Another (stupid?) paint question

I'm in the process of beginning to finish my Fancher Twister (FINALLY!). For the fuselage, I'm doing clear Brodak dope/silkspan as a base, sanding that out, and then planning to spray rattle-can rustoleum over that. I'm mainly interested in getting it done, at this point.

Anyway, my question: What kind of result might I expect if I do the same thing on the open bays (clear dope over the silkspan, sand smooth, then rustoleum)? I'm thinking the dope would shrink the 'span, then the rustoleum would be a relatively quick finish...

Opinion?

Tim

HEAVY

Very heavy and rustoleum doesn't stick well to dope. It will stick better to other sub surface preps. I have used it over dope but it doesn't last.I know a lot of people will say I use it all the time over dope and it's OK.Don't put Rustoleun over dope.
Ed

So what can you spray rustoleum over? Does it need anything?

My last three planes used Rustoleum on the solid portions, such as a profile fuselage or a plank wing. On the first I used a dope sealer layer and white Rustoleum enamel. It's a 1/2A racer and I've been using 35% nitro fuel with no problems. The paint's been on it for about a year now. The next plane I used Rustoleum Automotive Primer (Gray) as the filler and base coat. I sanded it as thin as I dared, but it was a continuous layer. The blue enamel topcoat seems to adhere just fine. Again, a 1/2A using lots of nitro. The current project has epoxy/glass over bare wood, then Rustoleum Auto Primer. It is in the "fix the defects" stage now before a red topcoat. No problems so far. Also of note: I have had good adhesion of the enamel on top of Monokote where I painted over the wing fillets and overlapped the covering. I scuffed the covering with Scotchbrite and cleaned it with isopropyl.

One key is to set the painted plane in the sun after the paint has set up. It seems like it needs a bit of encouragement (UV?) to fully cure. I have been careful not to fly a plane (or get hot fuel on it) until it gets past the "rubbery" stage.

The enamel paint is always heavier than I'd like, but has been a better compromise for me than dope that takes forever to paint and just washes off high nitro planes.

One final opinion: Rustoleum is waaaaaay better that LusterKote!

Hope you pick something that you're real happy with!!!

Dave
LA_Flyer
From somewhere near Manhattan Beach, Ca
(Prop 65 and AQMD impacted zone)

LAST EDITED ON Oct-08-04 AT 09:09 PM (CDT)
 
Tim, I have put Rustoleum over nitrate dope. It works OK untill you have to make a repair and paint over the repair. Then you have to put on more nitate and then Rustoleum. But then your applying nitate over the Rustoleum that is not part of the repair, therin lies the problem (incompatability) ie. MESS.
The rustoleum way is heavier and as above it can create a mess.
I'd stick with Lustrecote or one of the Brand name Dopes.
I have used the Rustoleum on three planes, and will not use it again.

Jerry X-highflyinguy

What is the time frame for rustoleum paint. how long does it take to dry to the touch, and for complete drying after spraying? Also what works best for thinning, paint thinner, meneral spirits or what?

Tim,

Over the solid areas I use Duplicolor Dent and Scratch Filling primer and the Rustoleum over that, no problem. Over open bays I'm afraid you'd add way too much weight, the stuff goes on fairly heavy to get it to flow out. If it isn't covered yet then just dye the silkspan with RIT. You saw the picture of my Super Clown in blue silk and Rustoleum, its very acceptable in the weight department.

Thanks, all, for the replies. I've been planning all along to do the wing with silkspan/dope, and I think I'll stick to that plan... I was just wondering what the effect would be of using rustoleum on the wing. From what I've seen here, I think I'll stick to my original plan. I'm not too concerned about making it pretty, but I would like to get it in the air as quickly as possible. However, unnecessray weight would not be a positive.

Tim

Untill you can fly your planes a season with out crashing it is a good idea to spend as little time on finish as needed. Monocote makes a good fast covering/finish. Makes for easy repairs also.
Light wieght as well.

