Side by side ejection seat question

[stilton]

On aircraft such as the A6, B52 even the B2 with side by side ejection seats
do both crewmembers always eject simultaneously ?


And if not, what prevents the second 'ejectee' being eviscerated in the rocket plume from the first ?

[wiggy]

Even the dear the old JP was side by side, though no rocket pack, it was a purely gun seat, so no rocket plume, as I suspect is at least one type on your list (the B52?) There was presumably a risk of mechanical interference between the seats on ejection if you went purely simultaneously but no one ever really mentioned it.

As far as seats with rocket packs, firstly on all the ones I knew of the rocket didn't fire until the seat was well up the rails thanks to the gun which gave the seat the initial push.. I however do know of an almost simultaneous double ejection on an F4 (obviously tandem rather than side by side but as a crew you are still quite proximate) with the pilot just going first and as a result the nav suffered superficial burns from the rocket plume from the pilots seat as they both left the aircraft in very close formation with the nav trailing the pilot...not nice for the nav but he certainly wasn't eviscerated.

[Runaway Gun]

They are also biased to boost you in opposite directions. Left to left, right to right (hopefully).

[Wander00]

Canberra rear seats ditto

[Wokkafans]

Is there any compensation for the divergent seat vectors if the aircraft is banked and close to the ground? Are there any mechanisms to take account of similar factors?

[kenparry]

They are also biased to boost you in opposite directions. Left to left, right to right (hopefully).

AFAIK, the side-by-side ones I sat on (JP, Vampire T11, Hunter T7/T8) all had parallel rails. Anyone know better?

[oldmansquipper]

IIRC... On many MB products Sequencing (Either mechanical or electronic) prevents confliction. Divergence is often built into the airframe on seat installation. For the MB upgrade to Cessna A/T 37 historics in Oz, a guide device was retro-fitted to the cockpit structure to make sure the seat did not impact the cockpit canopy framework on exit and also ensured separation.

I know nothing about other manufactures but if its a Chinese seat it will probably have features remarkably like those made by MBA. If you know what I mean....

[Ken Scott]

And if not, what prevents the second 'ejectee' being eviscerated in the rocket plume from the first ?

Not strictly an ac but on the US Gemini spacecraft which used ejector seats instead of an escape rocket the seats were angled at 12 degs from the vertical to ensure that the 2 astronauts diverged during an ejection.

In their case they were departing from a closed pressurised cabin full of 100% oxygen which might have reacted unfavourably with the rocket exhaust! In at least one test the doors also failed to open in sequence & the test manikins went through them on their seats which would've killed any human occupants, this might explain the reluctance of the astronauts to pull the handle on Gemini 6: the engines shutdown after ignition but with a cockpit indication that the rocket had started to lift off. Wally Schirra should've pulled the handle, would've had he been in the sim, but went with his gut instinct that the rocket hadn't moved. The 'right stuff' indeed.

[wiggy]

Kenp, like you I don't recall there being obvious divergence on the JP seats, and I don't recall it ever being mentioned to me as either a stude or an instructor. Certainly if there was one it wasn't big enough to be obvious when you did the seat checks. Of course canting the seats would have resulted in one or both being sat "off vertical.

Ken S, re the comment about Gemini ejections I think it was Tom Stafford who said that due the fact they had been saturated in O2 for some time if they had of ejected they would looked like firecrackers.

[dsc810]

Only slightly related
I recall a T38 Talon (tandem seating) with an engine failure on takeoff where both occupants ejected at the same time and the ejector seats hit each other causing both to malfunction with the inevitable double fatal outcome.

[old,not bold]

When I had my rides in a Hunter T7 (Forward Air Controller course, Chivenor, 1963 or '64, can't remember) the pilot's briefing was succinct and clear; "If I tell you to eject, I'll be gone by the time your brain has registered it, so don't bother asking why, just pull one of the handles."

In that case, simultaneous ejection on parallel rails would probably not have been a problem.

[wiggy]

Only slightly related
I recall a T38 Talon (tandem seating) with an engine failure on takeoff where both occupants ejected at the same time and the ejector seats hit each other causing both to malfunction with the inevitable double fatal outcome.

Sad, sometimes bad stuff happens...

The F-4 had a sort of potential nasty where if the rear seater pulled the handle just before the front seater the rear seater would be going up the rails just as the front seat canopy ejected.... the rear seater would quite possibly "collect" the canopy with probably fatal results. As a result the SOP was if time was short the front seater would eject without warning, leaving the nav to eject PDQ..which in turn is why the nav got burns in the ejection I referred to early in the thread.

