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Brodak Kits - Tissue/Silk/Poly?

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Brodak Kits - Tissue/Silk/Poly?

Post  larrys4227 on Sun Aug 16, 2015 12:51 pm

Howdy folks -- Quick question that some of you may be able to answer.

The covering material included in Brodak kits is ..... ?

I keep calling it silkspan, but is it really silkspan or is it polyspan or simple tissue? I was comparing what I got out of the Jumpin' Bean to what came in a Brodak Vampire. They both look identical. I figured the 1/2a supplied covering would be a lighter grade than a 35-sized Vampire, but doesn't seem to be any difference.

Specifically, what is it that Brodak puts in their kits?

Thanks a bunch,

Larry
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Re: Brodak Kits - Tissue/Silk/Poly?

Post  Ken Cook on Sun Aug 16, 2015 2:02 pm

It's silkspan and not very good quality. I use it strictly for planked and sheeted surfaces. It has poor strength and poor wet strength not to mention it doesn't shrink well on open bays. Polyspan is the new silkspan. I don't use silkspan or the likes on 1/2A planes because it ends up in a constant battle of repairs.Anytime I used it on open bays , it ended up in what I call the potato chip stage. It literally shattered mainly due to sun exposure and hard landings.  They generally don't land well resulting in cartwheel or flip over landings and it won't take the punishment that the grass gives it. By the time you invest the amount of material required onto it to do a 1/2 way decent finish you more than likely exceeded the weight of a iron on covering. Silk would certainly offer the strength but at the same time it can crush a 1/2A model. Polyspan is much more durable than silkspan even the heaviest offered which was Sig GM silkspan currently not available. I believe the silkspan suppliers stopped making silkspan within the past 2 years. John Brodak recognized this early on and stocked up on quite a bit of 00 and 000 silkspan. He doesn't have the silkspan for larger stunters which was K&S silkspan. They're currently not making it and many scrambled quickly to snatch it up when announced it would no longer be offered.
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Re: Brodak Kits - Tissue/Silk/Poly?

Post  larrys4227 on Sun Aug 16, 2015 9:21 pm

Thanks Ken .... the last couple weeks I've been working with the supplied brodak covering on the Jumpin Bean and it does seem to be fragile.  Thats what has me worried about landings in grass .... repairs. The plane primarily is for practice finishing.  I have a Prowler on the bench and want to do a half decent job on the finish.

A few years ago, I recovered a Flight Streak and sprayed it with Rustoleum. I "seem" to notice a difference between that covering and Brodaks.  The covering I used on the FS I've been saving for the Prowler.  It was given to me about 5-6 years ago ... but in very good condition.

I just dug out the package, and the label says:

K&S Engineering
#402 "SGM" Medium Silkspan
20 Pieces - $2.39

The Flight Streak still looks the same as the day I covered it ....but with a couple holes in the bottom of the wing.  All of them due to my fingers poking through due to rough handling.  Of course the FS has landing gear, so I can't really say how it would hold up to full contact in the grass.

A quick search shows RSM has polyspan and I have read in other places that its pretty tough stuff.  It might be the ticket I need for the Jumpin Bean. Since the wings on the JB only have dope around the edges, now might be a good time to stop ....strip the wings .... get some polyspan .... and do this with better material.  I'm in no rush .... the Prowler wing is finished, but I haven't even started on the fuse. Long way to go before the Prowler is ready for dope.

Decisions, decisions .... Smile

The pic below shows the JB with the supplied Brodak covering ......only the edges are doped down. It did tighten up real good on the open bays though. I've been happy with the result so far.

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Re: Brodak Kits - Tissue/Silk/Poly?

Post  Ken Cook on Sun Aug 16, 2015 11:16 pm

Larry, I wouldn't rip it off. If puncture resistance is a concern, put another layer on it. One thing I do with combat models (vintage) is to use Phil Cartier's SLC covering to cover and place silkspan over it. Phil's covering is very lightweight. It also irons on. It's a special covering which is similar to Mylar but has a treatment on it which can accept paint or adhesives. It could be used as is with paint but silkspan over it is extremely strong. My Jumping Bean is one my father built in the mid sixties. I recovered it with silkspan which looks great but on it's first outing the clip popped off the plug and went right through the outboard wing. I looked at my son and just had to chuckle. I couldn't believe it. Fortunately, it was an easy non detectable repair.

Polyspan is a neat product but it demands a bit of a new learning curve. It's critically essential to double and triple coat ribs, wingtips and sheeted areas. Basically what I'm suggesting is that anywhere your going to be sanding or any high spots needs to have enough dope on them to prevent you from burning through and fuzzing the surface. If that happens it becomes very difficult to repair. Ca over it smoothed out with a finger helps if you don't glue yourself to it. Compound curves are also a bit troublesome. Iron and a heat gun assists this process. Polyspan shrinks with heat after it's applied. Sometimes you have to do both simultaneously. Ken
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Re: Brodak Kits - Tissue/Silk/Poly?

Post  larrys4227 on Mon Aug 17, 2015 1:02 pm

I think thats a pretty good idea to add another layer ... rather than ripping it off. I'll still get some polyspan .... I have all the tools to work with it (heat guns and trim irons.)

I watched a couple videos this morning .... very informative and pretty easy to apply.

Thanks!

BTW, today when I was flying the Vampire ... it decided to start undressing the monocoat. Grrrrrrr .... I really dislike plastic film. Now I have yet another project .... strip the wings and get out the dope.

Never again will I cover a plane with plastic .....
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Re: Brodak Kits - Tissue/Silk/Poly?

Post  Ken Cook on Mon Aug 17, 2015 1:39 pm

Larry, I have been a fan of Monokote for a long time. I always felt it held itself above and beyond all others. Top Flite however is just another name nowadays and the covering is nothing like what it was. I believe Great Planes owns them currently. It doesn't feel the same, smell the same or work the same. It bags out in the sun and it's very very problematic on the tips. Monokote was always the tougher film to work with on the tips but this constant strive to make stuff cheaper certainly doesn't help matters. Don't give up on the iron on film. Some of the Ultra cote coverings are very high end and durable.One thing I do is to use nicely cut strips of packing tape ironed on over the seams on the leading and trailing edge. This really seals the deal and prevents oil creepage and fluttering covering. Ken
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Re: Brodak Kits - Tissue/Silk/Poly?

Post  RknRusty on Mon Aug 17, 2015 3:22 pm

I too am a Monokote lover, though I may not even know what the original stuff was like. I do know that every color and batch are a little different to apply. But I have done some nice looking jobs with it, and it stays put. Never had a problem with it letting go, and patches are almost invisible.

I do understand wanting to use the "Real thing" though. I have one of Bob Zambelli's beautiful old I-beam winged stunters and I wouldn't think of disrespecting it with any other than an old style re-finish. So I'll be learning to do it, hoping i can get to it before too long. Maybe this Winter.
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Re: Brodak Kits - Tissue/Silk/Poly?

Post  larrys4227 on Mon Aug 17, 2015 10:31 pm

Hahaha .... I must be doing something wrong with applying plastic. Every plane I have that has it requires some type of constant maintenance to keep it attached. Yet my doped planes are always fly 'em, wipe 'em and hang 'em.

In hindsight, I should have done something earlier with the Vampire ... I did notice the leading edge had a lip on it where the plastic was just starting to come apart. Eh ... I can't keep up with it all. LOL!

The bad part is that in the area where the plastic stripped back ..... the color part is still attached to the wood. Dealt with this before and its a darn nuisance trying to get it off.
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