The Lockheed YF-12 was an American
Mach
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3+ capable, high-altitude
interceptor
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* Interceptor aircraft (or simply "interceptor"), a type of point defense fighter aircraft designed specifically to intercept and destroy enemy aircraft
* Ford Crown Victoria Police Interceptor, a police car
* ...
prototype
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, developed and manufactured by American
aerospace
Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial and military applications. Aerospace engineering consists of aeronautics and astrona ...
company
Lockheed Corporation
The Lockheed Corporation was an American aerospace manufacturer. Lockheed was founded in 1926 and later merged with Martin Marietta to form Lockheed Martin in 1995. Its founder, Allan Lockheed, had earlier founded the similarly named but ot ...
.
It was developed during the late 1950s and early 1960s as a potential replacement for the
F-106 Delta Dart interceptor for the
United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
(USAF). The YF-12 was a twin-seat version of the then-secret single-seat
Lockheed A-12 reconnaissance aircraft operated by the
Central Intelligence Agency
The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...
(CIA); unlike the A-12, it was furnished with the
Hughes AN/ASG-18 fire-control radar
A fire-control radar (FCR) is a radar that is designed specifically to provide information (mainly target azimuth, elevation, range and range rate) to a fire-control system in order to direct weapons such that they hit a target. They are sometim ...
and could be armed with
AIM-47 Falcon (GAR-9)
air-to-air missile
The newest and the oldest member of Rafael's Python family of AAM for comparisons, Python-5 (displayed lower-front) and Shafrir-1 (upper-back)
An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying a ...
s. Its
maiden flight
The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets.
The maiden flight of a new aircraft type is alwa ...
was on 7 August 1963. Its existence was publicly revealed by President
Lyndon B. Johnson on 24 February 1964; this move was to provide
plausible deniability
Plausible deniability is the ability of people, typically senior officials in a formal or informal chain of command, to denial, deny knowledge of or responsibility for any damnable actions committed by members of their organizational hierarchy. Th ...
for the CIA-operated A-12 fleet, which closely resembled the prototype YF-12.
During the 1960s, the YF-12 underwent flight evaluations by the USAF, but funding to put it into operational use was not forthcoming partly due to the pressing demands of the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
and other military priorities. It set and held speed and altitude world records of over and over (later surpassed by the closely-related
SR-71 Blackbird
The Lockheed SR-71 "Blackbird" is a long-range, high-altitude, Mach 3+ strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Corporation. It was operated by the United States Air Force ...
), and is the world's largest, heaviest and fastest crewed interceptor. Following its retirement by the USAF, it served as a research aircraft for
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
for a time, which used it to develop several significant improvements in control for future supersonic aircraft.
Design and development
In the late 1950s, the
United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
(USAF) sought a replacement for its
F-106 Delta Dart interceptor. As part of the Long Range Interceptor Experimental (LRI-X) program, the
North American XF-108 Rapier, an interceptor with Mach 3 speed, was selected. However, the F-108 program was canceled by the
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in September 1959.
[Pace 2004, pp. 45–46.] During this time, Lockheed's Skunk Works was developing the A-12
reconnaissance aircraft
A reconnaissance aircraft (colloquially, a spy plane) is a military aircraft designed or adapted to perform aerial reconnaissance with roles including collection of imagery intelligence (including using photography), signals intelligence, as ...
for the U.S.
Central Intelligence Agency
The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...
(CIA) under the ''Oxcart'' program.
Kelly Johnson, the head of Skunk Works, proposed to build a version of the A-12 named AF-12 by the company; the USAF ordered three AF-12s in mid-1960.
[Pace 2004, pp. 46–47.]
![YF-12 Forward Chine](https://upload.wikimedia.org/wikipedia/commons/a/a2/YF-12_Forward_Chine.jpg)
The AF-12s took the seventh through ninth slots on the A-12 assembly line; these were designated as ''YF-12A'' interceptors.