[Just This Once...]

No doubt my memory is shot full of holes but I recall that the JP seats were divergent by a few degrees - not to a level that you would notice in the cockpit but with both guns extended the split was visable. The preferred technique though was for sequential ejections, which required a higher safe ejection speed on t/o (120kts?) when flown dual. I think.

[Wander00]

ISTR that the in Gnat the seats were inclined towards each other and if fired together would meet 70 ft above the aircraft. Therefore the instructor need to go first

[wiggy]

No doubt my memory is shot full of holes but I recall that the JP seats were divergent by a few degrees - not to a level that you would notice in the cockpit but with both guns extended the split was visable. The preferred technique though was for sequential ejections, which required a higher safe ejection speed on t/o (120kts?) when flown dual. I think.

Interesting, never saw one with both guns extended...fortunately.

It has been a while but I don't recall any formal minimum speed limit for ejection whilst dual, other than the normal seat limit of 0/90.

[kenparry]

It has been a while but I don't recall any formal minimum speed limit for ejection whilst dual, other than the normal seat limit of 0/90.

With you on that, wiggy.

Somewhere from the back of my mind comes a thought that JP & Hunter 7/8 seats may have been "handed". Anyone remember? If so, it could be that the guns & rails were in matching pairs with an asymmetry on each that canted out the trajectory but had the seats mounted parallel in the cockpit. It's all many years ago and my ageing brain is unable to recall.

The other part of the vague recollection is that the seats may have had a second letter suffix that defined the side they were to be mounted? Anyone know?

[stilton]

Thanks for all the good information, the detail i'm not clear on is when there's a delay before the second seat fires.

The remaining crewmember is still seated in the cockpit when the adjacent seat launches if for only a brief time, surely the rocket efflux would affect him ?

Some responses state that a gun initially fires the seat before the rocket takes over however I thought this was only on much older seats and that newer models provide a far less violent ejection using a rocket.


Which takes me back to my original question !

[Timelord]

Stilton, I think that on even the most modern seats the initial impetus is provided by a gun. Only when the seat has travelled X distance up the rails does the rocket fire.

[Buster Hyman]

Wasn't an issue on the F111...;)

[Just This Once...]

Stilton, I think that on even the most modern seats the initial impetus is provided by a gun. Only when the seat has travelled X distance up the rails does the rocket fire.

Yes a gun or catapult does the initial work before the rockets (if fitted) do their thing. The seat rocket plume can still get very close to other occupants though, but this has to be seen in the context of the emergency itself, potentially rockets firing on the canopy (very close!) or an exploding charge on the transparency (bomb going off by your head). These are all violent events that your protective equipment has to cater for.

[wiggy]

Stilton, it's down to what JTO said.

Regardless of whether you are single seat, side by side or tandem seated an ejection is a really violent event (it has to be, it's too gentle or "soft "you are possibly not going to escape in time) and passenger comfort is not really an issue, survival is all that counts, so a lot of what happens in and around an ejection is designed to be quite close to human tolerances and certainly on older seats you can expect at the very least to get smacked around, bruised, cut or worse, though I believe some newer seats (ACES) claim to be more user friendly.

As far as rocket packs and dual seating is concerned from memory on seats I sat on the gun (sometimes called a catapult) started things moving, the rocket pack fired when the seat is about 6 feet up the rails and it burnt for a very short time (AFAIK well under a second). Even if the two seats end up in close formation, with one in the rocket plume of the other, as in the F4 ejection I keep going on about, your protective equipment (fire resistant suit and under that in theory at least a roll neck shirt/and or a natty scarf, plus helmet, visor, gloves etc) should make the short exposure to the plume survivable in the vast majority of cases...you are not sat there wearing a t-shirt, shorts and a light weight headset.

