The F-35’s Martin-Baker Ejection Seat

Thanks for that 'brang_it_front' there are some other F-35 stories there that need a tickle please. TAH TIA

Martin-Baker Requalifying F-35 Seat To Accommodate New Helmet
Source: http://aviationweek.com/combat-aircraft ... new-helmet
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More critically, it also had to factor in the new helmets, which are much larger and heavier now because of the new helmet-mounted display model that has replaced the cockpit-mounted head-up display.
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This article is poorly written, misleading to many.

"New helmets, which are much larger and heavier" ... compared to what? We established in another thread that the new Gen III HMD helmet, the subject of this article is lighter than the previous F-35 HMD helmets, AND roughly in the middle of the range of the other helmets currently in use by the USAF / USN on the F/A-18 and F-16 aircraft.

Not only that, but you don't have a pound or two of weight extended away from your head for night vision goggles like you do in an F-18 or an F-16. Question: what happens if you have to eject from a Gen 4 aircraft and you are wearing NVGs? Do you have to remove the NVGs before you eject? Is it safe to eject from a Gen 4 aircraft with NVGs hanging off the front of your head? I mean, that is a not-insignificant amount of weight (NVGs) on a not-insignificant moment arm.

Martin-Baker Requalifying F-35 Seat To Accommodate New Helmet
Source: http://aviationweek.com/combat-aircraft ... new-helmet
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When news of the failures became public, the U.S. Air Force banned pilots who weighed less than 136 lb. from flying the aircraft. One Air Force pilot was reassigned to a different aircraft type as a result.
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As others have pointed out, how difficult would it be for the author to note how many other tactical aircraft and their ejection seats permit pilots less than 136lb to pilot them? (Is not the answer zero?)

Martin-Baker Requalifying F-35 Seat To Accommodate New Helmet
Source: http://aviationweek.com/combat-aircraft ... new-helmet
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The lighter helmet led to a center-of-gravity shift. As for the seat itself, the company has adjusted the software in the seat sequencer, which, as its name suggests, sequences the timings of the various ejection processes, including opening the drogue, releasing the seat and deploying the main parachute.
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Now it's a lighter helmet? Wait a minute... a few paragraphs ago, it was a "much larger and heavier helmet"... now it's a "lighter" helmet? This article is poorly written and confusing at best, misleading at worst.

The article also raises the potential of future versions of the helmet posing a problem even though it also talked about how the fixes actually exceeded requirement. It's not hard to figure out that exceeding the requirement basically created a margin for helmet growth.

Air Force: Removal of F-35 pilot weight restrictions eyed for April
13 Feb 2017 Valerie Insinna

"WASHINGTON — The Air Force could be ready to remove restrictions on lightweight F-35 pilots as early as April, following fixes to the aircraft’s ejection seat and helmet.

But Martin-Baker’s US16E ejection seat is not completely in the clear yet. Even if the newly modified pilot-escape system meets requirements, the service may still press ahead with certifying a second ejection seat as a bulwark against potential risks in the future, said Brig. Gen. Scott Pleus, who heads the Air Force’s F-35 integration office....

...testing of the modified escape system is mostly complete, and the F-35 Joint Program Office (JPO) has provided that data to the Air Force Lifecycle Management Center, which functions as the service’s airworthiness authority, Pleus told Defense News during a Feb. 10 interview.

One last test remains, an “electro-environmental” demonstration scheduled for March that validates that the escape system fires only when triggered. After reviewing the data, Air Force engineers and airworthiness experts will produce a final report, he said....

...“We anticipate that by April, we should have a response from our airworthiness authority,” a role performed by Lt. Gen. John Thompson, Air Force Life Cycle Management Center commander. “If that were to be the case, there would be a series of retrofits that would be required for the seats. That would probably take a few months, and at that point, we would have a capability of opening the pipeline to lightweight student pilots." [grils ]

Martin-Baker and Rockwell Collins have made three major changes to their products in order to make the escape system safe for lightweight pilots.

A new switch in the US16E ejection seat alters the parachute loads to accommodate pilots of different weight ranges, and a head support panel helps protect the head and neck from stress upon ejection. The weight of the Rockwell Collins helmet has also dropped from 5.1 to 4.6 pounds....

...Pleus said. But even if restrictions are lifted, the service may decide to qualify ACES 5 nonetheless.

Given the number of F-35s planned to be purchased by the Air Force — 1,763 in total — Pleus believes that there would be value to qualifying a second seat, in case further problems with the US16E surface later down the road. But service leaders will have to weigh that against the UT ejection seat’s cost and capability, he added.

