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This is a discussion on aviation developments within the Space & Defense Technology forum, part of the Global Defense & Military category; Originally Posted by gf0012-aust well, its a FRU and replacement is probably found somewhere within the maint manuals I wouldn't ...


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Old January 26th, 2017   #16
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well, its a FRU and replacement is probably found somewhere within the maint manuals

I wouldn't have thought that its actually a regular event - they're designed to survive nearfield explosions - they're designed to survive g forces 4 levels above frame stress alerts - so there's a message in there already
What is FRU?
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Old January 26th, 2017   #17
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What is FRU?
Field replaceable unit, right? So you mean the entire canopy is FRU?
I bet it's an expensive FRU... But I'm sure they designed it to withstand the stresses as well as temperature effects (those two, by the way, are not necessarily related). That is why I am wondering what those temperature exposures are (would give me a pretty good indication of what how hot the canopy can be heated in production).
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Old January 26th, 2017   #18
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Field replaceable unit, right? So you mean the entire canopy is FRU?
I bet it's an expensive FRU... But I'm sure they designed it to withstand the stresses as well as temperature effects (those two, by the way, are not necessarily related). That is why I am wondering what those temperature exposures are (would give me a pretty good indication of what how hot the canopy can be heated in production).
they're made in an autoclave - which is way above the heat generated in any stressed flight regime
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Old January 26th, 2017   #19
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they're made in an autoclave - which is way above the heat generated in any stressed flight regime
The question is whether the temperatures that they are rated for in use are the same as those they're exposed to when they're made in an autoclave. Probably not.
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Old January 26th, 2017   #20
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The question is whether the temperatures that they are rated for in use are the same as those they're exposed to when they're made in an autoclave. Probably not.
There were reports that the Soviet Mig-31s had their speed ceiling reduced because the canopy could not handle the temperatures at very high speeds. I don't know what those canopies are made of, but it indicates that there is a significant thermal load on these things.
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Old January 26th, 2017   #21
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The question is whether the temperatures that they are rated for in use are the same as those they're exposed to when they're made in an autoclave. Probably not.
??

nothing made in an autoclave is designed to survive in the temps that the autoclave uses once the pressing has been completed. Its not how autoclaves work

its the same principle used in manufacturing components for submarines in autoclaves

the components are designed to pass destruction tests across a range of conditions way beyond normal stress induced fighting conditions.

the multiple and disparate physical components used to make c0ckpits underdo signifcant change when they are in the autoclave - its similar to the changes that occur when carbon fibre is formed in an autoclave
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Old January 26th, 2017   #22
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??

nothing made in an autoclave is designed to survive in the temps that the autoclave uses once the pressing has been completed. Its not how autoclaves work

its the same principle used in manufacturing components for submarines in autoclaves

the components are designed to pass destruction tests across a range of conditions way beyond normal stress induced fighting conditions.

the multiple and disparate physical components used to make c0ckpits underdo signifcant change when they are in the autoclave - its similar to the changes that occur when carbon fibre is formed in an autoclave
Any idea how hot autoclaves get for these processes?
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Old January 26th, 2017   #23
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Any idea how hot autoclaves get for these processes?
400C for the F-22 which is a quad laminate and fusion bonded acrylic, poly and optical glass

no idea for F-16 which is only triple laminate polycarb
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Old January 26th, 2017   #24
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400C for the F-22 which is a quad laminate and fusion bonded acrylic, poly and optical glass

no idea for F-16 which is only triple laminate polycarb
Thanks. Within limits for what I have in mind.
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Old January 26th, 2017   #25
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Thanks. Within limits for what I have in mind.
bear in mind that the max temp that an SR71's c0ckpit glass reached was under the forming temp of the F-22 c0ckpit glass making autoclave

the temps around the canopy are not universal and evenly distributed either
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Old January 26th, 2017   #26
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bear in mind that the max temp that an SR71's c0ckpit glass reached was under the forming temp of the F-22 c0ckpit glass making autoclave

the temps around the canopy are not universal and evenly distributed either
I'm not worried about the transparent conductor layers getting exposed to high temperatures during usage - that should be fine (for optical and electrical properties as well as thermal stresses), I'm primarily concerned with the process temperatures needed to coat them. But it sounds like that should not be a major problem either.
Thanks.
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Old January 26th, 2017   #27
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I'm not worried about the transparent conductor layers getting exposed to high temperatures during usage - that should be fine (for optical and electrical properties as well as thermal stresses), I'm primarily concerned with the process temperatures needed to coat them. But it sounds like that should not be a major problem either.
Thanks.
optical transports react to heat, if you build comms transports into the c0ckpit laminates then you will witness adverse results
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Old January 26th, 2017   #28
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optical transports react to heat, if you build comms transports into the c0ckpit laminates then you will witness adverse results
They do, unfortunately, but that is a separate (or next, I should say) problem to worry about. At least one doesn't need to worry about permanent degradation of its properties.
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Old January 26th, 2017   #29
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They do, unfortunately, but that is a separate (or next, I should say) problem to worry about. At least one doesn't need to worry about permanent degradation of its properties.
Are the optical properties (light transmission) or electrical conductivity important for the reason you mentioned?
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Old January 26th, 2017   #30
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They do, unfortunately, but that is a separate (or next, I should say) problem to worry about. At least one doesn't need to worry about permanent degradation of its properties.
if the bearer is corrupted then the signal its managing is compromised - in that sense you do have a permanent degradation as you have an unintended consequence.

If there is (especially) a (tactical) decision made using that compromised dataset, then there can be severe even if unintended consequences

heat kills, no matter how benign it may seem. if the transport path suffers temp variations, then that is just as bad as an imperfectly drawn cable where the result is reflection and refraction

optical transports won't change the outcome.
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