DonFromTX
Well Known Member
That is correct, perfectly flat with protective covering, you bend it to install it.
Van's Air Force
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Time for new rear window ...
- Thread starter JerryG150
- Start date
Probably just prefer to fly. I just don't spend a lot of time admiring the machine's appearance. I am in awe of the way they perform.
joedallas
Well Known Member
txaviator
Well Known Member
You caught me Joe.... I guess that's what I get for having the fuselage crate laying in the floor, never opened
I learn something new every day. I'm hoping to get the skin on the wings in the next few days, and then I can crack open the fuse crate.
But on a positive note, it must be a stout plane, this RV-12. Because the EF-2 tornado that ravaged my home, didn't even touch my shop located in my back yard / pasture
Bill_H
Well Known Member
Keeping everyone informed - I have sent a powerpoint file with photos of my crazing incident and with detailed ideas for solution testing to txaviator - gary(dot)robertson(at)sbcglobal(dot)net. (Yes, I'm an engineer if you had to ask...)
He will forward it to DELTAHOTEL - (DH - if you are reading this you can contact me directly at billhollifield AT iname DOT com)
I encourage others to send their crazing pics as well - more pics could really help the student's test methodology.
He will forward it to DELTAHOTEL - (DH - if you are reading this you can contact me directly at billhollifield AT iname DOT com)
I encourage others to send their crazing pics as well - more pics could really help the student's test methodology.
txaviator
Well Known Member
Bill H and others,
Sorry for the delay. I've been out of the office and away from the computer for a few days. I called our plant today (remote from my main office), and I am gathering up the scraps to deliver locally, to our team of professor and his college students. Bill, I will forward your excellent Powerpoint to him as well.
Many thanks,
Sorry for the delay. I've been out of the office and away from the computer for a few days. I called our plant today (remote from my main office), and I am gathering up the scraps to deliver locally, to our team of professor and his college students. Bill, I will forward your excellent Powerpoint to him as well.
Many thanks,
JerryG150
Well Known Member
pictures ...
I think the magic number was four "dousings" ... two by me and two by linemen ...
When I messed up, I barely pulled the trigger and whoosh ... the rear window, the side of the plane and my pants were dripping in gasoline.
I still haven't ordered a new rear window from Van's ... spent the last 2 weeks with my grandchildren in NC, DC and Baltimore.
My rear window also has some paint on it professionally done by the paintshop to cover the rollbar and rear support of the rollbar that'll have to be redone when my window is finally replaced.
Here are a few of pictures I took today.
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[/IMG]
I think the magic number was four "dousings" ... two by me and two by linemen ...
When I messed up, I barely pulled the trigger and whoosh ... the rear window, the side of the plane and my pants were dripping in gasoline.
I still haven't ordered a new rear window from Van's ... spent the last 2 weeks with my grandchildren in NC, DC and Baltimore.
My rear window also has some paint on it professionally done by the paintshop to cover the rollbar and rear support of the rollbar that'll have to be redone when my window is finally replaced.
Here are a few of pictures I took today.
fuel spill wedge?
This is the first picture I have seen of the fuel cap location for the 12. It is very close to the window that from all the reading does not like fuel on it. Would it be worth considering a small wedge, about the size of a rudder stiffener along the edge of the window bent mostly over that would direct spilled fuel away from the window? It wouldn't be perfect, but it may deflect some or most of the fuel from the window. It would be a reminder to be careful too.
With the LSA restrictions on speed, I can't imagine a 1" wedge bent to about 130degrees would cause much problem with air flow. Just a thought.
[/IMG]
This is the first picture I have seen of the fuel cap location for the 12. It is very close to the window that from all the reading does not like fuel on it. Would it be worth considering a small wedge, about the size of a rudder stiffener along the edge of the window bent mostly over that would direct spilled fuel away from the window? It wouldn't be perfect, but it may deflect some or most of the fuel from the window. It would be a reminder to be careful too.
With the LSA restrictions on speed, I can't imagine a 1" wedge bent to about 130degrees would cause much problem with air flow. Just a thought.
flyboy1963
Well Known Member
some additional lexan thoughts.....
hey guys, as I've said a million times, I'm not an expert, but have seen this many times, and wanted to flesh out some of the ideas...at risk of repeating what others have said.
lexan ( polycarbonate) is not meant to be bent more than a few degrees. cold forming 90 degrees like this rear window, introduces stress as evidenced by the obvious checking through the sheet.
The edge is very different from the face; it is like a loaf of italian bread. splash something on the outside, it mostly rolls off. Hit the exposed core, it easily 'soaks' in, even vapours may attack the material over time.
