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Rear window

F

Flyer68

Well Known Member
Did I read on here that the after market rear window is no longer available?
As I recall it was formed and tinted, and some builders used it instead of Van's?
 
Yes, the maker discontinued making them, I think getting them delivered was a big problem, since they were formed with the curvature instead of the flat original. There was also a lot of discussion that the original window was structural, and the tinted one made of different material might be a bad thing. I have both, have not decided which to install yet. The original does not like fuel spilled on it, the replacement does not mind fuel.
 
Bad thing

Don,

What was the "bad thing" about the material of the curved tinted rear window? I have one and I recall some back and forth about plexiglass and lexan but I don't recall what people were worried about. :confused:
 
The concern seemed to center on strength of the replacement window material vs the original. There were those that thought we might be weakening the fuselage structure by this "untested" window, as I recall even Vans cautioned about it. I am no engineer, but if the rear window holds the plane together we are all in a heap of trouble, and if I recall correctly, my tinted replacement is thicker than the original. There are always those that want to see extensive testing before trying something.
 
rear window

Has there been much cracking around the screws that go into the roll bar. It seems to me that it doesn't take much to crack the window there.
Has anyone else had this problem?
 
Thanks Don, I do recall the structural questioning.

I haven't read about any cracking but there may be some out there.
 
Makes me wonder how long it will be until vandals realize all they need is a gasoline container to vandalize a window they cannot break.
I also wonder when gasoline crazes it, does it effect its strength appreciably?
 
Something may have changed. I very carefully made a rubber mat shield for when fueling, to avoid spillage touching the window. Then the VERY FIRST TIME I fueled the plane - from the flo-fast system using one hand with the crank - the hose popped out and made a big spill behind the mat and on the window!! darn!! But I quickly wiped it off with a rag as thoroughly as I could and there was no effect at all on the window. Now I jam in a no-lint rag with the plastic tube in the fueling port.
 
Bill_H said:
Something may have changed. I very carefully made a rubber mat shield for when fueling, to avoid spillage touching the window. Then the VERY FIRST TIME I fueled the plane - from the flo-fast system using one hand with the crank - the hose popped out and made a big spill behind the mat and on the window!! darn!! But I quickly wiped it off with a rag as thoroughly as I could and there was no effect at all on the window. Now I jam in a no-lint rag with the plastic tube in the fueling port.
Click to expand...

I frequently use Plexus to clean the plexi. I've had two instances of blowback with 100LL on the glass with no ill effects. Don't know if it is because of the Plexus film, a different material being used, or dumb luck.

I make sure I park nose into the wind, and fill VERY slowly. I keep my eyes and ears close to the filler and stop the pump when I hear the fuel start coming up the tube.
 
Hey folks,

I have a small crack around one of the screws holding it to the fuselage skin. It has been there for two years and hasn't increased in size the least bit.

As most of you know, I burn nothing but 100LL in New Blue. And even after three years of fueling this airplane, I sometimes get a geyser despite my best efforts. This always results in some fuel getting on the rear window. So far, I have seen no ill effects.
 
Cracks around screws

I have lots of cracks around the screws, all on the side where the fuel filler is - which I suppose could be a conincidence. All of the screws are loose enough that they can be turned with my fingers. I have had several spills around the filler. I use a hand pump fitted to a jerrrycan. As soon as the can is nearly empty air rushes in and "boils up" inside the big filter I use. On windy days (sometimes helicopter wind) my rubber mat blows away which, of course, is just what you don't want with fuel blowing around.

Cheers...Keith
 
If one has the Moeller gauge, could you not watch it to see when you were getting up to the splash back point?
 
suggestion to fuel-proof the lexan window....

hey guys, I'm not a -12'er, but am pretty familiar with the materials.
If you want to keep the lexan window for whatever reason, you can apply ( or have a sign shop do it) laminate to the outside of the lexan.
The polyester series of laminates are quite solvent resistant, and will have minimal effect on the clarity, although some waviness is apparent.
The edge of the lexan is still a weak point, and repeated fuel exposure will contribute to crazing. I suggest trying to seal it with an acrylic sealer.

I can suggest a couple; 3M 7248 - 2mil, 8912 - 3mil, and 8991 - 4mil, all should conform easily to the single curve of the -12 rear glass.
the stuff ranges from about $1 to $2 per square foot.
 
The "geysering" effect has very little to do with the level of fuel in the tank. What happens is that if fuel is being pumped in too quickly, sometimes it will fill the neck. There is no way for the air to escape the tank except thru the filler neck. It will push it back out, hence the geyser.

You gotta be careful when fueling with unfamilar nozzels.
 
flyboy1963 said:
hey guys, I'm not a -12'er, but am pretty familiar with the materials.
If you want to keep the lexan window for whatever reason, you can apply ( or have a sign shop do it) laminate to the outside of the lexan.
The polyester series of laminates are quite solvent resistant, and will have minimal effect on the clarity, although some waviness is apparent.
The edge of the lexan is still a weak point, and repeated fuel exposure will contribute to crazing. I suggest trying to seal it with an acrylic sealer.

