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  #21  
Old 04-27-2010, 07:47 AM
vernhendershott vernhendershott is offline
 
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Location: Spruce Creek, FL
Posts: 370
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This really is a very simple issue to solve and the current rear window material is not a part of the solution, much like the window in the fuel tank, the rear window is made from a material that is not correctly suited to the job required of it. Lets not wast a lot of money replacing rear windows with the wrong material just to get the same result each time. With great care you may keep fuel off of the rear window most of the time, but you can not keep fuel fumes off of it as the fuel vent is just inches away from it and with out a major change in the fuel system that is where it will be.

The fix is simple lets get one of the windshield companies from Trade-A-Plane who do this for a living to select the correct material for this use and if, as I suspect, it requires heat shaping over a mold to work then lets get on with it and get a rear window that works just like the one in a Cessna 150 which lasts for many years even with fuel spilled on it from time to time.

Lets light a candle instead of complaining about the darkness.

Best regards,
Vern
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  #22  
Old 04-27-2010, 08:13 AM
jte65 jte65 is offline
 
Join Date: Feb 2008
Location: Avon, Indiana
Posts: 341
Default Link to Makrolon Product Datasheet

After reading the various posts, I looked at the Makrolon website to see exactly what the product data sheet said regarding resistance to various chemicals. I have provided the link below. The specific reference to fuels is on page 3 where it states "Makrolon? is not resistant to the standard
carburetor and diesel fuels. The low-molecular, aromatic hydrocarbons that are present in carburetor fuel, in particular, cause cracking in parts that
are subject to stress."


http://plastics.bayer.com/plastics/e...31/KU28057.pdf

I do tend to agree with Vern- even with great care, there will be some point where fuel finds its way to the window. Too bad because in all other ways, it seems like the Makrolon is a great material- very durable.

Jeff
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  #23  
Old 04-27-2010, 09:17 AM
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RudiGreyling RudiGreyling is offline
 
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If true that the window is not compatible with fuel then it is not a good material choice. I guarantee you will spill fuel at some time. Then What? I hope Vans is taking note...Rudi
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  #24  
Old 04-27-2010, 11:20 AM
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flyboy1963 flyboy1963 is offline
 
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Location: Lake Country, B.C. Canada
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Default Lexan woes

Until a better solution is found, I'd try sealing the edges AND holes ( which of course are raw edges) with a latex based sealer. Even silicone can cause problems with it's components.
Makrolon and other polycarbonates are better suited to glazing applications, but we just keep forcing them into use because they bend easily, and are less prone to cracking in fabrication and use. I could never stand the optics.
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  #25  
Old 04-27-2010, 12:09 PM
JohnF JohnF is offline
 
Join Date: Jan 2005
Posts: 458
Default New Unit

Vern, I agree 100%...it should be possible to get a Plexiglass unit molded to pretty much be a direct replacement...I'd rather buy one rather than a Lexan one every now and then as I have an 'accident.'

JohnF
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  #26  
Old 04-27-2010, 01:11 PM
gpiney gpiney is offline
 
Join Date: Jan 2005
Location: The Beautiful NJ Shore
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I know a bunch of ex-ultralighters (now Sport Pilots) who have known of this problem for years. All of them have some type of rubber mat with channels, that they put over the filler neck, that will direct any spillage directly to the ground. Without 1 drop touching the airframe. Most 'accidents' are caused by overfilling/overflowing.
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  #27  
Old 04-27-2010, 06:57 PM
BigJohn BigJohn is offline
 
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Location: Gloversville, NY
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Quote:
Originally Posted by flyboy1963 View Post
Until a better solution is found, I'd try sealing the edges AND holes ( which of course are raw edges) with a latex based sealer. Even silicone can cause problems with it's components.
What would that "latex based sealer" be? My first thought for a sealer was silicone, but you say that isn't a good idea.
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  #28  
Old 04-27-2010, 07:06 PM
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flyboy1963 flyboy1963 is offline
 
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Default sealant

John,
we went thru a variety of sealants on the windshield of our previous homebuilt.....from the grey putty using to caulk window frames, to silicone ( which crazed the edge of lexan). It seemed that regular household exterior latex caulking, like DAP, mono etc, worked well, stayed flexible, and pretty much glued the window in, should a fastener work it's way loose.
Perhaps the boat-building, snowmobile, jet ski or motorcycle industries have something better, as they use polycarbonate windshields as well.
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  #29  
Old 04-29-2010, 06:06 PM
dick seiders dick seiders is offline
 
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Posts: 905
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Vern, I agree 100%, with your proposed solution. but lets not be too hard on the complainers. After all is said and done they get a lot more accomplished bringing light to the problems usually resulting in the necessary improvement than philosophy ever will.
Dick Seiders
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  #30  
Old 05-10-2010, 06:41 PM
jersey jersey is offline
 
Join Date: May 2010
Location: Wharton, Texas
Posts: 122
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I want to let all the RV 12 builders out there know that I have found someone who can heat mold Plexiglass to fit the aft window. He's been building experimentals since the mid 80's so he knows our pain. He just finished mine and charged me $250.00. Beautiful craftmanship and it fits perfectly!!! It took several weeks to get it but its worth it. He's from the local chapter so I didn't have to pay shipping etc.

I will be installing the lexan for purposes of getting the plane air worthy but will replace it if I have problems with the lexan. Before I posted this I asked him if he would be willing to build more, and he said he would for the RV 12 and RV 7A. He now has molds for both aircrafts. If any one is interested let me know I will forward contact info etc.

I used the dark tint to help keep the gas tank cool.

Below is link

http://img199.imageshack.us/img199/4876/aftglass.jpg

Gary Eldridge
RV 12 - 99.00%
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