Thought you might enjoy reading this article sent to me days ago! LONG, BUT A GREAT READ!
Bill Weaver : SR-71 BREAKUP
Among professional aviators, there's a well-worn saying: Flying is simply
hours of boredom punctuated by moments of stark terror. And yet, I don't
recall too many periods of boredom during my 30-year career with Lockheed,
most of which was spent as a test pilot.
By far, the most memorable flight occurred on Jan. 25, 1966. Jim Zwayer, a
Lockheed flight test reconnaissance and navigation systems specialist, and I
were evaluating those systems on an SR-71 Blackbird test from Edwards AFB,
Calif. We also were investigating procedures designed to reduce trim drag
and improve high-Mach cruise performance. The latter involved flying with
the center-of-gravity (CG) located further aft than normal, which reduced
the Blackbird's longitudinal stability.
We took off from Edwards at 11:20 a.m. and completed the mission's first leg
without incident. After refueling from a KC-135 tanker, we turned eastbound,
accelerated to a Mach 3.2-cruise speed and climbed to 78,000 ft., our
initial cruise-climb altitude.
Several minutes into cruise, the right engine inlet's automatic control
system malfunctioned, requiring a switch to manual control. The SR-71's
inlet configuration was automatically adjusted during supersonic flight to
decelerate air flow in the duct, slowing it to subsonic speed before
reaching the engine's face. This was accomplished by the inlet's center-body
spike translating aft, and by modulating the inlet's forward bypass doors.
Normally, these actions were scheduled automatically as a function of Mach
number, positioning the normal shock wave (where air flow becomes subsonic)
inside the inlet to ensure optimum engine performance.
Without proper scheduling, disturbances inside the inlet could result in the
shock wave being expelled forward--a phenomenon known as an "inlet unstart."
That causes an instantaneous loss of engine thrust, explosive banging noises
and violent yawing of the aircraft--like being in a train wreck. Unstarts
were not uncommon at that time in the SR-71's development, but a properly
functioning system would recapture the shock wave and restore normal
operation.
On the planned test profile, we entered a programmed 35-deg. bank turn to
the right. An immediate unstart occurred on the right engine, forcing the
aircraft to roll further right and start to pitch up. I jammed the control
stick as far left and forward as it would go. No response. I instantly knew
we were in for a wild ride.
I attempted to tell Jim what was happening and to stay with the airplane
until we reached a lower speed and altitude. I didn't think the chances of
surviving an ejection at Mach 3.18 and 78,800 ft. were very good. However,
g-forces built up so rapidly that my words came out garbled and
unintelligible, as confirmed later by the cockpit voice recorder.
The cumulative effects of system malfunctions, reduced longitudinal
stability, increased angle-of-attack in the turn, supersonic speed, high
altitude and other factors imposed forces on the airframe that exceeded
flight control authority and the Stability Augmentation System's ability to
restore control.
Everything seemed to unfold in slow motion. I learned later the time from
event onset to catastrophic departure from controlled flight was only 2-3
sec. Still trying to communicate with Jim, I blacked out, succumbing to
extremely high g-forces. The SR-71 then literally disintegrated around us.
From that point, I was just along for the ride.
My next recollection was a hazy thought that I was having a bad dream. Maybe
I'll wake up and get out of this mess, I mused. Gradually regaining
consciousness, I realized this was no dream; it had really happened. That
also was disturbing, because I could not have survived what had just
happened. Therefore, I must be dead. Since I didn't feel bad--just a
detached sense of euphoria--I decided being dead wasn't so bad after all.
AS FULL AWARENESS took hold, I realized I was not dead, but had somehow
separated from the airplane.
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Thought you might enjoy reading this article sent to me days ago! LONG, BUT A GREAT READ! Bill Weaver : SR-71 BREAKUP Among professional aviators, there's a well-worn saying: Flying is simply hours of boredom punctuated by moments of stark terror. And yet, I don't recall too many periods of boredom during my 30-year career with Lockheed, most of which was spent as a test pilot. By far, the most memorable flight occurred on Jan. 25, 1966. Jim Zwayer, a Lockheed flight test reconnaissance and navigation systems specialist, and I were evaluating those systems on an SR-71 Blackbird test from Edwards AFB, Calif. We also were investigating procedures designed to reduce trim drag and improve high-Mach cruise performance. The latter involved flying with the center-of-gravity (CG) located further aft than normal, which reduced the Blackbird's longitudinal stability. We took off from Edwards at 11:20 a.m. and completed the mission's first leg without incident. After refueling from a KC-135 tanker, we turned eastbound, accelerated to a Mach 3.2-cruise speed and climbed to 78,000 ft., our initial cruise-climb altitude. Several minutes into cruise, the right engine inlet's automatic control system malfunctioned, requiring a switch to manual control. The SR-71's inlet configuration was automatically adjusted during supersonic flight to decelerate air flow in the duct, slowing it to subsonic speed before reaching the engine's face. This was accomplished by the inlet's center-body spike translating aft, and by modulating the inlet's forward bypass doors. Normally, these actions were scheduled automatically as a function of Mach number, positioning the normal shock wave (where air flow becomes subsonic) inside the inlet to ensure optimum engine performance. Without proper scheduling, disturbances inside the inlet could result in the shock wave being expelled forward--a phenomenon known as an "inlet unstart." That causes an instantaneous loss of engine thrust, explosive banging noises and violent yawing of the aircraft--like being in a train wreck. Unstarts were not uncommon at that time in the SR-71's development, but a properly functioning system would recapture the shock wave and restore normal operation. On the planned test profile, we entered a programmed 35-deg. bank turn to the right. An immediate unstart occurred on the right engine, forcing the aircraft to roll further right and start to pitch up. I jammed the control stick as far left and forward as it would go. No response. I instantly knew we were in for a wild ride. I attempted to tell Jim what was happening and to stay with the airplane until we reached a lower speed and altitude. I didn't think the chances of surviving an ejection at Mach 3.18 and 78,800 ft. were very good. However, g-forces built up so rapidly that my words came out garbled and unintelligible, as confirmed later by the cockpit voice recorder. The cumulative effects of system malfunctions, reduced longitudinal stability, increased angle-of-attack in the turn, supersonic speed, high altitude and other factors imposed forces on the airframe that exceeded flight control authority and the Stability Augmentation System's ability to restore control. Everything seemed to unfold in slow motion. I learned later the time from event onset to catastrophic departure from controlled flight was only 2-3 sec. Still trying to communicate with Jim, I blacked out, succumbing to extremely high g-forces. The SR-71 then literally disintegrated around us. From that point, I was just along for the ride. My next recollection was a hazy thought that I was having a bad dream. Maybe I'll wake up and get out of this mess, I mused. Gradually regaining consciousness, I realized this was no dream; it had really happened. That also was disturbing, because I could not have survived what had just happened. Therefore, I must be dead. Since I didn't feel bad--just a detached sense of euphoria--I decided being dead wasn't so bad after all. AS FULL AWARENESS took hold, I realized I was not dead, but had somehow separated from the airplane.