Try glueing scraps with methylene chloride; two exposed faces will barely bond, two edges will melt together like butter. My point being, if you can seal the edge, you may achieve more resistance to degradation from solvents etc.
idea #2; since optics are not critical, after sealing the edge, apply a clear polyester laminate to the outer face, ( graffiti film, like window tint) which will repel the occasional splash of gas.
by the way, a quick Google of Vivak shows that it is meant for indoor displays, and has no UV inhibitors, so I would expect it to perform worse than lexan or plexi that is intended for outdoor use. ( possibly yellow, harden, craze etc.)
hey guys, as I've said a million times, I'm not an expert, but have seen this many times, and wanted to flesh out some of the ideas...at risk of repeating what others have said.
lexan ( polycarbonate) is not meant to be bent more than a few degrees. cold forming 90 degrees like this rear window, introduces stress as evidenced by the obvious checking through the sheet.
The edge is very different from the face; it is like a loaf of italian bread. splash something on the outside, it mostly rolls off. Hit the exposed core, it easily 'soaks' in, even vapours may attack the material over time.
Try glueing scraps with methylene chloride; two exposed faces will barely bond, two edges will melt together like butter. My point being, if you can seal the edge, you may achieve more resistance to degradation from solvents etc.
idea #2; since optics are not critical, after sealing the edge, apply a clear polyester laminate to the outer face, ( graffiti film, like window tint) which will repel the occasional splash of gas.
by the way, a quick Google of Vivak shows that it is meant for indoor displays, and has no UV inhibitors, so I would expect it to perform worse than lexan or plexi that is intended for outdoor use. ( possibly yellow, harden, craze etc.)
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engineerofsorts
Well Known Member
Stress/crazing/heat forming relationship
In my ignorance, I'll ask any noted authority on everything: Does the crazing we see happen only when the polycarbonate is stressed? Or will spilling Mogas on an unstressed sheet also cause crazing? Could we heat-form the polycarbonate, like one does with acrylic, to relieve the stress and thereby minimize the crazing??? As I understand it, polycarbonate can be heat formed, but requires a bit higher forming temperature.
In my ignorance, I'll ask any noted authority on everything: Does the crazing we see happen only when the polycarbonate is stressed? Or will spilling Mogas on an unstressed sheet also cause crazing? Could we heat-form the polycarbonate, like one does with acrylic, to relieve the stress and thereby minimize the crazing??? As I understand it, polycarbonate can be heat formed, but requires a bit higher forming temperature.
OK - here's a data point in the FWIW Dept:
Just spent 3 days flying the RV-12 demo airplane (N412RV) down in Oregon with Mike Seager (43 landings and not one call to the insurance company.)
The airplane rear windows looked brand new (maybe they WERE brand new! Ha!)
Asked Mike about this fuel surge back situation. Never happened to him he said. We stopped for gas twice in Scappoose. I asked the gas boy - who fuels the airplane almost daily. He claimed no knowledge and no problems. I noted the gas pump nozzle was BIG - almost completely filling the filler neck (and allowing minimal space for expansion air to exit the tank.)
He let me listen to the gurgle as it came up the filler neck. He completely "topped off" each time and seemed to be running the nozzle "wide open."
Like I said - FWIW.
Bob Bogash
N737G
Just spent 3 days flying the RV-12 demo airplane (N412RV) down in Oregon with Mike Seager (43 landings and not one call to the insurance company.)
The airplane rear windows looked brand new (maybe they WERE brand new! Ha!)
Asked Mike about this fuel surge back situation. Never happened to him he said. We stopped for gas twice in Scappoose. I asked the gas boy - who fuels the airplane almost daily. He claimed no knowledge and no problems. I noted the gas pump nozzle was BIG - almost completely filling the filler neck (and allowing minimal space for expansion air to exit the tank.)
He let me listen to the gurgle as it came up the filler neck. He completely "topped off" each time and seemed to be running the nozzle "wide open."
Like I said - FWIW.
Bob Bogash
N737G
BUT...Has there been a change in the filler location?
I remember Scott saying also in an earlier thread that there was never a splash back problem with the demo aircraft.
BUT, the original demo plane had the gas filler in a different (lower) location than the kits actually shipped.
This is a picture of the original plane when Karen and I rode in it at Van's in '09. Bob, you just saw it, is the gas filler now higher or in the same lower location??
This is an apples and oranges comparison if the filler is still in the lower position.
If it is still in the old position and it works so well in the old position why was it moved?
Tony
I remember Scott saying also in an earlier thread that there was never a splash back problem with the demo aircraft.
BUT, the original demo plane had the gas filler in a different (lower) location than the kits actually shipped.