[SpazSinbad]

More info than anyone needs to know about 2 x side by side ejection seats in an S-3 Viking:

IE-1 escapac: escapac (http://www.ejectorseats.co.uk/escapac.html)

FREE S-3B Viking NATOPS PDF (43.3Mb) http://air.felisnox.com/view.php?name=s3b.pdf

http://i98.photobucket.com/albums/l261/SpazSinbad/NewNewAllBum/S-3B%20Viking%20NATOPS%20ejection%20sequenceFORUM.gif~original (http://s98.photobucket.com/user/SpazSinbad/media/NewNewAllBum/S-3B%20Viking%20NATOPS%20ejection%20sequenceFORUM.gif.html)

[superplum]

From the training days; later seats MB Type 3 or 4 et al accelerate to 88fps (60Mph) in 0.2 sec. Bearing in mind human reactions etc, simultaneous ejection would be difficult to achieve unless thro' a Command Ejection system. Rocket packs achieve the divergence (sideways) by means of "handed" rocket pack venturis.......and remember, the occupant's chute should be opening after approx 2.25 secs (or less) after seat initiation.
:cool:

[Davef68]

Just a pedantic point - I presume the OP means incinerated rather than eviscerated?

[SpazSinbad]

Some NANOsecondary from the S-3B NATOPS....
"...2.25.7.1 Command Ejection. When the command ejection (all crew) option is exercised, the two aft crew seats will eject 0.52 second(s) before the two forward crew seats. This time delay coupled with seat thrust trajectory assures separation between the four crew-members...."
&
"...2.25.3 Lateral Separation System. A system to maintain lateral separation during multicrew command ejection (crew eject) is provided by thrust from a small rocket thruster and the aerodynamic vane. As the seat separates from the aircraft, the aerodynamic vane [see below] is mechanically deployed into the airstream. The vane works in conjunction with the yaw thruster to rotate the seat into a trajectory that ensures lateral separation from the other seat trajectories. The lateral separation system provides a 60-foot distance between the seats during command ejection...."

http://i98.photobucket.com/albums/l261/SpazSinbad/NewNewAllBum/S-3BnatopEjectionSeatAEROvaneFORUM.gif~original (http://s98.photobucket.com/user/SpazSinbad/media/NewNewAllBum/S-3BnatopEjectionSeatAEROvaneFORUM.gif.html)

http://i98.photobucket.com/albums/l261/SpazSinbad/NewNewAllBum/S-3BvikingNATOPSejectionSequenceFORUM.gif~original (http://s98.photobucket.com/user/SpazSinbad/media/NewNewAllBum/S-3BvikingNATOPSejectionSequenceFORUM.gif.html)

http://i98.photobucket.com/albums/l261/SpazSinbad/NewNewAllBum/S-3B%20Viking%20NATOPS%20ejection%20sequence%20TIME%20forum.gi f~original (http://s98.photobucket.com/user/SpazSinbad/media/NewNewAllBum/S-3B%20Viking%20NATOPS%20ejection%20sequence%20TIME%20forum.gi f.html)

[stilton]

Thanks gents for the detailed replies, that does clarify things.


And yes 'incinerated' would have been a better word than 'eviscerated !

[goofer3]

A bit of "flame". Ark Royal, November 1964, and pictures showing "Jane" and two experimental rocket assisted ejection seats. "As the float reached the end of the catapult the seats were fired, the dummies were ejected high into the air and then drifted gently down on their parachutes into the sea where they were rapidly recovered."

http://<a href=http://s981.photobucket.com/user/goofer33/media/MB%20ejection%20seats%20Jane%201%20800_zpslo6z3lte.jpg.html target=_blank>http://i981.photobucket.com/albums/ae294/goofer33/MB%20ejection%20seats%20Jane%201%20800_zpslo6z3lte.jpghttp://i981.photobucket.com/albums/ae294/goofer33/MB%20ejection%20seats%20Jane%201%20800_zpslo6z3lte.jpg
http://i981.photobucket.com/albums/ae294/goofer33/MB%20ejection%20seats%20Jane%202%20800_zpsftimtogx.jpg

[Wetstart Dryrun]

The later marks of Buccaneer lost those rakish good looks

[goofer3]

I don't think they were too confident as they are "both" in prayer mode :E.

[riff_raff]

Early missions flown by space shuttle Columbia had side-by-side ejection seats for the two man crews. The crew members had widely different views regarding these ejection seats.

Here's what STS-1 pilot Bob Crippen had to say: "In truth, if you had to use them while the solids were there, I don’t believe you’d—if you popped out and then went down through the fire trail that’s behind the solids, that you would have ever survived, or if you did, you wouldn't have a parachute, because it would have been burned up in the process. But by the time the solids had burned out, you were up to too high an altitude to use it. ... So I personally didn't feel that the ejection seats were really going to help us out if we really ran into a contingency."

And here's what STS-1 commander John Young had to say: https://youtu.be/JLU4CK7UHd4

[Just This Once...]

