Windshield/Windscreen thickness question

[P Morel]

I have a Model IV Speedster. I replace my windscreen last summer with .080 Lexan from Aircraft Spruce. Making sure the cutouts were sanded and no sharp corners, I installed it with no issues. Except I noticed some stress lines at the door post and carry through tube area. I know this is relatively common for a single lexan sheet installation.

The question I have is....has anyone in the group installed .060 Lexan and if so, has anyone had any issues with the thinner sheet. My thoughts are with the thinner sheet, there is less stress at the compound curve points and the curves of the windscreen should have little effect on wind at around 90mph.

I've researched a replacement windshield from LP Aero and although the cost is around $500, I found a few installation discrepancies on this forum about breakage during installation.

Your thoughts?

[DesertFox4]

Paul, I’d think .060 for the Speedster might be a little light. Too much deflection at speed. I used .093 on my model 4 and still had some deflection at speeds from 125 to 140 mph. Always get some crazing at the mentioned locations after some time in service. I did go through two windshields in 13 years.

[GuppyWN]

I’ve seen a windshield with the thin stuff. The windshield caves in at cruise. No bueno.

[Dusty]

I use 1.5 mm lexan which is good to 120 kts,after that it begins to move. Thicker lexan is more solid but stress cracked after around 3 years.

[P Morel]

You guys are right.....that's why I ask the pro's. Heading to Aircraft Spruce to get the thicker. Thanks!

[Slyfox]

why do they always break on the left side. I had enough of that, so I installed the preformed just a few weeks ago. love it

[HighWing]

The standard IV came with the thinner Lexan .060 and the Speedster came with the thicker - .093. With my current project I installed the thicker as that was what was in the unfinished kit that I finished. I have some serious crazing with one area that a fingernail scrub tells me has cracked through. I will be using the thinner in the upcoming switch out. In the first IV I had with the thinner material, i changed it out twice for crazing and typical scratches, but it never cracked through. I did see the caving mentioned, but only when diving into the deep canyons in eastern Idaho.

Checking the specs, the recommended minimum bend radius using the material we typically consider is 100 times the thickness so the 1/16" - .060" the minimum bend radius is 6 inches. 9.3" for the 3/32" - .093" and 11.8" for the 1/8". In every instance we are far exceeding its recommended physical limits.

Another note, Lexan or polycarbonate is heavily saturated with water so the typical heat gun use on the corner bends should be used with caution or the water can form tiny steam bubbles that can obscure clarity. It is always heat soaked at temps slightly below boiling for removing moisture before heat forming.