“If at some point if an issue arises with the Martin-Baker seat, or from a cost effectiveness or safety standpoint, we would make a decision over which was the better seat,” he said. “Right now, we have no data about the ACES 5 seat. Is it safer? It might not be. Is it more expensive or cheaper? I don’t know that.”...

...The JPO had hoped that the service would be able to remove flight restrictions on lightweight pilots by the end of last year, but it took longer than anticipated for the companies and program office to synthesize test data. In September, officials said the program office and Lockheed Martin had already put together a preliminary retrofit strategy and had ordered the parts needed to begin modifying the seats.

It will take about two years for all of the F-35s to move through the pipeline, JPO officials said then."

Source: http://www.defensenews.com/articles/air ... y-as-april

I still think the ACES 5 plan is a USAF ploy to deviate from seat commonality with the USMC, for the purpose of creating more space for pilot head movement.

Not only that, but you don't have a pound or two of weight extended away from your head for night vision goggles like you do in an F-18 or an F-16. Question: what happens if you have to eject from a Gen 4 aircraft and you are wearing NVGs? Do you have to remove the NVGs before you eject? Is it safe to eject from a Gen 4 aircraft with NVGs hanging off the front of your head? I mean, that is a not-insignificant amount of weight (NVGs) on a not-insignificant moment arm.

If they are not down and locked, they will disconnect at like 3G's or something around that…….have had that happen on accident, and it is not great as they will immediately fall to the floor and jam your control stick (in a center stick designed aircraft). If down and locked, they would pop off due to air loads theoretically, but I also know of a couple guys who jumped out at high speed off the coast of San Diego with goggles on, and they lost their helmets in the process. Not sure how much of this was interaction of the NVG's and helmet and air loads, or if it was just simply due to the high speed (nearly supersonic). Standard briefing item during "ejection" is to get the goggles off your helmet if you have the time.

Well the doomsayers will have to find another issue to wring their hands over.

Not only that, but you don't have a pound or two of weight extended away from your head for night vision goggles like you do in an F-18 or an F-16. Question: what happens if you have to eject from a Gen 4 aircraft and you are wearing NVGs? Do you have to remove the NVGs before you eject? Is it safe to eject from a Gen 4 aircraft with NVGs hanging off the front of your head? I mean, that is a not-insignificant amount of weight (NVGs) on a not-insignificant moment arm.

If they are not down and locked, they will disconnect at like 3G's or something around that…….have had that happen on accident, and it is not great as they will immediately fall to the floor and jam your control stick (in a center stick designed aircraft). If down and locked, they would pop off due to air loads theoretically, but I also know of a couple guys who jumped out at high speed off the coast of San Diego with goggles on, and they lost their helmets in the process. Not sure how much of this was interaction of the NVG's and helmet and air loads, or if it was just simply due to the high speed (nearly supersonic). Standard briefing item during "ejection" is to get the goggles off your helmet if you have the time.

Probably the high speed, as the NACES II is limited to 600 Kts on paper. A few MiG-29 pilots have ejected out near supersonic (and actually supersonic) with the Russian style helmets (holes in them) had less aerodynamic loads on the way out.

A F/A-18E pilot out of Oceana ejected at high speed with JHMCS on his helmet, and as I recall the helmet stayed on, but the pilot had a sore neck from the added forces. He was lucky to survive the ejection. NATOPS warnings were updated after the mishap.

I don't really get the whole issue with lightweight pilots and why so much work and money is used to accommodate such pilots. From Martin Baker web page:

Crew boarding mass ranges:
Mk. 10 (a really long list of aircraft): 69.2 – 112.2 kg
Mk. 14 (F-18 and T-45): NACES original - 79.1 to 117.4 kg, NACES P3I - 62.7 to 131.7 kg
Mk. 16 for Rafale: 63.5 to 106.0 kg
Mk. 16 for EF Typhoon: 61.0 to 133.5 kg

Mk. 16 for F-35 (dressed): 57.1 Kg (126 lbs) to 132.4 kg (292 lbs)

So, F-35 ejection seat should accommodate quite a bit lighter and also heavier pilots than most other ejections seats. Is there really need for that? What makes F-35 need to accommodate lighter pilots than other jets? Btw, are there really fighter pilots that weigh even close to 130 kg (285 lbs)? All fighter pilots I've ever seen have been have been way, way smaller than that and would need to carry full infantry combat load to reach that weight.

