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Author Topic: Polyspan over open bays only  (Read 2212 times)

Offline kevin king

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Polyspan over open bays only
« on: January 25, 2023, 01:26:56 AM »
Has anyone here tried using Polyspan on the open bays only, then covered the rest of the wing with Silkspan?  Ive never tried it so any tips would be appreciated.
Thanks.

Kevin

Offline Jim Hoffman

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Re: Polyspan over open bays only
« Reply #1 on: January 25, 2023, 03:36:11 AM »
I and others first cover entire open bay wing with carbon mat (0.2 lb/ ft2), do not put CF on cap strips. CF makes for a hard sharp edge where the wood ends. Break all CF edges

Then apply Polyspan to the open bay area with above a 1 inch overlap on the Polyspan perimeter.  While filling Polyspan with clear dope add extra material to the Polyspan edge to help blend

Online Miotch

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Re: Polyspan over open bays only
« Reply #2 on: January 25, 2023, 08:17:50 AM »
I and others first cover entire open bay wing with carbon mat (0.2 lb/ ft2), do not put CF on cap strips. CF makes for a hard sharp edge where the wood ends. Break all CF edges

Then apply Polyspan to the open bay area with above a 1 inch overlap on the Polyspan perimeter.  While filling Polyspan with clear dope add extra material to the Polyspan edge to help blend

Interesting.  But how do you cover an open bay wing with CF and not put it on the capstrips ??  Or do you mean cover the wood on the open-bay wing with CF, but not the capstrips ? I'm thinking that must be what you mean because why would you cover the open bay itself with CF ....

Online Dennis Toth

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Re: Polyspan over open bays only
« Reply #3 on: January 25, 2023, 09:36:30 AM »
I think Kevin has it right they use the CF on the leading and trailing edge sheeting then apply the polyspan over it and the rest of the wing. I have read that polyspan works well on "I" beamers that have no sheeting at all. I think you could go straight to covering without the CF and it will be fine. Two tips: make sure you run the grain spanwise and second put the shiny/smooth side up.

Best,    DennisT

Offline Jim Hoffman

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Re: Polyspan over open bays only
« Reply #4 on: January 25, 2023, 02:24:23 PM »
To clarify……. Cover all the sheeting of your open bay wing with CF mat.  Do not cover cap strips with CF.  Then Polyspan

Pure Polyspan on I- beam wings with no balsa sheeting is an excellent option

Online Matt Colan

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Re: Polyspan over open bays only
« Reply #5 on: January 25, 2023, 04:15:31 PM »
To illustrate what Jim is describing, here is how I did it on my new classic airplane I’m working on. The only difference is I covered the open bays first and then went over the top with the carbon veil up to the edge of the sheeting. It hides the seam very well after a couple coats of clear and gentle sanding of the veil
Matt Colan

Offline kevin king

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Re: Polyspan over open bays only
« Reply #6 on: January 27, 2023, 01:20:52 AM »
Thank you for you for sharing everyone. 👍

Kevin

Offline David Ebers

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Re: Polyspan over open bays only
« Reply #7 on: January 28, 2023, 11:51:29 AM »
 I don't have e enough finishing g skills to fill a sewing thimble. I've covered a profile fuselage with cv and an open frame tail feathers on an rc airplane with polyspan. I'm curious why use carbon veil and polyspan on an open wing (I understand that cv doesn't shrink).

Offline Jim Hoffman

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Re: Polyspan over open bays only
« Reply #8 on: January 28, 2023, 12:19:22 PM »
I don't have e enough finishing g skills to fill a sewing thimble. I've covered a profile fuselage with cv and an open frame tail feathers on an rc airplane with polyspan. I'm curious why use carbon veil and polyspan on an open wing (I understand that cv doesn't shrink).

A well finished CL stunt model has the balsa wood grain filled.  An external layer of silkspan or carbon veil adds stiffness to the structure and fills lighter than raw balsa (IMO).  The carbon veil also adds an apparent surface hardness as well.

Polyspan is very puncture proof (silkspan is not) and adds lots of stiffness to an open bay wing.

Online Dennis Toth

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Re: Polyspan over open bays only
« Reply #9 on: July 22, 2023, 07:54:17 PM »
Has anyone used polyspan on Flite Streak style wing/wing tips? These tips are rather thin and I was wondering if the polyspan will laydown on them>

Best,    DennisT

Offline Motorman

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Re: Polyspan over open bays only
« Reply #10 on: July 22, 2023, 09:53:28 PM »
I've pretty much given up trying to get polyspan to go around compound curves. I use polyspan lite from the free flight guys just over the open bays only then, cover eveything with the lightest iron on covering I can find which right now is my short supply of Coverite Microlite.

MM 

Offline Steve Scott

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Re: Polyspan over open bays only
« Reply #11 on: September 01, 2023, 11:55:45 AM »
I plan on finishing my S1 Ringmaster w/polyspan on the wings but want to know how best to achieve a clear no color finish.   I did one a couple of decades ago with the old iron-on Black Baron Silkspun Coverite and sealed it with BB clear (smelled like varnish).  It looked great and was pretty durable.

I managed to cover the wingtips with the same piece of polyspan as the rest of the wing on a prior RM.

Offline john e. holliday

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Re: Polyspan over open bays only
« Reply #12 on: September 01, 2023, 06:25:04 PM »
I tried Poly Span when a gentleman had it at VSC.  It was the first Time I had seen it.  I also bought a bottle of the yellow dye and learned later do not brush it.  It was very easy to work with using dope back then.  Now the carbon fibre I bought a roll and used it on the plane I was working on at the time.  Also learned real fast do not back stroke withe brush when putting it down.  Could not get the fibers back in place.  What is left of the roll is some where in the shop.  In fact I don't use dope any more.  The last bit  I had turned to jelly and would not thin out. D>K
John E. "DOC" Holliday
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AMA 23530  Have fun as I have and I am still breaking a record.


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