Aero LP Windshield and bubble doors

[DanB]

Well, last weekend was my first attempt at installing the acrylic windshield on the Model IV...it didn't go well to say the least.:cool: I didn't even get a hole drilled and it cracked at the top of the pilots side (inside the hole) about 3/4" in. It was stop-drilled at that point and I decided I didn't want to mess with it any more. I went and got some polycarb and that went on very well.
I decided to try my hand at the bubble doors...nope. This stuff is a real PITA. My opinion is a person shouldn't have to tip-toe around a plane trying to get it built.

[n85ae]

Try a step drill, it will drill easily without the the cracking.

Jeff

[n85ae]

Odd coincidence I actually have an undrilled co-pilot side bubble door in
my hangar for a Model 5

Jeff

[jdmcbean]

When drilling acrylic you MUST use an acrylic drill bit. Using a standard drill bit will almost always chip and crack acrylic.

Step drills can work well but be careful.

[RobS]

Boat builders experience similar problems. A nice description of the issue and methods to minimize the risks when drilling acrylics can be found here.

http://bertram31.com/proj/tips/drill_acrylic.htm

[n85ae]

I own both step drills, and the bits sold by LP Aero, and have reground some
of my own. You mileage may vary, but for me I've had no cracking with step
drills, but have cracked acrylic with the LP Bits, and my own reground bits.

Regards,
Jeff

[jrthomas]

I would advise anyone thinking about using an LP acrylic windshield to think long and hard before spendingthe money. I should have just thrown my $500+ is the garbage. That's where my windshield ended up. Mine cracked around the front spar on the pilots side when I set it in place. I was only positioning it in place. I repaired it and figured the cuff would cover the crack so I went ahead, planning to use it anyway. I used extreme caution from then on, drilled all my holes with no problem. I got my buddy, who is an experienced builder, to help me set it off to do some final trimming.Under its own weight it cracked again in our hands,this time on the passenger side at the front wing spar. I had no problem drilling the holes but my belief is that there was a manufacturing problem that caused my windshield to be overly brittle at the point where they cracked. I called LP but was never able to get a live person. I left a message explaining my problem and asked that they return my call but I never got a call back. On the positive side, I used the LP bubble doors and I never had any problem. I used the bits they included, drilled very slowly and had no problems. I did my trimming with a Dremel and used a belt sander for the fine fitting and everything turned out real nice. I believe my windshield was defective maybe due to the curing process where it was shaped and moulded around the front spars. I did some "torture testing" with some scrap pieces of the same windshield and it would handle some pretty bad abuse, everywhere except at that same spot at the spars. I'm not trying to trash LP. I love the doors. This is just what happened to me and if it helps some of y'all avoid the same bad experience as me, that's a good thing. James Thomas

[DesertFox4]

jrthomas- I was helping Dan when the LP windshield broke. Same deal as yours. I was positioning it into place against its own weight and it popped at the front pilots side carry through, like yours. I mentioned to Dan to expect the chance that even in our 100 degree temps. the acrylic may break. I've heard some stories of the same outcome. BTW, no holes had yet been drilled.
Dan picked up a 4x8 sheet of .093 "Lexan" from one of our local TeamKitfox members , thanks DesertFox1.:) We used my old windshield as a template and I think we had a new windshield ready to install in less than two hours of cutting and sanding. Saved weight also. Just didn't save any money or time. You win some, and .....some you don't.

[DanB]

James,
As you described in detail how your windshield broke...so it went with mine. It broke as we were positioning the thing. And it broke on the pilots side towards the front. I also think the cuff will cover it, but I didn't want to mess anymore with it. I also had two quite experienced Kitfoxers helping with it, but it broke just the same. I wouldn't say it was defective, I believe it is just the nature of the beast. I know I will be quite happy with my polycarb windshield and doors as I won't need to baby them.

Ha...noticed Steve posted just b-4 I did. Sometimes things just don't go the way you plan them, but like Steve said, we were ready for anything to happen. There have been too many battle scars emerge from the ranks to think we were entering anything less than a war zone. It was certainly no ones fault...the stuff just went. My hat is off to both Steve and Murle Williams for the countless hours they have invested in helping me finish up my project. Thanks guys!

