This short video reviews the differences in properties between the two popular plastics used for windshields and doors in experimental aircraft: Lexan (polycarbonate) and Plexiglass (acrylic).
I found this video to be very informative. The gentleman spoke Claire And slow enough to understand him. The give me every answer I could have possibly have thought of to ask. Well done my friend
You can Glue Acrylic to each other with Acetone. Apply the acetone to an edge and then press/ clamp to a flat acrylic surface for it to Bond to each other.
Such great and instructional videos. Finally used the RU-vid setting of speeding up to 150% speed as you normally talk quite slowly. Works for me. Keep up the videos...
What we need is a hybrid of both. I know of a situation of a pilot having his windshield shatter without warning. He got down safely, although he did sustain some scratches to his face. Imagine if a bird flew into it, it might not have ended the same way. What would be best would be to get some sort of laminate that could offer the best of both, particularly for the windscreen.
I imagine somewhere there's a laminate solution for a windshield, such as a piece of poly sandwiched between layers of acrylic to give it rigidity and strength. If something were to hit it, the poly keeps it from shattering and you can safely land (or stop in the case of a land vehicle). Then if possible replace the outer layer or replace the entire windshield. The outer layers would not only keep it rigid but also keep it from scratching and hopefully keeping it from yellowing/fogging which is common on poly windows in race cars.
I wish I could give you an idea of how much your videos have helped me. I bought a used Kitfox, this is my first airplane ever, the airplane has not flown for the last 15 years and I have used so many of your videos as home build school for me. I bought lexan that is guaranteed not to go yellow for 10 years.
In the marine environment, polycarbonate has been found to become. Brittle after a few years of constant UV exposure, making it more fragile than acrylic. Many use thicker acrylic.
Excellent presentation, there is also a problem with forming lexan to make windshields and formed door windows. Could you please mention the problems with heating lexan to form on molds. Thank you.
An additional consideration can be heat expansion. Those panels will change size with the temperature. One material is more stable, sorry can't remember which (plexi I think?).. This can cause problems with frames, fasteners, seals, etc
I want to try to build my own DIY e cymbals. I was thinking about vaccum forming them from real cymbals. At first I thought about acrylic glas, because it is nice and rigid and so on, but I have not thought about it shattering so easily. I do not want it to crack on the first hit. Do you think polycarbonate would do better here? I would glue on some rubber padding to the beat zone and edge to protect it from scratches and silence it a bit more. Can you glue polycarbonate or will it make it brittle?
This guy is cool he has stewie on his plane. Good info I'm going with lexan for my adv bike windshield because it won't shatter in my face when I go down.
The problem with the door is its lack of rigidity. It broke because of all the stress on the acrylic. Vibration is also a big factor in the cause of cracks in brittle materials.
You mention that polycarbonate scratches easily, and that scratches cannot be sanded or buffed out. True... BUT... There is a fast, easy way to remove scratches from polycarbonate. Simply play a loose flame from a propane torch gently over the scratched area. They will disappear like magic!
3:30 This is actually wrong, the fact that polycarbonate didn't break means that it's less brittle NOT that it is stronger. Acrylic has higher tensile, compressive and flexural strength.
I was thinking the same thing. I don't believe most people understand even simple basics about engineering. And when it comes to placing yourself 12,000 feet AGL? That is kind of scary.
Quick note to try on your scratched Lexan. Lexan is a material that like to return to its original condition. Take a heat gun and heat the scratched area, starting with a low setting. Slowly bring your heat up until the scratched surface returns to its original condition. This method often restores light scratches to an un-noticeable condition. Give it a try on some negligible area. It really works.
@1:30 ..yep already know acrylic isn't gonna go down like that lol. Cutting acrylic isn't as hard as u make it out to be. I use a miter saw or a table saw with a 80tooth 10inch 30dillar blade from harbor freight. Also I believe bullet proof glass tends to sandwich poly between acrylic.
What about resistance to bird strikes? I would think that the acrylic (Plexiglas) would shatter and possibly injure the front seat occupants? Any comments on windshield impact damage?
When I worked with acrylic, I used to run the drill backwards, heating it up as it worked the bit through it, never lost a piece to cracking from that.
watch a fire video of the difference between acrylic and polycarbonate. Plexiglass/acrylic is ridiculously flammable and keeps on burning and dripping flaming pieces long after the flames have stopped igniting it. It should be banned!!!
Great video but as mentioned below the properties listed under "Strength" are not strength. Strength = allowable stress which in tension or shear is simply force /area, bending is more complex ( stress =My/I) but for the same bender and same thickness of material, strength reduces to the ability to resist force. So if the Lexan bends before the acrylic under the same force then the yield strength of the acrylic is higher. The property you want to explore here is "toughness" or the ability of a material to absorb energy up to fracture (= the area under the stress-strain curve).
Does light transmission for Acrylic over 10+ years go down to 85% from 92% when it was new (if used outside), and if yes then why? One last question is I'm thinking of buying some 150 x 150 cm extruded acrylic to rest on top of 4 corner poles but don't want it to bend in the middle if it's too thin and when it snows (each pole will be 15 cm from the edge). What is the minimum thickness do you think I should use? Because every mm costs money I don't want more thickness than is needed.
