F-35 Canopy vs F-22 Canopy

Design and construction
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hotpogger

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Unread post10 Feb 2021, 16:49

So I noticed that the canopies of the F-22 and the F-35 are very different in color.
Raptor:
Image
F-35:
Image

Why is this? And which is better/more effective?
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wrightwing

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Unread post10 Feb 2021, 17:00

Better/more effective at what? They both do what they were designed to do.
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hotpogger

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Unread post11 Feb 2021, 02:46

Better/more effective at what? They both do what they were designed to do.


Better at being stealthy/doing it's job. Ofc they're both doing what they're designed to but what is known about them/what is different, and which may be better?
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linkomart

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Unread post11 Feb 2021, 06:58

hotpogger wrote:
Why is this? And which is better/more effective?


My guess is that F-22 canopy is gold plated and that the F-35 has an ITO plating. Both are there for stopping radar energy to get in to the cocpit. All conductive transparent layers have their pro and con, so why they choose the one or the other probably depends on the requirements.

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hornetfinn

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Unread post11 Feb 2021, 07:53

That's because they have different design and manufacturing process. While they are designed to do the same things, they are actually quite different. Here are some descriptions:

https://www.dsiac.org/wp-content/upload ... cument.pdf

F-35:
One of the more complex processes is that for the F-35 canopy fabricated by GKN Aerospace Transparency Systems. The acrylic and other special materials-based shell is loaded into a forming tool in an oven heated to 200F where the canopy forms over a span of approximately 3 days. During that time, a control system automatically adjusts clamps to control the forming process and ensure the shape remains uniform

The interlayer materials include polyurethane, silicone, and other proprietary materials with tailored optical properties that are used to bond the core plies together [1]. The interlayer materials can provide additional safety features such as bird-impact resistance, pressure “failsafe” capability, and anti-ice/anti-fog systems [5]


F-22:
The F-22 canopy, depicted in Figure 4, is the largest piece of monolithic polycarbonate material being formed today. It has no canopy bow (frame), which is conducive to superior optics throughout the canopy (not just in the front) and offers the requisite low-observable features. The canopy is 3/4-in. thick and is actually made of two 3/8-in.-thick sheets that are heated, fusion bonded (the sheets meld to become a single piece), and then drape forged [8].


There is also differences in exact composition of coatings used in the canopies:
2.2.2 Coatings
Interior and/or exterior coatings may be applied to help protect transparencies and aircrews from various operational or environment threats, and they provide improved low-observable performance, solar-heat reduction, laser protection, and/or electromagnetic shielding. Such technologies are designed to be compatible with night vision systems and other optical requirements.

On some aircraft, the protective coating may have an obvious tint. A similar tinting may perform several different functions depending on the aircraft on which it is applied. For example, the gold coating on EA-6B canopies, depicted in Figure 5, protects the crew from the radiation emitted by their own jamming pods. Similar coatings on aircraft like the F-16 and F-22 may be used to prevent radiation from threat radar systems being reflecting off the interior cockpit structure to help reduce the aircraft radar cross-section


Interesting patent from PPG Industries which supplies coatings to F-22 and F-35 and most other US military aircraft:
https://patents.google.com/patent/US20120328859A1/en

I think F-22 canopy uses Indium Zinc Oxide (ITO) in the coating and F-35 might use Aluminum Doped Zinc (AZO) as indicated in the patent. There is probably not that much difference in stealth qualities, but AZO is significantly cheaper and has greater flexibility (can be made thicker and can be more durable) and resistance to corrosion (good especially for naval applications).
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hornetfinn

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Unread post11 Feb 2021, 10:48

Have to add that AZO has become popular in recent years in replacing ITO in many applications where transparencies need some kind of coatings like solar cells or LCD displays. It also happens to be very good material for coating stealth aircraft canopie, just like ITO. However ITO was more mature and well known material when F-22 was designed, so they went with that.
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linkomart

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Unread post11 Feb 2021, 13:33

Agree with hornetfinn, although pretty sure ITO is Iridium tin oxide, not zink.

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hornetfinn

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Unread post11 Feb 2021, 13:53

linkomart wrote:Agree with hornetfinn, although pretty sure ITO is Iridium tin oxide, not zink.

regards.


:oops: Correct it's Tin and not Zinc... Although I in ITO is actually Indium and not Iridium. :D
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linkomart

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Unread post11 Feb 2021, 14:25

hornetfinn wrote:
linkomart wrote:Agree with hornetfinn, although pretty sure ITO is Iridium tin oxide, not zink.

regards.


