Skunk Works engineers also optimized the A-12 cross-section design
to exhibit a low radar profile. Lockheed hoped to achieve this by
carefully shaping the airframe to reflect as little transmitted
radar energy (radio waves) as possible, and by application of
special paint designed to absorb, rather than reflect, those waves.
This treatment became one of the first applications of stealth
technology, but it never completely met the design goals.
Test pilot Lou Schalk flew the single-seat A-12 on April 24, 1962,
after he became airborne accidentally during high-speed taxi
trials. The airplane showed great promise but it needed
considerable technical refinement before the CIA could fly the
first operational sortie on May 31, 1967 - a surveillance flight
over North Vietnam. A-12s, flown by CIA pilots, operated as part of
the Air Force's 1129th Special Activities Squadron under the
"Oxcart" program. While Lockheed continued to refine the A-12, the
U. S. Air Force ordered an interceptor version of the aircraft
designated the YF-12A. The Skunk Works, however, proposed a
"specific mission" version configured to conduct post-nuclear
strike reconnaissance. This system evolved into the USAF's familiar
SR-71.
Lockheed built fifteen A-12s, including a special two-seat trainer
version. Two A-12s were modified to carry a special reconnaissance
drone, designated D-21. The modified A-12s were redesignated M-21s.
These were designed to take off with the D-21 drone, powered by a
Marquart ramjet engine mounted on a pylon between the rudders. The
M-21 then hauled the drone aloft and launched it at speeds high
enough to ignite the drone's ramjet motor. Lockheed also built
three YF-12As but this type never went into production. Two of the
YF-12As crashed during testing. Only one survives and is on display
at the USAF Museum in Dayton, Ohio. The aft section of one of the
"written off" YF-12As which was later used along with an SR-71A
static test airframe to manufacture the sole SR-71C trainer. One
SR-71 was lent to NASA and designated YF-12C. Including the SR-71C
and two SR-71B pilot trainers, Lockheed constructed thirty-two
Blackbirds. The first SR-71 flew on December 22, 1964. Because of
extreme operational costs, military strategists decided that the
more capable USAF SR-71s should replace the CIA's A-12s. These were
retired in 1968 after only one year of operational missions, mostly
over southeast Asia. The Air Force's 1st Strategic Reconnaissance
Squadron (part of the 9th Strategic Reconnaissance Wing) took over
the missions, flying the SR-71 beginning in the spring of
1968.
After the Air Force began to operate the SR-71, it acquired the
official name Blackbird-- for the special black paint that covered
the airplane. This paint was formulated to absorb radar signals, to
radiate some of the tremendous airframe heat generated by air
friction, and to camouflage the aircraft against the dark sky at
high altitudes.
Experience gained from the A-12 program convinced the Air Force
that flying the SR-71 safely required two crew members, a pilot and
a Reconnaissance Systems Officer (RSO). The RSO operated with the
wide array of monitoring and defensive systems installed on the
airplane. This equipment included a sophisticated Electronic
Counter Measures (ECM) system that could jam most acquisition and
targeting radar. In addition to an array of advanced,
high-resolution cameras, the aircraft could also carry equipment
designed to record the strength, frequency, and wavelength of
signals emitted by communications and sensor devices such as radar.
The SR-71 was designed to fly deep into hostile territory, avoiding
interception with its tremendous speed and high altitude. It could
operate safely at a maximum speed of Mach 3.3 at an altitude more
than sixteen miles, or 25,908 m (85,000 ft), above the earth. The
crew had to wear pressure suits similar to those worn by
astronauts. These suits were required to protect the crew in the
event of sudden cabin pressure loss while at operating
altitudes.
To climb and cruise at supersonic speeds, the Blackbird's Pratt
& Whitney J-58 engines were designed to operate continuously in
afterburner. While this would appear to dictate high fuel flows,
the Blackbird actually achieved its best "gas mileage," in terms of
air nautical miles per pound of fuel burned, during the Mach 3+
cruise. A typical Blackbird reconnaissance flight might require
several aerial refueling operations from an airborne tanker. Each
time the SR-71 refueled, the crew had to descend to the tanker's
altitude, usually about 6,000 m to 9,000 m (20,000 to 30,000 ft),
and slow the airplane to subsonic speeds. As velocity decreased, so
did frictional heat. This cooling effect caused the aircraft's skin
panels to shrink considerably, and those covering the fuel tanks
contracted so much that fuel leaked, forming a distinctive vapor
trail as the tanker topped off the Blackbird. As soon as the tanks
were filled, the jet's crew disconnected from the tanker, relit the
afterburners, and again climbed to high altitude.
Air Force pilots flew the SR-71 from Kadena AB, Japan, throughout
its operational career but other bases hosted Blackbird operations,
too. The 9th SRW occasionally deployed from Beale AFB, California,
to other locations to carryout operational missions. Cuban missions
were flown directly from Beale. The SR-71 did not begin to operate
in Europe until 1974, and then only temporarily. In 1982, when the
U.S. Air Force based two aircraft at Royal Air Force Base
Mildenhall to fly monitoring mission in Eastern Europe.
When the SR-71 became operational, orbiting reconnaissance
satellites had already replaced manned aircraft to gather
intelligence from sites deep within Soviet territory. Satellites
could not cover every geopolitical hotspot so the Blackbird
remained a vital tool for global intelligence gathering. On many
occasions, pilots and RSOs flying the SR-71 provided information
that proved vital in formulating successful U. S. foreign policy.
Blackbird crews provided important intelligence about the 1973 Yom
Kippur War, the Israeli invasion of Lebanon and its aftermath, and
pre- and post-strike imagery of the 1986 raid conducted by American
air forces on Libya. In 1987, Kadena-based SR-71 crews flew a
number of missions over the Persian Gulf, revealing Iranian
Silkworm missile batteries that threatened commercial shipping and
American escort vessels.
As the performance of space-based surveillance systems grew, along
with the effectiveness of ground-based air defense networks, the
Air Force started to lose enthusiasm for the expensive program and
the 9th SRW ceased SR-71 operations in January 1990. Despite
protests by military leaders, Congress revived the program in 1995.
Continued wrangling over operating budgets, however, soon led to
final termination. The National Aeronautics and Space
Administration retained two SR-71As and the one SR-71B for
high-speed research projects and flew these airplanes until
1999.
On March 6, 1990, the service career of one Lockheed SR-71A
Blackbird ended with a record-setting flight. This special airplane
bore Air Force serial number 64-17972. Lt. Col. Ed Yeilding and his
RSO, Lieutenant Colonel Joseph Vida, flew this aircraft from Los
Angeles to Washington D.C. in 1 hour, 4 minutes, and 20 seconds,
averaging a speed of 3,418 kph (2,124 mph). At the conclusion of
the flight, '972 landed at Dulles International Airport and taxied
into the custody of the Smithsonian's National Air and Space
Museum. At that time, Lt. Col. Vida had logged 1,392.7 hours of
flight time in Blackbirds, more than that of any other
crewman.
This particular SR-71 was also flown by Tom Alison, the National
Air and Space Museum's Chief of Collections Management. Flying with
Detachment 1 at Kadena Air Force Base, Okinawa, Alison logged more
than a dozen '972 operational sorties. The aircraft spent
twenty-four years in active Air Force service and accrued a total
of 2,801.1 hours of flight time.
http://www.nasm.si.edu/research/aero/aircraft/lockheed_sr71.htm