I can suggest a couple; 3M 7248 - 2mil, 8912 - 3mil, and 8991 - 4mil, all should conform easily to the single curve of the -12 rear glass.
the stuff ranges from about $1 to $2 per square foot.
Click to expand...

The Lexan used to make the RV-12 rear window already has a laminated coating on it. It is the same material that is used extensively by Nascar.

As you mentioned, even with the coating, the unprotected edges (and screw holes) are still vulnerable.
 
I am planning to fly to Oshkosh for the show, and am not looking forward to the first fillup with 100ll. I do use a rubbery mat (home depot) when fueling to cover the Lexan and fuse just aft of filler neck. I cut a hole in the mat for the filler ring. The mat is large enough that it covers about 30% of the rs rear Lexan. Hopefully that will provide the necessary protection.
Dick Seiders
 
dick seiders said:
I am planning to fly to Oshkosh for the show, and am not looking forward to the first fillup with 100ll. I do use a rubbery mat (home depot) when fueling to cover the Lexan and fuse just aft of filler neck. I cut a hole in the mat for the filler ring. The mat is large enough that it covers about 30% of the rs rear Lexan. Hopefully that will provide the necessary protection.
Dick Seiders
Click to expand...

Dick,
100LL isn't the big concern, it is auto fuel with ethanol.
 
dick seiders said:
I am planning to fly to Oshkosh for the show, and am not looking forward to the first fillup with 100ll. I do use a rubbery mat (home depot) when fueling to cover the Lexan and fuse just aft of filler neck. I cut a hole in the mat for the filler ring. The mat is large enough that it covers about 30% of the rs rear Lexan. Hopefully that will provide the necessary protection.
Dick Seiders
Click to expand...

Dick,

Just a note regarding 100LL fill-ups at OSH or any FBO. NEVER let the lineman add fuel to your tank! Insist on doing it yourself, run the hose very slowly (I know, patience doesn't come easy to a pilot), and put your ear close to the filler port so you can tell when to stop by the sound. Keep a rag handy to wipe up any spill quickly. Follow these simple procedures and stop worrying!

John
 
craze-y back window ...

I've about 75 hours on my Hobbs and noticed my back window's craze patterns from about 20 hours. The craze pattern hasn't gotten worse with the additional hours on the Hobbs. The craze "shoulder" areas of the back window run from the top by the rollbar to the bottom where the craze pattern reaches the backmost section of the window where it attaches to the fuselage.

I've tried to fill the tank very slowly ... but still I may get that overflow action. I use all 3 kinds of fuel for my RV-12... 100LL from the truck, MoGas from the gas tank at Lockwood Aviation and auto fuel with 93 octane and 10% ethenol ... I've gotten quite proficient holding and filling my -12 with a five gallon red plastic gasoline "can" and a funnel.

Here are the pictures of my back window ... as with a tiny ding here or there on my -12, I try not to sweat the small stuff (I'm not always successful).:rolleyes:


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Geez Jerry, that is a starnge little pattern. That's too bad. Can you tie it back to any particular incident so you can tell which type of gas might have caused it?
 
lexan and it's wonderful properties eh?

...sorry guys, I have to report that cold formed lexan can 'craze' without much apparent cause. The windshield of our Jodel did it several times, even though we covered it, and it wasn't flown frequently. It was not a radical tight bend; actually looks a lot like the rear -12 application.
It eventually broke along one of the crazelines when I was polishing it enthusiastically.
The lexan 'dries out' and loses some of its properties. Most manufactured lexan sheet is actually intended for hi-impact glazing, ( flat, properly suspended), not cold forming a bend into it!...or drilling a lot of holes near the edges.
if properly dried and heated before forming, it will react quite differently...although that process induces a whole other suite of possible effects...cooling & tempering stresses etc.
 
DonFromTX said:
So, with all the crazing and cracking, maybe it is not such a great structural necessity after all?
Click to expand...

I have seen incidents of crazing... I have not seen incidents of cracking.

The integrity of a crazed window vs one that is cracked would be very different in my opinion.


Side comment -
I never said that using an alternate window would for sure be bad.
What I did say was that when completing all of the test scenarios as specified in the ASTM's for testing the structure, that the rear window proved to be a structural component in transferring the tail loads into the fwd fuselage.

Other window alternatives might work just as well, but the main point is, the window supplied in the RV-12 kit has been through an extensive testing process to prove it is suitable... no other alternative windows have (so the suitability is only a guess).
 
I like to worry as it keeps me from doing dumber things than I usually do.

So Scott am I to understand that if 100ll splashes on my rear window it's not a problem? If so I didn't know that. I thought Lexan was affected by all fuels. I have always used the mat I described as spilling fuel (mogas 91) tends to soften fuse paint around the neck.

