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Author Topic: Polyspan, Poly T, Thermalspan?  (Read 1122 times)

Offline Target

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Polyspan, Poly T, Thermalspan?
« on: February 10, 2018, 07:36:15 PM »
Looking to do a (real) finish on some upcoming builds.
As a kid, I had done a few tissue and stick jobs with dope.

Now that I'm an adult (?), I want to use Polyspan and dope to cover a few models, and figuring out what to buy is a bit daunting.

Tom Morris sells "Poly Tissue" on this site. So far it is the most economical, but only comes in 13" wide rolls. Is it the same as Polyspan? I assume coming from hi, it is just what I want....

RSM sells Polyspan, which I assume is exactly the right stuff. It comes 20" wide.

Harris Aerospace supposedly sells some stuff that is doesn't care which way it is laid on, and is supposed to be the same price as regular Polyspan.

Fly2Build has a roll of Polyspan that is 4' x 20', but it is $40. But that would last quite a while and seems to be a pretty good deal if you want it wider. Tom Morris's stuff is cheaper but you would have to buy 4 rolls to equal one of these 4' wide rolls.

Please chime in, especially if you have direct experience with more than one of the above products and purchases
Regards,
Chris
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Online George Truett

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Re: Polyspan, Poly T, Thermalspan?
« Reply #1 on: February 10, 2018, 07:41:18 PM »
I have bought several rolls of Poly Tissue from Tom and they look like they were cut from wider stock. If width is an issue I would call or email Tom and see if you can get a wider roll.

Online Jim Svitko

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Re: Polyspan, Poly T, Thermalspan?
« Reply #2 on: February 10, 2018, 07:50:55 PM »
Over the years I have come across some products that I can only call polyspan clones.  That is, they are very similar to polyspan but of lower quality.  I doubt that these products are the Starline brand.  The weave is rather thin in some areas.  I doubt if I could ever fill it with dope.  I also wonder about how it will react when shrunk or when dope is applied.  I hesitate to use it.

I have the Thermal Span.  The weave is denser.  It has no grain.  It is as strong chord-wise as span-wise.  It is attached like polyspan, shrunk like polyspan, and filled with dope like polyspan.  It also has an inside surface and an outside surface.  The rolls I have are 14 inches wide by about 16 feet long.

I think Thermal Span is superior to polyspan.  I will use it instead of polyspan.

Offline Target

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Re: Polyspan, Poly T, Thermalspan?
« Reply #3 on: February 10, 2018, 08:01:18 PM »
Thanks Jim.
I surely do not want one of the lower quality products!
I have an email in to the folks at Harris that sell the Thermalspan material. I might buy some of the Tom Morris PolyT if I can get confirmation that it is just a different name for the same real polyspan material.

Do you remember what the 14" x 16' rolls of Thermal Span cost you?

Thanks again!

R,
Chris
Regards,
Chris
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Offline Target

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Re: Polyspan, Poly T, Thermalspan?
« Reply #4 on: February 10, 2018, 08:05:15 PM »
I have bought several rolls of Poly Tissue from Tom and they look like they were cut from wider stock. If width is an issue I would call or email Tom and see if you can get a wider roll.

So, would you say it is just a narrower width version of regular polyspan?
Just making sure I don't get a low quality product. Seems like Tom Morris's product might be a trimming from some wider roll that can't be used by the original customer, and maybe that is why the price is a little better.
I'll have to measure how wide the chords are on the roots of the wings I intend to cover are.
Do you or have you overlapped the covering? I would assume if so you feather it in somehow.

Thanks!
Regards,
Chris
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Online Jim Svitko

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Re: Polyspan, Poly T, Thermalspan?
« Reply #5 on: February 10, 2018, 08:40:06 PM »
A roll of Thermal Span, 14 inches X 16 feet, is $13.60.  My last order was for three rolls.  I included $5 extra for shipping since Shannon Harris did not know what the exact shipping cost would be.  When the package arrived the postage on the address label was $4.19.

The literature supplied with the Thermal Span said it is also available in 23 inch width.  I don't think I would ever need it that wide.

I usually have a tough time determining which side is outside.  This is supposed to be the smoother side but both sides look the same, feel the same.  If not for the colored dot to mark the outside surface I might have to make a guess.  I hope the person who attached the colored dot got it on the correct (outside) surface. 


Offline Motorman

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Re: Polyspan, Poly T, Thermalspan?
« Reply #6 on: February 10, 2018, 09:07:35 PM »
Whatever you do don't get the stuff at the fabric store. It looks just like polyspan but it ain't.
There will be a sunny day and we will fly our airplanes.