This is a picture of the original plane when Karen and I rode in it at Van's in '09. Bob, you just saw it, is the gas filler now higher or in the same lower location??
This is an apples and oranges comparison if the filler is still in the lower position.
If it is still in the old position and it works so well in the old position why was it moved?
Tony
JerryG150
Well Known Member
Position different ...
If you look at the picture of the fuel filler on my -12 (as well as everyone else's) on page 6 of this thread, you'll see our tank filler is higher up and considerably closer to the rear window than on Van's demo RV-12. Perhaps the longer neck builds more back pressure when fuel is pumped in.
Oh well ... It is what it is ...
If you look at the picture of the fuel filler on my -12 (as well as everyone else's) on page 6 of this thread, you'll see our tank filler is higher up and considerably closer to the rear window than on Van's demo RV-12. Perhaps the longer neck builds more back pressure when fuel is pumped in.
Oh well ... It is what it is ...
The fuel filler on 412RV is not still in the location shown in the photo. It was moved because it works better in the higher position.
Bill_H
Well Known Member
Note to new buiders. We all hope to hear about the tests as mentioned earlier in this thread. In advance of those results, If I was building now, I would do the following. It might help and I can't see how it would hurt - maybe someone can point out where I am wrong!
1. Seal the bottom edge of the lexan with metal tape up to the edge line of the fuselage skin overlapping the holes. (this would be hidden under the fuselage skin). This would be a "u-shaped" piece of tape. That would be about 1/4 inch "above" the holes on both sides of the window. Then cut out the holes.
2. Somehow seal the holes with silicone as I was putting in the attachment screws. Probably using masking tape "above" the screw holes on the inside as I was doing it to avoid a mess.
These two things should be of no concern to any DAR.
3. After certification I would strongly consider adding an external auto window tint film. That might cause a DAR comment if done before and it also might not stand up to being bent if applied when flat before window installation. That's one of the test items.
FWIW -just what I'd do and I am no expert!
I am being really careful while I wait for the tint film results. That might address the surface crazing remote from the edge that the pics show that I have not yet experienced.
1. Seal the bottom edge of the lexan with metal tape up to the edge line of the fuselage skin overlapping the holes. (this would be hidden under the fuselage skin). This would be a "u-shaped" piece of tape. That would be about 1/4 inch "above" the holes on both sides of the window. Then cut out the holes.
2. Somehow seal the holes with silicone as I was putting in the attachment screws. Probably using masking tape "above" the screw holes on the inside as I was doing it to avoid a mess.
These two things should be of no concern to any DAR.
3. After certification I would strongly consider adding an external auto window tint film. That might cause a DAR comment if done before and it also might not stand up to being bent if applied when flat before window installation. That's one of the test items.
FWIW -just what I'd do and I am no expert!
I am being really careful while I wait for the tint film results. That might address the surface crazing remote from the edge that the pics show that I have not yet experienced.
txaviator
Well Known Member
A possible 'simple' solution!
Hey folks,
I have not forgotten about the tests we all discussed a few weeks back, the data points sent to me, and nor have I forgotten about the generosity of the college teacher and his aviation students who volunteered to conduct the tests.
However, I recently found out that there may be a really easy solution to the problem at hand. While a l do a huge amount of in-house manufacturing (vacuum-forming, assembly, etc), all of my acrylic and polycarbonate work is done by another facility. Think of the included rear -12 window that Van's provides: that is precision cut-out, on a VERY expensive multi-axis CNC router. While I haven't seen the Van's rear windows being made, it is the exact same final result that I have produced for my windshields that we manufacture. Anyway, I don't wish to dole out hundreds of thousands for the CNC when I can have it done by someone already owning the machines. Let me give you a quick background on where I am heading with all this nonsense, that so far has nothing to do with fuel on an RV-12 window:
I recently was courted by the largest acrylic and polycarbonate producer in the world. They were formerly known as GE Plastics (if that tells you anything about their size) until they bought the company from GE and changed the name. I was anticipating this meeting with the new company for almost 2-weeks, and planned to ask about the fueling issues on the polycarbonate as soon as we hashed out all the details of my business. I was speaking to the GM of the facility, surrounded by engineers, and when I told them the RV-12 issue, and he immediately said "That's a no-brainer. That's a simple fix!" He proceeded to rattle off a part number of some product that seemed like it was 20-digits long. Of course I[had no idea what product he was referring to. But as he elaborated, he said to think of any gas pump in America. All the signage on the pumps, let's say where a pump may say 'TEXACO'....that's polycarbonate material. And it is final-covered in the material I was told about. Think of an actual gas pump being subjected to fuel for years, yet you never see any signage on the pumps that is crazed or distorted.
