Lockheed YF-12

Infobox Aircraft
name= YF-12
type= Interceptor
manufacturer= Lockheed Corporation


caption= YF-12A undergoing flight testing.
designer= Clarence "Kelly" Johnson
first flight= 7 August 1963
introduced=
retired=
status=Cancelled
primary user= United States Air Force
more users=
produced=
number built=3
unit cost= US$15-18 million (projected)Knaack, 1978.]
developed from= Lockheed A-12
variants with their own articles=

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.

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.Green and Swanborough, 1988, page 350.] The existence of the aircraft was not officially revealed until 29 February 1964.Air Force Museum Foundation, 1983, p. 133.] 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.

Operational history

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, 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.Landis and Jenkins 2005, p. 44.]

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.

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. 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. [Drendel 1982, p. 6.]

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. [Landis and Jenkins 2005, p. 49-55.]

Variants

;YF-12A : ;F-12B : Production version of the YF-12A; canceled before production could begin. [Landis and Jenkins 2005, p. 46.] ;YF-12C : Fictitious designation for a SR-71 provided to NASA for flight testing. The YF-12 designation was used to hide the existence of SR-71. [Landis and Jenkins 2005, p. 49-50.]

pecifications (YF-12A)

aircraft specifications

plane or copter?=plane
jet or prop?=jet
ref="Lockheed's SR-71 'Blackbird' Family" [Goodall and Miller, 2002.]
crew=2
capacity=
length main=101 ft 8 in
length alt=30.97 m
span main=55 ft 7 in
span alt=16.95 m
height main=18 ft 6 in
height alt=5.64 m
area main=1,795 ft²
area alt=167 m²
airfoil=
empty weight main=60,730 lb
empty weight alt=27,604 kg
loaded weight main=140,000 lb
loaded weight alt=63,504 kg
useful load main=
useful load alt=
max takeoff weight main=124,000 lb
max takeoff weight alt=56,200 kg
more general=
engine (jet)=Pratt & Whitney JTD11D-20A
type of jet=high-bypass-ratio turbojet with afterburner
number of jets=2
thrust main=20,500 lbf
thrust alt=91.2 kN
afterburning thrust main=31,500 lbf
afterburning thrust alt=140 kN
max speed main=Mach 3.35
max speed alt=2,275 mph, 3,661 km/h
max speed more=at 80,000 ft
cruise speed main=
cruise speed alt=
cruise speed more=at 75,000-90,000 ft (23,000-27,000 m)
never exceed speed main=
never exceed speed alt=
stall speed main=
stall speed alt=
range main=3,000 mi
range alt=4,800 km
ceiling main=90,000 ft
ceiling alt=27,400 m
climb rate main=
climb rate alt=
loading main=
loading alt=
thrust/weight=
more performance=
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

YF-12 aircraft on display

The sole remaining YF-12A is located::* National Museum of the United States Air Force, at Wright-Patterson Air Force Base, near Dayton, Ohio. 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.

References

;Notes;Bibliography
* Air Force Museum Foundation Inc. "US Air Force Museum". Dayton, Ohio: Wright-Patterson AFB, Ohio, 1983.
* Drendel, Lou. "SR-71 Blackbird in Action". Carrollton, Texas: Squadron/Signal Publications, 1982, ISBN 0-89747-136-9.
* Goodall, James and Miller, Jay. "Lockheed's SR-71 'Blackbird' Family". Midland Publishing, Hinchley, England, 2002. ISBN 1-85780-138-5.
* Green, William and Swanborough, Gordon. "The Complete Book of Fighters". New York: Barnes & Noble Inc., 1988. ISBN 0-07607-0904-1.
* Jenkins, Dennis R. "Lockheed Secret Projects: Inside the Skunk Works". St. Paul, Minnesota: MBI Publishing Company, 2001. ISBN 978-076030914-8.
* 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. ISBN 0-912799-59-5.
* Landis, Tony R. and Jenkins, Dennis R. "Lockheed Blackbirds", revised edition, Specialty Press, 2005. ISBN 1-58007-086-8.

ee also

aircontent
related=
* Lockheed A-12
* M-21/D-21 drone
* SR-71 Blackbird
similar aircraft=
lists=
* List of military aircraft of the United States
* List of Lockheed aircraft
* List of fighter aircraft
see also=

External links

* [http://www.nasa.gov/centers/dryden/pdf/88796main_YF-12.pdf "Mach 3+: NASA/USAF YF-12 Flight Research, 1969-1979" by Peter W. Merlin (PDF book)]
* [http://www.sr-71.org/blackbird/yf-12a-1/ YF-12A Flight Manual] and [http://www.sr-71.org/photogallery/blackbird/06935/ YF-12A #60-6935 Photos on SR-71.org]
* [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2380 YF-12 fact sheet on USAF Museum site]
* [http://gmaps.tommangan.us/blackbirds.html Blackbird Spotting maps the location of every existing Blackbird, with aerial photos from Google Maps]
* [http://home.att.net/%7Ejbaugher/1960.html USAF Aircraft Serial Numbers for 1960, including all A-12s, YF-12As, and M-21s]