Windows/Skylight Thickness

[Archer39J]

Looking around I see mention of mostly 1/16" (.060") thk polycarbonate. jaredyates suggests this might be a little too thin on the upper windows. What are other folks using?

My source for PC, Makrolon specifically, can only do solar grey in 1/8" (.118") minimum thickenss. Though I want the side windows clear I would really like the skylight to be tinted, but don't want the weight penalty of 1/8".

[whee]

I used 3mm acrylic. Because of the large size of the skylight I wasn't comfortable with anything thinner. Steve's Aircraft STC for the Pacer call for 1/8" poly or acrylic and it is a fair bit smaller.

You may also consider the toughness of poly in regards to emergency egress. Here is a quote from another forum that made me pause:

Because I have laid with a badly injured back in a cub with avgas pouring down over both myself and my injured wife and tried in vain to kick out the skylight, and could not do it. All the time waiting and listening for the muffled "woomp" sound that would signal the end of both of us. Windshield was blocked with a large tree trunk, right wing torn off, aircraft on it's right side. The only way we got out was via the slider, because it was in tracks I was able bow it until it popped out. Yes, Lexan is cheaper, Yes it is easier to work with, but in my opinion it has no place in aircraft unless the hole is to small to crawl out of. I am always amazed at folks who will spend thousands of dollars on survival gear, but never give a second thought about how they might live long enough to use it. I guess you have to experience the terror of being wet with fuel and unable to get not only yourself but the one you love out of harms way to fully understand what I am talking about. Don't misread this post, it's not a lecture or a condemnation of those who want to use Lexan, just one man's experience which some may wish to consider, life is all about options. Fly safe

[Archer39J]

Certainly something to consider, though I'm not really a fan of something that large that has the potential to shatter. Acrylic on the windows maybe, for egress and chem resistance.

[Archer39J]

Of course I could always just film tint the 1/16", hmm...

[Mark Goldberg]

I think Bob has said that 1/8" on a skylight would be the minimum. He has used 1/16" on the side windows. I like about .100 on the side windows minimum. I used 1/8" on my 4 place side windows. Bob likes Lexan for the skylight because it is dam near indestructible. Acrylic is OK if it is installed with all the steps done properly to insure it will not crack and depart the plane. Edges and holes carefully deburred is the most important. And the attach holes bigger than the screws that hold it with rubber or something around the screws to allow the uneven expansion and contraction of the materials. Mark

[JimParker256]

Or leave it clear, and use a two-way sliding "shade" to block the sun when you want to. I'm probably going to go that route, using RV "day/night shades" (with the same fabric on both the forward and aft "shades"). The center "slider" will probably be fixed in place, and the fore/aft parts will retract into the center when I don't need/want the shade. Doing it this way allows individual adjustments for the front and back seat. Here's a source: https://www.campingworld.com/shoppin...t-shades/1869d Note that you'll probably install these shades above the trim mechanism - right next to the skylight, so you need to use the "inside the window" measurement technique.

In the picture on the website, you can see the darker shade at the top (night shade - blocks almost all light), with a middle bar (divider/slider), and the lower shade that is more translucent and will let some light through. This link is for the "custom size/configuration" shade builder, where you can pick both fabrics as well as the length/width of the shade to custom-fit your window. They are pretty light-weight, and have the advantage of providing shade when you want it, and providing visibility when you want it. Pretty cheap, in aircraft terms!

[Archer39J]

Well now that's an idea! I had envisioned something similar but couldn't readily find an off the shelf source. Thanks!

[Archer39J]

I do recall reading that as Bob's preference now that you mention it, that'd certainly make it easier on me but for 2X the weight. Surprising builders would halve that though, I guess it hasn't caused any issues? At least I haven't read of any.

[Battson]

I used 3mm acrylic. Because of the large size of the skylight I wasn't comfortable with anything thinner. Steve's Aircraft STC for the Pacer call for 1/8" poly or acrylic and it is a fair bit smaller.

You may also consider the toughness of poly in regards to emergency egress. Here is a quote from another forum that made me pause:

I am also using 3mm acrylic for the larger windows, and 2mm for the much small lower door windows (which are custom).
I have found this material thickness durable, chemical resistant, and stiff enough to avoid any unwanted drumming.

A friend used thin stuff for the large windows, and was unhappy with the amount of drumming.

[Archer39J]

Is that 3mm on the skylight as well?

[Battson]

Yep skylight too.

[rodsmith]

I used 1/8th dark gray tinted lexan for the skylight. Had the option of light or dark gray, I took a chance on dark. Looks almost black from the outside but good visibility from the inside, should help with heat.

[Archer39J]

I've been going back and forth on light or dark. I think dark might be the better choice.

[schu]

I thought that .093 was okay for a skylight. That's what I have and it's pretty tough. Do I really need 1/8?

[Mark Goldberg]

Lexan or acrylic? If you are using .093 acrylic for the skylight I might reconsider. I am willing to ask Bob about it for you. Mark

[schu]

It's lexan, and I would like to know what Bob says, thanks!

[alaskabearhawk]

I used 1/8th poly-carbonate tinted light gray, treated on two sides with TEC 2000 for the skylight. For the side windows I ordered .093 clear poly-carbonate, also treated on both sides with TEC 2000. I put a piece of Makrolon in AVGAS and left it in overnight....didn't faze it at all.

http://www.noxtat.com/products/tec-2000-tec-satin/tec-2000/

[whee]

Where are you guys getting you tinted PC? Part of the reason I went with acrylic is because I couldn't find tinted scratch resistant PC. It was either tinted or scratch resistant but not both.

[schu]

I'm kinda kicking myself for buying the wrong stuff, I don't know if I can return it. I'm tempted to just run it because it's way stronger than 1/8 acrylic which seems to be excepted, and because I'll put #8 screws every 4". On the first flight I'll know if it works or not, if it drums, then I'll need to replace it, if it doesn't, it's fine. For now I'll wait for an answer from the Bob.

[Archer39J]

Haven't read anything about drumming with even .060” on the skylight, the main complaint seems to be with the side windows. But like you said you can always swap it out if you’re not satisfied.

[Archer39J]

So I think I’ve decided to use 1/8” acrylic for rigidity and chemical resistance on the skylight. Transparent light smoke at 57% transmission, this correlates to a “medium gray” tint via LP Aero that provides the kit windshields. My windshield is solar gray with UV block at 77% so the skylight will be a bit darker. TAP’s dark smoke is 36% which I think would be a little too dark. Side windows will be the same thickness per Mark G’s suggestion but clear.

Im fortunate to have a local TAP store that’ll do a sheet for ~$100 so its not too bad to change it in the future if I want. Link below has the acrylic as well as tech data and working instructions, good instructions for polycarbonate too and worth a look if you’re going to be working plastics.

https://www.tapplastics.com/product/...ent_colors/519