This just crossed my mind as I was thinking about lightweight interior options. A few planes I fly (don't own) simply have no interior, where you can see the inside of the fabric from inside the plane. People worry about UV degradation to the fabric from the outside through the paint, dope, etc. But I've never heard of people worrying about sunlight coming through windows/skylights and damaging exposed fabric from the back side. Is there something I'm missing or is this a real worry if a plane didn't have an interior?

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When I was covering my kitfox I asked that question of the polyfiber rep. He recommended to use a brush to coat the inside of the fabric with polyspray (The silver UV protection coat) in areas exposed to sunlight. I did that but it wasn't pretty.

[quote="dogpilot"]Interesting point......
Plastic, ie. Plexiglass offer no reduction in UV in its normal form. It is fairly easy to get 10% disability from the VA for "Helmet Halo" skin cancers for military pilots, it is unfortunately a sad side effect of flying around in a plastic bubble at altitude.

Since I "fought" the bad UV transmission of all types of (plexi) glasses in my research activities I was surprised to read the above.
Neither did I have any problems whatsoever with many long flights under the big canopies of my glider(s) and so I briefly (re)searched and found this:

".....We also asked Mecaplex about the transmission of UV light through the canopy. The canopies do not totally screen out UV, but do absorb about 95% of it. That means the sun is no problem. For long flights which may reach high altitudes, pilots with no previous exposure to strong sun should use a topical sunscreen. Direct UV-Blocker are not necessary.
Tinted canopies even give a little better protection from UV rays."

(https://www.dg-flugzeugbau.de/en/librar ... -dg-glider)

So it seems that different types of "plexiglass" are used for airplanes/helicopters and gliders.

never stop learning...

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The price difference in windshields for the Bearhawk between standard clear and UV-blocking "solar grey" is about $300.

$580 vs $901 from LP Aeroplastics. Pretty much all plexi can be had in UV-blocking variety.

There might be a clear UV blocker you can brush onto exposed fabric, instead of going with the ugly salmon-pink Polyfill. My dad coated his ultralight sails with something that he sprayed on with an airless paint system. Of course, being certified, it's probably verboten to apply an unapproved coating.

Zzz wrote:The price difference in windshields for the Bearhawk between standard clear and UV-blocking "solar grey" is about $300.

$580 vs $901 from LP Aeroplastics. Pretty much all plexi can be had in UV-blocking variety.

There might be a clear UV blocker you can brush onto exposed fabric, instead of going with the ugly salmon-pink Polyfill. My dad coated his ultralight sails with something that he sprayed on with an airless paint system. Of course, being certified, it's probably verboten to apply an unapproved coating.

The pink isn't the UV block. The silver/grey is. If you go with clear then you will see the pink that is applied to fill the weave. Kind of a mute point on ASAs scout as ACA doesn't use polyfiber.

A1Skinner wrote:

Zzz wrote:The price difference in windshields for the Bearhawk between standard clear and UV-blocking "solar grey" is about $300.

$580 vs $901 from LP Aeroplastics. Pretty much all plexi can be had in UV-blocking variety.

There might be a clear UV blocker you can brush onto exposed fabric, instead of going with the ugly salmon-pink Polyfill. My dad coated his ultralight sails with something that he sprayed on with an airless paint system. Of course, being certified, it's probably verboten to apply an unapproved coating.

The pink isn't the UV block. The silver/grey is. If you go with clear then you will see the pink that is applied to fill the weave. Kind of a mute point on ASAs scout as ACA doesn't use polyfiber.

ACA might not, but the dude who rebuilt it did use Polyfiber. It's very pink inside. I sorta dig it.

This is an interesting discussion.

asa wrote:

A1Skinner wrote:

Zzz wrote:The price difference in windshields for the Bearhawk between standard clear and UV-blocking "solar grey" is about $300.

$580 vs $901 from LP Aeroplastics. Pretty much all plexi can be had in UV-blocking variety.

There might be a clear UV blocker you can brush onto exposed fabric, instead of going with the ugly salmon-pink Polyfill. My dad coated his ultralight sails with something that he sprayed on with an airless paint system. Of course, being certified, it's probably verboten to apply an unapproved coating.

The pink isn't the UV block. The silver/grey is. If you go with clear then you will see the pink that is applied to fill the weave. Kind of a mute point on ASAs scout as ACA doesn't use polyfiber.

ACA might not, but the dude who rebuilt it did use Polyfiber. It's very pink inside. I sorta dig it.

This is an interesting discussion.

There I go putting my foot in my mouth again. Sorry Zzz.
I agree, very interesting.

In 2010, finishing my Bearhawk, I spoke with Jon ?Goldbaum, Stits Poly-Fiber owner, and he said interior UV protection not necessary. FWIW!

Talked to my dad. He said he used PPG DU-1000 "Durethane" to coat his ultralight sails.

I don't really think it's a big deal. Not sure I'd bother, especially if you store the airplane with sunshades when parked.

I’d be more worried about poking a hole in said fabric than UV. It’s amazing how easy it is when wrestling “stuff” in the back of a plane to poke something.

Then again, maybe it’s just me.....

MTV

Right now Stewarts is working with some clear UV blockers. Nothing much new about them but a different application.
I've been doing fabric for over 35 years and never heard of a problem with it, but anything is possible. I'm reminded of that any time I say "never". Some of the polyurethane paints have a bunch of UV block in them already, inherently. I think MTV is on the right track...I've patched more holes from crap getting stuck through the side when there isn't some sort of interior. Before the advent of polyester fabric, the average cover job was lasting about 10-15 years so it wasn't a real big worry about UV, plus it was more apt to rot than get weak from the sun.
John

Not really the same but I built a fixed frame soft top for my boat a few years ago. Rather than pay a couple grand for a canvas cover I used to opportunity to work on my fabric covering skills. Towards the rear of the top there are a couple areas where the sun shines on the inside. Those areas of fabric are discolored. The boat sits outside March-Nov. I didn’t used a certified paint system so maybe it’s not a valid data point.

I used Stewarts on my BH and I was told I should put the primer (UV barrier coat) anywhere the inside of the fabric will be exposed to sun.

MTV makes a solid point about poking holes from the inside. I would have a few holes in my plane if I hadn’t put the 3/8” foam on the inside.