Best type of plastic for windows and skylight

[Gary Wallace]

Ive tried searchin on this topic with no luck..looking for recommendations for best plastic for doors and skylight. Thanks!

[svyolo]

Lexan (polycarbonate)is just about unbreakable, which is bad if you are trying to break out of a wreck. It also doesn't handle chemicals well (bad for windshield?).

Acrylic is easier to damage and harder to cut and drill without cracking. It is more chemically resistant. You might need thicker acrylic to keep it from breaking.

The kit windshield is acrylic I believe, I am using Acrylic for the front windows (for now), and Lexan for everything else.

With Covidmania good luck finding either. Luckily I bought mine beforehand. I hope I don't ruin a piece because I can't buy it local right now.

[alaskabearhawk]

FWIW, I'm using Makrolon polycarb coated with Noxtat for my windows and skylight. The coating makes it impervious to avgas. It's originally designed for high-traffic urban areas in bus stops, etc...easy to clean up graffiti and resistant to damage. I put a small piece in avgas for 24 hrs with no ill effect on the plastic. The same chunk has been kicking around my shop for the last two years, tossing it around, tools get put on it, etc. It still looks like new. Not cheap...

[John Bickham]

Not an expert but did learn one thing post installation of my Lexan skylight and windows. The are several different grades of Lexan. There are grades of Lexan that are scratch resistant. It is a little dusty here in New Mexico and just cleaning can scratch it up pretty bad. If I dont have a water source to "flush" the surface first, I dont clean it. If you go with Lexan, may want to consider scratch resistant grades.

[JimParker256]

Plus 1 on the "scratch resistant grades"... I usually keep a 1-gallon bottle of water (screw top) in my plane whenever I'm flying away from home base, both for emergency consumption and for rinsing the dust off the windshield before cleaning it.

[Bcone1381]

Ive tried searchin on this topic with no luck..looking for recommendations for best plastic for doors and skylight. Thanks!

For the Patrol, Bob calls out .080 - .100" thick Acrylic (Plexiglas) for the side windows, and .060" thick Lexan for the sky light.

This is a link the "Acrylic Sheet Fabrication Manual" written by Plexiglas. It cover Cutting, Drilling, Machining, finishing, Cementing, and maintaining Plexiglass. I followed it and was able to cut, drill, finish, my side windows without waste or cracking a single hole. For example, It taught me to drill a pilot hole, fill it with wax, then drill the finish hole using an acrylic drill bit.

https://www.plexiglas.com/export/sites/plexiglas/.content/medias/downloads/sheet-docs/plexiglas-fabrication-manual.pdf

Screen Shot 2020-12-03 at 1.40.11 PM.png
Screen Shot 2020-12-03 at 1.38.42 PM.png

[Battson]

I have used Acrylic everywhere with no regrets whatsoever. Windshield, windows, door windows, skylight.

We had no problems with cutting or drilling whatsoever, you must have to be unlucky or careless to crack it. You need to oversize holes because all plastics changes size a lot as ambient temperature changes.

We even walked on the windows with gravel on our boots when the plane was upside down, it barely scratched - so little that I am still using the same windows today and don't notice.

Fuel will get on the side windows - this cannot be avoided. Maybe even the skylight at some stage. Acrylic is resistant to AVGAS 100LL even after long exposure. I am told Lexan will craze almost immediately on contact with fuel.

[alaskabearhawk]

Not if it's coated. I soaked a piece of coated polycarb in avgas for 24hrs and it didn't touch it. Made a believer out of me...

[Mark Goldberg]

Bob likes Lexan for the skylight because it is such tough material. If an acrylic skylight cracks and departs the plane - it could be catastrophic. Mark

[Pbruce]

I have been mulling this over and I’m still torn. Acrylic is cheap, UV, chemical and scratch resistant and might allow escape in an accident. I totally respect where Mark is coming from though in reiterating the advice of the designer in good faith: Bob recommends polycarbonate with good reason-it’s strong. (also 6 times as expensive for the UV/scratch resistant type I can buy).

However, I wonder about the real risk of the skylight panel “departing the aircraft”, in terms of likelyhood and also severity of outcome. Why would it depart and how catastrophic would that really be? I’m imagining that a goose hitting at the top of windscreen/front of skylight might do it. I can think of few other causes. But I might still prefer that to the goose hitting the middle of the windscreen, where it would hit me. If the Patrol suddenly loses its skylight, does that not mean that I’m flying an open-cockpit Patrol? It seems like that’s probably a manageable outcome. This line of thought (not so much the cost) has me gravitating toward 1/8 acrylic.

I realize that these risks are mine to evaluate but I wonder if there are other factors I haven’t considered. Thanks

[Rollie]

I used lexan for the sky light and Plexiglas for the side windows. My reasoning was that lean is stronger but scratches easier than Plexiglas. I expect the side windows to get touched and cleaned more often than the skylight so I wanted them to be more resistant to getting scratched. Seems to be working so far.

[whee]

If your doing standard windows then I’d use plexi (acrylic). It is simply better suited for the job, IMO. If you are making seaplane doors then I’d suggest lexan (polycarbonate) because it is tougher. It will resist cracking where the door curves. I used acrylic for all my windows because I couldn’t find tinted polycarbonate. Both my doors have cracked where the acrylic follows the curve of the doorframe. Rob found some tinted polycarbonate on eBay so I’m waiting to see how it works for him.

Polycarbonate is tough but it is soft so scratches easily and on its own it is not UV resistant. However, coated polycarbonate is very durable stuff. I used scratch resistant, UV stabilized Makrolon (pc) for the windshield on my boat. The boat is outside at least 10 months of the year and the windshield looks great. It has wipers that run on the pc and I’ve even accidentally smacked the windshield a couple times with my 60lb anchor. I’m sure glad my windshield isn’t glass or acrylic.

[alaskabearhawk]

I bought tinted polycarbonate for my skylight from a company in AK. The owner is a complete jerk, so I found out who the distributor is and they are located in CA. I had to buy a whole sheet for the rest of the windows but it was worth it not having to deal with the guy here in AK. That was a couple of years ago, so who knows how expensive it is now! www.eplastics.com

[zkelley2]

Interesting. I've worked with image plastics here in town, who will even mold stuff for you. And CAC plastics in the valley, who does certified aircraft parts anyways, and they also do a lot of fiberglass and carbon work.

[alaskabearhawk]

It wasn't either of those companies. CAC Plastics has always bent over backwards for me...great folks. I don't know anything about Image plastics. The company I was talking about is Cadillac Plastics and is no longer in business.

[Pbruce]

I was going to use 2mm for sides. I’ve learned from reading every thread that it’s too thin and will drum. Mark said he used 1/8” which he says is nice and stiff but heavy. I found 2.5mm locally for another 50 bucks, and a weight penalty of 2.1 lbs. Has anyone used 2.5 mm successfully (I’m looking for an inflight report-does it drum?). Thanks

[rodsmith]

I'm interested in any responses. I bought .100 lexan (2.5mm) for my seaplane doors just before reading on the forum that .125 should be used to prevent drumming.

[robcaldwell]

I used 1/8" lexan on my doors, and 1/16" on my skylight. Happy with it so far.

[jaredyates]

Do we have positive reports of 2.5 being too thin? I used 1/16 polycarbonate on the standard upper side windows and it was definitely too thin. Good for the skylight though.

[Pbruce]

Thanks everyone. I think I’m going to go with 1/8” acrylic all around unless I get a pirep from someone who used 2.5 mm acrylic on the sides confirming no drumming. I’ll go with 1/8 acrylic or polycarbonate on the skylight, leaning toward acrylic at the moment