Fighter planes: why aren't frameless canopies more common?

To my knowledge (which I imagine will be amended later in this thread), the only two fighter planes that utilize frameless canopies are the F-16 and F-22. I’m not a fighter pilot, but ISTM that the visibility advantage of a frameless canopy (relative to a canopy that incorporates metal bracing in the pilot’s field of view) is rather large. So why isn’t the frameless canopy more common?

Isn’t most aerial combat done by missile these days, meaning that the pilot wouldn’t be able to see the enemy plane no matter what canopy is used?

EDIT: and doesn’t the F-35 have a HUD that lets you look through the plane, meaning the canopy could be painted over and not change fighting ability?

The F-16 was the first one piece canopy + windshield. The frame separating the two is called a “canopy bow”. Pronounced like the decoration on a gift, not like the front of a ship.

Since that time the F-22 and F-35 have one piece canopies. The F-35 is weird in that the whole windshield + canopy unit pivots like the other two, but there is a (narrow) windshield bow incorporated into the moving unit.

The F-18 was a virtual contemporary of the F-16 and has the traditional separate fixed windshield and pivoting canopy. Other countries’ aircraft from at/after the F-16 era are a mix.
Lack of a bow is a huge boon to visibility. OTOH, now the much larger structure needs to survive 600mph birdstrikes without all that metal nearby to support it. It also has to have certain bullet & AAA shrapnel resistant properties. So it has to be real thick. Thick curved transparent surfaces pose optical issues.

Especially directly in front of the pilot’s line of sight you want the windshield/canopy to be very optically flat. That way things look like where they really are, not elsewhere after being refracted through a curved lens. Keeping the pilot, the HUD, and the outside world correctly aligned is the only way to hit what you’re aiming at.

Manufacturing a one piece canopy with all that capability was beyond state of the art prior to the F-16. As a result they were stunningly expensive. Which also meant that, unlike a traditional thin canopy, if it got badly scratched we put up with it. A traditional canopy could be polished out, or replaced much more cheaply. USAF has a big budget in the aggregate, but pennies are pinched all up and down the line.

Historically canopy mechanisms have been problematic. Sometimes they pop open and sometimes they refuse to open. Redundancy is expensive in both $ and performance and not much used in the fighter biz.

Having the canopy come off in flight from an e.g. F-18 is not good news, but it’s usually survivable since the windshield is still in front of the pilot. If the canopy comes off an F-16 the pilot is sitting atop a 500mph windshield-less motorcycle. His/her arms are promptly pulled out into the wind and the shoulders broken as they flail behind/alongside the seat. Nobody has the strength to pull their arms back in against the wind. Sucks to be you.

If the F-16 canopy cannot open the seat cannot eject. In fighters with windshields there are provisions to either shatter the plastic with embedded det cord or simply to eject through it, with blades on the top of the seat partly clearing the way through what’s effectively a brittle shatter-prone material. In the F-16 the canopy is far too rugged to blow up or break through. It’s gotta be that extra tough to survive the birds since it’s also the windshield.

For ground rescue after a fire or crash landing or such a traditional canopy can be opened with a quick squirt of fire extinguisher CO2 to embrittle it, and a quick whack with a crash axe. The F-16 canopy has to be cut apart slowly with a power saw. The Lexan tends to melt welding the kerf closed behind the saw. It also takes a long time. Certainly more than is available if there’s a fire nearby. Sucks to be you.

In all there are plusses and minuses to one-piece canopies. Which explains why they’re not one-offs, but they’re not all that common either.
IMO yellowjacketcoder overstates the degree to which outside vision is obsolete.

The F35’s all aspect synthetic vision projected onto the helmet visor *might *reduce the adverse impact of a canopy bow. But it’s not quite as magic as the breathless press rreleases make it sound. If the pilot points his face down between his knees he doesn’t “see” through the aircraft. Instead he sees symbology that represents the known targets, nav info, etc., appropriate to that direction. Superimposed over a low-res general IR view. See AN/AAQ-37 Electro-optical Distributed Aperture System - Wikipedia for more.

Cool stuff? Hell yes! 20/20 X-ray vision? Nope. Not yet anyway.

During the 1982 non-war between Israel and Syria during the former’s invasion of Lebanon, there was a major air war over the Bekaa (Beqaa) Valley in E. Lebanon.

The Israeli’s wiped out most of the Syrian jets without a single loss.

The Israeli pilots never targeted a Syrian jet visually. It was all electronics. See a blip on the screen. Hit the “make that blip go away” button. Blip goes away.