[Landis and Jenkins 2005, pp. 40–41.] The main changes involved modifying the A-12's nose by cutting back the chines to accommodate the huge
Hughes AN/ASG-18 fire-control radar originally developed for the XF-108 with two
infrared search and track sensors embedded in the chine leading edge, and the addition of the second cockpit for a crew member to operate the fire control radar for the
air-to-air missile
The newest and the oldest member of Rafael's Python family of AAM for comparisons, Python-5 (displayed lower-front) and Shafrir-1 (upper-back)
An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying a ...
system.
The modifications changed the aircraft's aerodynamics enough to require ventral fins to be mounted under the fuselage and engine nacelles to maintain stability. Three of the four bays previously used to house the A-12's reconnaissance equipment were converted to carry Hughes
AIM-47 Falcon (GAR-9) missiles.
[ One bay was used for fire control equipment.
]
The first YF-12A flew on 7 August 1963.[Green and Swanborough, 1988, p. 350.] President Lyndon B. Johnson announced the existence of the aircraft[McIninch 1996, p. 15.] on 24 February 1964.[Air Force Museum Foundation, 1983, p. 133.][McIninch 1996, p. 14.] The YF-12A was announced in part to continue hiding the A-12, its still-secret ancestor; any sightings of CIA/Air Force A-12s based at Area 51 in Nevada could be attributed to the well-publicized Air Force YF-12As based at Edwards Air Force Base
Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is E ...
in California.[ The first public showing of the aircraft was on 30 September 1964 at Edwards.]
On 14 May 1965, the Air Force placed a production order for 93 F-12Bs for its Air Defense Command
Aerospace Defense Command was a major command (military formation), command of the United States Air Force, responsible for continental air defense. It was activated in 1968 and disbanded in 1980. Its predecessor, Air Defense Command, was est ...
(ADC).[Pace 2004, p. 53.] However, Secretary of Defense
A defence minister or minister of defence is a cabinet official position in charge of a ministry of defense, which regulates the armed forces in sovereign states. The role of a defence minister varies considerably from country to country; in som ...
Robert McNamara would not release the funding for three consecutive years due to Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
costs.[ Updated intelligence placed a lower priority on defense of the continental US, so the F-12B was deemed no longer needed. Then in January 1968, the F-12B program was officially ended.
]
Operational history
Air Force testing
During flight tests the YF-12As set a speed record of and altitude record of , both on 1 May 1965,[ and demonstrated promising results with its unique weapon system. Six successful firings of the ]AIM-47
The Hughes AIM-47 Falcon, originally GAR-9, was a very long-range high-performance air-to-air missile that shared the basic design of the earlier AIM-4 Falcon. It was developed in 1958 along with the new Hughes AN/ASG-18 radar fire-control system ...
missiles were completed, and a seventh failed due to a gyro failure on one of the missiles. The last one was launched from the YF-12 at Mach 3.2 at an altitude of to a JQB-47E target drone off the ground.[Landis and Jenkins 2005, p. 44.] The missile did not have a warhead but still managed to hit the B-47 directly and take a 4-foot section off its tail. The Air Force considered it a success and ordered 96 aircraft and had an initial budget of $90 million to further testing, but this was withheld by Secretary of Defense McNamara, who on 23 November 1967[Knaack, 1978.] put it towards the much less successful F-106X program that nearly failed.
The successful AIM-47 Falcon missile was increased in size and performance and became the AIM-54 Phoenix missile for the F-14 Tomcat
The Grumman F-14 Tomcat is an American carrier-capable supersonic aircraft, supersonic, twinjet, twin-engine, two-seat, twin-tail, variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experi ...
. The AN/ASG 18 radar was upgraded to become the AN/AWG-9
The AN/AWG-9 and AN/APG-71 radars are all-weather, multi-mode X band pulse-Doppler radar systems used in the F-14 Tomcat, and also tested on TA-3B. It is a very long-range air-to-air system with the capability of guiding several AIM-54 Phoenix ...
and APG-71, which added the ability to track multiple targets.
One of the Air Force test pilots, Jim Irwin
James Benson Irwin (March 17, 1930 – August 8, 1991) was an American astronaut, aeronautical engineer, test pilot, and a United States Air Force pilot. He served as Apollo Lunar Module pilot for Apollo 15, the fourth human lunar landi ...