Regarding letting the ramp guys fuel my plane that NEVER happens. Fifteen yrs ago when I landed for fuel at Lynchberg, VA in my 172 I happened to look out the window as I was filing IFR for next leg. I almost broke the door getting it open to yell to the ramp guy to stop moving my airplane by pulling it by the very tip of the prop. I do all the necessary work thank you.
Dick Seiders
 
rvbuilder2002 said:
Side comment -
What I did say was that when completing all of the test scenarios as specified in the ASTM's for testing the structure, that the rear window proved to be a structural component in transferring the tail loads into the fwd fuselage.
Click to expand...

That's an interesting comment. The fact that the window was found to transfer loads during testing and was therefore `structural' is not surprising, but from previous discussions I got the impression that the window was designed from the start to be a structural component. It seems that may not be the case. Neverthless changing to a different material or design would place you in the `untested' zone.
 
rgmwa said:
That's an interesting comment. The fact that the window was found to transfer loads during testing and was therefore `structural' is not surprising, but from previous discussions I got the impression that the window was designed from the start to be a structural component. It seems that may not be the case. Neverthless changing to a different material or design would place you in the `untested' zone.
Click to expand...

I think maybe my words are getting twisted around somewhat.

It was expected that the window would transfer load. The testing to verify compliance with the ASTM proved that it does.
The rear window material wasn't primarily chosen for it strength. It was chosen because it can be CNC punched to make it quick/simple to install.
 
dick seiders said:
I like to worry as it keeps me from doing dumber things than I usually do.

So Scott am I to understand that if 100ll splashes on my rear window it's not a problem? If so I didn't know that. I thought Lexan was affected by all fuels. I have always used the mat I described as spilling fuel (mogas 91) tends to soften fuse paint around the neck.

Regarding letting the ramp guys fuel my plane that NEVER happens. Fifteen yrs ago when I landed for fuel at Lynchberg, VA in my 172 I happened to look out the window as I was filing IFR for next leg. I almost broke the door getting it open to yell to the ramp guy to stop moving my airplane by pulling it by the very tip of the prop. I do all the necessary work thank you.
Dick Seiders
Click to expand...

Dick,
I didn't mean to imply that you could be carefree with other fuels other than Ethanol laced auto fuel.

You were sounding like you had a heightened level of concern because you would be using 100LL instead of auto fuel. <"I am planning to fly to Oshkosh for the show, and am not looking forward to the first fillup with 100ll.">
I was just saying that you are already using a fuel that can be more problematic than the 100LL you will have to use while traveling, so it shouldn't cause you any additional concern.
 
rvbuilder2002 said:
I think maybe my words are getting twisted around somewhat.

It was expected that the window would transfer load. The testing to verify compliance with the ASTM proved that it does.
The rear window material wasn't primarily chosen for it strength. It was chosen because it can be CNC punched to make it quick/simple to install.
Click to expand...

Can't be clearer than that. :)
 
Rear Window

I recently put two gallons of car gas in my 12, according to PAP checklist, to check for fuel leaks, when disaster struck!

As I poured in the gas, a few drops struck the lexan and immediately numerous fine cracks (crazing) appeared. Since I had not seen the thread on lexan and gasoline here, I was surprised, to say the least.

Van's says a "Caution Note" is in section 5 of the manual (concerning lexan & gasoline), but why isn't it in section 25 where the instructions for installing the aft window are located? Or, better yet, why not in the PAP fueling checklist ? This isn't the sense of responsibility I've come to expect over the three Van's projects I've completed in the last 14 years.

So, now I'm faced with living with a very ugly rear window or replacing it with (you guessed it) another lexan unit. By the way, does anyone have an extra aft window, either lexan or plexiglass, laying around? Don, are you willing to part with one of yours?

Walt Shipley
RV-12 (DAR coming Friday)
RV-8 (sold, now resides in Australia)
RV-8A (sold)
 
Sure, I will part with one of mine - as soon as I figure out which one I want to install:D
Walt Shipley said:
I recently put two gallons of car gas in my 12, according to PAP checklist, to check for fuel leaks, when disaster struck!

As I poured in the gas, a few drops struck the lexan and immediately numerous fine cracks (crazing) appeared. Since I had not seen the thread on lexan and gasoline here, I was surprised, to say the least.

Van's says a "Caution Note" is in section 5 of the manual (concerning lexan & gasoline), but why isn't it in section 25 where the instructions for installing the aft window are located? Or, better yet, why not in the PAP fueling checklist ? This isn't the sense of responsibility I've come to expect over the three Van's projects I've completed in the last 14 years.

So, now I'm faced with living with a very ugly rear window or replacing it with (you guessed it) another lexan unit. By the way, does anyone have an extra aft window, either lexan or plexiglass, laying around? Don, are you willing to part with one of yours?

Walt Shipley
RV-12 (DAR coming Friday)
RV-8 (sold, now resides in Australia)
RV-8A (sold)
Click to expand...
 
Alternate rear window source is available

I talked with Carl Eldridge recently who now makes a 12 rear window out of Vivak, a clear plastic which, supposedly, is unbreakable, won't crack, and is not effected by fuel or solvents. He no longer makes a plexiglass window. His new window is predrilled on the fuselage side but you must match drill holes on the roll bar side. Cost is $200 + $15-20 freight. His email is [email protected]
 
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