Windshield

[Allen Sutphin 705]

Was going to order my windshield today but AS&S said it was truck shipped. I don't want to pay that price for shipping so am going to try to get it locally. I just assumed everybody uses a lexan type material. I believe my old one is .093 plexiglass which is why the stress cracks near the wing roots. Polycarbonate is what they use or is it plexiglass? 

[1avidflyer 1983]

I would use polycarbonate in .060" thickness.  I get it from a place in Duluth called Seeley plastics, and it cost $50 for a 4' x 8' sheet.  It will roll up into a 1' or so circle.  Check on line, or maybe a local glass company can get it included on an order they already have going, and you can beat the shipping that way perhaps.  JImChuk

[Allen Sutphin 705]

My challenger used .060 lexan and I thought it was a little on the flimsy side. And the Fox windshield is a little wider. I think polycarbonate is the only thing to use. Plexiglass cracks way to easy. Will check locally for it. Thanks.

[1avidflyer 1983]

I'm using .060" thick on my Avid MK IV with the Jabiru engine, and it will do all of 100 MPH.  At that speed it starts to buckle back against the tubes a bit.  Doubt your plane will ever get that fast on  55 HP, unless you put it into a good dive.  JImChuk

[Allen Sutphin 705]

Probably never get that fast. Though my challenger would do it on 50 hp. I might reconsider my options and drop down in thickness a bit depending on what is available locally. I am still expecting the 55 hp to surprise me. I learned years ago that horsepower #'s are just numbers to sell engines, torque does all the work. At 5000 rpm the 55 hp puts out more torque than the 582. On take off, the 582 would win hands down, but cruise could be totally a totally different ballgame. But then I've been wrong before.

[1avidflyer 1983]

My friend that had the A model Avid had the same engine as you.  It really didn't compare to any 582 or 532  I had.  And his plane was lighter.  This motor started off on his gyrocopter when he replaced the 503 he had on there with the Hirth.  He didn't see much if any improvement in performance with the new Hirth on the gyro.  Later he went to fixed wing, and put the Hirth on the A model Avid.  It did get him up off the ground and that was a good thing.  JImChuk

[Allen Sutphin 705]

Whatever it is, will be what it is, good or bad. If its a dog then changes will be made. Time will tell.  A lot of variables also fall into the formula. I won't fudge numbers, if it doesn't work to my liking then I'll say so.

[1avidflyer 1983]

Keep it light, and it will give you lots of fun.  If you wanted a speed demon, probably a Kitfox is not the best plane to have.  Mostly at least for me, I fly around fairly close to home, so what's the rush I figure.  JImChuk

[Allen Sutphin 705]

Speed isn't my thing anymore. Last few years I am a local flyer,too.  A 60 or 70 mph machine suits me just fine.

[NorthIdahoAvidflyer 374]

Was going to order my windshield today but AS&S said it was truck shipped. I don't want to pay that price for shipping so am going to try to get it locally. I just assumed everybody uses a lexan type material. I believe my old one is .093 plexiglass which is why the stress cracks near the wing roots. Polycarbonate is what they use or is it plexiglass? 

Yes, I've seen both used in the front but poly is the one most people go with. Plexi will shatter if hit. You will still get the stress cracks in the corners no matter what you use because of the tight radius in those corners. I used a heat gun to heat the bend area slightly which helped. 

There are a few different manufactures of the Poly. Ask the supplier which brand is the most scratch resistant, The last stuff I installed scratches very easy and I wont use it again. 

[Buckchop 479]

Just my opinion but id NEVER use .060 in either of mine KF model 1 again. To flimsy, so i changed both mine and my splayed wider doors in .080, bends just fine, dont need heat unless u want to.  Little thicker and u never know it durring install.  A full 4x8 sheet here is $150 and plenty to do all the windows in a model 1. 

And im no speed demon either, local flying and i love the 55-65 cruising around enjoying the day. 

Edited 6 Jun 2019 by Buckchop

[nlappos 413]

There are scratch resistant polycarbonates from all the manufacturers. I asked one guy for a quote, it was about 3 times the cost of the regular softer poly, but when I redo my windows, I will go that way. 

I suggest you ask the plastics company what they have in the hard, scratch resistant poly and they can quote it.

[Cloud Dancer 69]

Was going to order my windshield today but AS&S said it was truck shipped. I don't want to pay that price for shipping so am going to try to get it locally. I just assumed everybody uses a lexan type material. I believe my old one is .093 plexiglass which is why the stress cracks near the wing roots. Polycarbonate is what they use or is it plexiglass? 

Yes, I've seen both used in the front but poly is the one most people go with. Plexi will shatter if hit. You will still get the stress cracks in the corners no matter what you use because of the tight radius in those corners. I used a heat gun to heat the bend area slightly which helped. 

There are a few different manufactures of the Poly. Ask the supplier which brand is the most scratch resistant, The last stuff I installed scratches very easy and I wont use it again. 

I've worked as a machinist for decades and two of those years I made eye glasses for Vision 4 Less. We sold mainly two types of lens material and all the "experts" including the store manager and lab manager referred to them as "plastic" and "polycarbonate". I was the "old" guy that had a hard time teaching these kids in their 30's and 40's that I might know something about their field that they didn't know. They don't understand that "polycarbonate" IS a plastic! While their "plastic" lens were a lower grade material than the "polycarbonate" lens they are in fact both plastics. We have a similar situation going on in this conversation concerning "Lexan" and "polycarbonate" for windshields. For the record; they are both "polycarbonate" plastic. "Lexan" is a trade name for "polycarbonate" made by a specific vendor.