, would go on to become a NASA astronaut and walk on the Moon.
The program was abandoned following the cancellation of the production F-12B, but the YF-12s continued flying for many years with the USAF and with NASA as research aircraft.
NASA testing
The initial phase of the test program included objectives aimed at answering some questions about implementation of the B-1. Air Force objectives included exploration of its use in a tactical environment, and how airborne early warning and control
Airborne or Airborn may refer to:
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* ''Airborne'' (1962 film), a 1962 American film directed by James Landis
* ''Airborne'' (1993 film), a comedy–drama film
* ''Airborne'' (1998 film), an action film sta ...
(AWACS) would control supersonic aircraft. The Air Force portion was budgeted at US$4 million. The NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
tests would answer questions such as how engine inlet performance affected airframe and propulsion interaction, boundary layer noise, heat transfer under high Mach conditions, and altitude hold at supersonic speeds. The NASA budget for the 2.5-year program was US$14 million.
The YF-12 and SR-71 originally suffered from severe control issues that affected both the engines and the physical control of the aircraft. Wind testing at NASA Dryden and YF-12 research flights developed computer systems that nearly completely solved the performance issues. Testing revealed vortices from the nose chines interfering with intake air, which led to the development of a computer control system for the engine air bypasses. A computer system to reduce unstarts was also developed, which greatly improved stability. They also developed a flight engineering computer program called Central Airborne Performance Analyzer (CAPA) that relayed engine data to the pilots and informed them of any faults or issues with performance and indicated the severity of malfunctions.
Another system called Cooperative Airframe-Propulsion Control System (CAPCS) greatly improved the control of supersonic aircraft in flight. At such high speeds even minor changes in direction caused the aircraft to change position by thousands of feet, and often had severe temperature and pressure changes. CAPCS reduced these deviations by a factor of 10. The overall improvements increased range of the SR-71 by 7 percent.
Of the three YF-12As, AF Ser. No. 60-6934 was damaged beyond repair by fire at Edwards AFB during a landing mishap on 14 August 1966; its rear half was salvaged and combined with the front half of a Lockheed static test airframe to create the only SR-71C.
YF-12A, AF Ser. No. 60-6936 was lost on 24 June 1971 due to an in-flight fire caused by a failed fuel line; both pilots ejected safely just north of Edwards AFB. YF-12A, AF Ser. No. 60-6935 is the only surviving YF-12A; it was recalled from storage in 1969 for a joint USAF/NASA investigation of supersonic cruise technology, and then flown to the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio
Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater Day ...
on 17 November 1979.[
A fourth YF-12 aircraft, the "YF-12C", was actually the second SR-71A (AF Ser. No. 61–7951). This SR-71A was re-designated as a YF-12C and given the fictitious Air Force Serial Number 60-6937 from an A-12 to maintain SR-71 secrecy. The aircraft was loaned to NASA for propulsion testing after the loss of YF-12A (AF Ser. No. 60–6936) in 1971. The YF-12C was operated by NASA until September 1978, when it was returned to the Air Force.][Landis and Jenkins 2005, pp. 49–55.]
The YF-12 had a real-field sonic-boom overpressure value between 33.5 and 52.7 N/m2 (0.7 to 1.1 lb/ft2) – below 48 was considered "low".[Dugan, James F. Jr]
"Preliminary study of supersonic-transport configurations with low values of sonic boom"
p. 18. NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
Lewis Research Center
NASA John H. Glenn Research Center at Lewis Field is a NASA center within the cities of Brook Park and Cleveland between Cleveland Hopkins International Airport and the Rocky River Reservation of Cleveland Metroparks, with a subsidiary facilit ...
, March 1973. Retrieved: March 2012. (PDF)
Variants
;YF-12A: Pre-production version. Three were built.
;F-12B: Production version of the YF-12A with various improvements such as an increased combat radius from 1,200 to 1,350 nautical miles and an improved fire control system with increased bomber detection range from 100 to 125 miles; canceled before production could begin.
