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Silkspan weight recommendation

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Silkspan weight recommendation

Post  SuperDave on Sun May 13, 2012 10:10 am

Silkspan comes in three weights: 00 = fine, SG = medium, and SGM = heavy.

For 1/2A control-liners, I have found 00 to be far too fragile to be used in this application becaue it will puncture VERY easily.

Even if 00 is provided in a 1/2A control line kit, I recommend it be replaced with at least SG to make the silkspan covering more durable in actual useage. Only if I were greatly concerned with flight would I resort to 00 silkspan.
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Re: Silkspan weight recommendation

Post  nitroairplane on Sun May 13, 2012 10:56 am

Dave: Have what do you use for for smaller than 1/2a stuff?
I have only ever used it a handful of times and they were on rubber powered planes and a .020 stik and I had no problem with puncturing.
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Re: Silkspan weight recommendation

Post  andrew on Sun May 13, 2012 11:14 am

I like the medium weight silkspan.
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Re: Silkspan weight recommendation

Post  SuperDave on Sun May 13, 2012 11:16 am

Nitro:

00 silkspan might be fine for rubber-power stuff but for 1/2A control-line give me SG. Papered my "Baby Ringmaster" with thd 00 provided in the kit by Brodak. A small plastic part (a bellcrank) fell off my work surface and pentrated straight through the top and bottom panels of a freshly papered and doped wing. GRRRRRRR! Once I strip off the damaged papering (double GRRRRRR!) I'll redo it with SG and repeat the process.

Moral of the story: When weight is a primary concern go with 00; when durability is a parimary concern go with SG. Save SGM for the larger airplanes in Classes B and C.
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Re: Silkspan weight recommendation

Post  andrew on Sun May 13, 2012 11:25 am

SuperDave wrote:

A small plastic part (a bellcrank) fell off my work surface and pentrated straight through the top and bottom panels of a freshly papered and doped wing. GRRRRRRR! Once I strip off the damaged papering (double GRRRRRR!) I'll redo it with SG and repeat the process.

One of the nice things about silkspan is the ease of repair. But, don't cut a patch with scissors, tear it out. This will leave the edges jagged and feathered. When doped over the hole, the edges will blend with the underlying silkspan and become almost invisible.
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Re: Silkspan weight recommendation

Post  nitroairplane on Sun May 13, 2012 11:27 am

andrew wrote:
SuperDave wrote:

A small plastic part (a bellcrank) fell off my work surface and pentrated straight through the top and bottom panels of a freshly papered and doped wing. GRRRRRRR! Once I strip off the damaged papering (double GRRRRRR!) I'll redo it with SG and repeat the process.

One of the nice things about silkspan is the ease of repair. But, don't cut a patch with scissors, tear it out. This will leave the edges jagged and feathered. When doped over the hole, the edges will blend with the underlying silkspan and become almost invisible.
Yup Andrew, that is my biggest problem with clear films, they look too dark when over lapped.
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Re: Silkspan weight recommendation

Post  gcb on Sun May 13, 2012 11:42 am

The 00 can be used in 1/2A, but I prefer SG. The lighter silkspan you use, the more imperative that you apply it with grain running the proper direction. For example, if you look at the silkspan, you can see straight strands and wavy strands. The straight ones are referred to as the "grain". The grain should run spanwise on the wing because it is much stronger and resists tear better. That way it supports the airframe and is more tear resistant from twigs in the field. Likewise, if you apply it chordwise, a twig may cause a rip upon landing. You can tell if you have applied it chordwise because it will have more sag between ribs when it shrinks.

The heavier the silkspan, the harder it is to read the grain. My guess is that the heavier is made by multiple layers of the light stuff with grain in multiple directions. This is onlt a GUESS, I have not read anything about this.

I prefer the medium on 1/2 A planes because not only is it stronger but it is also takes less dope to get a decent finish.

But still, if you must fly where the field is not raked, and is full of twigs, you might want consider one of the synthetics that is more tear resistant.

George
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Re: Silkspan weight recommendation

Post  gcb on Sun May 13, 2012 12:06 pm

andrew wrote:One of the nice things about silkspan is the ease of repair. But, don't cut a patch with scissors, tear it out. This will leave the edges jagged and feathered. When doped over the hole, the edges will blend with the underlying silkspan and become almost invisible.