Seems an odd thing to say as lots of things are bad 'if still there' when you eject. The engineers thought that pickling-off the solid boosters gave the crew a viable escape system; thoughts that were revisited several years later.

[Traffic_Is_Er_Was]

The F-4 had a sort of potential nasty where if the rear seater pulled the handle just before the front seater the rear seater would be going up the rails just as the front seat canopy ejected.... the rear seater would quite possibly "collect" the canopy with probably fatal results.

The F-14 must have had this too.......RIP Goose!

[Chef Bruz]

In the documentary for the making of Top Gun, it is revealed that the scenario where Goose is lost is based on an actual loss of a RIO in an F14 that was in a flat spin ejecting up into the canopy.

The interesting point is that the scene had to be convincing, as well as throw no bad light on the Navy...

[Traffic_Is_Er_Was]

Funny thing is that in a film full of unconvincing air combat scenes, I find the ejection scene the least convincing.

[stilton]

Unconvincing ?


You can't be serious..

[wiggy]

I'll have to recheck out the Top Gun scene when I've got better internet or I dig out the DVD but TBH I've never seen an ejection scene on TV or film that's been particularly convincing. As I mentioned earlier an ejection can be a really brutal event, and whilst others will no doubt have different opinions I think it's probably v difficult to recreate the sheer speed, violence and noise (especially at high speed ) associated with the real thing. Most dramatised scenes seem to show an unconvincing "pop" or "bang" and somebody being lofted out of the airframes as if by a strong spring ....it is not like that, most certainly not on a rocket seat...........

[SpazSinbad]

A4G pilot reported the violence of ejection at zero/zero more or less - Escapac 1C3

http://www.youtube.com/watch?v=8Hj-RRBm6QA

http://www.youtube.com/watch?v=bz_Pc03Y5zI

http://www.youtube.com/watch?v=eY9KW0nxRSg

[SpazSinbad]

Submitted by: JRJarrell: Viking Lore and Stories (http://www.vikingassociation.com/viking-lore.php)
“Am sure you're aware, or its been pointed out, but the list of "fallen comrades" on the website in the History section is missing several who were lost in Vikings before 1980.

Very quickly, as I recall, the first casualty was an enlisted non-aircrew (and non-seat qualed) [?] plane captain who was riding in the back on a VS-41 ferry flight from NORIS to Burbank. The jet was scheduled to go to 22 and MCPO Harry Maddox of 22 was there waiting for it. And Harry climbed into the cockpit and shut down the jet after the mishap! Jim "Marv" Roy, as MO in 22 then, knows the story better.

My recollection is acft touched down fast and pilots ejected (LCDR Wally Ables and Lt Buck Johnson as I recall) thinking they had brake failure. They weren't injured, but, as only pax in the back, the other seat burned the p/c [plane captain passenger], seat, chute, et al.

Thus the soon to follow NATOPS change prohibiting only one backseater....”
“The design requirement for the S-3 was to have a command escape system that would extract all four crew members from the airplane by activation of either the pilot or copilot ejection seats. The heart of this system was the four Escapac 1E-1 ejection seats. Each seat was tailored to its position, so that the trajectory of the seats would avoid colliding with other crew members or other ejection hardware. This image shows all four test dummies out of the cockpit during the sled test.” http://www.lockheedmartin.com/content/lockheed/us/news/features/2016/C1S3VikingPilot/_jcr_content/center_content/image_4.img.jpg/1478559510524.jpg

http://i98.photobucket.com/albums/l261/SpazSinbad/NewNewAllBum/VikingS-3testEjectionForum.jpg~original (http://s98.photobucket.com/user/SpazSinbad/media/NewNewAllBum/VikingS-3testEjectionForum.jpg.html)

[SpazSinbad]

Four-Crew, Sequenced Ejection System, Zero/Zero to 450 KIAS Ejection Capability [S-3 Viking]:
"The design requirement for the S-3 was to have a command escape system that would extract all four crew members from the airplane by activation of either the pilot or copilot ejection seats.

The heart of this system was the four McDonnell Douglas Escapac 1E-1 ejection seats. Each seat was tailored to its position, so that the trajectory of the seats would avoid colliding with other crew members or other ejection hardware.