The solution he mentioned is exactly what some folks proposed early on: it's a clear specialty film that can be applied to the polycabonate sheet, in the area that would possibly be splashed by fuel. It wouldn't need to cover the entire rear window. I was told it is crystal clear, and while it would be easier to apply it with the back window still flat, it would be possible to apply the material once the window is bent and installed. I was told that the film is a highly specialized substrate, with a specialty adhesive backing. I asked if it was similar to a window tint, and was told yes, but that fuel would melt a typical window tint film in a heartbeat.
So here's what I'm now proposing we do: they ordered me a sample sheet of this specialty material, and I should have it within a few weeks. They didn't stock it in their Dallas facility. I will send this new material up to the college (testing) folks, along with the samples of scrap polycarbonate. We will find out VERY quickly if it performs as stated, but I have tremendous faith in the guys that told me it was THE solution to the problem.
If it works, I would think that Van's could possibly look at providing a small die-cut piece of this material with the kit, and the problem of the window crazing talk will quickly diminish? We will see. I will notify Van's of our findings. If it performs flawlessly, I will see what I can do about being able to provide the material to folks who already have their pink slips. For those (like me) still building, we'd need to ask Mel or one of the other DAR's if we can apply it before installing the window. It's what I would consider purely 'cosmetic', but I don't know the specific rule that the Feds require the DAR's to follow. I'll also gladly provide the magic part number / manufacturer of this material, once I get it. Then while the tests are being done, perhaps we can do some online research of the product in the interim.
Really sorry for the loooong post, guys. But I wanted to fully explain where we are at, and let you know the solution sounds extremely promising.
Take care,
Hey folks,
I have not forgotten about the tests we all discussed a few weeks back, the data points sent to me, and nor have I forgotten about the generosity of the college teacher and his aviation students who volunteered to conduct the tests.
However, I recently found out that there may be a really easy solution to the problem at hand. While a l do a huge amount of in-house manufacturing (vacuum-forming, assembly, etc), all of my acrylic and polycarbonate work is done by another facility. Think of the included rear -12 window that Van's provides: that is precision cut-out, on a VERY expensive multi-axis CNC router. While I haven't seen the Van's rear windows being made, it is the exact same final result that I have produced for my windshields that we manufacture. Anyway, I don't wish to dole out hundreds of thousands for the CNC when I can have it done by someone already owning the machines. Let me give you a quick background on where I am heading with all this nonsense, that so far has nothing to do with fuel on an RV-12 window:
I recently was courted by the largest acrylic and polycarbonate producer in the world. They were formerly known as GE Plastics (if that tells you anything about their size) until they bought the company from GE and changed the name. I was anticipating this meeting with the new company for almost 2-weeks, and planned to ask about the fueling issues on the polycarbonate as soon as we hashed out all the details of my business. I was speaking to the GM of the facility, surrounded by engineers, and when I told them the RV-12 issue, and he immediately said "That's a no-brainer. That's a simple fix!" He proceeded to rattle off a part number of some product that seemed like it was 20-digits long. Of course I[had no idea what product he was referring to. But as he elaborated, he said to think of any gas pump in America. All the signage on the pumps, let's say where a pump may say 'TEXACO'....that's polycarbonate material. And it is final-covered in the material I was told about. Think of an actual gas pump being subjected to fuel for years, yet you never see any signage on the pumps that is crazed or distorted.
The solution he mentioned is exactly what some folks proposed early on: it's a clear specialty film that can be applied to the polycabonate sheet, in the area that would possibly be splashed by fuel. It wouldn't need to cover the entire rear window. I was told it is crystal clear, and while it would be easier to apply it with the back window still flat, it would be possible to apply the material once the window is bent and installed. I was told that the film is a highly specialized substrate, with a specialty adhesive backing. I asked if it was similar to a window tint, and was told yes, but that fuel would melt a typical window tint film in a heartbeat.
So here's what I'm now proposing we do: they ordered me a sample sheet of this specialty material, and I should have it within a few weeks. They didn't stock it in their Dallas facility. I will send this new material up to the college (testing) folks, along with the samples of scrap polycarbonate. We will find out VERY quickly if it performs as stated, but I have tremendous faith in the guys that told me it was THE solution to the problem.
If it works, I would think that Van's could possibly look at providing a small die-cut piece of this material with the kit, and the problem of the window crazing talk will quickly diminish? We will see. I will notify Van's of our findings. If it performs flawlessly, I will see what I can do about being able to provide the material to folks who already have their pink slips. For those (like me) still building, we'd need to ask Mel or one of the other DAR's if we can apply it before installing the window. It's what I would consider purely 'cosmetic', but I don't know the specific rule that the Feds require the DAR's to follow. I'll also gladly provide the magic part number / manufacturer of this material, once I get it. Then while the tests are being done, perhaps we can do some online research of the product in the interim.
