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Posted for "Craig Berland" <cberland@systems3.net>:
Long but interesting read.
Craig Berland
[ amazing story of lots of good news after one failure -Rob ]
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. 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 face plate. 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 face plate, try to estimate my height above the
ground, then locate that "D" ring. Just as I reached for the face
plate, I felt the reassuring sudden deceleration of main-chute
deployment.
I raised the frozen face plate 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 mi. 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 face plate 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, 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 min. 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 briefly 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 mi. long and 10 mi. 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 microswitch, not
my departure. Bill Weaver flight tested all models of the Mach-2 F-104
Starfighter and the entire family of Mach 3+ Blackbirds--the A-12,
YF-12 and SR-71. He subsequently was assigned to Lockheed's L-1011
project as an engineering test pilot, became the company's chief
pilot and retired as Division Manager of Commercial Flying Operations. He
still flies Orbital Sciences Corp.'s L-1011, which has been modified
to carry a Pegasus satellite-launch vehicle (AW&ST Aug. 25, 2003, p.56).
An FAA Designated Engineering Representative Flight Test Pilot, he's
also involved in various aircraft-modification projects, conducting
certification flight tests.
"For those who fly....or long to."
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