Onex windshield

[mccool]

Has anyone replaced their windshield with acrylic? It's much more resistant to gasoline. It would have to be formed of course, but that's not all that difficult to do a flat wrap.

[GordonTurner]

You should check on this, but I think acrylic is more brittle which isn’t good should you have a bird strike.

[13brv3]

Has anyone replaced their windshield with acrylic? It's much more resistant to gasoline. It would have to be formed of course, but that's not all that difficult to do a flat wrap.

When I had my fuel spill incident, both the windscreen and canopy were destroyed. I'm betting you've seen the thread:
viewtopic.php?f=5&t=7711

While the acrylic may (I've never verified it) be more resistant, the fuel will still attack drilled holes and edges. It only took a tiny wisp of fuel seeping along the canopy hinge to ruin the canopy. I wouldn't call that very resistant at all.

I have also heard that Lexan/Polycarbonate is better for it's resistance to breaking. I've come sooooo close to some big birds. It's probably best to focus your effort on avoiding the fuel spill, at least for as long as you can.

[mccool]

You should check on this, but I think acrylic is more brittle which isn’t good should you have a bird strike.

I could be wrong, but I think Sonex is the only company using polycarbonate windshields. All my other builds used acrylic as well. Also how many bird strike have occurred in the last 10 years?
That being said I don't plan to change mine any time soon.

[Bryan Cotton]

I could be wrong, but I think Sonex is the only company using polycarbonate windshields. All my other builds used acrylic as well. Also how many bird strike have occurred in the last 10 years?
That being said I don't plan to change mine any time soon.

I have hit two birds so far in my flying career. Fortunately neither came through the windshield.
I know a Waiex builder who hit a bird. Damaged the leading edge of the wing.
When I was at the Sikorsky flight test facility in Florida one year, we heard a mayday call on the radio. We were working on the ramp and saw the Jet Ranger flying in slowly, as they got close could see the windshield was busted and the front seat pax was holding it to keep the remains from blowing into the cabin. They were greeted by an ambulance and the bloody guy who got out of the back took the turkey buzzard out with him and threw it on the ramp. They were doing powerline patrol.
Some operators in the Gulf used to swap out the Sikorsky S76 windshields for lighter plastic ones. There was an accident where a bird came through, knocked the engine control levers off the roof and in the process cut both engines. They all died.
The fuel sensitivity is a pain especially given how close the fueling point is. My A model Waiex is definitely better than the Onex in that regard. I'm always careful but have had one major fuel incident, which seems to have turned out ok. Flooded it with water right away. My shirt was a loss. Still I'm glad to have lexan up front. I see it as a significant safety advantage even if only Sonex does it.

[Bryan Cotton]

Here is a little video I did a few years ago:

[Skippydiesel]

There is no doubt, that polycarbonate is much tougher than acrylic.

There is no doubt, that polycarbonate is more susceptible to damage from hydrocarbons (fuel being the most likly culprit). Also more susceptible to abrasion (scratching).

The angle of the Sonex windscreen (whatever it is made from) also has a big part to play, in resisting damage/penetration from objects (birds) in flight.

To archive similar penetration resistance, acrylic would have to be thicker = weight.

There is a bloke , here in Australia, that will sell you preformed acrylic windscreens, for Sonex.

There being no clear winner, I guess it's up to the builder to decide which windscreen is best for his aircraft.

So far, I am happy with my polycarbonate, despite its tendency to scratch. I did replace the tinted one with clear. Tinted, along with bugs, adds to the loss of visibility.

[WesRagle]

Hey Ace,

I did some experimentation with lexan and fuel. I posted the results here: https://sonexbuilders.net/viewtopic.php?f=58&t=5813&hilit=lexan#p43915.

Anyway, the experiment showed that poly-carbonate is only destroyed by fuel if it is under stress. So, if you want both toughness and fuel resistance, and you can figure out how to form a flat wrap from lexan, problem solved.

Wes

[Skippydiesel]

Hi Ace,

"Anyway, the experiment showed that poly-carbonate is only destroyed by fuel if it is under stress. So, if you want both toughness and fuel resistance, and you can figure out how to form a flat wrap from lexan, problem solved."

You have come up with some very interesting results for polycarbonate exposed to hydrocarbons (fuel). Take the flat wrap, stress inducing, technique, for fitting a Sonex windscreen, out of the picture by heat forming and all the fuel spill worries will history.

You are probably aware that polycarbonate is available in a scratch resistance finish. Unfortunatly it can't be used for flat wrapping/bend fitting. It would be great if the two negatives, fuel & scratch susceptibility, to polycarbonate could be addressed by your heat forming technique. Do you know if the scratch resistant product, can be heat formed?

The problem, as I see it is how to heat form, a polycarbonate windscreen, for a Sonex/Waiex, without access to an industrial sized oven? Any suggestions?

[WesRagle]

Do you know if the scratch resistant product, can be heat formed?

The problem, as I see it is how to heat form, a polycarbonate windscreen, for a Sonex/Waiex, without access to an industrial sized oven? Any suggestions?

No and no.

I did talk with Todd of Todd's Canopies many years ago about forming a complex canopy using lexan. He said he was never able to achieve good results "blowing" lexan.

I would add that for this to work you would have to be very careful tightening the screws that attach the canopy.

Wes