Lockheed YF-12

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YF-12
YF-12A undergoing flight testing.
Type	Interceptor
Manufacturer	Lockheed Corporation
Designed by	Clarence "Kelly" Johnson
Maiden flight	7 August 1963
Status	Cancelled
Primary user	United States Air Force
Number built	3
Unit cost	US$15-18 million (projected)[1]
Developed from	Lockheed A-12

The Lockheed YF-12 was an American prototype interceptor aircraft, which the United States Air Force evaluated as a development of the highly-secret Lockheed A-12 that also spawned the now-famous SR-71 Blackbird.

Contents 1 Design and development 2 Operational history 2.1 USAF testing 2.2 NASA testing 3 Variants 4 Specifications (YF-12A) 5 YF-12 aircraft on display 6 References 7 See also 8 External links

[edit] Design and development

The United States Air Force (USAF) YF-12 program was a development of the Lockheed A-12 OXCART spy plane designed for the Central Intelligence Agency (CIA) and first flown 26 April 1962, the first YF-12A flew on 7 August 1963.^[2] The existence of the aircraft was not officially revealed until 29 February 1964.^[3] Lockheed was able to interest the US Air Force in the project after the Air Force had been forced to cancel the XF-108 Rapier, a Mach 3-capable interceptor intended to replace the F-106 Delta Dart in service. It was pointed out that an aircraft based on the A-12 would provide a less costly alternative to the XF-108, since much of the design and development work on the YF-12 had already been done and paid for. In 1960, the USAF agreed to take the 11th through 13th slots on the A-12 production line and have them completed in the YF-12A interceptor configuration.

The main changes involved modifying the aircraft's nose to accommodate the Hughes AN/ASG-18 fire-control radar originally developed for the XF-108, and the addition of a second cockpit for a crewmember to operate the fire control radar. The nose modifications changed the aircraft's aerodynamics enough to require ventral fins to be mounted under the fuselage and engine nacelles to maintain stability. Finally, bays previously used to house the A-12's reconnaissance equipment were converted to carry four Hughes AIM-47 Falcon (GAR-9) missiles.^[2]

[edit] Operational history

[edit] USAF testing

During flight tests the YF-12As set a speed record of 2,070.101 mph (3331.505 km/h) and altitude record of 80,257.86 feet (24,462.6 m), both on 1 May 1965,^[3] and demonstrated promising results with their unique weapon system. Six successful firings of the AIM-47 missiles were completed. The last one launched from the YF-12 at Mach 3.2 at an altitude of 74,000 ft (22,677 m) to a JQB-47E target drone 500 feet (152 m) off the ground.^[4]

In 1965 the Air Force placed an order for 93 F-12Bs, but this was cancelled due to budget cuts by Secretary of Defense Robert McNamara. The rationale for the cancellation was, in part, the belief that the Soviet Union did not possess a bomber fast enough to warrant the investment in an interceptor of this speed. The program was abandoned at that point, but the YF-12s continued flying for many years with the USAF and with NASA as research aircraft.

[edit] NASA testing

Of the three YF-12As, #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 one and only SR-71C. That aircraft was nicknamed "The Bastard" by its pilots, as it did not fly quite straight. It is unique among all SR-71s as it still carries the ventral fins under its nacelles – an artifact of its YF-12 lineage which does not exist on any other SR-71. YF-12A #60-6936 was lost on 24 June 1971 due to an inflight fire caused by a failed fuel line; both pilots ejected safely just north of Edwards AFB.

YF-12A #60-06935 is the only surviving YF-12A; it was recalled from storage in 1969 for a joint USAF/NASA investigation of supersonic cruise technology, it was then flown to the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio on 17 November 1979.^[3] The initial phase of this program included test 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 AWACS would control supersonic aircraft. The Air Force portion was budgeted at $4 million US dollars. The NASA 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.^[5]

A fourth YF-12 aircraft, the "YF-12C", was actually the second SR-71A (61-7951). The airplane was loaned to NASA for propulsion testing after the loss of YF-12A (60-6936) in 1971. The SR-71A was re-designated as a YF-12C and given a fictitious serial number 60-6937 (used an A-12). The YF-12C was operated by NASA until September 1978, when it was returned to the Air Force. Today, this aircraft is on display at the Pima Air Museum in Tucson, AZ.^[6]

[edit] Variants

YF-12A 

F-12B 

Production version of the YF-12A; canceled before production could begin.^[7]

YF-12C 

Fictious designation for a SR-71 provided to NASA for flight testing. The YF-12 designation was used to hide the existence of SR-71.^[8]

[edit] Specifications (YF-12A)

Data from Lockheed's SR-71 'Blackbird' Family^[9]

General characteristics

• Crew: 2
• Length: 101 ft 8 in (30.97 m)
• Wingspan: 55 ft 7 in (16.95 m)
• Height: 18 ft 6 in (5.64 m)
• Wing area: 1,795 ft² (167 m²)
• Empty weight: 60,730 lb (27,604 kg)
• Loaded weight: 140,000 lb (63,504 kg^[2])
• Max takeoff weight: 124,000 lb (56,200 kg)
• Powerplant: 2× Pratt & Whitney JTD11D-20A high-bypass-ratio turbojet with afterburner
  • Dry thrust: 20,500 lbf (91.2 kN) each
  • Thrust with afterburner: 31,500 lbf (140 kN) each

Performance

• Maximum speed: Mach 3.35 (2,275 mph, 3,661 km/h^[2]) at 80,000 ft
• Range: 3,000 mi (4,800 km)
• Service ceiling 90,000 ft (27,400 m)

Armament

• Missiles: 3× Hughes AIM-47A air-to-air missiles located internally in fuselage bays

Avionics

• Hughes AN/ASG-18 look-down/shoot-down fire control radar

[edit] YF-12 aircraft on display

List of YF-12 aircraft

Serial number	Model	Location or fate
60-6934	YF-12A	Transformed into SR-71C 64-17981 after fire damage in 1966
60-6935	YF-12A	U.S. Air Force Museum, Wright-Patterson AFB, OH
60-6936	YF-12A	Lost, 24 June 1971

The sole remaining YF-12A is located:

• National Museum of the United States Air Force, at Wright-Patterson Air Force Base, near Dayton, Ohio.^[3]

[edit] References

Notes

Bibliography

[edit] See also

Related development

• Lockheed A-12
• M-21/D-21 drone
• SR-71 Blackbird
  

Related lists

• List of military aircraft of the United States
• List of Lockheed aircraft
• List of fighter aircraft
  

[edit] External links

• Mach 3+: NASA/USAF YF-12 Flight Research, 1969-1979 by Peter W. Merlin (PDF book)
• YF-12A Flight Manual and YF-12A #60-6935 Photos on SR-71.org
• YF-12 fact sheet on USAF Museum site
• Blackbird Spotting maps the location of every existing Blackbird, with aerial photos from Google Maps
• USAF Aircraft Serial Numbers for 1960, including all A-12s, YF-12As, and M-21s

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