Israeli electronics played an important role in the overall ‘kill chain’, just as electronics have in aerial warfare since at least the British long range air defense radar network ‘Chain Home’ in 1940. However, actual kills by Israeli fighters in the 1982 engagements were almost all within visual range. One source gives 8 by guns, 54 by IR missiles (two inherently ‘WVR’ weapons, at least IR missiles were back then) and 12 by radar guided missiles (US AIM-7’s) for a slightly lower total than sometimes quoted. Around 1/2 the radar guided missiles were launched beyond visual range (BVR). A slightly higher % of US/coalition kills in the 1991 war were BVR, varying depending how you count head on engagements where the missiles were launched BVR but the launching pilot spotted the target at or before the missile warhead’s detonation.

In general the higher performance of jets meant that visibility (and pilot eyesight capability) got more important in post WWII fighter combat not less. Because fighters were going faster and faster, their turning circles got bigger and bigger (even with higher sustained g’s), so they got further apart during combat than in WWII (let alone WWI) and easier to lose sight of during combat. But their weapons could hit at least as far as they could see, unlike WW’s or Korean War fighter weapons, so it was typically even more important to see the enemy first, though it had always been important, and be able to keep track of him visually at longer range.

It is arguable that has finally begun to reverse as fighter aerodynamic performance has leveled off in last couple of decades, whereas it’s more realistic to assume fighters will actually frequently engage beyond visual range. That’s been technically possible since at least the 60’s but tended not to actually happen often because rules of engagement wrt friendly fire tended to prevent it. In recent decades stuff like non-cooperative target recognition technology in radars* and improved infrared imaging systems have made it more likely. But there hasn’t been large scale air combat in last 20+ yrs to prove the full extent of that. And systems like the F-35’s Distributed Aperture System (imaging IR where the pilot can ‘look through the plane’ at all angles) are just reaching service.

*which can read small modulations in the return signal characteristic of particular types of a/c.

LSLGuy, I just want to say that detailed, well-written, and (most importantly) well-informed posts like yours above are the chief reason I love the SDMB. Thanks for your consistently excellent contributions.

@commasense: I feel some obligation to give the taxpayers some value for all the money they spent on my behalf. Thank you one and all. It may have only been a fraction of a penny apiece, but it you all paid for it. I for one am grateful.

@Corry El:'Zactly.

Dogfighting is chasing dots in the haze. Lethal dots. Getting and retaining visual contact with the enemy is as important and vastly *more *difficult than it was in the WWII days.

BVR shooting at blips is big in all-out war against e.g. Russia or China.

For the half-assed but nonetheless expensive US participations in battle of the last 30 years we’re stuck with VID followed by dogfight to shoot. There were workarounds in my era that permitted shooting blips if all our systems were having a good day. I can only assume that has gotten more and better since. But it was *not *something we could plan on having.

Very interestingly Russian doctrine still sees BVR combat as not being useful. Here is anarticle by someone who is Russian/believes in Russkie doctrine.

His final conclusion

Emphasis and question marks on F16 mine.

IIRC the Japanese version of the F16, the Mitsubishi F-2 deleted the single piece canopy.

Correct. The F-2 has a substantially larger forward fuselage to accommodate a (then-unique) AESA radar. So they couldn’t just stick the F-16 canopy on it, and redesigning a one-piece canopy and building tooling for a relatively limited-production aircraft would have been prohibitive. Building it for the F-16 was also expensive for the reasons LSL mentioned, but mitigated somewhat due to the huge production runs.

Interesting info from the Russians. That’s more detail than I had read in years.

One factor that’s perhaps not accounted for is that at various times and places the shot doctrine is to fire, watch it go for a few seconds and then fire a second round before the first one has gotten to the target.

The intent of course is that whatever the theoretical P[sub]k[/sub] of the missile is, you improve the odds on a successful combat outcome by shooting twice. e.g. two shots with an 80% P[sub]k[/sub] missile naively gives a 96% P[sub]k[/sub] outcome. I say “naïve” because the shots aren’t fully independent; the missiles themselves are, but the rest of the environment that determines success or failure is mostly shared.

At the expense of a) often wasting one or the other missile, and more importantly for this discussion, halving the effective P[sub]k[/sub] scorecard. Two shots one kill or two shots zero kills both make the stats look worse than taking the same single shots at different targets would.
As to control stick ergonomics … I flew the A model. The stick grip had 6 buttons / levers / triggers. Each in a very different place and with different feel and motion(s). It was rather difficult to screw that up.

The C model had a new stick with a couple more multifunction switches on it. That might have been a bridge too far. I don’t recall ever hearing about it being a problem. OTOH, I left the service as the first Cs were coming in. My contact since has been vicarious; yakking with various airline guys who flew/still fly Cs in the Guard. That’s not a real great source for detailed info they’d have to choose to volunteer since I wouldn’t think to ask…

Buck fever is always an issue. Despite the thousands of sorties flown in Kuwait & Iraq, missile shots are still few and far between. Nobody develops proficiency in actually shooting live missiles. OTOH live bomb drops are a dime a dozen and hence folks don’t often make switch errors there.