:oops: Correct it's Tin and not Zinc... Although I in ITO is actually Indium and not Iridium. :D

Good, correct. I read sloppy. (Wouldn't know the difference between the two anyway)

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XanderCrews

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Unread post11 Feb 2021, 15:34

hornetfinn wrote: (can be made thicker and can be more durable) and resistance to corrosion (good especially for naval applications).


This would be consistent with international requirements for F-35 and bird strikes as required by UK (if not more nations) its the same reason the F-35 has a "Bow" that makes it look like a 2 piece canopy:

Image

If not for UK requirements, that little black Rainbow there on the Canopy above the instrument panel would not exist.
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milosh

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Unread post11 Feb 2021, 18:43

XanderCrews wrote:
hornetfinn wrote: (can be made thicker and can be more durable) and resistance to corrosion (good especially for naval applications).


This would be consistent with international requirements for F-35 and bird strikes as required by UK (if not more nations) its the same reason the F-35 has a "Bow" that makes it look like a 2 piece canopy.

If not for UK requirements, that little black Rainbow there on the Canopy above the instrument panel would not exist.


Two piece canopy would remain even if UK didn't requre better bird strike protecion.

Two piece canopy is better solution for ejection. Protect pilot from sudden air blast and allow easier underwater ejection.
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magitsu

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Unread post11 Feb 2021, 18:49

milosh wrote:Two piece canopy would remain even if UK didn't requre better bird strike protecion.

Didn't hornetfinn just copypaste a few posts before wall of text which said that it's not a two piece canopy? Only looks like it due to the bow, which is seen in XanderCrews' picture.

Here's another
The F-35 transparency comprises a framed windshield and canopy made from stretched acrylic. The
canopy is produced from a single piece of acrylic

https://www.gknaerospace.com/globalasse ... /f-35.pdf/

Here's a likely source of confusion
The X-35 canopy was a two-piece, side-opening design with a conventional bow frame. The F-35 is a one-piece, forward-opening design with an integrated bow frame. The change improves signature characteristics while maintaining low weight. The bow frame was moved back slightly to improve visibility.

https://www.codeonemagazine.com/f35_art ... item_id=28

Anyway,
transparency as the assembly is commonly referred to, comprises a framed windshield and canopy that is produced from a single piece of stretched acrylic, with no steps or gaps in the outside mold line.

every canopy is manufactured and verified to extremely tight tolerances. Each canopy is then optically mapped and matched to a specific aircraft as part of the assembly process, with optical deviation data stored in onboard systems to correct the pilot’s view of the outside world, in real-time.

The canopy is built to withstand the impact of a 4-lb bird at 480 knots on the reinforced windscreen and 350 knots on the canopy crown without breaking. Specialty coatings are applied to the finished canopy to maintain low-observable or stealth characteristics.

https://www.sme.org/technologies/articl ... et-canopy/

More about the canopy mapper and its inventor:
https://www.codeonemagazine.com/article.html?item_id=72

Ejection through canopy testing (2020)
The purpose of this test was to demonstrate that the ejection seat is able to penetrate through the canopy without severely injuring the pilot if there is ever a failure with the Transparency Removal System (TRS); TRS is a charge designed to fracture the cockpit canopy acrylic prior to ejection.

https://www.aerodefensetech.com/compone ... ries/36906

Luke Egress Airmen reduce F-35 canopy shaped charge replacement time by 120 hours
https://www.luke.af.mil/News/Article-Di ... y-120-hou/

Here's a bit about the underwater and RAF preference part from 2006:
viewtopic.php?p=79948#p79948
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XanderCrews

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Unread post11 Feb 2021, 20:33

Great and thorough post, Magitsu


Yep on the det cord, something carried over form the Harrier. if the airplane is in a hover and starts to "fall" There is ZERO airspeed to move the canopy out of the way and clear of the seat(s) moreover, you're ejecting from an airplane that is low to the ground (little time) and actually dropping (bizarre/unique scenario) the parachute has a special "canopy opener" and some other unique features as well.
Last edited by XanderCrews on 11 Feb 2021, 20:36, edited 1 time in total.
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ricnunes

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Unread post11 Feb 2021, 20:34

In order to confirm that the F-35's canopy is indeed a single piece, one just have to search for photos with the F-35's canopy opened like for example:

Image

Image

Image
“Active stealth” is what the ignorant nay sayers call ECM and pretend like it’s new.
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Unread post11 Feb 2021, 20:42

Attachments
F-35canopyTestDOOD.jpg
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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