Steve Westphal

Am currently building a Sterling Fokker DR-1 for .049 and a Herr Bonanza for .049 both to use my Cannon micro unit(4 ch.) I like the idea of the look of Sig's Koverall as it is fabric based but it has been so long since I have used it, I can't remember how light it is. Is there a better option for these small planes. Thanks.

Jim Thomerson

Koverall is going to be way too heavy and the fabric look would be out of scale on these airplanes. Personally I would go with tissue and dope. I'd use Sig Litecoat and add some more plasticizer. Actually, I'd probably do the fuselage in silk and tissue the wing and tail.

Jim

ajcoholic

My Feedback: (10)

Yes, that stuff is for larger airplanes (about twice the weight of regular covering like Monokote once it is painted).

Hey are you two guys related or something (same avatar pics)

AJC

johnvb-RCU

My Feedback: (1)

Koverall also shrinks like, um, a black hole(?), in my experience. The fin on my Seniorita (3/16" hard balsa frame) has some interesting wobbles in the inner structure.

For this size model I would use Airspan with dope and then a clear finish of some sort, water based polyurethane for preference.

LouW

Finished Koverall (dope) is comparable to monokote in weight, but many times stronger. I have used it down to a .10 powered Miss America, and it is great. On my Perky (Norvel .61 powered) I used Polyspan, which is comparable to GM silkspan. I have used litespan on some rubber powered models but it shrinks so little it's sometimes hard to get a taut cover. Thats not a bad thing if the frame is very light construction, but can be a nuisance on powered models that you want to look good.

The picture is a .15 powered model covered with Koverall and dope, and flies great.

sturmvogel

LouW...When you used Polyspan how did you finish it? I've only clear doped it and wondered if color dope works-the instructions only mention dye for coloring. It does come out light and looks like OO silkspan used to...
Bob Peteroson

LouW

I normally use clear dope to which I have added analine dye. I spray it on and the finished covering looks like the old silkspan finish. If brushed, the dyed dope looks streaked. It also takes colored dope. Any finish that you used on silkspan will work on polyspan. There is a difference in the two sides. One side will finish a little smoother than the other. Since the material is waterproof, you can't dye the covering like you could silkspan. This afternoon I'll try to get a picture and add it to this post.

Andrew

LouW --

I have several questions: I've covered a lot with silkspan, but never dyed it. Do you add dye to the water bath when you initially wet out the silkspan and do you need to let it soak for a while before wringing it out? What were you using for dye? When we attach the silkspan, normally we get a strong blush from the initial coating of dope which usually clears under later coats. Does the blushing have any impact on the coloring? Is the dyed silkspan sufficiently opaque to cover lettering or blemishes on planked areas? Lastly, I have used the standard talc/dope mixture for filling the weave -- do you need to brush or spray more coats of clear to cover and is the finish glossy?

Sorry to have so many questions, but I really like colored tissue and the idea of using dyed silkspan is very appealing.

Lastly, what is the .15 powered yellow and white model in your previous post -- I like its looks.

Thanks,

Andrew

LouW

It's been a few years since I dyed any silkspan, but I used Rit dye (from the grocery store). I always did it in two stages, I dyed it first then covered. I put it in the dye for a few minutes until the color looked about right, then hung it up to dry. As I remember I also sometimes sprayed the dye with a spray bottle then let it dry. I guess you could cover at the same time but the dye would get on everything. When covering I would merely dampen the dyed paper.

If you allow the covering to dry completely it shouldn't blush. I've only had blushing when I have doped in wet weather, then a little retarder in the dope will usually prevent it. Any blemishes or printing will show through dyed silkspan. I have never used a filler on silkspan or polyspan. Two or three coats of dope usually results in a glossy finish. I now only use silkspan on rubber powered models. It is not nearly as strong as polyspan and seems brittle by comparison.

The .15 powered model in my previous post is my own "designed and built from scratch" airplane that I call the "Goldfinch". It's quite a little acrobat.

I have attached two pictures, one is a "miss America" that is covered with Koverall. The fuselage is stick structure like a SIG Senior and is painted with colored (grey) dope. The wings are sprayed with dyed dope. The other is "Perky" a .061 powered model and the wings are covered with Polyspan and sprayed with dyed dope. Both of these models were built from magazine plans that I inlarged to the size I wanted. The Miss America is about four years old and has more than a hundred flights. The Perky is about two years old and has seen a lot of flying also.

LouW

Covering weight is not really a factor with airplanes such those. The Miss America in my last post has a wing span of 50 inches, compared to 42 inches for the Herr Cherokee. The total covered area is 770 sq. in. (0.59 sq. yd.) including the fuselage. The weight of the doped Koverall (2.0 oz. per sq. yd.) is 1.18 oz. or 3.7% of the total. If I had used transparent Monokote (1.7 oz. per sq. yd.) the savings would have been only 0.3 oz. or less than 1%. Even using Litespan (.85 oz. per yd.)I would have only saved 0.68 oz. (2%) total weight.

The only real limitation to the use of Koverall on such models is the ability of the structure to resist the shrinkage forces. If non-tautening dope is used, the shrinkage forces of the Koverall alone are not very much. I used regular dope on the Miss America with no problem.

The biggest advantage of Koverall I've found is that it is the strongest and most puncture resistant model covering I have ever used. Its fabric appearance would certainly enhance the Focker but since the full scale Cherokee is all metal, regular monokote might look better.