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Jul 14, 2014, 09:22 PM
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lukes221's Avatar
actually dispite how simple they really a snazzy covering job can really make them pop. Ive seen some really nice looking ones.
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Jul 15, 2014, 08:18 AM
CC (Certified Curmudgeon)
flyerinokc's Avatar
Back in the day I had the old Midwest Sweet Stik and she was really a sweet flier like all stiks! I went with the traditional red but used black and white checkerboard instead of the white with the German crosses on it. I had to change it up a little!
Jul 15, 2014, 02:00 PM
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tailskid2's Avatar
I'll let the owner 'fix' the color scheme
Jul 15, 2014, 03:46 PM
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CryHavoc's Avatar
Looks great Balsabird!

A while back I traded a guy for a partially built Uproar 60. The kit wood was hideous. No wonder Tower discontinued that kit. At first glance I thought I would be able to just finish it up most ricky tic but after getting it home and looking it over well, going through the rest of the pieces in the box and all, I can see why he gave it up. But, with determination and elbow grease, even my ugly little Uproar looked great in the bare wood bones when I finished it. There is just something magical about even a lowly ugly duckling airframe in its bare bones.

Anyway, a nice cover cover job and its ready to fly with..... you guessed it, an Enya. An .80X to be precise. I was bumping up against a time crunch so I didn't take pics though, but I'll try to get some soon.

Later,
Mike
Aug 03, 2014, 10:34 PM
Balsadustus Producerus
Thread OP
Sorry about the delay, all, but the last two weeks here have been very hot and humid, for some reason. Wasn't like this last few years.

The butyrate dope order from Aircraft Spruce arrived near two weeks ago, the silk is sitting next to the Stik and I'm waiting for drier days. Retarder, added to the dope along with the thinner, will slow down evaporation and prevent blushing, but these days' relative humidity is near 85%; retarder won't help much with that going on The full-size project I'm doing, recovering a Citabria rudder after a weld repair at the steering arm rib, is also waiting for better weather. If the retarder works on that, I'll try it on the Stik, using the customer's airplane as a test article

Until I find that out, I'm cleaning up the building bench for the next project, a Doug Spreng Stormer. The fuselage is pretty much framed, and it's time for building the wing. Since it is a constant-chord design, I'll be using the A-Justo Jig for better alignment--I hope.

Anyway, I'll keep posting as things happen.
Latest blog entry: Single Channel Case
Aug 04, 2014, 10:21 AM
CC (Certified Curmudgeon)
flyerinokc's Avatar
It seems like the humidity around here has been just as high, weird summer for sure!
Aug 04, 2014, 11:40 AM
UAS Pilot - FAA# *******HRK
CryHavoc's Avatar
Quote:
Originally Posted by Balsabird
........I'm cleaning up the building bench for the next project, a Doug Spreng Stormer. The fuselage is pretty much framed, and it's time for building the wing. Since it is a constant-chord design, I'll be using the A-Justo Jig for better alignment--I hope.

Anyway, I'll keep posting as things happen.
Is this the one he called the 'Flattop Stormer'?
Aug 16, 2014, 10:32 PM
Balsadustus Producerus
Thread OP
The 'Flattop Stormer' is the second version published out of several. One I'm doing is the first version published in May 1962 'American Modeler'. Flattop is similar except no turtledeck. I just like the lines of the first one, is all.
Latest blog entry: Single Channel Case
Aug 16, 2014, 11:16 PM
Balsadustus Producerus
Thread OP
Finally, a weekend with a little time

Before I start, I will say what I'm about to show here, is definitely not the last word on how to silk a model. This is how I go about doing what I've seen many others do. There are probably other, better and faster ways of silking and this works for me. It's surprisingly similar to covering a full-size airplane.

First, there is one more pass over everything with fine sandpaper, then dust removal. I'm using Randolph butyrate dope on this project, which is formulated for use on full-size airplanes. Those who resell butyrate for model use usually reduce it some before packaging it in their containers, but this is right off of Aircraft Spruce's shelf, and the formulas I use assume this.

I reduce (thin) the clear with butyrate thinner 1:1, using non-tautening clear. I'll use non-tautening for this in an effort to reduce warping sheet surfaces, such as the rudder. Two coats are brushed on everything the silk will touch, even if I don't want it stuck down on everything, yet. Otherwise, when the dope is applied to the silk, it will soak into the unsealed balsa and leave pinholes, difficult to fix. So, ribs, spars, servo cutouts and the like get two coats although I won't be attaching the fabric to them yet.