Online Jim Svitko

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Re: Polyspan, Poly T, Thermalspan?
« Reply #7 on: February 10, 2018, 09:13:21 PM »
Whatever you do don't get the stuff at the fabric store. It looks just like polyspan but it ain't.

This lousy material might be the polyspan clones I referred to.  I did not get it at fabric stores.  Someone might have thought that this material was as good as regular polyspan and sold it as such.

Offline Target

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Re: Polyspan, Poly T, Thermalspan?
« Reply #8 on: February 10, 2018, 10:51:51 PM »
Thanks all of you.
I'll see what comes of my email to Harris Aerospace, and go from there.
14" does seem OK for most U/C planes. Might be marginal on an old RC Sailplane I might try using it on. That thing has a huge wing.
Regards,
Chris
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Online George Truett

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Re: Polyspan, Poly T, Thermalspan?
« Reply #9 on: February 11, 2018, 09:22:13 AM »
Chris,

I can't compare Tom's material to the original, I have only ever seen that sold by Tom.  My last purchase was 3 rolls, 2 of them seem to have a factory edge on one side while the other looks scissor cut.  The third roll has the scissor edge on both sides.  I doubt it's factory cutoff, my thought is Tom is buying wide rolls and cutting to a width that makes sense for his customers but you'll have to ask him.  I have attached a copy of the instructions he includes, you can see an expert opinion on overlapping.

Offline Avaiojet

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Re: Polyspan, Poly T, Thermalspan?
« Reply #10 on: February 11, 2018, 12:02:54 PM »
Target,

No interest in silk?

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Offline Fredvon4

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Re: Polyspan, Poly T, Thermalspan?
« Reply #11 on: February 11, 2018, 01:28:31 PM »
Chris
When I came back I searched for silk span and got steered to RSM Polyspan

Got some..watched Robert Storick's  how to video

works well for me

Found out about film over (any) fabric... so now use SLC over the poly span and basically elimnate the heavy doping
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Offline Dennis Nunes

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Re: Polyspan, Poly T, Thermalspan?
« Reply #12 on: February 11, 2018, 10:07:09 PM »
I've used Polyspan on several models. I can come out heavy as it took many coats of dope to get the "grain" filled. And make sure you put the smooth side up! If you're not careful with the heat you get small holes that need to be repaired too. Some of these you don't see until you get some color applied. Also, if you sanded through to the Polyspan, you had to deal with the "fuzzies".

As you are away, you can no longer buy silkspan. However, here on StuntHanger there was a discussion on using "Exam Table Barrier" or "Doctor's" paper. I purchased a case (12 rolls) of the TIDE 981004 "Crepe" paper for $25.00. Each roll is 21 inches wide by 125 feet long and is equivalent to medium silkspan! I couldn't find a company that would sell it by the roll, so I ended up buying a case. I've given most of it away as 12 rolls would last me 10 lifetimes.

It is the same as silkspan! I've covered 3 stunt planes with it so far and it works just like silkspan - no difference. I just saw on eBay that a you can buy a case for $28.94 which includes free shipping. See the link below. That's less than $2.50 a roll!

https://www.ebay.com/itm/TIDI-981004-Crepe-Exam-Table-Barrier-125-Length-21-Width-White-Pack-of-12/192260071688?hash=item2cc397e108:g:DD8AAOSwi0xZ91ZL

If at first you don't succeed ---- let someone else try it!  ;)

Offline Robert Whitley

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Re: Polyspan, Poly T, Thermalspan?
« Reply #13 on: February 11, 2018, 11:39:07 PM »
After 40 years away from aero modelling I tried the Doctors examination “ silkspan” on a Baby Flite Streak and a full size Flite Streak.it seemed to apply the same as I remembered from long ago but seemed a bit lighter or thinner than I remembered medium silkspan to be .
Nonetheless it went on fine wet, shrunk very well and filled well with three to four coats of dope.
Now to see how it takes primer and colour coats,
I used to use nylon but can’t seem to find a source for it now.