Why not dopety dope. It dries quick, repairs are straightforward. Fuel proof enough. Usually light, even if you're heavy handed. I would spray the dope on if at all possible. You can put a spray system together for under a hundred dollars. I've been using a $15 dollar touch up gun. Spray, take it apart soak and clean. Start with a fifty fifty mix of dope and thinner. Use a sample board to test spray. I use piece of scrap lumber. Add thinner if it orange peals. A splash of retarder if it keeps drying before it hits the surface. I never did it before last year, just decided to go for it. Even my first attempts looked better than the brush on hairy results I used to get. I monocote the wings. Dope and silkspan the solid sections. Still crashing and learning...

>I'm in the process of beginning to finish my Fancher Twister
>(FINALLY!). For the fuselage, I'm doing clear Brodak
>dope/silkspan as a base, sanding that out, and then planning
>to spray rattle-can rustoleum over that. I'm mainly
>interested in getting it done, at this point.
>
>Anyway, my question: What kind of result might I expect if
>I do the same thing on the open bays (clear dope over the
>silkspan, sand smooth, then rustoleum)? I'm thinking the
>dope would shrink the 'span, then the rustoleum would be a
>relatively quick finish...
>
>Opinion?

Tim;

A couple of things I have learned with with the Fancher Twister (and stock Twister) over the years when it comes to finishing the wing.

The Twister wing has no sheeting from the LE up to the spars. That and the fact that it is a rectangle means the wing likes to twist. It also has a tendency to flex. Twisting gives us warps, and flexing gives us an eventual failure. To overcome that, you can do two things. One is to cover with silkspan or silk. Silkspan and/or silk will not stretch after being doped. To keep weight down, I often go with dyed finishes. As you are in Canada, your summer sun probably does not have the intensity it has here in Gawga, but dyed finishes will fade. So, it is a good idea to keep your plane covered when it isn't flying.

Or, you can go with a film finish. Although I hate the cost, I keep going back to Monocoat for film. It is tough and tends to "hold its shrink" so to speak better than the others I have tried. It will also give you a light finish in terms of weight. The problem with film, though, is that it will stretch a little, and that encourages the flexing again. What I did on my last FT built with the Sig ribs was to put some diagonal bracing between the spars after installing the ribs. I made my diagonals from some 1/20 left over from a foam wing skin I did a long time ago. I think I stripped them at 3/16" wide. Weight gain was negligable. It is amazing what the diagonal braces and the the TE web fillers will do to stiffen up the Twister wing.

There are lots of Twisters out there with stock wings and film covering that are flying fine and will continue to. A wing that flexes, though, will fail sooner than one that doesn't

Keep me posted as to how it comes along. Are you still keeping a photo log?

V/r

LAST EDITED ON Oct-09-04 AT 10:04 AM (CDT)
 
" Are you still keeping a photo log?"

Yup... having a digital camera means never having to say you're sorry. Snapped these two pics just moments ago. As you can see, I've asked the above question early enough, while it's still a mostly theoretical discussion. The fuse now has a few coats of clear dope on it, as well as a layer of silkspan, and I think it's probably almost ready for wet sanding. I'm planning to finish the fuse before installing the wing, that should make the whole job easier to do.

I've decided to stick with my standard silkspan-and-dope wing, I just won't do a "pretty" job of it. I'll just slap it on, initially, in the hope that I can get this plane in the air before Christmas. Then, over the winter, perhaps I'll spend time making it look better...

Edit: No, the flaps aren't yet permanently installed... just dry-fit to make sure everything will line up properly... Permanent installation to follow wing-to-fuse installation, of course...

Tim

A
>wing that flexes, though, will fail sooner than one that
>doesn't
>
>Bob Kruger

Ron B.
F4Fguy

Bob:

Not necessarily true. A wing that flexes distributes the stresses more evenly over the span.As long as the stress is well within the elastic limit of the materials,the flexing wing will out-live the "stiff" one. A stiff structure will shift the stress inboard and give higher local stresses inboard of the tips. The ideal structure would flex according to the load at any point producing an elliptical deflection. The "trick" is to design in the flex spanwise without causing warping.

For an excellent example look at a B-47 or B-52 on the ground and in the air. The wing is designed to flex several feet under load.

Also,please note, I'm only addressing the issue of structure. A flexing wing will have other problems,not the least of which is hinge binding on a flapped wing.

17 feet for the BUFF, the wing flew well before the rest of the airplane.