Really sorry for the loooong post, guys. But I wanted to fully explain where we are at, and let you know the solution sounds extremely promising.
Take care,
"works better" means? holds more? better venting? angle of filler neck too low? larger fuel tank? curious the thinking behind the move...sounds to be a favorable one.
Bill_H
Well Known Member
Great news Gary!! But remember even with a new Magic film, I bet if the fuel touches an edge or seeps around the screw into the inside of a hole (as mine did in one second) that film would not stop that edge-based crazing. I bet we will still need a method for edge and screw-hole sealing but this does sound like a very possible solution to surface crazing.
RFSchaller
Well Known Member
Home Depot Solution?
Is there a reason you guys don't buy a sheet of lexan at Home Depot and cut a new window using the old one as a pattern? I'm asking because I just noticed a few crazes and that is what I plan to do if it gets worse.
Is there a reason you guys don't buy a sheet of lexan at Home Depot and cut a new window using the old one as a pattern? I'm asking because I just noticed a few crazes and that is what I plan to do if it gets worse.
rear window
Carl makes them out of a material called Vivak. It's made by Bayer and is impervious to chemicals like gasoline. I have one installed and it's great! I'm not sure he's making them any more, but I would check before I went to Van's. His address is: Carl Eldridge <[email protected]>
Carl makes them out of a material called Vivak. It's made by Bayer and is impervious to chemicals like gasoline. I have one installed and it's great! I'm not sure he's making them any more, but I would check before I went to Van's. His address is: Carl Eldridge <[email protected]>
RV-12 Pages 25-05 and 25-06
Note plans page updates have been made in regards to this issue.
See http://www.vansaircraft.com/public/service-rv12.htm Page 25-05 and 25-06
The aft window is made with a MR5000 coating a material used in NASCAR windows to protect against fuel damage. This coating does not cover the cut edges of the window. The changes to the above pages do cover a method of sealing the aft window edges to prevent damage.
Note we also looked into using Vivak but over time it will break down in sunlight. Those RV-12's using windows made from Vivak will need replacement again due to that damage.
Note plans page updates have been made in regards to this issue.
See http://www.vansaircraft.com/public/service-rv12.htm Page 25-05 and 25-06
The aft window is made with a MR5000 coating a material used in NASCAR windows to protect against fuel damage. This coating does not cover the cut edges of the window. The changes to the above pages do cover a method of sealing the aft window edges to prevent damage.
Note we also looked into using Vivak but over time it will break down in sunlight. Those RV-12's using windows made from Vivak will need replacement again due to that damage.
JerryG150
Well Known Member
lucky us ...
The revisions to section 25-5 and 25-6 are an answer to all our problems... We just have to order a new window, mix up some gas tank sealant, eat a few Popsicles and practice our cake decorating skills. I feel lucky because I haven't yet painted my RV-12 and that will make it much easier to follow the instructions in the new revisions ... Oh, wait a minute, my plane is painted and if I remember correctly, I hate working with gas tank sealant.
A rear window made of another material more impervious to gas, molded or unmoulded, even at twice the price would be more favorable to me.
We had better do an absolutely perfect job of cake decorating because even a minimum amount gas will effect the window. After allowing the gas tank sealant to cure around the rear window a few days ... We can always spill a gallon of 100LL on the newly protected window to see how well we protected that rear window ...
If we have to replace the rear window, for whatever reason, after following the revision we'll need a scraper as well as a screwdriver ... That could be not only messy but pretty difficult on a painted plane.
I'm getting used to the way my back window looks ... All crazed within a foot of the gas filler cap and cracked near all the screws but on the bright side, I no longer fear the linemen splashing gas!
The revisions to section 25-5 and 25-6 are an answer to all our problems... We just have to order a new window, mix up some gas tank sealant, eat a few Popsicles and practice our cake decorating skills. I feel lucky because I haven't yet painted my RV-12 and that will make it much easier to follow the instructions in the new revisions ... Oh, wait a minute, my plane is painted and if I remember correctly, I hate working with gas tank sealant.
A rear window made of another material more impervious to gas, molded or unmoulded, even at twice the price would be more favorable to me.
We had better do an absolutely perfect job of cake decorating because even a minimum amount gas will effect the window. After allowing the gas tank sealant to cure around the rear window a few days ... We can always spill a gallon of 100LL on the newly protected window to see how well we protected that rear window ...
