Sunday, May 1, 2011

Mayday! Pilots In Distress Describe 'Punching Out'

Punching Out: Stories Of High-Speed Ejections
Edited By James Cross
Paperback, 336 pages
St. Martin's Griffin
List price: $14.99

William Weaver ? 1966

Over the course of a thirty year career with Lockheed, most of which was spent as a test pilot, I had the opportunity and good fortune to fly some of the most advanced and exciting aircraft of their times. These included all models of the F-104, the first operational Mach 2 fighter aircraft, and the Blackbird family of Mach 3+ airplanes (A-12, YF-12 and SR-71). I had a great many memorable experiences and, although there is a well-known saying that flying is hours of boredom punctuated by moments of stark terror, I don't recall too many periods of boredom on these programs.

By far, the most memorable experience occurred on January 25, 1966 on an SR-71 test flight out of Edwards Air Force Base. Jim Zwayer, a Lockheed Flight Test Reconnaissance and Navigation systems specialist, and I were scheduled to conduct a flight to evaluate these systems and also to investigate procedures to improve high mach cruise performance by reducing trim drag. This involved flying with the center of gravity (CG) further aft than normal, which also reduces longitudinal stability.

We took off from Edwards at 11:20 A.M. and completed the first leg of the mission without incident. After refueling from a KC-135 tanker, we climbed back up to cruising speed and initial cruise-climb altitude (Mach 3.2 and 78,000 ft.) proceeding eastbound on the test plan route. Several minutes after start of cruise, a malfunction of the right inlet automatic control system was experienced and manual control was required to correct the condition.

During supersonic flight, the engine inlet control functions to decelerate air flow in the inlet so that it is at subsonic speed at the face of the engine. This is accomplished by aft translation of the inlet center body spike and modulation of inlet forward bypass doors. These are normally scheduled automatically, as a function of Mach number, to position the normal shock wave (where the air flow becomes subsonic) at a location in the inlet which will provide optimum performance. If the proper inlet scheduling is not maintained, inlet disturbances can occur which result in the shock wave being expelled forward of the inlet. This phenomenon is called an inlet "unstart" and results in an instantaneous loss of thrust on that engine, accompanied by loud, explosive banging noises and violent yawing of the aircraft.

It was once described as like being in a train wreck. Unstarts were not uncommon at that time but with a properly functioning system, the shock wave could be recaptured and normal operation resumed.

Shortly after entering a programmed turn to the right in a 35-degree bank, an unstart occurred on the right side. The aircraft immediately rolled further right and started to pitch up. With the control stick as far left and forward as it would go and no response from the airplane I knew we were in for a wild ride. I tried to tell Jim what was happening and to stay with what was left of the airplane until we reached lower speed and altitude because I didn't think the chances of surviving an ejection under those conditions (Mach 3.18 and 78,800 ft.) were very good.

However, the G forces built up so rapidly that the words came out garbled and unintelligible, as revealed when the cockpit voice recorder was recovered. It wouldn't have made a difference anyway because the cumulative effects of malfunctions combined with reduced stability, higher angle of attack in the turn, speed, altitude, etc., resulted in forces being imposed on the aircraft that exceeded the restoring authority of the flight controls and Stability Augmentation System. Although everything seemed to be happening in slow motion, I was later informed that the time from onset of the event until catastrophic departure from controlled flight was a matter of two to three seconds.

As I was trying to communicate with Jim, I blacked out from the extremely high G forces and, from that point on, was just along for the ride. My next recollection was thinking that I was having a bad dream and hoping that I would wake up and get out of this mess. As I began to regain consciousness, I realized that this was not a dream and that it had really happened. That was disturbing because I was convinced that I could not have survived what had happened, so I thought I must be dead. Then I remember thinking that, since I didn't feel bad ? kind of a detached, euphoric feeling ? being dead wasn't so bad after all. I became fully conscious and realized I was not dead and had somehow become separated from the airplane. I had no idea how this could have happened because I did not intentionally activate the ejection system. I could feel myself falling and could hear the rushing of air and what sounded like straps flapping in the wind, but could not see anything because my pressure suit face plate had frozen over and I was looking out through a layer of ice. The pressure suit was inflated so I knew that the emergency oxygen supply in the seat kit attached to my parachute harness was functioning. This was of critical importance because it not only supplies oxygen for breathing but also for pressurization of the suit which prevents the blood from boiling at those extreme altitudes.

I didn't appreciate it at the time, but with the suit pressurized as it was, I was also provided with physical protection against the intense buffeting and G forces I had been subjected to ? kind of like being in your own escape capsule.

My next thoughts were about stability and my body tumbling at that altitude. If the body starts tumbling at high altitude where there is insufficient air density to resist these motions, centrifugal forces sufficient to cause physical injury can develop. For that reason, our parachute system included a small diameter stabilizing chute designed to deploy automatically shortly after ejection and seat separation. Since I had not intentionally activated the ejection system and assumed all these automatic functions were dependent on initiation of a proper ejection sequence, I was concerned that the stabilizing chute may not have deployed.

However, I was able to determine that I was falling vertically with no tumbling motion, so the little chute had deployed and was doing its job. My next concern was about the main parachute, which is designed to open automatically at fifteen thousand feet. Again, I wasn't sure the automatic opening function was going to operate. I still couldn't see through the iced up face plate so was unable to determine my altitude and didn't know how long I had been blacked out or how far I had fallen. I tried to feel for the manual opening D-ring on the front of my chute harness but, with the suit inflated and my hands numb from the cold, couldn't locate it. Finally, I decided I'd better open the face plate and try to estimate my height above the ground and find the D-ring. Just as I reached up to open the faceplate, I felt a sudden deceleration indicating main chute deployment. It was a reassuring feeling indeed!

Excerpted from Punching Out, edited by James Cross. Copyright 2011 by James Cross. Excerpted with permission of the editor.

Source: http://www.npr.org/2011/04/26/135741235/few-pilots-survive-risky-high-speed-ejections?ft=1&f=5

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