Windows/Skylight Thickness

Archer39J

Archer39J

4 Place Kit Builder
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".
 
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
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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.
 
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
 
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!
 
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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.
 
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Well now that's an idea! I had envisioned something similar but couldn't readily find an off the shelf source. Thanks!
 
whee said:
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:
Click to expand...

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.
 
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.
 
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?
 
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
 
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.
 
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.
 
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.
 
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
 
Matt - Bob says you should be fine. He says: "Lexan is tough stuff". You do need to support it in the middle or a couple places. It would not be happy without some support. MG
 
Yea, I cut out the original supports that went on either side of the trim wheel, then added 1/2 square tubing in their place. I may also add another piece left to right in the middle. Overall, it's well supported.
 
Brooks posted an excerpt from the Patrol plans a couple posts prior to this one. I am doing the skylight, and wanted to make sure I did the front correctly. If I put the windshield/skylight joint at the same height as the kit (B model, I think same as the A in this regard), will that be a decent match with the wings, or did anyone have to alter the side formers on the fuselage on the kit 4 place fuselage?

I had originally bought some 1/2" sq steel tube for the middle formers, but decided to try aluminum channel instead. I thought it would be lighter. 3/4" 1/16" wall. I made a wood and aluminum former to slowly bend the channel, while holding the legs solidly in place. I did manage to make 2 useable pieces out of two 8 foot sections of channel, but after I was done, the legs still have some distortion in them. Only noticeable if you look end to end.

Then I grabbed the 1/2" square 4130, put 2 big bolts in a big vice, and bent 2 pieces to match in about 10 minutes each. They look great, were very easy to make, and weighed 10 oz each compared to 8 for the aluminum. The steel is a lot stiffer, but I am sure the channel is more than strong enough. I haven't decided yet. 1" aluminum angle would probably also be good, but the 1/2" tube is much smaller visually.
 
I'm waiting until I have the wings in place to finish mounting the skylight and windshield. I recall the manual saying you can bolt up a template and that will get you close but I don't want to chance it. Good to hear about the steel though, 1/2" 4130 square tube is a good choice I figure, might have done that myself if I had to do it again. AL channel looks nice though, but yeah I went through a few to get usable ones, no ripples luckily.
 
I'm with you Dave. I have some ideas for the skylight but I'm not going to finalize anything until I get the wings and windshield on and see how everything goes together.
 
I don't know if there is a B model kit flying yet. I believe most of the fuselage is the same. Not sure if the upper formers are the same as the A, but the airfoil is different.

I think I will hold off mounting the windshield/skylight connector.
 
I don't know if there is a B model kit flying yet. I believe most of the fuselage is the same. Not sure if the upper formers are the same as the A, but the airfoil is different.

I think I will hold off mounting the windshield/skylight connector.
 
Does anyone have a picture of how they secured the side windows to the door frame? I am doing the flip-up (aka seaplane) doors. The doors are 3/4in square tubing with an AL frame around the perimeter and AL bisecting the door where the door handle is. I have lots of door pics, but none that really show how the window is attached to the AL frame on the inside. Looking for ideas...thanks!

Door.jpg
 
On our blue plane I sandwiched the plastic between the steel and aluminum. On 303AP there is a bent aluminum angle with one leg against the steel and one leg against the plastic. The plastic sits inside the steel opening.
 
I guess the question is how is it all attached? Is there sealant on one side? Both? Do the fasteners go through the window or just through the frame?
 
Best to not put any holes in the side window plexi. Best to attach the angles or the frame pieces like Bob shows in his Book (and now given with the kits). Then sandwich the plexi between the inside and outside frame/trim pieces. Capture the plexi instead of drilling holes in it. Mark
 
Unfortunately I never received Bob's book. But that's ok...I have this forum and LOTS of other resources. It's just that sometimes I just can't find an answer or a good picture.
 
I took some 1/2 in thick puck board and cut slots in on my table saw to fit the window thickness then cut into pices that would fit into 3/4 in U channel. I basically used a 90 degree angle piece at the bottum so i could put the window in and used a strip of alum to hold the window glide in screwed to the door frame. Installed the fore and aft piece first then the upper piece assembled with my windows and slid the bottum in. Makes a nice sliding window and no rubbing of the panes. I screwed .020 alum bent 90 degrees for a handle to the fore and aft end of the panes.

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Paul I sandwiched the window plastic between the outer aluminum skin and aluminum angles which were riveted onto the frame of the windows.
 
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