Offline Dennis Nunes

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Re: Polyspan, Poly T, Thermalspan?
« Reply #14 on: February 11, 2018, 11:47:08 PM »
There is also a TIDI 916213 paper which is the light weight paper. Was it the TIDI 981004?
If at first you don't succeed ---- let someone else try it!  ;)

Offline goozgog

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Re: Polyspan, Poly T, Thermalspan?
« Reply #15 on: February 12, 2018, 04:57:50 AM »
Hello Target,
                     If the wing you are covering is so big that 14 inches
won't cover the chord, then maybe you should consider polyester
dress lining.
  last week, I covered the wing of my Wildman 60 with Tom Morris'
Polyspan. ( see picture ) It's a good product and very easy to apply
but it might be a little light for C/L planes if you aren't also adding
a layer of paper. I have other successful 600 sq/inch planes with
Silkspan over Polyspan.

   The dress lining is a great alternative. It sticks down with
nitrate, goes around curves and heat shrinks beautifully.
It does require a layer of silkspan to get a light finish but
it is brutally strong. Not as light as polyspan but for models
as big as a Flight Streak or bigger, it's great
You just buy it at a fabric store for about $5.00 a yard.
  I've covered at least eight models with the dress lining
and all of them have won their share of trophies.

If you want, send me an PM and I'll mail you a small sample.

Cheers!



Keith Morgan

Offline Target

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Re: Polyspan, Poly T, Thermalspan?
« Reply #16 on: February 12, 2018, 08:04:56 PM »
Ok, see guys, I'm a little confused.
I realize that the paint is the "finish" and that the covering just supports that, and is somewhat porous.
But covering with Polyspan, then something over that also just makes me think that will be heavier.
I realize the goal is to get rid of the porosity, and add stiffness to the airframe, but covering twice seems like you didn't pick the right thing.

I am very very good with monocote. I have been called "AR" by my RC sailplane flying and buddies with attentions to detail. My experience with dope and tissue was pre-teen though so a LONG time ago!!

I don't REALLY know what material to use for covering, and I assume that the first plane will come out fine, and later ones will be improvements.
While I care about appearance, models to me are for flying, so lightness and stiffness trump (sorry) appearance.

I have been told by the OFB's that I started flying C/L with that Polyspan is what to use on open structures and Esaki Tissue is good for solid areas, to seal the grain and make a good base for paint (also the tissue adds a lot of stiffness, I am told). So, my ARC SV-11 that I want to put a "REAL" finish on, I planned to Polyspan (Now probably Thermal Span) the wings, and fuse, and use tissue on the tail and probably flaps. Then paint in one form or another.

Is that a bad plan?

Charles- I have no idea if I have an interest in silk or not, as you can probably figure out from the above.

I appreciate the input, but some clarity would be nice. Will a Polyspan covered wing be heavier than one with Polyspan and something else, after paint?

Thanks!
Regards,
Chris
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Offline Lauri Malila

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Re: Polyspan, Poly T, Thermalspan?
« Reply #17 on: February 12, 2018, 10:29:04 PM »
Who would be the first to use ripstop polyester (Icarex etc.) in a stunt plane? A little different method of working with it but I’m quite sure it would be better than Polyspan.

Lauri

Offline john e. holliday

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Re: Polyspan, Poly T, Thermalspan?
« Reply #18 on: February 13, 2018, 12:10:27 PM »
In my opinion, if you want a dope finish try this.  Get some SLC or mylar covering for the open areas and put it down.  Then put your poly-span on over it.  It will take a lot les dope to fill and also add strength to the covering.   I do it just the opposite so I can have a finish that looks like silk span/poly-span with a nice sheen to it with the SLC/mylar on top.  Go through the finish section and look at some of the pictures.

Now if you want a really light finish go with SLC/mylar for covering every thing.  Then take a scouring foam scouring pad and buff the SLC/Mylar to a dull look.   Then finish with your dope the normal way and be light on the sanding.   I have some spots on my DOC Special that I am trying to fix now as I was to heavy with the sand paper on the primer. D>K
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Offline Fredvon4

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Re: Polyspan, Poly T, Thermalspan?
« Reply #19 on: February 13, 2018, 12:58:55 PM »
Search larry Rengers...SLC over posts
Look in the gallery at many of Bobby Mears Combat museul planes... many are Faux Silk n Dope...using "span and SLC or Doculam

Point is true silk, polyspan, silkspan, thermospan...all need some sort of dope or paint to fill and make drum tight

This adds some weight

Laying down a tight open bay covering with say.. RSM Polyspan is easy... over covering it with very light weight Phil Cartier Super Light Covering (SLC) is a simple way to eliminate all the dope layers and much lighter and actually stronger.... color....over the SLC is easy becaus it is already preped for paint..... de grease...skuff with scotch pad if needed... spray color lightly until opaque...done
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