One of the most amazing aviation stories I've ever read.
If Aviation Captures you, then you might want to consider reading it.
Mach 3.18 In-Flight Breakup Of An SR-71 Blackbird
Date: Jan. 25, 1966
by Bill Weaver, Chief Test Pilot, Lockheed
Among professional aviators, there's a well-worn saying: Flying is
simply hours of boredom punctuated by moments of stark terror. But 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 specialist, and I were evaluating
systems on an SR-71 Blackbird test from Edwards. 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, reducing 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 airflow 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 seconds. Still trying to communicate with Jim, I blacked out,
succumbing to extremely high g-forces.
Then the SR-71 literally disintegrated around us. From that point, I
was just along for the ride. And 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.
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 somehow I had
separated from the airplane.
I had no idea how this could have happened; I hadn't initiated an
ejection. The sound of rushing air and what sounded like straps
flapping in the wind confirmed I was falling, but I couldn't see
anything. My pressure suit's face plate had frozen over and I was
staring at a layer of ice.
The pressure suit was inflated, so I knew an emergency oxygen cylinder
in the seat kit attached to my parachute harness was functioning. It
not only supplied breathing oxygen, but also pressurized the suit,
preventing my blood from boiling at extremely high altitudes. I didn't
appreciate it at the time, but the suit's pressurization had also
provided physical protection from intense buffeting and g-forces. That
inflated suit had become my own escape capsule.
My next concern was about stability and tumbling. Air density at high
altitude is insufficient to resist a body's tumbling motions, and
centrifugal forces high enough to cause physical injury could develop
quickly. For that reason, the SR-71's parachute system was designed to
automatically deploy a small-diameter stabilizing chute shortly after
ejection and seat separation. Since I had not intentionally activated
the ejection system--and assuming all automatic functions depended on a
proper ejection sequence--it occurred to me the stabilizing chute may
not have deployed.
However, I quickly determined I was falling vertically and not
tumbling. The little chute must have deployed and was doing its job.
Next concern: the main parachute, which was designed to open
automatically at 15,000 ft. Again I had no assurance the
automatic-opening function would work.
I couldn't ascertain my altitude because I still couldn't see through
the iced-up faceplate. There was no way to know how long I had been
blacked-out or how far I had fallen. I felt for the manual-activation
D-ring on my chute harness, but with the suit inflated and my hands
numbed by cold, I couldn't locate it. I decided I'd better open the
faceplate, try to estimate my height above the ground, then locate that
"D" ring. Just as I reached for the faceplate, I felt the reassuring
sudden deceleration of main-chute deployment.
I raised the frozen faceplate and discovered its uplatch was broken.
Using one hand to hold that plate up, I saw I was descending through a
clear, winter sky with unlimited visibility. I was greatly relieved to
see Jim's parachute coming down about a quarter of a mile away. I
didn't think either of us could have survived the aircraft's breakup,
so seeing Jim had also escaped lifted my spirits incredibly.
I could also see burning wreckage on the ground a few miles from where
we would land. The terrain didn't look at all inviting--a desolate,
high plateau dotted with patches of snow and no signs of habitation.
I tried to rotate the parachute and look in other directions. But with
one hand devoted to keeping the face plate up and both hands numb from
high-altitude, subfreezing temperatures, I couldn't manipulate the
risers enough to turn. Before the breakup, we'd started a turn in the
New Mexico-Colorado-Oklahoma-Texas border region. The SR-71 had a
turning radius of about 100 miles at that speed and altitude, so I
wasn't even sure what state we were going to land in. But, because it
was about 3:00 p.m., I was certain we would be spending the night out
here.
At about 300 ft. above the ground, I yanked the seat kit's release
handle and made sure it was still tied to me by a long lanyard.
Releasing the heavy kit ensured I wouldn't land with it attached to my
derriere, which could break a leg or cause other injuries. I then tried
to recall what survival items were in that kit, as well as techniques I
had been taught in survival training.
Looking down, I was startled to see a fairly large animal- perhaps an
antelope- directly under me. Evidently, it was just as startled as I
was because it literally took off in a cloud of dust.
My first-ever parachute landing was pretty smooth. I landed on fairly
soft ground, managing to avoid rocks, cacti and antelopes. My chute was
still billowing in the wind, though. I struggled to collapse it with
one hand, holding the still-frozen faceplate up with the other.
"Can I help you? " a voice said. Was I hearing things? I must be
hallucinating. Then I looked up and saw a guy walking toward me,
wearing a cowboy hat. A helicopter was idling a short distance behind
him. If I had been at Edwards and told the search-and-rescue unit that
I was going to bail out over the Rogers Dry Lake at a particular time
of day, a crew couldn't have gotten to me as fast as that cowboy-pilot
had.
