Comment Re:This is the next step (Score 3, Interesting) 424
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. 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."