5:42 what special coating can I use? I’m from Florida and the UV and the heat is causing struggle on my project , what do you recommend? Great video by the way
Well, a good video as always, Appreciated ! - But I wish you would mention that there is a distinct difference in the optical properties between the two materials. I have had Lexan in side-windows that are not very important and its ok there but I would not want to use Lexan as a Windshield in my planes because of the lousy optical properties of it. Plexiglass for the windshield for sure on my stuff. Best Regards, Lars
Good video, but a quick off-topic note on the broken door... I had identical well-fitted CH701 pilot-side doors open in flight and break at speeds under Vne. Root cause was prop wash getting under bottom-front corner of the door and bending it back till it fractured during a powered (but sub Vne) descent. Neither latch point failed, only the door. Solution is a third latch point at lower front of door on pilot side to ensure -zero- gap for prop wash to get under.
yes, this is a point. but I am afraid acrylic is a little bit fragile especially at 2mm,3mm thickness. polycarbonate almost meet the same optical properties with acrylic at thses thickness. best reagrds,Daisy
Which has better insulation properties from the cold? Which is better for using to replace my household window with? I had 1/2" thick dual pane Andersen window. Thanks
Thank you sir Awesome explanation with clarity. Should safety not win n be 1st consideration over price when building plexiglass or lexan usable items ( not toys or other one time use lab flasks etc).? Also can both plastics be not overlaid to get all properties? Good day
I wat to make double wall acrylic similar to double wall POLYCARBONATE sheets. Do you think the double wall acrylic with have a better insulation property's that the double wall polycarbonate ? I'm attempting to make a glass studio/office.
I am researching to build a rally fairing for my enduro bike. Acryllic seems a clear cut winner except that it can shatter. I will drop my bike, it always happens at some point in enduro riding. Is there any way I could treat the acryllic to make it a bit more flexible? If not I'll have to go with Lexan I think.
I would recommend using acrylic. It's cheap enough that when it breaks you can just get another one. Plus it wouldn't scratch as easily from dirt, rock, and limbs
Other variations of Lexan suffer from exposure to ozone and also ammonia, which makes many ordinary window cleaners very bad, especially if you are cleaning home plastic window block inserts, or worse, an airplane windscreen, where micro stress fracturing can go unnoticed until a stress event causes failure that the original would not have experienced. Military aircraft may use advanced Lexan type polycarbonates for their vastly superior strength, but likely with additives and coatings that add too much cost for civilians to consider; they can also probably enforce stricter maintenance protocols to avoid problematic chemicals that civilians will fail to recognize, and when that item needs replacing, we civilians pay for it, as well, anyhow. Lexan can have scratches polished out - but that removes the UV protective and anti-scratch coatings. Low speed aircraft may not be at high risk from bird strikes, etc. and so acrylic is the accepted trade-off, but above a few hundred miles per hour, you don't want an acrylic windshield between your cockpit and the stray goose. For hobbyists, Lexan can be more aggravating to work with, as many glues don't bond it as easily as acrylic; regular plexiglass can be heated, molded, bent, and polished to a glassy sheen, with only cutting and drilling issues to consider, but solvent welding and many other gluing options make for easy craft uses that don't require bulletproof shields.
Actually, there are many examples of uv/ scratch resistant coated polycarbonate that lasts great and ate around the same as a regular automotive safety glass. In order to protect the uv protected polycarbonate and maintain upkeep, using a ppf covering works wonders and there's reason it can't hold up well
so you stated that PC can be enhanced to manage it's poor performance when exposed to UV. What about the poor performance of acrylic when exposed to stress...how can acrylic be enhanced to manage its Achilles heel?
Why use acrylic at all on light aircraft? Surely the risk of vibrations and impacts cracking the whole thing is much worse than it tinting a bit over time but being incredibly solid with polycarb.
I don't know why anyone would still use plexiglass, other than than their excessively anal A&P won't let them use something better on a certified aircraft. I detest acrylics. I worked in the eyeglass industry and polycarbonate lenses have nearly totally eliminated acrylic CR39 lenses. For good reason.
Seems like damned if you do the damned if you don't if you make your doors out of polycarbonate we're going to have to replace them due to the UV light from the sun. But not last chance of it breaking and cracking or virtually no chance of breaking and cracking. If you buy the stuff that has a UV coating on it and you get a deep scratch in it and send it out I guess you lose the coating that blocks the UV that's just a matter of time before it gets destroyed by the sun. Any idea how long it takes before the UV destroys the poly on average? Thank you for your time
That's weird. I hear plenty warn of fuel issues with polycarb, but on McMasterCarrs website says for their "Clear Impact-Resistant Polycarbonate" that it has excellant chemical resistance to Bleach, Diesel Fuel, Gasoline, Hydrogen Peroxide, Isopropyl Alcohol, Phosphoric Acid, Water. Unless they only mean that stuff wont destroy it, but could still alter the quality.
Hi Sir, Are you sure about your claim that Polycarbonate in incompatible with gasoline? You know I consulted Cole Parmer database and for all types of gasoline listed there the compatibility is stated as Excellent with Polycarbonate. What source did you use?
Isn't that interesting! I believe you - however, I have personally ruined several door windows on my aircraft from spilling/splashing auto fuel on them. And there are plenty of other pilot/builders with the same reaction. A quick Google search of "gasoline and polycarbonate" will reveal the confusion also. The greatest and quickest damage occurs when gas gets into the rivets used to hold the poly material to its support frame. This means the gas is getting to the edge of the poly sheet. Hard to understand that the edge is more sensitive than the surface....
@@HomebuiltHELP Alright. Thanks for the reply. My plan is to do a head gasket replacement on my car. I plan to use a sheet of polycarbonate to cover the engine block and other gasket surfaces during the time I'm not working on them so that no oxidation will form on the surfaces. I think I'm going to experiment first with a tiny sheet and some chemicals involved (like motor oil and WD-40) to see what happens.
