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- Joined: 01 Oct 2003, 03:48
TC-I'm curious Kevin, as to the physiology of punching out at Mach 3+, and at 85K+. Would seem to me, that with very little air up there, and with a full pressure suit on, that windblast would not be a problem, right? Also, this would hopefully prevent flail injuries, associated with Mode 2 and 3 ejections. Dunno if you know of this story or not. There are two very similar ones that happened about 2 years apart. In 1993, a student F-15 pilot, Jon Council, was taking his initial solo F-15 flight, to signify graduation from F-15 training at Tyndall AFB. During the flight, while going supersonic, I believe there was an engine fire, and no time to slow the jet down. He was forced to bail out, going well over Mach 1. Albeit heavily injured, he survived the ejection, and was able to eventually return to flying status. The other story, that of former USAF Capt. Brian Udell, I'm sure you're very familiar with. But, those two stories can clearly show the difference between bailing out at high speed and heavy wind resistance, rather than high speed, and little to no air resistance.
This issue belongs in its own thread I think so I am starting this one.
You are quite correct about the difference. The SR-1 seat is considered a Low-Q seat where Q is dynamic pressure. Q is the force of the wind blast on the seat/man configuration usually in foot pounds of pressure. The SR-71 does indeed go Mach 3+, but basically never exceeds about 450 Knots Equivelant Air Speed (KEAS). The issue is that as the air gets thinner with altitude, the air pressure at a given ground speed drops. Below 10,000 ft there is a minimal change, but it still does change.
So, the SR-71 is tooling along at about 2000mph, but the TDI (Triple Display Indicator) might read 400KEAS, 78000ft, Mach 3.2. On ejection the pilot and RSO would experience forces similar to a plane flying 400kts below 10000ft. They would also experience the different phenomenom of aerodynamic heating. The air molecules they are encountering are further apart, leading to the lower pressure, but they are also still relatively moving at 2000mph to the speed of the crew (confusing sentence, but it seems it would make less sense if I said it the other way- the crew is going 2000mph and the air molecules are stationary- which is the accurate way of describing it.) For this speed/altitude combination, the aerodynamic heating pulse would raise the temperature of the leading edges of the seat and occupant several hundred degrees for a fraction of a second. The pressure suit protects the occupant against this.
For the X-15 seat at 70,000 ft and Mach 4 the heat pulse was expected to be about 600 degrees for example.
Now, there were no ejections from an SR-71 at speed/altitude believe it or not. There was one mishap where a pilot was extracted from the aircraft at nearly top speed, but even there some decelleration had to have occurred before the extraction. That one was where an SR-71 pitched up and disintegrated (aft CG IIRC). The airflow across the forebody was in a near vertical direction due to the pitch up and the vacuum effect tore open the external canopy jettison handle hatch. The handle was whipped out into the airstream and jettisoned the canopies. The violence in the breakup had rendered the pilot unconcious, and killed the RSO. The pilot was next aware of a feeling akin to floating in total whiteout. It took him a few seconds to realize he was freefalling in an inflated pressure suit with the visor fogged. Well, he wasn't technically free-falling as he was descending under the parachute pack mounted drogue. (Lockheed C-2 Modified seat, with piggyback drogue on the parachute.) It turns out the cockpits hit the ground with no seat in the rear, and the seat in the front cockpit. The force of the air whipping through the front cockpit had somehow deployed the drogue. The opening shock of it had broken the lap belt and released the pilot from the seat, extracting him from the cockpit. In the next few seconds something in the aft cockpit struck the seat firing handle and ejected the RSO's body. As he descended the pilot was certain he had not ejected and thus was not sure the parachute would automatically deploy at 10,000ft as it was set to do barostatically. He finally decided to open the visor and risk blacking out from lack of oxygen. As he reached for it, the parachute deployed so he was just at 10kft.
He saw his RSO descending under a parachute, unfortunately he was already beyond help. The RSO's C-2 had functioned perfectly and there were no additional injuries to his body from the ejection sequence.
Now, I wasn't aware of Jon Council's ejection (I have a friend who tracks all ejectees, I track significant issues with ejections, and try to keep track of most ejections), but Udell's story is on my web site under Pilot's Reports. CAPT. Udell was a friend of my mentor, and his story is a great example of two things. First is how much punishment the wall of air can inflict on the human body, and second is how much some people can endure. Udell recieved, if I rememeber correctly, two broken legs, two dislocated arms, a major gash in the back of one thigh, and a hematoma that covered his entire face. There may have been more, but that is more than enough to most people. The legs were broken in mid-calf at the bottom edge of the ejection seat as the wind blast (Q-Force) pushed them back under. The wind force between his legs forced them outwards and on one side the calf guard triangles on his ACES II was bent outward 90 degrees by the force of his leg, and on the other it was bent 45 degrees. On one side his thigh pushed outward on the cast aluminum ejection handle to the point the metal sheared and his leg moved outbound of that, with the jagged metal cutting into his thigh. His arms were both ripped outward and backward dislocating them, although one of them popped back into place sometime before he landed. His helmet and oxygen mask were torn from his head and his face was battered by the wind to the degree that it was swollen 'to the size of a basket ball'. This was at an estimated speed of 780 MPH (why MPH? I can't find anyone who can tell me why this is the published speed. I'll have to get the mishap report someday to see what it says.)
Udell ejected in a vertical dive over the Atlantic Ocean at about 6000ft. He would have been in the water in the seat had he delayed about 0.5 second! His WSO was not as lucky. Although he ejected first, he was killed by the damage to his body from the wind. I won't go into details, but suffice it to say Udell's legs stayed in position on the seat for a fraction of a second longer than his WSO, and that is what saved his life.
On landing Udell did something I find totally amazing. Since most people have a hard time entering the one man life raft in a swimming pool with all four limbs functional I find it mind boggling that he managed to climb into his raft with only one limb working while at sea! He tried to inflate his life raft's additional flotation cells with a hose, but wasn't able to get an air seal on the hose until he grasped his lips with THREE fingers and his thumb. Try that and see how much his face was stretched out of shape.
Udell is not the first person to survive ejection at supersonic speed. That claim goes to George Smith, a F-100 test pilot for NAA. He took some 15 months to get out of the hospital. Udell took 18 months to get back into the pilots seat of a F-15 (with a knee brace...)
There is a Russian test pilot who ejected at Mach 2.5 and wants to claim the title of fastest ejectee. I checked it out and came up with about a 425 KEAS speed for his ejection at some 37,000ft. There are several reasons I won't declare anyone the fastest ejectee. First, you have to compare KEAS to KEAS as far as I am concerned. Second, in most ejections it is subjective to determine the ejection speed. In the MiG pilot case it is based on his recollection of his Mach Meter a second or two before he ejected. In other cases it is based on radar tapes which may or may not have a correlation to the exact second of ejection. Third I don't have information on every ejection in the world. Who knows if the Chinese have a faster ejection, or if the Russians, Ukranians, French, etc.
The Ejection Site
(Gee, now I have to get lunch and wolf it down in less than 10 min!)