;YF-12C: Fictitious designation for an SR-71 provided to NASA for flight testing. The YF-12 designation was used to keep SR-71 information out of the public domain.[Landis and Jenkins 2005, pp. 49–50.] From 1971 to 1978, 61-7951 was temporarily loaned to NASA from the Air Force as "YF-12C #06937".
Operators
;
*United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
*NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research.
NASA was established in 1958, succeeding t ...
Accidents and incidents
*24 July 1971 YF-12A 60-6936 (Article 1003) was lost in an accident near Edwards Air Force Base, California, United States.
Aircraft on display
;YF-12A
* YF-12A, AF Ser. No. 60-6935 (Article 1002) – at the National Museum of the U.S. Air Force
The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is the ...
, Wright-Patterson AFB
Wright-Patterson Air Force Base (WPAFB) is a United States Air Force base and census-designated place just east of Dayton, Ohio, in Greene and Montgomery counties. It includes both Wright and Patterson Fields, which were originally Wilbur Wri ...
, Dayton, Ohio
Dayton () is the sixth-largest city in the U.S. state of Ohio and the county seat of Montgomery County. A small part of the city extends into Greene County. The 2020 U.S. census estimate put the city population at 137,644, while Greater Day ...
. This aircraft has small patches in its skin, on the starboard side below the cockpit. The patches cover holes caused by the "spurs" of a crewman who had to evacuate the plane after an emergency landing.
* SR-71C, AF Ser. No. 61-7981 (portion of the former YF-12A AF Ser. No. 60-6934) is on display at the Hill Aerospace Museum, Hill AFB, Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
."YF-12A/60-6934."
Hill Aerospace Museum. Retrieved: 16 April 2013.
Specifications (YF-12A)
See also
References
Notes
Citations
Bibliography
* Air Force Museum Foundation Inc. ''US Air Force Museum''. Dayton, Ohio: Wright-Patterson AFB, 1983.
* Donald, David, ed. "Lockheed's Blackbirds: A-12, YF-12 and SR-71". ''Black Jets''. AIRtime, 2003. .
* Drendel, Lou. ''SR-71 Blackbird in Action''. Carrollton, Texas: Squadron/Signal Publications, 1982, .
* Goodall, James and Jay Miller. ''Lockheed's SR-71 'Blackbird' Family''. Hinchley, England: Midland Publishing, 2002, .
* Green, William and Gordon Swanborough. ''The Complete Book of Fighters''. New York: Barnes & Noble, 1988, .
*Jenkins, Dennis R. ''Lockheed Secret Projects: Inside the Skunk Works''. St. Paul, Minnesota: MBI Publishing, 2001, .
*Jenkins, Dennis R. and Tony R. Landis. ''Experimental & Prototype U.S. Air Force Jet Fighters.'' Minnesota, US: Specialty Press, 2008, .
*Knaack, Marcelle Size. ''Encyclopedia of US Air Force Aircraft and Missile Systems: Volume 1 Post-World War II Fighters 1945–1973''. Washington, DC: Office of Air Force History, 1978. .
*Landis, Tony R. and Dennis R. Jenkins. ''Lockheed Blackbirds''. North Branch, Minnesota: Specialty Press, revised ed., 2005, .
*McIninch, Thomas.
. Center for the Study of Intelligence, Central Intelligence Agency, 2 July 1996. Retrieved: 10 April 2009.
*Pace, Steve. ''Lockheed SR-71 Blackbird''. Swindon: Crowood Press, 2004, .
External links
''Mach 3+: NASA/USAF YF-12 Flight Research, 1969–1979'' by Peter W. Merlin (PDF book)
YF-12A Flight Manual
an
YF-12A #60-6935 Photos on SR-71.org
YF-12 fact sheet on USAF Museum site
* NASA videos: ttps://www.youtube.com/watch?v=5SwyJTJagq8 Take-offbr>Mid-air Refueling
The Lockheed Martin YF-12 NASA documentary
{{Authority control
F-012
Lockheed F-12
Twinjets
Tailless delta-wing aircraft
NASA aircraft
Cancelled military aircraft projects of the United States
Low-wing aircraft
Aircraft first flown in 1963