If we have to replace the rear window, for whatever reason, after following the revision we'll need a scraper as well as a screwdriver ... That could be not only messy but pretty difficult on a painted plane.
I'm getting used to the way my back window looks ... All crazed within a foot of the gas filler cap and cracked near all the screws but on the bright side, I no longer fear the linemen splashing gas!
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Why not Vivak UV?
I'm no materials guy, but I looked up Bayer's Vivak online. They have a version called Vivak UV that they recommend for exterior use with a ten year guarantee. That means it'll probably make 15. It's available in flat sheets in a wide range of thicknesses; they claim it forms easily and has very high breaking strength. Another claim is 'resistance to harsh chemicals'.
Anybody out there know about this stuff?
Here's the link: http://www.sheet.bayerpolymers.com/...tm?PHPSESSID=d55cefb87d9c69cbf6a902c0c39705a0
I'm no materials guy, but I looked up Bayer's Vivak online. They have a version called Vivak UV that they recommend for exterior use with a ten year guarantee. That means it'll probably make 15. It's available in flat sheets in a wide range of thicknesses; they claim it forms easily and has very high breaking strength. Another claim is 'resistance to harsh chemicals'.
Anybody out there know about this stuff?
Here's the link: http://www.sheet.bayerpolymers.com/...tm?PHPSESSID=d55cefb87d9c69cbf6a902c0c39705a0
txaviator
Well Known Member
As I continue to chase this issue (being IN the plastic business as mentioned) I have tried to look at the Vivak material in my recent quest for info. It's the same stuff I am told, used on gas pump faces across the globe. But the problem is that it's not available in a thickness even close to our -12 rear windows. I have my -12 rear window already mapped in Solid Works software. As soon as me and my manufacturer find a suitable material, our CNC machine can crank out these new windows as quickly as anyone wants them.
I'm also still looking into the magic film, but as others have mentioned, I am not so sure it is the absolute solution. While it may repel the fuel, it's still apparently difficult to apply- and still get a crystal clear (ie: no bubble/wrinkle) finish. The true solution is a material that is not ruined by fuel. I'm working on it, fast and furious...I promise.
I also have a request into Cessna, of all organizations. The Skycatcher I have been flying, has two fuel sumps on each side of the plane, directly by the giant windows in each door. If the wind is blowing, anytime you pull a fuel sample, it literally goes everywhere- including the door windows. Yet, there is no sign of any problem on these windows. If I can get someone to give me the manufacturer/material of those Skycatcher windows, the problem will be solved (without Pro-Seal and all this other stuff being mentioned).
Are people using Ethanol Auto Fuel in Sky Catchers?
That is the primary issue with the RV-12 window.
The other factor is that it is not flat (like the Sky Catcher door window probably is). The strain induced from curving the material makes it much more sensitive to crazing by the influence of chemicals.
dick seiders
Well Known Member
Flying two and 1/4 years and no window problems yet. I do place a rubber sheet over the window with a fuel filler cutout which is a drag, but maybe it helps in event of spill/spray of fuel.
I choose not to use the newly proposed solution using fuel sealant on the window. Failure of seal later makes the window replacement on a painted (or unpainted) airplane a major project likely including a removal of tank, and replacement and re finishing of the surrounding skin. Additionally there is the messy installation process of the preceding "fix" as well.
Dick Seiders 120093
I choose not to use the newly proposed solution using fuel sealant on the window. Failure of seal later makes the window replacement on a painted (or unpainted) airplane a major project likely including a removal of tank, and replacement and re finishing of the surrounding skin. Additionally there is the messy installation process of the preceding "fix" as well.
Dick Seiders 120093
txaviator
Well Known Member
I've been told by my polymer extruder (they ARE the big boys: they own and produce Lexan, which is the world's largest brand/extruder of polycarbonate, as well as all other polymers), that any standard/typical clear optic polycarbonate (be it Lexan, Makrolon like the factory uses, etc.) will be affected eventually by any type of fuel, be it ethanol auto fuel, non-ethanol auto fuel, 100LL, etc.
It was stated earlier that the curvature of the window has something to do with the possibility of crazing due to chemical contact. I haven't asked my extruder about that, so I can't comment now, but I will inquire!
I'm digging into this, as I've promised for quite some time now. I really don't like the idea of popsicle sticks and ProSeal on my newly installed rear window. There MUST be a better solution, and if anyone can figure it out, it is my polymer extruder. As the world's largest at what they do, they are the experts and I am awaiting their solution. I will pass along their information when I obtain it. The quicker the better!
