https://en.wikipedia.org/wiki/Lockheed_U-2
The Lockheed U-2, nicknamed "Dragon Lady", is an American single-jet engine,
ultra-high altitude reconnaissance aircraft operated by the United States Air
Force (USAF) and previously flown by the Central Intelligence Agency (CIA). It
provides day and night, high-altitude (70,000 feet; 21,336 m), all-weather
intelligence gathering. The U-2 has also been used for electronic sensor
research, satellite calibration, and communications purposes.
Early versions of the U-2 were involved in several events through the Cold War,
being flown over the Soviet Union, China, Vietnam, and Cuba. In 1960, Gary
Powers was shot down in a CIA U-2A over the Soviet Union by a surface-to-air
missile. Another U-2, piloted by Major Rudolf Anderson, Jr., was lost in a
similar fashion in the Cuban Missile Crisis of 1962.
The U-2 is one of a handful of aircraft types to have served the USAF for over
50 years. The newest models (TR-1, U-2R, U-2S) entered service in the 1980s. The
current model, the U-2S, received its most recent technical upgrade in 2012.
They have taken part in post-Cold War conflicts in Afghanistan and Iraq, and
supported several multinational NATO operations.
Background
After World War II, the U.S. military desired better strategic aerial
reconnaissance to help determine Soviet capabilities and intentions. Into the
1950s, the best intelligence the American government had on facilities deep
inside the Soviet Union were German Luftwaffe photographs taken during the war
of territory west of the Ural Mountains, so overflights to take aerial
photographs of the Soviet Union began. After 1950, Soviet air defenses
converted for reconnaissance duty such as the Boeing RB-47, were vulnerable to
anti-aircraft artillery, missiles, and fighters. Richard Leghorn of the USAF
suggested that an aircraft that could fly at 60,000 feet (18,300 m) should be
safe from the MiG-17, the Soviet Union's best interceptor, which could barely
reach 45,000 feet (13,700 m). He and others believed that Soviet radar, which
used American equipment provided during the war, could not track aircraft above
65,000 feet (19,800 m).
The highest-flying aircraft available to America and its allies at the time was
the English Electric Canberra, which could reach 48,000 feet (14,600 m). The
British had already produced the PR3 photo-reconnaissance variant, but the USAF
asked for English Electric's help to further modify the Martin B-57 (the
American licensed version of the Canberra) with long, narrow wings, new engines,
and a lighter-than-normal airframe to reach 67,000 feet (20,400 m). Air Research
and Development Command mandated design changes that made the aircraft more
durable for combat, but the resulting RB-57D aircraft of 1955 could only reach
64,000 feet (19,500 m). The Soviet Union, unlike the United States and Britain,
had improved radar technology after the war, and could track aircraft above
65,000 feet (19,800 m).
The design that gives the U-2 its remarkable performance also makes it a
difficult aircraft to fly. It was designed and manufactured for minimum airframe
weight, which results in an aircraft with little margin for error. Most aircraft
were single-seat versions, with only five two-seat trainer versions known to
exist. Early U-2 variants were powered by Pratt & Whitney J57 turbojet engines.
The U-2C and TR-1A variants used the more powerful Pratt & Whitney J75 turbojet.
The U-2S and TU-2S variants incorporated the even more powerful General Electric
F118 turbofan engine.
High aspect ratio wings give the U-2 some glider-like characteristics, with an
engine out glide ratio of about 23:1, comparable to gliders of the time. To
maintain their operational ceiling of 70,000 feet (21,000 m), the early U-2A and
U-2C models had to fly very near their never-exceed speed (VNE). The margin
between that maximum speed and the stall speed at that altitude was only 10
knots (12 mph; 19 km/h). This narrow window is called the "coffin corner",
because breaching either limit would likely cause airflow separation at the
wings or tail. For most of the time on a typical mission the U-2 was flying less
than five knots above stall speed. A stall would cause a loss of altitude,
possibly leading to detection and overstress of the airframe.
