move efficiently enough before the adhesive dries. Everything has to be in its proper place. Uncork the champagne and invite Beyonce over to celebrate if you succeed!

Hi Crabby - yes I haven't posted anything in quite a while, it's too bad we lost all the old stuff, this might have been mentioned in one of the old discussions. That's an interesting idea, my only worry is the structure is really delicate and it might be hard to even lightly peel the paper off, those 1/32" square diagonals break everytime I pick it up!

Maybe spray the 3M into a container, and dilute it with a solvent. It could be brushed onto the fuselage framework so that the covering could be applied in a conventional manner, and not have to deal with overspray. I think some of the Science Olympiad folks use this technique with "veggie bag" covering.

I've also heard of rubber cement diluted with naphtha used in a similar manner to glue film covering onto balsa structures.

I've tried thinning the spray with Toluene before but wasn't happy with it, ditto rubber cement with naptha, but I try to stay away from toxic chemicals. Along a similar line, I was thinking of dissolving some uhu glue stick in rubbing alcohol and brushing it on, as you say. A friend of mine pointed out, however, that you probably don't want to get the really light balsa wet, which doesn't happen with the spray, so I'm not sure.

Here’s another wet noodle to toss at the wall, stuff the fuse with tissue paper, just enough to catch most of the overspray. You aren’t going crazy with it anyway so the tissue on the inside will catch 90% of the overspray. 

In the end you will probably just slide strips of card stock in between the framing members: in through the top longerons and out through the bottoms. If you make em long enough you can suspend the whole apparatus between 2x4s or books.

Another interesting idea, maybe some variation of this idea will work, only part I'm worried about is those damn diagonals sticking and getting broken when I remove it. But I have to think about this.

Thanks for the suggestions, I'm ready to cover today and hate to ruin the fuselage, I have to think some more about these suggestions, I'll let you know what I end up doing, should be a learning experience!

[Crabby]

One last thing then I’ll shut up. I remember seeing my dad use a long watercolor brush (the one you use to do tree branches and long narrow stuff with really thin white glue. Of course you need to practice meditation for 30 mins prior, to clear the brain clutter.

[Flyguy]

I decided to take a break on covering the fuselage until I can digest some of these ideas, so today I wanted to see if I could do a Piserchio hook for indoor so that I can wind outside the plane. Pretty happy with the results, I was able to (carefully!) slide in a wound motor and hook it on the peg, then remove the carbon rod. I don't want to take the carbon fiber peg in and out and am going to lightly glue it in place. Have to be careful but it works!

[Flyguy]

I ended up using UHU glue stick, gently rubbed on the structure and cross-pieces, even lightly on the diagonals! Just right off the stick, you can see it go on, I thought it worked fairly well, though the spray is better and that's how I did the wing/stab/rudder. I did the top and bottom first and cut those out with my heating iron. However, when it came to the sides, I realized I couldn't use the iron without probably getting a hole on the adjacent covered top/bottom, so I tried my supersharp trimming blades and that worked! Came out at 5.95 grams, not too bad, next step is to get it in the air.

[Flyguy]

Well, I got it in the air, here's the video:  https://www.youtube.com/watch?v=K3umrqO8Wgg

Flies nice! It actually inspired me to get going on another one (you always need two with the loss rate at the armory!). This time I chose the Columbia II for several reasons - Ron Williams book gives full size plans and I'm affiliated with Columbia (and Manhattan). Made my own wheels, which was a first, first with four spokes with .032" x .040" rims and .032 x .040" spokes, the hub is a tissue tube rolled on 1/32" wire. The second set came out a little nicer: .025" x .040" rims. .032" sq. spokes, same tissue hub, weight 22 mg. So far, I've got the fuselage and wheels done, will probably wait a bit for the rest since I won't be flying it this season anyway, I need to get some flying time with the Babyshark!