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TEST PILOTS ACCOUNT OF INFLITE BREAK UP (SR 71) (LONG)



 
 
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Old January 29th 06, 03:42 PM posted to rec.aviation.owning
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Default TEST PILOTS ACCOUNT OF INFLITE BREAK UP (SR 71) (LONG)

******************

For those of you who think you have had a wild ride, read this:
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 sat ellite-launch
vehicle. An FAA Designated Engineering Representative
Flight Test Pilot, he's also involved in various
aircraft-modification
projects, conducting certification flight tests.

  #2  
Old January 30th 06, 06:01 AM posted to rec.aviation.owning
external usenet poster
 
Posts: n/a
Default TEST PILOTS ACCOUNT OF INFLITE BREAK UP (SR 71) (LONG)


"caleb" wrote in message
ups.com...
******************

For those of you who think you have had a wild ride, read this:
Bill Weaver : SR-71 BREAKUP



http://www.contrailsmagazine.com/1.3/1.3PDF/Contrails2(SR71).pdf

Copyright 2006 McGraw Hill Companies Inc.


 




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