The seats were to work from zero airspeed, zero altitude up to 450 KCAS and all crewmembers were to be extracted in less than a second. The front two seats and the rear seats went out in pairs; the rear seats went out first, followed 0.5 second later by the front seats. The rear seats had a wider arc trajectory than the front seats for lateral separation purposes. All seats were designed to fire through the Plexiglas overhead canopy enclosures which is shattered by cutters on the top of the seats.

Development of the escape system took place first in the lab, but was tested with instrumented dummies on a rocket sled at NAS China Lake, California, in about twenty-four different combinations and airspeeds. All ejections at all speeds were successful the first time tested with no redesigns required.

In Service Successes and Failures: Several successful in-envelope ejections occurred from the S-3 over the years of service use. The only glitch was discovered inadvertently, when an ejection from an S-3A landing in Burbank for a factory mod resulted in a fatality.

It was discovered that all the tests had been conducted with both seats occupied, even with the extremes of weight in opposite seats, but no tests had been conducted with one seat empty next to a full seat.

The fatality was caused by a single point failure in the seat-man separation mechanism which prevented the seat to sequence. In addition, it was discovered that the deceased crew member had received severe burns from the rocket in the empty seat. From that point on, either both seats had to be occupied, or ballast was required in the unoccupied seat to avoid the possibility of rocket burns from the empty seat....”
Code One: S-3 Viking Test Pilot Perspective · Lockheed Martin (http://www.lockheedmartin.com/us/news/features/2016/C1S3VikingPilot.html)

[stilton]

Very interesting, so the answer to my original question seems to be yes, the remaining
occupant in the cockpit after an ejection can be badly hurt or even killed if the system is not operated as planned.

[izod tester]

"The F-4 had a sort of potential nasty where if the rear seater pulled the handle just before the front seater the rear seater would be going up the rails just as the front seat canopy ejected.... the rear seater would quite possibly "collect" the canopy with probably fatal results. "

This was in fact a real nasty - XV397 on 1 June 1973. The navigator who had initiated ejection first was struck by the pilot's canopy. Thereafter, the RAF Phantom sop was for the pilot to announce the need for ejection by doing so.

[Harley Quinn]

Very interesting, so the answer to my original question seems to be yes, the remaining
occupant in the cockpit after an ejection can be badly hurt or even killed if the system is not operated as planned.

I think that is a standard consequence of (military) aviation.

[Madbob]

Stilton


I don't have any definitive information but a U2 (T-bird) crashed in September 2016 in California the instructor was killed even when video shot at the time showed two ejections and two parachutes, which appeared to have opened normally at a good height (i.e. well above the ground).


I can only speculate that the rear seater may have struck the front seater's canopy (or his seat) and being killed as a result. There's a thread on PPruNe with the photos I refer to. I have not seen any accident report published but I am hardly going to be on a distribution list to receive one!




MB

[wiggy]

This was in fact a real nasty ( F-4, front canopy etc)

Yes, I was aware that there had indeed been sadly been a real case on the RAF F-4 of a front canopy/rear seat occupant collision with fatal results.........

the RAF Phantom sop was for the pilot to announce the need for ejection by doing so.

Certainly that was the standard brief for "time critical" ejections....as I recall it there was a bit of latitude if the problem was less time critical but yes, if in any doubt at all the front seater went first without any announcement.

Of course it didn't always quite work out as briefed... :oh:

stilton...<< ......even killed if the system is not operated as planned>>.
HQ: "I think that is a standard consequence of (military) aviation".

Harley; agreed, no startling revalation or mystery to it.

[stilton]

Clever H Quinn !


Your 'summary' ignores the original question, if you re-read it you might get the point.


Thanks for the other informative replies.

[Treble one]

If there is a command eject option in a two seater and it's set to 'both' presumably whoever pulls first goes first????

[Timelord]

Not so in the GR4. Whoever pulls the handle the back seater goes first (0.3 secs delay) and then the front seater (0.7 secs delay). And the trajectories are offset left and right.

[SpazSinbad]

Tandem Seat TA-4 Ejection Sequence Switch from NATOPS manual

http://i98.photobucket.com/albums/l261/SpazSinbad/NewNewAllBum/TA-4ejectionSelectSwitchNATOPSforum.gif~original (http://s98.photobucket.com/user/SpazSinbad/media/NewNewAllBum/TA-4ejectionSelectSwitchNATOPSforum.gif.html)

[nipva]

And the trajectories are offset left and right.

And if at low level, from experience, you land about 100m apart

[Treble one]

Thanks for the information gentlemen

Glad you are able to tell the tale nipva....

TO