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General control line discussion => Open Forum => Topic started by: Bootlegger on November 22, 2009, 12:45:34 PM
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Guy's I am thinking about "double covering" the wing with silkspan, first layer "OO" silkspan, then second with "G M" silkspan.
What are your thought's and would you do it another way, and why???
As usual, Thanks a Lot......
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Thanks Ty, I'm gonna do away with thar idea...
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Gil, go to www.freeflightscale.com then the technical tips section, and see how my mate Mike uses Silk over jap tissue! Very interesting.
Cheers Neville
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Gil,
Yesteryear it was common for some people to use two layers of light silkspan.
I have never done it, however.
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I used that technique on a Smoothie I still have. Labor intensive as light tears easily and you have to do it twice. Still, a successful experiment as it filled fast, is light, and as strong as heavy silkspan. Will I do it again?, probably not. 8)
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One layer SGM, lotsa dope, OR.............Mono.............................................
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I have had success with covering just the open bays using the thin mylar (like used on the European combat models) fixed down with a heat sensative glue (thinned Evostick) then covering the whole wing or stab with a single layer of light tissue. This combination gives much superior puncture resistance, huge torsional rigidity, lighter weight than 2 thickness of light tissue - probably due to the much reduced dope use to fill. There are a couple of downsides. It can be tricky to get the tissue on without ripples (but I have a similar problem with double covering in tissue). If using a mixture of clear and colored finish care must be taken with masking tape removal to avoid separating the tissue from the mylar as it shows a slightly different shade of clear.
My friend Brian covers his models in a similar way but used the light tissue in place of the mylar. He has found that he can get the second coat on without ripples by water shrinking the second layer of tissue then once it is dry and shrunk washing the entire surface with a generous coat of pure thinners. This seems to stick the tissue down without allowing it to slacken.
http://www.machineconcepts.co.uk/aeromodelling/brians_engine/brian_with_model_after_flight.jpg (http://www.machineconcepts.co.uk/aeromodelling/brians_engine/brian_with_model_after_flight.jpg)
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For Mylar and silkspan it's easier to use SLC from the Core House, I've done a couple ships covered with SLC then medium silkspan and both turned out great. SLC has the adhesive built in and is suppose to have a finish that can be painted directly. I recommend using a scotch bright pad to scratch the surface then a wipe down with acetone before putting on the silkspan. This insures it will stick and I've not had any masking tape lifting issues.
The result is a silkspan finish that is light and maybe tougher than polyspan. I'm using SLC on the FJ-4 carrier airplane I'm building and going to try painting directly over the SLC with dope. If you would like to see how it turns out I will be posting updates in the Building a fun carrier thread in the carrier section.
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Hi Bob or anyone,
Does the SLC need primer over it before the color ?? TIA
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Hi Bob or anyone,
Does the SLC need primer over it before the color ?? TIA
Only on the seams and that's more to cover them than anything.. The recommended primer is duplicator rattle can sandable primer available from most any auto parts house. One warning, it will dissolve with prepsol and/or other degreasers even after it's cured for several days.
I can't seem to get SLC around compound curves so I just cut it anyplace it doesn't lay down, put a coat of finish resin on the edge and any wood left bare to seal the edges and wood. Wipe it off with a paper towel, next day lightly sand and hit with the primer. When the primer is dry sand smooth and it's ready for color. I wouldn't do a whole airplane this way as the primer can add weight real quick but for spot areas it's great.
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Only on the seams and that's more to cover them than anything.. The recommended primer is duplicator rattle can sandable primer available from most any auto parts house. One warning, it will dissolve with prepsol and/or other degreasers even after it's cured for several days.
I can't seem to get SLC around compound curves so I just cut it anyplace it doesn't lay down, put a coat of finish resin on the edge and any wood left bare to seal the edges and wood. Wipe it off with a paper towel, next day lightly sand and hit with the primer. When the primer is dry sand smooth and it's ready for color. I wouldn't do a whole airplane this way as the primer can add weight real quick but for spot areas it's great.
Great tip, Bob!
Mongo