Role
High-altitude reconnaissance aircraft
National origin
United States
Manufacturer
Lockheed Skunk Works
Designer
Clarence "Kelly" Johnson
First flight
1 August 1955
Introduction
1957
Status
In service
Primary users
United States Air Force
Central Intelligence Agency (former)
NASA
Republic of China Air Force (former)
Produced
Number built
104
Because of the high operating altitude and the cockpit's partial pressurization,
equivalent to 28,000 feet pressure altitude, the pilot wears a partially
pressurized space suit, which delivers the pilot's oxygen supply and provides
emergency protection in case cabin pressure is lost. While pilots can drink
water and eat various liquid foods in squeezable containers through a
self-sealing hole in the face mask, they typically lose up to six pounds of
weight on an eight-hour mission. Most pilots chose to not take with them the
suicide pill offered before missions. If put in the mouth and bitten, the
After a pilot almost accidentally ingested an L-pill instead of candy during a
December 1956 flight, the suicide pills were put into boxes to avoid confusion.
When in 1960 the CIA realized that a pill breaking inside the cockpit would kill
the pilot, it destroyed the L-pills, and as a replacement its Technical Services
Division developed a needle poisoned with a powerful shellfish toxin and hidden
in a silver dollar. Only one was made because, as the agency decided, if any
pilot needed to use it the program would probably be canceled.
To decrease the chance of developing decompression sickness, pilots breathe 100%
oxygen an hour prior to take off to remove nitrogen from the body. A portable
oxygen supply is used prior to entering the aircraft. Since 2001, more than a
dozen pilots have reportedly suffered the effects of decompression sickness,
including permanent brain damage in nine cases; initial symptoms include
disorientation and becoming unable to read. Factors increasing the risk of
illness since 2001 include longer mission durations and more cockpit activity.
Conventional reconnaissance missions would limit pilot duties to maintaining
flight path for camera photography. Operations over Afghanistan included more
real time activities, such as communication with ground troops, increasing their
bodies' oxygen requirements and the risk of nitrogen bubble formation. U-2
pilots now exercise during oxygen pre-breathing. In 2012, modifications were
initiated under the Cockpit Altitude Reduction Effort (CARE), increasing the
cabin pressure from 3.88 psi to 7.65 psi, a 15,000 foot altitude equivalent. The
urine collection device also was rebuilt to eliminate leakage.
The U-2 remains in front-line service more than 50 years after its first flight
with the current U-2 beginning service in 1980. In the mid-1990s, it was
converted from the U-2R to the U-2S, receiving the GE F118 turbofan engine. This
is due primarily to its ability to change surveillance objectives on short
notice, something that surveillance satellites cannot do. The U-2 outlasted its
Mach 3 replacement, the SR-71, which was retired in 1998. A classified budget
document approved by the Pentagon on 23 December 2005 called for the U-2's
termination no earlier than 2012, with some aircraft being retired by 2007. In
January 2006, Secretary of Defense Donald Rumsfeld announced the U-2's pending
retirement as a cost cutting measure during a larger reorganization and
redefinition of the USAF's mission. Rumsfeld said that this will not impair the
USAF's ability to gather intelligence, which will be done by satellites and a
growing supply of unmanned RQ-4 Global Hawk reconnaissance aircraft.
Specifications (U-2S)
General characteristics
Crew: One
Length: 63 ft (19.2 m)
Wingspan: 103 ft (31.4 m)
Height: 16 ft (4.88 m)
Aspect ratio: 10.6
Empty weight: 14,300 lb (6,486 kg)
Max. takeoff weight: 40,000 lb (18,144 kg)
Performance
Maximum speed: 434 knots (Mach 0.67, 500 mph, 805 km/h)
Cruise speed: 373 knots (Mach 0.56, 429 mph, 690 km/h)
Range: 5,566 nmi (6,405 mi, 10,308 km)
Service ceiling: 70,000+ ft (21,300+ m)
lift-to-drag: 23:1 (maximum)
Flight endurance: 12 hours
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