The biggest difference in "polycarbonate" material from any vendor is if it was made by "casting" or "extruding" the stuff. To machine the stuff or bend the stuff or scratch the stuff all varies from vendor to vendor but cast verses extruded needs to be looked at depending on your application. I can machine it on a lathe or mill all day long if it's cast. If it's extruded it melts at a lower temperature and likes to stick to the tooling making it hard to get a good finish. I wish I could say "this is best" but the truth is "best" is a whole can of worms I don't want to open. For eyeglasses we used "cast" material. Most of your "shooter" glasses and safety glasses are "polycarbonate" material for impact resistance.

Heat works for tight bends but depending on if it's cast or extruded, the amount of heat will vary. If you want a uniform thickness then you will chose one over the other. You want the cheapest one, you will choose one over the other. There's no one size fits all. Just like airplanes, one kind cannot do it all.

Link here to a plastic vendor: https://www.acplasticsinc.com/informationcenter/r/what-is-lexan I'm not recommending them, it's the first link I found with info on Lexan for you. This site does not go into the difference between cast and extruded but you can find that online in many places too.

[Allen Sutphin 705]

Keep it light, and it will give you lots of fun.  If you wanted a speed demon, probably a Kitfox is not the best plane to have.  Mostly at least for me, I fly around fairly close to home, so what's the rush I figure.  JImChuk

A Kitfox or Avid was my plane of choice. Just so happens that while I was looking, one became for sale within 40 miles from me. Might have gave a little more for it but I didn't have to run all over the country looking at "great plane" which ends up being a near basket case. I liked my model 4 so I knew an Avid/Fox was what I wanted and evidently at the right time cause not many of the older ones available now days.The only fault of mine was it was an anvil. But good tubing, good wood and everything solid so it was worth the time to rebuild it right. At least to me.

[Yamma-Fox 403]

Alright well I'm gonna give this a shot.  

Now everyone can tell me how it wont work, but I'm gonna waste some time and $80 on it and see if I can go from 'scratched pretty damn bad' to 'that actually looks pretty decent'.

I'll be happy if I can get to pretty decent because that is how a new one looks after a year or two anyhow.

 

 

[Allen Sutphin 705]

I've used similar type stuff on GA windshields and it does work on plexiglass. Never used it on polycarbonate. I have removed a few scratches from polycarbonate with a heat gun, don't try this at home, boys and girls, cause one has to be extremely careful.

[Cloud Dancer 69]

I've used similar type stuff on GA windshields and it does work on plexiglass. Never used it on polycarbonate. I have removed a few scratches from polycarbonate with a heat gun, don't try this at home, boys and girls, cause one has to be extremely careful.

The experts; the lab manager and store manager at the eye glass store I made glasses at swore there was no way to remove scratches from customers glasses. They were partly correct. My father was a watchmaker when I was a child in the 60's. People would bring in their watches to get new crystals put in because they were so scratched you could no longer read the dials to tell time. I heard him say 100's of times "You don't need a new crystal, I'll buff that out for you." And he did! He used jewelers rouge and a light touch. The glass lens he could apply more pressure but you can easily melt a polycarbonate lens and end up with distortion. While the eye glass place didn't buff customers prescription glasses, I often buffed out my cheap readers while working there to get a few more miles out of them. I melted a few pair too! Even a little buffing will change the prescription but with readers it's not a big deal. If I had to see out of them full time I'd have to agree that they should not be buffed to remove scratches.

As far as the scratch remover kit were talking about, yes it will work. It will fix cd's and dvd's if the scratches are not too deep also. I've used plastic polishes for motorcycle helmet shields too to get a few more years of life out of them. If your new to the process I'd suggest doing the front and center sections last to give you time to practice on the less important sections. The drill attachment will work fast. It can destroy a window fast too. Heat is your enemy when power polishing plastics. Keep the tool moving to prevent heat buildup and clean the window a couple of times before you start. Any grit not washed off your window before you start will work against you and put more scratches in than your removing. I've often taken my regular jewelers rouge and a buff on a drill out to fix a headlight on a car that's dulled more white than clear. It fixes them right up. If you get carried away and distort a section, stop. You cannot fix it and any attempt to do so will only dig your grave deeper. That's about when I decide I need a new pair of glasses or a new shield on a helmet, a mistake makes up my mind for me. The cast material is far easier to buff than the extruded but you can bring either material back some. Don't try to get it perfect or you will run the risk of going too far. You will be surprised how much yellow you can buff out too.

[Willja67 144]

I'm looking for windshield material and reading what I can find before making my choice. I was going through the build manual and specifically the service bulletins and found something really interesting. Can't remember which one but I think #43?  

It was about the windshield on the model 4 speedster. It stated that originally .118 poly was used for the windshield but it cracked too easily so they recommended going to .090 poly. Certainly the speedster has a higher Vne than 100mph? After all I've  read about windshields starting to buckle around 100 mph I have to wonder if the angle the windscreen leans back at and perhaps the way it is supported at the bottom contribute significantly to its ability to not buckle? I'm going to be building a whole new cowling and changing the shape of the windscreen a little(nothing drastic) and wondered what the thinking was on this?

[akflyer 1427]

I have use the 090.  it might push in a little but not bad and it forms much better around the tight corners at the top.  Use a little heat to form the corners and your good.