[jrthomas]

It seems to me that there's a problem around the carry through tube since we both had cracks there. I went back to the Lexan like you did and I'm very pleased with the way my windshield turned out. Lexan is some amazing stuff. When I did my torture test on some scraps of acrlyic from the windshield, I pushed the limits just to see how much it would take to really mess up. It would bend a good amount before breaking, a lot more bending than would ever take place in a normal windshield installation. I believe the carry thru tube area is a weak spot. Since I also have LP acrlyic bubble doors I did some practice drilling holes in the scrap stuff. I believe the key is to use the bits supplied by LP and use light pressure, especially if you're drilling near the edges. If I leaned on the drill too much drilling near the edge, it would crack. The doors turned out great. I'd highly recommend them but go slow. I tied up way too many hours installing mine just being overly cautious. James Thomas

[HighWing]

I have had one experience with the LP windshield while helping on the Series V that was here for a while. I bought my drills from Tap Plastics and had no trouble there, but the fit was terrible around the spar bends. I had read of the horror stories and we were in a serious sweat while installing it. One thing the instructions caution about is letting the windshield sit on it's own weight. What we did there was lay the windshield on a large plastic garbage can to reducesome of the stretching forces between windshield and skylight portions of the acrylic. I also contacted LP but by email and after surmising a black hole swalled my email was surprized that after a couple of weeks they wrote back. The result was advice that the windshield was likely of an old design as they had improved the plug mold. What we had to do to get it installed was make a couple of fairly complex fiberglass fairings to close out the sort of ugly wing root area and to improve the fit at the door posts, a set of tapered shims that were about a quarter inch thick at the top tapering to nothing at the bottom. I can only imagine the cracks if we had forced the fit at the top sides of the windshield portion. Incidentally, the tech from LP said you could use heat to help, but with the warning that the acrylic has a memory and too much heat would cause it to want to return to a flat sheet.

I also like the Lexan.
Lowell
.

[jtpitkin06]

My experience has been quite different.
My LP Aeroplastics one-piece windshield/skylight fit perfectly right out of the box. (Delivered October 2010.) I lifted it into position this summer by myself using care to not let it flex in the forward spar area. It settled into position without cracking and required only minor trimming. It has been easy to drill with the proper bits.


Sorry to hear some builders have a hard time.


John Pitkin
Greenville, TX

[catz631]

Here is something to consider if you don't mind a two piece windshield. We had the same problem with a Rans S-6. Two windshields were cracked so the owner decided to skip the one piece problem. A strip of aluminum was drilled and nut plates riveted in so that the turtle deck and front windshield are two separate pieces. The aluminum strip runs at the top of the windshield and well out of eyesight.Each piece is fastened in with screws. This has worked out very well. The aluminum strip is about 1 1/2 to 2 inches wide and fits in nicely with the aircraft.
Another S-6 owner would like us to build one for him in the same manner as he has gone thru 3 windshields due to fuel spilling on the stressed corners of the Lexan and cracking/fretting at the leading edge of the wing.
Now the windshield on the Rans is a little different and it is Lexan but I believe the same principles would apply and it is not unattractive and certainly cheaper.You don't have to replace the entire thing if one piece cracks.
Dick
Excuse me ,I meant the windshield/skylight as two pieces NOT the turtle deck. It's too early and I have not had enough coffee.
Dick

[Dick B in KY]

My experience was exactly the same as John Pitkin's, no problem with install or drilling (done by myself), fit was excellent (only minor trimming). Windshield delivered in Aug 09.

Dick B

[jrthomas]

Like I said, I ended up with the the Lexan windshield and I couldn't be happier with the way it turned out. It's all one piece with the skylight. Another great addition was the Lexan turtledeck I bought from Kitfox. It's about 1/8" thick and dark tinted and a big improvement over the old style turtledeck. I used neoprene u-channel all around that gives a nice finished look and will make the cabin less drafty. With the full bubble doors I may have to wear a sombrero but the visibility is fantastic. It would probably be easy enough to buy a sheet of Lexan and do your own and save a few bucks but I'm happy. This was my 1st so I took the easy way. James Thomas

[avidflyer]

I guess I may as well post my horror story also. The guy I bought my unfinished Kitfox 4 kit from had bought one of these windshields also, it sat in the big cardboard box for about 15 years however. When I went to install it, I had it sitting in place and to reposition it just a bit, I lifted it about an inch on the front bottom left corner. I heard this little "plink" sound. There it was, a crack on the left side where the windshield goes up against the front wing carrythrough. Fortunatly there was the .090 Lexan that came from the factory with the kit, and that is what I made my windshield out of. Maybe my windshield cracked because it was old, but I would never pay for one of these myself. It is not that hard to make a windshield with Lexan. I've done about 6 of them over the years with my Avids and now the Kitfox and none of them broke from handling them. Take care, Jim Chuk

[JohnB]

Ok, now that I've had some time to cool down I will post my sad windshield story.