Using 320 grit aluminum oxide paper, I smooth the raised grain down. The pictures show the sequence of events. I like using the silk wet, as it's easier to position and smooth it out with water, as I can re-locate the fabric as needed before gluing it down. I'll wet it in a bowl, lightly squeeze out excess water, and apply. I stretch it out, make sure it's where I want it, get rid of wrinkles and sags, make sure the fabric weave is square to the wing structure, then brush the 1:1 dope through the wet silk and rub in down to the pre-doped framework, on the root rib, tip rib, leading edge and trailing edges only. Not on the other ribs or spars or anything else. This is done pretty much in one step, watching the fabric as it dries. If I'm slow, I'll re-wet the silk with a spray bottle, then continue with the stretching and doping. After the first surface is done, I'll let it dry and move on to a fuselage, tail or whatever is next. By the time that part is done, I can let it dry and return to the wing. Working back-and-forth this way means I don't waste time watching paint dry

After all is dry, I'll trim off excess silk from the edges, dope those edges down and do the next panel. I usually do both bottom surfaces first, then overlap the upper surface fabric over that. I prefer a minimum fabric overlap of 3/8 inch, but can't always get it. I also am careful to cover in such a way so as to not let an edge of the silk into the relative wind, but away from, which may, someday, help prevent the fabric from peeling off in flight. I've been using a natural bristle brush, the cheap disposable kind as they are the best for this type of coating. One inch wide works well for what I'm doing so far.

That's pretty much it, for now. As of this evening, I have one wing top surface to go, and most of the fuselage remains as well. I'll get to that during this week as time allows.
Last edited by Balsabird; Aug 16, 2014 at 11:42 PM.
Aug 16, 2014, 11:38 PM
Balsadustus Producerus
Thread OP
More pictures...

A word about fabric and how it's woven. Most fabrics I've worked with for covering airplanes have a square weave, meaning there are as many threads lengthwise as there are crosswise. This is good, as it minimizes uneven shrinking when doped, helping to prevent warped wings. I don't know about this silk from Dharma, so I assume the fabric does not have a square weave, but has more threads along the length, and fewer in the width: most fabric mills do it this way. Therefore, I ordered enough 8mm silk for the wing so I could use it with the selvage edge lengthwise with the wing span. Selvage means a finished edge, not able to unravel. If applied this way, sagging between ribs is less than if it's applied 90 degrees to the span. And, I can watch how the fabric grain goes on, as I proceed, and not let it get un-square with the wing. If the fabric weave is skewed in relation to the wing span or chord, this can cause warps you can't remove, as they were built-in during the covering process. I can build crooked airplanes all on my own; I don't need help from the silk
Latest blog entry: Single Channel Case
Aug 17, 2014, 06:57 AM
Build more, websurf less
FlyingW's Avatar
Nice job Balsabird. Nothing like a silk and dope finish. Haven't done one in many years, but seeing your work makes me want to try it again. This will be one serious vintage Stik.
Aug 17, 2014, 06:59 AM
Registered User
sirzeppu's Avatar
Beautiful.
Aug 18, 2014, 10:57 AM
CC (Certified Curmudgeon)
flyerinokc's Avatar
That brings back a lot of old memories!
Aug 18, 2014, 03:41 PM
Registered User
tailskid2's Avatar
Everytime I used to silk a wing, I would get a warp - ah, the errors of youth....
Sep 03, 2014, 11:45 PM
Balsadustus Producerus
Thread OP
Don't really want to do this as I feel like I'm bumping my own thread with no new items.

Covered the last wing panel, let it all dry and applied the first coat of butyrate, only to have the silk loosen and sag. A couple of days later, tried a second coat, with no change. After waiting a few more days, it's still not tight. So I called Consolidated Coatings, who own the Randolph brand, and talked with Jon. A modeler himself, but did not know why this happened. Said when they make the various dopes for fabric work, they are for full-size airplanes and to prevent over-shrinking, add enough plasticizer to slow down the shrinking action. Model airplanes don't need that, and actually, should not have that much plasticizer in the formula. Jon also mentioned silk can be a problem when used this way as the weave is already tight and has little or no room left for the dope to tighten it up. John Brodak, at Brodak Models, echoed this and was uncertain why the silk didn't tighten up in a couple of days. Might be non-tautening dope in a can labeled as tautening.

I called Sig Manufacturing, and the man there was not sure why this happened, either.

Jon, at Consolidated/Randolph, suggested leaving the wing out in sunlight for a few hours and see what happens. Nothing, actually, after most of the day outside. On a lark I tried a heat gun with no change.

As far as I have been able to find out, there are only two companies producing these type of coatings--Randolph and Certified Coatings. I looked up Certified online and could not find a way to contact them, so I ordered a quart of Certified clear tautening butyrate from Aircraft Spruce this afternoon, and will try it later this week. Hopefully, there will be a way to contact them on the can.

If this all comes to naught, I'll recover with Sig 'Coverall' and go from there, as this is backing up other projects I have in a line and want to complete as soon as I can. Fortunately, only the wing is an open structure, and the rest of the airplane, as sheetwood, is behaving normally with the silk covering. At worst, I'll have a Dacron wing with a silked everything else, but at least it'll be dope and fabric and not plastic
Latest blog entry: Single Channel Case


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