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E. D. Eliot
Well Known Member
Thanks Gary
Thanks for doing the research for us all. Hopefully, there is a 'best' solution as opposed to 'better'. Hope that you find the answer and that Van's will have a serious look at whatever you find.
Thanks for doing the research for us all. Hopefully, there is a 'best' solution as opposed to 'better'. Hope that you find the answer and that Van's will have a serious look at whatever you find.
CONSIDER THIS:
Refer to NORTH UP's reply. The surface is protected. It is the exposed cut edges and the holes that are the problem. Seal the edge and holes with Epoxy. "System Three Clear Coat epoxy resin is a very low viscosity (thin), almost colorless epoxy system".
First mask the window. Then fabricate a long narrow container for the epoxy by ripping away a third of the longitudinal surface of a 1" PVC pipe with your table saw and cap the ends. Fill with the epoxy to the dept that will include the holes when placing the edge of the window into the epoxy. Dip the edge of the window into the epoxy.
The question is would the epoxy "crack" when the window is bent and installed? Lets get a length of scrap plexiglass laying around the shop, dip it and see if it cracks. Epoxy is pretty flexible and can take many hours to reach a 100% cure - long enough to install the window.
Follow the instructions for sealing with Proseal but instead use Clear Silicone. Much easier to remove for replacement in the future.
Just stepping back and thinking out of the box - might be my lifetime experience as an Industrial Designer??
Refer to NORTH UP's reply. The surface is protected. It is the exposed cut edges and the holes that are the problem. Seal the edge and holes with Epoxy. "System Three Clear Coat epoxy resin is a very low viscosity (thin), almost colorless epoxy system".
First mask the window. Then fabricate a long narrow container for the epoxy by ripping away a third of the longitudinal surface of a 1" PVC pipe with your table saw and cap the ends. Fill with the epoxy to the dept that will include the holes when placing the edge of the window into the epoxy. Dip the edge of the window into the epoxy.
The question is would the epoxy "crack" when the window is bent and installed? Lets get a length of scrap plexiglass laying around the shop, dip it and see if it cracks. Epoxy is pretty flexible and can take many hours to reach a 100% cure - long enough to install the window.
Follow the instructions for sealing with Proseal but instead use Clear Silicone. Much easier to remove for replacement in the future.
Just stepping back and thinking out of the box - might be my lifetime experience as an Industrial Designer??
flyboy1963
Well Known Member
Jackkclark
Well Known Member
It can't hurt, right? W*R*O*N*G*!
I drilled and trimmed the canopy and rear window with only one tiny crack in canopy. (as fate would have it...it was the very last hole) Instead of "stop drilling" the crack, I melted a stop crack hole.
I attached canopy and rear window several months ago without incidence. Today, the painter was looking over the plane when he said "what caused all these cracks in your rear window?" My heart sank as I rushed to the window and saw a "star" (cracks or crazing) around every screw head attaching the window to the roll bar. However, NONE of the of screws attaching the window to the rear skins had any cracks, crazing or "stars."
What caused every hole over the roll bar to crack and absolutely none of the holes touching the skin to crack? The roll bar has threaded holes. The screws were not tight. They could have been removed with tweezers. The rear of the glass was attached with screws, washers and nuts...also not tight.
Later, my wife helped me removed the window. She asked "why do all these messed up holes feel sticky and have this red tint, while all the good holes feel smooth and look clear. Out of the mouths of babes (beautiful women) the problem was solved....I had put a small amount of Permatex Red Thread Locker on each screw inserted into each threaded hole in the roll bar. Although I used only a minute amount, the Permatex could easily be felt on both the top and bottom edge of the glass. Like the "Blob" (old movie) the stuff had climbed out of the hole and spread out on the glass around the hole...about the size of a dime. I took photos, but can't attach. It asked for a URL....ha. That's as far as I got. I will email if anyone wants to see a black star around 30 or 40 holes. I wonder if PERMATEX will buy me a new window?
I drilled and trimmed the canopy and rear window with only one tiny crack in canopy. (as fate would have it...it was the very last hole) Instead of "stop drilling" the crack, I melted a stop crack hole.
I attached canopy and rear window several months ago without incidence. Today, the painter was looking over the plane when he said "what caused all these cracks in your rear window?" My heart sank as I rushed to the window and saw a "star" (cracks or crazing) around every screw head attaching the window to the roll bar. However, NONE of the of screws attaching the window to the rear skins had any cracks, crazing or "stars."
What caused every hole over the roll bar to crack and absolutely none of the holes touching the skin to crack? The roll bar has threaded holes. The screws were not tight. They could have been removed with tweezers. The rear of the glass was attached with screws, washers and nuts...also not tight.