After reading the posts on this forum and the info from LP Aero, I enlisted the help of my wife and briefed her on how we had to handle the windshield without flexing the wing root areas. All was going well and we trimmed the sides at the door frame angles and around the wing roots. Then we carefully lifted the windshield back onto the fuselage to check our work. The fit was looking good, just need to move it a wee bit to align... and heard a loud POP!

And that's when the swearing started.

I ended up talking to George at LP Aero and he agreed to send me a new one at a good discount. He admitted that they occasionally crack one handling it at the factory.

We got the new one and finished fitting it today with no problems. So what did we do differently? Not too much other than being very anal about sanding and smoothing all edges immediately after making every cut and double checking that we have left no tooling marks or nicks that could be a stress riser. I would also advise to be careful and not make any square corners especially in the wing root area. Make nice smooth curves with no sharp corners.

Then for good measure, take a piece of acrylic and burn it to ashes. Take the ashes and bury them under a full moon at midnight along with a roosters foot.

Now if anyone needs a slightly cracked windshield to use as an offering to the acrylic gods, let me know.

[War Eagle]

I think I can feel your pain.

I sweated bullets handling my windshield. I know I was tough on myself about the fit but every time I lifted the windshield off to do some more work on it, I swear I aged a year worrying about cracking it.

I made it thru the fitting process without a crack but this was one of the most stressful parts about building the plane. http://www.teamkitfox.com/Forums/images/icons/icon10.gif

[kitfoxSwede]

One of the most nervous parts of my RV-4 build was the canopy, I managed to get through without any big problems by following these rules:
Keep the plexi warm
I used a couple of car heaters, as live in Sweden they were plentiful. Beware that the plexi will shrink when it cools down so the fit may change if you keep it too warm. Don´t ask me how I know...
Use a special drip bit
I made my own, it is easy do to. I don’t remember where I found the information on how to do it but it is available out there on the Internet somewhere. The main difference is to make sure that the drill bit does not cut but instead it should sort of grind away material. If it cuts like an ordinary drill it will crack the plexi, most of the time anyway.

Use a manual pop-rivet tool
A pneumatic riveter pulls to hard and fast when setting pop-type rivets. Luckily for me I tried on a scrap piece of plexi first.

A replacement RV-4 canopy costs something like 800$ plus shipping (about the same). Plus the cost for customs and tax. So I really did´t want to mess up. By the way if you buy a Sonex from overseas it is mandatory to buy a spare canopy. Says something about plexi, I guess.

[inzersv]

Ok, I need some info about the hardware for installing the windshield. The build manual says there are flat washers and finishing washers to install. I see part number 91245.000 (plastic washer), part number 91166.000 (Nut, AN364-832) and part number 91118.000 (Screw, AN526-832R10). Nothing else; I presumed the finishing washer was the plastic washer? Also, the instructions manual says nothing about what order to install the hardware. Again, I presume the plastic washer goes on the outside of the windshield, ie. between the windshield and the screw head. Can ya all help me?! :(

[Dave S]

Hey Stan,

I interpreted the instructions to mean use the plastic washer under the screw head.

[jiott]

Agree with Dave.

[inzersv]

Thanks guys. Did you use a washer with the locknut?

[68niou1]

I would like to know if more people have had negative experience with LP Aero acrylic than positive- mine was pretty much the same as most on this thread, spent $800 on doors and install kit(with the acrylic drill bit) had the right side crack on the 3rd hole and the left split on trimming after wasting two days fitting and screwing around. I got so fed up I put the original doors back on and said screw it!!! For that kind of money you can get a pair of doors for a car that actually fit without screwing around...... Ok rant over:D

[efwd]

I succeeded at drilling all my holes for the doors only to split a crack out to the edge on two screws when I tightened them down onto that soft pliable tape that the window is mounted on. Didn't require too much torque to do it either.