Good point Andrew. I think some of us older guys do that out of habit and it is good to point it out to newer folks.

For a utility or beater plane, I have also pulled the silkspan back together with a "T" pin and bridged any gap with dope or Ambroid. The "scar" would last until I wanted to make a proper repair.

Nitroplane, in all seriousness, how do you make a repair on clear film? I have never used it so I have no idea.

George
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Re: Silkspan weight recommendation

Post  Kim on Sun May 13, 2012 1:08 pm

You can also "mix and match". Baby Wulf, my perpetual FW-190 project, has light silkspan on it's wings, with a strip of medium up it's belly, with forward "plug planked" areas getting some light silkspan, bonded over the wood with clear dope.
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Re: Silkspan weight recommendation

Post  roddie on Mon May 16, 2016 8:06 am

Bumping this old thread because I've never used silkspan, but I have a lot of it. This is from several old (50+ years..) kit-boxes that were given to me with leftover balsa scrap etc. where the builders decided to use "silk" instead.

Some questions;

1. Does it degrade (unused) with age?

2. Can it's weight be somewhat determined by observing the weaves between differing sheets? (I site George's 1st post in this thread)

IIRC.. silkspan used to be supplied in some of the small plank-wing 1/2A C/L kits (Goldberg "Swordsman" and "Stuntman") I could be wrong about that.. but I seem to remember my Dad building a Swordsman for me back in the 1960's.. that he covered it's plank-wing with. The wing/stab was dk. green Aero-gloss dope and the fuse was gloss black. It was sharp looking.

3. Can I use silkspan on a plank-wing; using anything other than dope to adhere it?

I'm just wondering if I can get a decent rattle-can type finish.. without too much paint soaking into the wood.

4. Might the silkspan (assuming it's 00-grade) end up being a lighter-weight finish if less coats of paint are needed to cover?

I realize that this is not the conventional use for silkspan.. but I "do" have some unfinished plank-sheet surfaces for candidates.
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Re: Silkspan weight recommendation

Post  pkrankow on Mon May 16, 2016 9:05 am

roddie wrote:Bumping this old thread because I've never used silkspan, but I have a lot of it. This is from several old (50+ years..) kit-boxes that were given to me with leftover balsa scrap etc. where the builders decided to use "silk" instead.

Some questions;

1. Does it degrade (unused) with age?

2. Can it's weight be somewhat determined by observing the weaves between differing sheets? (I site George's 1st post in this thread)

IIRC.. silkspan used to be supplied in some of the small plank-wing 1/2A C/L kits (Goldberg "Swordsman" and "Stuntman") I could be wrong about that.. but I seem to remember my Dad building a Swordsman for me back in the 1960's.. that he covered it's plank-wing with. The wing/stab was dk. green Aero-gloss dope and the fuse was gloss black. It was sharp looking.

3. Can I use silkspan on a plank-wing; using anything other than dope to adhere it?

I'm just wondering if I can get a decent rattle-can type finish.. without too much paint soaking into the wood.

4. Might the silkspan (assuming it's 00-grade) end up being a lighter-weight finish if less coats of paint are needed to cover?

I realize that this is not the conventional use for silkspan.. but I "do" have some unfinished plank-sheet surfaces for candidates.

1 if stored properly, no. It may discolor. It may mold (fungus) it may do other things if it gets wet. Overheating is not good either. If it is discolored but does not shred with a light tug then it should be OK.

2 I don't know.

3 silkspan can be adhered with quite a few different products including polyurethane, stinky or water born, and a number of other paint like products. It can also be adhered with CA at the edges and shrunk with water and heat... but I am fuzzy about the process.

4 yes, using silkspan or carbon veil, or any of a number of covering materials can create a lighter fine finish due to not having to fill the grain completely. Care is required as getting a heavy finish is very very easy to do. I know how to add weight, it is easy. Saving weight is hard.

Consult the paint and finishing section of Stunthanger for more information the use of silkspan, or other covering material, over planking is common on larger planes.

http://stunthanger.com/smf/paint-and-finishing/


Phil
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Re: Silkspan weight recommendation

Post  roddie on Mon May 16, 2016 9:24 am

Thanks Phil. I may try different methods on some scrap sheets of balsa.. then weigh them after being painted for a week or so.. to see if there's any significant difference.

