Downwards ejection seats: the arguments in favour of them

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msxyz

Senior Airman
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Jul 17, 2012
Downwards ejection seats were employed in a few aircrafts of the '50s but they disappeared once the upwards firing ejection seats reached a certain maturity.

It's often assumed that engineers developed this method of abandoning an airplane solely because, above a certain speed, upwards ejection seats would not guarantee that the occupant will avoid an impact with the vertical rudder. And yet there must be other advantages that such system would have.

-Less energy involved. Ejecting upwards means that both gravity force and the airstream wash are pushing you against the fuselage (not to mention the looming vertical rudder at the back). Ejecting downwards gravity and air pressure are actually helping you gaining some distance from the plane.

-Less stressful on internal organs and spinal cord: as a consequence of the first point, you don't need a very powerful and sudden thrust to leave the cabin. The direction of the thrust also does not compress the spinal cord and the organs.

-Simple/More reliable? I'm thinking about the fact that also the canopy (or the cabin's roof) must be jettisoned. It means another ejection mechanism that must activate split seconds before the seat . A trapdoor unlocking and opening backwards (or being pushed by the seats itself) looks a simpler and more reliable mechanism.

Are there any other points I've missed?
 
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SaparotRob said:
The only thing I can think of is the problem of very low altitude ejection with a downward ejection seat.
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Sure: that's why you read that downwards firing ejection seats were unpopular with the crews. (Yet you don't hear any complaint by civil pilots about NOT having any ejection seat at all ). The minimum altitude for downwards firing ejection seats is around 1000ft or 300m which makes these seats not very useful for a botched take-off/landing and almost useless for carrier based aircrafts where most of the accidents happen at these times.
 
Can't make a downward seat zero/zero.... Also the downward seats from the 50's and 60's had minimum altitude restrictions, something like above 500 feet for the B-47. Don't know offhand what the requirements were for the early F-104 and the B-52 downward seats.
 
This is a picture of the Tu-22's seats for the crew (front to back: bomber, pilot, navigator). The trapdoors at the bottom were also used to enter the plane: the seats were lowered to allow the men to climb onto them. The Tu-22 was not the sole Russian aircraft employing a similar scheme.


 
Graeme said:
Bounder was another downward tosser...maybe when you hit the ground, you just 'Bounded' along?
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This nice model of the Myasischev M-50 shows how high those seats hanged from the bottom of the nose



If I had to fly that plane, I would have brought with me a long rope, just in case

Graeme said:
Interestingly, Bear had a conveyor belt...
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Another Myasischev plane, the M-4 had a similarly convoluted ejection scheme. There were five different escape hatches on the lower part of the fuselage, one of which was shared by the pilot, co-pilot and navigator which were ejected downwards in quick succession by a pneumatic system which shuffled the seats around. Other members of the crew had their own escape hatch, each equipped with a downwards firing ejection seat. (The plane also had a couple of hatches on the roof, for ditching at sea or belly landings).
 
msxyz said:
Downwards ejection seats were employed in a few aircrafts of the '50s but they disappeared once the upwards firing ejection seats reached a certain maturity.

Are there any other points I've missed?
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A few things - "Aircraft" is both singular and plural. "Aircrafts" is not a word.
msxyz said:
Yet you don't hear any complaint by civil pilots about NOT having any ejection seat at all
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Ejection seats were designed to remove the pilot from an aircraft that has or will become uncontrollable and more than likely that's going to happen in combat. Military aircraft generally don't glide well so if you have a low level catastrophic engine failure your options are minimal. Most civil aircraft are not going to have that need of emergency egress because the odds of a catastrophic structural failure that would render the airframe unflyable is at a minimum unless you're flying an aerobatic aircraft. I've flown in military aircraft with hot seats and I can tell you I had no intension of punching out unless I saw a wing depart the aircraft. I'll let some of our more military jocks chime in on this. The only GA aircraft with an egress system is the Cirrus SR20/22 series with their ballistic chute (CAPS) system and the only reason this was incorporated was because the aircraft was not put through spin testing during certification. It became a great sales feature.

Downward ejection seats are great at altitude, I think this point is obvious.
 
FLYBOYJ said:
I've flown in military aircraft with hot seats and I can tell you I had no intension of punching out unless I saw a wing depart the aircraft.
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You're not the first pilot that says this and I can understand why. I'm no pilot myself but an engineer and, looking at how they work, I can appreciate why they're truly a 'last ditch' option.

Downward ejection seats are great at altitude, I think this point is obvious.
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They seem to be much better than upwards firing seats in term of safety and comfort. Of course, they are also useless during take off and landings, or during very low altitude manoeuvres. Maybe somebody should try to patent an "all aspect" ejection seat that fires you upwards or downwards depending on the altitude and plane orientation (and with a different acceleration depending on the direction)!
 
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Seat design and operation limit determination is one heck of an engineering task for single direction launch. Adding a second direction would magnify the task significantly. The ACES2 and US-16E cover essentially every survivable launch parameter a pilot might get into. Zero/Zero seats when activated, read all the necessary data, run the launch determination calculations, process the decision and start the launch cycle0, all in a matter of microseconds. From sequence initiation to having the crew member on a chute is under 2 seconds for almost every seat design. Consider too, that depending on the seat and aircraft combination, there could be as many as 30-40 separate actions that have to happen in the correct sequences and timing windows to make a successful ejection.
It's one area where it really is rocket science! Supersonic ejection falls into a class all by itself.

Many years ago, my ultimate boss was fatally injured in an accident. He ejected well outside the parameters of the ACES2, and nearly made it. The differences for him between success and death was less than 1 second within the window of the decision to eject and actually initiating the sequence.
 
I think it was the Russians who first designed a seat that if it was fired and the aircraft was at an angle. The seat would 'recognise' the problem and automatically adjust the seat so it would climb.

Certainly could be wrong but I have something in the back of my mind on that.

The much maligned Yak 38 had an automatic firing ejector seat if the pilot got into difficulties at landing
 
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