Later, my wife helped me removed the window. She asked "why do all these messed up holes feel sticky and have this red tint, while all the good holes feel smooth and look clear. Out of the mouths of babes (beautiful women) the problem was solved....I had put a small amount of Permatex Red Thread Locker on each screw inserted into each threaded hole in the roll bar. Although I used only a minute amount, the Permatex could easily be felt on both the top and bottom edge of the glass. Like the "Blob" (old movie) the stuff had climbed out of the hole and spread out on the glass around the hole...about the size of a dime. I took photos, but can't attach. It asked for a URL....ha. That's as far as I got. I will email if anyone wants to see a black star around 30 or 40 holes. I wonder if PERMATEX will buy me a new window?
skydiverlv
Well Known Member
f1rocket
Well Known Member
After reading all the posts and threads regarding sealing the rear window, I couldn't find any solution posted other than what Van's recommends. I'm getting ready to permanently install my rear window as soon as I paint the interior so I plan to go with Proseal.
I think with Proseal properly installed and a little dab used on the screws as they are installed will ensure that no fuel can reach an untreated edge in the Lexan. And if that happens, then there's never a reason to replace the window so removal is less of an issue.
I think with Proseal properly installed and a little dab used on the screws as they are installed will ensure that no fuel can reach an untreated edge in the Lexan. And if that happens, then there's never a reason to replace the window so removal is less of an issue.
txaviator
Well Known Member
Unfortunately, no, I don't. My manufacturer hasn't come through with the correct solution IMHO. They suggested some sort of a film overlay (kind of like window tint) that they thought would work. However, it is VERY difficult to install to a flat window, not to mention a curved piece of Lexan already installed. This overlay was the same polymer that is commonly installed on the face of gas pumps.
As far as a fuel-proof material by itself, my people have yet to be of much help. It's a huge, global corporation...and every single time I think I have someone devoted to doing the research and talking to engineers, there seems to be a changing of the guard.
I'm still working on it, but I have no definitive solution as of yet. Unfortunately.
Paris12Man
Well Known Member
Agree!
So have I Gary!
So have I Gary!
RFSchaller
Well Known Member
Randy,
What ever you do don't make replacement a major issue. Mine is sealed with a bead on the top surface at the plex and skin interface. Paint seals the screws. I have a couple of crazing streaks that have been stable for over a year.
Rich
What ever you do don't make replacement a major issue. Mine is sealed with a bead on the top surface at the plex and skin interface. Paint seals the screws. I have a couple of crazing streaks that have been stable for over a year.
Rich
txaviator
Well Known Member
Let's Clarify For Folks Following This
The factory Vans rear window is NOT plexiglass, which is generically/also known as acrylic!!! I'm thinking some people may be saying "plexiglass" when that isn't true.
The factory rear window IS Lexan, also known generically as polycarbonate.
Typically speaking, acrylic/plexiglass will NOT bend and contour to the fuse without cracking in pieces. However, polycarbonate/Lexan can be bent. As a matter of fact, it's darn near unbreakable- by curving/bending.
I mention this just to set the record straight for those studying the fuel crazing issues.
I 'think' I recall someone years ago, that was heat shaping/forming (aka: drape forming) a plexiglass/acrylic rear window. Again, plexiglas/acrylic can't be cold formed (ie: bent). However, Lexan/polycarbonate can be hand bent all day long. I'm certain there are a few folks flying that bought the formed/draped acrylic product.....but anyone with a factory window has Lexan/polycarbonate as the window substrate.
The factory Vans rear window is NOT plexiglass, which is generically/also known as acrylic!!! I'm thinking some people may be saying "plexiglass" when that isn't true.
The factory rear window IS Lexan, also known generically as polycarbonate.
Typically speaking, acrylic/plexiglass will NOT bend and contour to the fuse without cracking in pieces. However, polycarbonate/Lexan can be bent. As a matter of fact, it's darn near unbreakable- by curving/bending.
I mention this just to set the record straight for those studying the fuel crazing issues.
I 'think' I recall someone years ago, that was heat shaping/forming (aka: drape forming) a plexiglass/acrylic rear window. Again, plexiglas/acrylic can't be cold formed (ie: bent). However, Lexan/polycarbonate can be hand bent all day long. I'm certain there are a few folks flying that bought the formed/draped acrylic product.....but anyone with a factory window has Lexan/polycarbonate as the window substrate.
RFSchaller
Well Known Member
A rose by any other name would smell as sweet.
The point is don't glue the shiny transparent thing in so tight you can't get it out for future replacement.
The point is don't glue the shiny transparent thing in so tight you can't get it out for future replacement.