I like the tacking with thin CA suggestion. Wondering if lightly-spraying (rattle-can) afterward will adequately adhere the silkspan to the wood.. I could see how it could get heavy if not careful.
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Re: Silkspan weight recommendation

Post  kevbo on Mon May 16, 2016 10:12 am

Hiya Roddie!

Silkspan has a grain. It tears easier one direction than the other. As sold, the grain runs the long direction of the sheets, but it should be fairly obvious if you tear a corner each direction.

When covering open bay wings, running the grain spanwise will reduce the sag between ribs a bit.

When covering balsa sheeted areas, running the silkspan grain across the balsa grain will help reinforce the balsa from splitting. This last is especially helpful on sheet balsa wings that tend to split along the trailing edge.
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Re: Silkspan weight recommendation

Post  roddie on Mon May 16, 2016 12:30 pm

Thanks Kev, I've had pretty good luck with just priming-sealing/painting my plank-wings.. but am ISO achieving a nicer finish that won't weigh too much. (aren't we all...) Smile I used to use Aero-Gloss Sanding Sealer followed by brushing-on their pigmented dope.. but the last several models that I've built have had rattle-can finishes.

Should I be concerned with warping because of shrinkage? Does silkspan tend to shrink more with or across it's grain?

I'll be attempting to finish/fly my T33 1/2A speed model this Summer, and want it to have a smooth but also lightweight finish.

What about foam? Could silkspan be adhered to it; to form a membrane that might take relatively fuel-proof paint(s) that might otherwise attack the foam.. or would any viable adhesion method be attacked by the paint as well? Maybe thinned white glue perhaps?
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Re: Silkspan weight recommendation

Post  kevbo on Mon May 16, 2016 2:40 pm

I think the dope tries to shrink it equally in all directions, but in an open bay, the cross grain tension is resisted more by the grain. On sheeting, it might be better to use non-shrinking cellulose dope instead of butyrate. If you are only looking for a smooth surface finish over sheeting, japanese tissue might take less paint/filler/dope/sealer to fill it's texture than silkspan.
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Re: Silkspan weight recommendation

Post  NEW222 on Mon May 16, 2016 5:04 pm

roddie wrote:Thanks Kev, I've had pretty good luck with just priming-sealing/painting my plank-wings.. but am ISO achieving a nicer finish that won't weigh too much. (aren't we all...) Smile I used to use Aero-Gloss Sanding Sealer followed by brushing-on their pigmented dope.. but the last several models that I've built have had rattle-can finishes.

Should I be concerned with warping because of shrinkage? Does silkspan tend to shrink more with or across it's grain?

I'll be attempting to finish/fly my T33 1/2A speed model this Summer, and want it to have a smooth but also lightweight finish.

What about foam? Could silkspan be adhered to it; to form a membrane that might take relatively fuel-proof paint(s) that might otherwise attack the foam.. or would any viable adhesion method be attacked by the paint as well? Maybe thinned white glue perhaps?  

Back to the post above. Yes you can put it on foam. I would suggest using Minwax Polyurethane, as this is what I use with good results, although other brands will probably work just as well. I will also mention that I use the oil based, not the water based. I cannot comment on the water based stuff as I have never used it but I hear it works just as well.
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Re: Silkspan weight recommendation

Post  roddie on Mon May 16, 2016 6:32 pm

NEW222 wrote:
roddie wrote:Thanks Kev, I've had pretty good luck with just priming-sealing/painting my plank-wings.. but am ISO achieving a nicer finish that won't weigh too much. (aren't we all...) Smile

What about foam? Could silkspan be adhered to it; to form a membrane that might take relatively fuel-proof paint(s) that might otherwise attack the foam.. or would any viable adhesion method be attacked by the paint as well? Maybe thinned white glue perhaps?  

Back to the post above. Yes you can put it on foam. I would suggest using Minwax Polyurethane, as this is what I use with good results,  although other brands will probably work just as well. I will also mention that I use the oil based, not the water based. I cannot comment on the water based stuff as I have never used it  but I hear it works just as well.

I am surprised that the oil-based poly doesn't attack the foam.. but that's encouraging. The little "Voo Doo" foamie I'm building doesn't need much work to finish it. I was going to use a low-temp white iron-on covering.. but would rather go with an "antique-white" finish with dk. red booms/stab. and trim.




blah blah blah.. I just can't seem to get out of my own way. This one I'd really like to have ready for when Ron Cribbs comes out my way this Summer.
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