I read this about a canopy failure on an F22 back in 2006. Pilot was trapped and the canopy would not open. As LSLGuy said back when the thread was fresh; breaking open a one piece canopy is not the easiest thing in the world, in the case linked above, they had to call the Fire Brigade… I take it pulling the ejection handle was not an option?

I’ve been lurking here for a year or three before signing up, and had noticed your expertise and have been impressed, informed and entertained.

But I am in awe of this one. I wish I could say it’s because I knew these things,but I can’t:o

My admiration for this response is based on my own experience as an expert in a field, trying to convey information to laymen or novices.

The clarity, brevity and organization of your remarks make for easy reading and comprehension.

I have clarity and knowledge, but I was blessed with brevity like Rosanne Barr was blessed with poise and good looks.:smiley:

Down boy. I believe LSLGuy is married.:stuck_out_tongue:

Interesting that that news link is still fully intact. It’s amazing how many 11 year old cites are 404 instead.

I know exactly zero about the specifics of the F-22 canopy & ejection system. But building on that article, we can derive a few likely-to-be-facts.

We see the canopy is one piece and from the “after” pix we see it’s pretty thick. So the ol’ CO2 & crash axe trick would not be expected to work. The fact they chose to use the sawzall further supports that contention. Rest assured they were following a published procedure in somebody’s tech manual that was sorted out years before by Lockheed’s engineers. This isn’t ad libbery.

Which leads to the conclusion that ejecting through it a stuck canopy won’t succeed. What would happen instead is a good question.

In the case of the F-16, pulling the seat ejection handle armed a couple things on the seat then it directly fired only the canopy jettison system. If, and only if, the canopy departed the aircraft would a ripcord attached to the canopy pull the pin that fired the seat. I will speculate that the F-22 arrangement is substantially the same.

This leads to three failure modes times two circumstances, only two of which are relevant to this event and neither is a real good outcome:

If you choose to eject and pull the handle and the canopy leaves but the seat doesn’t, what next? On the ground you can climb out, hoping like hell the seat doesn’t fire before you get out of the way. In the air you’re screwed; ride it in.

If you choose to eject and pull the handle and absolutely nothing happens, what next? On the ground you sit there waiting for the fire department to cut you out, hoping like hell the canopy and/or seat doesn’t fire while they’re working. In the air you’re screwed; ride it in.

If you choose to eject and pull the handle and the canopy ejectors fire but the canopy doesn’t depart the aircraft, what next? On the ground you sit there waiting for the fire department to cut you out, hoping like hell the now fully-armed seat doesn’t fire while they’re working. Meantime you’re sitting in a small space full of noxious gases. And may have had your eardrums shattered by the pressure spike when the charges fired in the enclosed space which didn’t quickly become an open space. In the air you’re screwed; ride it in.

You’ll notice very few happy outcomes in that list.

Given that they’d already tried to open the canopy via the normal electrical motor means and (presumably) the backup hand-crank means without success, it’s a good bet the locking mechanism has disconnected somehow or jammed. Hitting that mechanism with a pyrotechnic sledgehammer has real low odds of success.

When you’re in a hole, rule #1 is “Stop digging.” Where that me and the airplane was not on fire I’d do as they did: don’t try to eject; instead wait for the fire department.

If OTOH the airplane as on fire big-time I’d give ejection a try. But with the clear understanding that I’m very likely committing suicide to avoid being killed. Some days it sucks to be you.


ETA: I just gave LSLGuy a smooch yesterday for the quality of his posts. This PDA is getting out of hand.

Fighter planes are not immune to ground fire, especially when forced into close support roles.

I would guess replacing a ruined canopy is cheaper than replacing a ruined canopy and cockpit interior. After all, ejection sets are literally rocketed out and flames licking over a control panel however momentarily can’t do it any good. Most of the time an election system is activated, the plane’s gonna die anyway so I doubt preserving the interior is on the list of things to consider.

It would have been cool, though.

Posting to say thanks for the insightful and well written post on LSLGUY’s part. That was highly informative. I always want this guy to respond to my posts, I always get a viable answer!

Question though, Is there a limit to the depth and breadth of the scratches that will cause the USAF to scrap the canopy out of safety concerns? 600MPH and a scratch could easily become an instant crack, can’t it?

Thanks. I do presume, that with the Raptor, and F16 style canopies, the old WW2 and possibly early Jet age solution of “shoot the canopy with your pistol and then bail” is not an option.

Why did they not go for an explosive charge laden canopy like with the Harrier