For a start the requirement was for the weights noted. Technology moves ahead so I'll guess the trendsetters knew the weights could be accommodated. The trick for getting more small women as fighter pilots is to be able to use the seat and with the seat UP (I joke - aren't I naughty). For the heavy hitters one has to acknowledge that HOOMens are getting bigger - taller and fatter - all the time. Throw in their extra gear for fighting under NBCD (nuckclear, biologicatal, chem-trails & something or other) and you have heavy peeps indeed. A-4 pilots of old suffered under an incredible weight of combat survival gear that slowly was removed because 'combat ceased' so to speak. Anyways have a look at some of the heavy-necked USofA fiter pilotes of today to see where things are headed. Females in general will probably make better co-ordinater (I'll be back) F-35 pilots in the air because they do multi tasking well OR so I have heard - many times. But YMMV.

So, F-35 ejection seat should accommodate quite a bit lighter and also heavier pilots than most other ejections seats. Is there really need for that? What makes F-35 need to accommodate lighter pilots than other jets? Btw, are there really fighter pilots that weigh even close to 130 kg (285 lbs)?

I know a few guys in the 250-ish range (tall folks), though I agree, 285 is pretty big even for a "big" guy. I also know a number of girls who are at the light end of the spectrum. On the light side, I've known a few female WSO's who were too light to wear JHMCS. I think that is the realm where most of the problems would come from.

Thank you Spaz and 35_aoa for your insights. So it seems that female pilots are the reason for lower weight limits. I think it's good that women can also become fighter pilots as some might well make very good pilots. Interesting that there are such big fighter pilots around. I've sat and "flown" in F/A-18 simulator (Weapons Tactics Trainer/WTT, you probably know that one 35_aoa) with realistic cockpit (AFAIK) and had no problems with my dimensions (I'm 193 cm/6'4" and was about 100 kg/220 lbs then). So I can see big dudes fitting inside but never thought there were fighter pilots bigger/heavier than me around...

Back in the dim days years ago I read that the data used to make the A-4 cockpit REALLY SMALL was from WWII era when blokes were a lot smaller. Throw in corn fed Americans & others in the 1960s and there was a real problem. Some potential A-4 pilots were disqualified for either being too tall or too small. I have seen evidence of both issues with some pilots at either extreme in the RAN FAA (Fleet Air Arm). I have mentioned that the smaller chap had to sit on an illegal phone book to see over the front to carrier deck land, sometimes he did not have time, or forgot to, relock his seat harness so he would smash his helmet visor into the gunsight during arrest. Tall pilots would likely smash knees/toes during an ejection because leg/thigh length was not below limits. There were other factors. The rocket seat had a weight limit but I don't recall now if that was ever an issue - just some esoterica. One pilot complained that the zero/zero almost ejection was very violent. However the seat did save his life - flying a jet is never going to be a picnic - perhaps the F-35 is one.

Thank you Spaz and 35_aoa for your insights. So it seems that female pilots are the reason for lower weight limits. I think it's good that women can also become fighter pilots...

I would be reluctant to attribute new standards solely to small women pilots. This requirement is also driven by ally cultures that have smaller men than our US corn fed Nebraska farmer kids. There will be light weight Japanese and Korean men pilots as well. Limiting the range of weights unnecessarily will always keep talented individuals from your pool of applicants. I recall how frustrating it was at the USAF Academy that our basketball players were limited to 6ft 6 (? or smaller) when cadets were expected to be aircrew eligible unless by exception (medical track etc.)

Anyway it is not JUST women.... and getting and retaining pilots right now is tough.(Airlines) We need as wide a range as possible from Physics. It doesn`t matter what the F-4/15/16/18 seats were set at .. back in the day..

FWIW,
BP

So, F-35 ejection seat should accommodate quite a bit lighter and also heavier pilots than most other ejections seats. Is there really need for that? What makes F-35 need to accommodate lighter pilots than other jets? Btw, are there really fighter pilots that weigh even close to 130 kg (285 lbs)?

I know a few guys in the 250-ish range (tall folks), though I agree, 285 is pretty big even for a "big" guy. I also know a number of girls who are at the light end of the spectrum. On the light side, I've known a few female WSO's who were too light to wear JHMCS. I think that is the realm where most of the problems would come from.

Some of the astronauts were a tight fit in the T-38, although within technically range for the older seats. The new Mk.16T seats are rated for wider range pilots. At least one Mk. 16T seat was used with a lightweight (apparently female) pilot.

Incidentally, they have been known to use custom lightweight helmets for lighter weight pilots and WSOs, including JHMCS. A waiver or two might be involved. One male F-35 pilot was temporarily grounded until the custom helmet was fitted, and it definitely wasn't LtCol. Christine Mau who uses a standard helmet.