The gentleman was Albert Mitchell, Jr., owner of a huge cattle ranch in
northeastern New Mexico. I had landed about 1.5 mi. from his ranch
house--and from a hangar for his two-place Hughes helicopter. Amazed to
see him, I replied I was having a little trouble with my chute. He
walked over and collapsed the canopy, anchoring it with several rocks.
He had seen Jim and me floating down and had radioed the New Mexico
Highway Patrol, the Air Force and the nearest hospital.
Extracting myself from the parachute harness, I discovered the source
of those flapping-strap noises heard on the way down. My seat belt and
shoulder harness were still draped around me, attached and latched.
The lap belt had been shredded on each side of my hips, where the
straps had fed through knurled adjustment rollers. The shoulder harness
had shredded in a similar manner across my back. The ejection seat had
never left the airplane. I had been ripped out of it by the extreme
forces, with the seat belt and shoulder harness still fastened.
I also noted that one of the two lines that supplied oxygen to my
pressure suit had come loose, and the other was barely hanging on. If
that second line had become detached at high altitude, the deflated
pressure suit wouldn't have provided any protection. I knew an oxygen
supply was critical for breathing and suit-pressurization, but didn't
appreciate how much physical protection an inflated pressure suit could
provide.
That the suit could withstand forces sufficient to disintegrate an
airplane and shred heavy nylon seat belts, yet leave me with only a few
bruises and minor whiplash was impressive. I truly appreciated having
my own little escape capsule.
After helping me with the chute, Mitchell said he'd check on Jim. He
climbed into his helicopter, flew a short distance away and returned
about 10 minutes later with devastating news: Jim was dead. Apparently,
he had suffered a broken neck during the aircraft's disintegration and
was killed instantly.
Mitchell said his ranch foreman would soon arrive to watch over Jim's
body until the authorities arrived. I asked to see Jim and, after
verifying there was nothing more that could be done, agreed to let
Mitchell fly me to the Tucumcari hospital, about 60 mi. to the south.
I have vivid memories of that helicopter flight, as well. I didn't know
much about rotorcraft, but I knew a lot about "red lines," and Mitchell
kept the airspeed at or above red line all the way. The little
helicopter vibrated and shook a lot more than I thought it should have.
I tried to reassure the cowboy-pilot I was feeling OK; there was no
need to rush. But since he'd notified the hospital staff that we were
inbound, he insisted we get there as soon as possible. I couldn't help
but think how ironic it would be to have survived one disaster only to
be done in by the helicopter that had come to my rescue.
However, we made it to the hospital safely--and quickly. Soon, I was
able to contact Lockheed's flight test office at Edwards. The test team
there had been notified initially about the loss of radio and radar
contact, then told the aircraft had been lost. They also knew what our
flight conditions had been at the time, and assumed no one could have
survived. I explained what had happened, describing in fairly accurate
detail the flight conditions prior to breakup.
The next day, our flight profile was duplicated on the SR-71 flight
simulator at Beale AFB, Calif. The outcome was identical. Steps were
immediately taken to prevent a recurrence of our accident. Testing at a
CG aft of normal limits was discontinued, and trim-drag issues were
subsequently resolved via aerodynamic means. The inlet control system
was continuously improved and, with subsequent development of the
Digital Automatic Flight and Inlet Control System, inlet unstarts
became rare.
Investigation of our accident revealed that the nose section of the
aircraft had broken off aft of the rear cockpit and crashed about 10
mi. from the main wreckage. Parts were scattered over an area
approximately 15 miles long and 10 miles wide. Extremely high air loads
and g-forces, both positive and negative, had literally ripped Jim and
me from the airplane. Unbelievably good luck is the only explanation
for my escaping relatively unscathed from that disintegrating aircraft.
Two weeks after the accident, I was back in an SR-71, flying the first
sortie on a brand-new bird at Lockheed's Palmdale, Calif., assembly and
test facility. It was my first flight since the accident, so a flight
test engineer in the back seat was probably a little apprehensive about
my state of mind and confidence.
As we roared down the runway and lifted off, I heard an anxious voice over the intercom.
"Bill! Bill! Are you there?"
"Yeah, George. What's the matter?"
"Thank God! I thought you might have left." The rear cockpit of the
SR-71 has no forward visibility--only a small window on each side--and
George couldn't see me. A big red light on the master-warning panel in
the rear cockpit had illuminated just as we rotated, stating: "Pilot
Ejected." Fortunately, the cause was a misadjusted micro switch, not my
departure.
Last edited: 19-Dec-07 04:23 AM
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