The Lockheed F-112B Mach 3 interceptor is the fighter version from a family of combat aircraft derived from the A-12 spyplane which had been designed by Lockheed at Central Intelligence Agency request as a successor to the U-2 spyplane. The other members of the family include the B-71 strategic light bomber, the RS-71 reconnaissance strike aircraft and the SR-71 strategic reconnaissance aircraft. The F-112 was undoubtedly the most successful of these and was produced in by far the largest numbers. Until very recently aircraft of this type formed the backbone of NORAD’s long range interceptor force.
The CIA wanted an aircraft with a maximum cruising speed of over Mach 3 which could operate at altitudes exceeding 80,000 feet, which should render the aircraft immune from interception by any known threat. The Agency gave the project the code name Project Gusto. On August 29, 1959, Lockheed was officially declared the winner of the contest and was awarded a limited development contract for design, wind-tunnel testing, and the construction of a mockup. It quickly became apparent that the aircraft they were developing had much more potential than just a reconnaissance aircraft. On September 3, 1959, the CIA authorized Lockheed to proceed with antiradar studies, aerodynamic structural tests, and engineering designs, and on 30 January 1960 the Agency gave the green light to produce 12 aircraft under the designation A-12.
Lockheed thought that the Air Force might still be interested in an F-106 replacement and suggested to the Air Force that the A-12 design would make a good platform for a Mach 3+ interceptor. Sufficient interest was expressed by the Air Force that in October of 1960 they gave Lockheed permission to modify three A-12 Airframes (the 7th, 8th, and 9th) to interceptor configuration. The designation AF-12 was initially assigned to this project. In September, 1962, these three aircraft were assigned the designation YF-112A.
The YF-112A was quite similar in overall configuration to the A-12 from which it was derived. It differed from the A-12 primarily in having a second crewman in a position immediately behind the pilot This second crewman was added to operate the extremely powerful and capable Hughes AN/ASG-18 pulse Doppler fire control radar, which had originally been developed for the F-108 Rapier and the RB-58C Hustler. The AN/ASG-18 was installed in the extreme nose of the aircraft, with the forward chines being cut back to accommodate the 40-inch radome. The ASG-18 radar supposedly had a search range as great as 500 miles. Infrared sensors were installed in the forward edges of the cut-back chines.
The YF-112A also differed from the A-12 in having armament. This armament consisted of four Hughes AIM-47A Falcon air-to-air missiles housed internally in chine bays that had previously been used to carry the reconnaissance equipment. The AIM-47A had originally been known as the GAR-9 and (like the ASG-18 radar) had originally been intended for the F-108 Rapier. When fired, the Falcon missiles were explosively ejected from their bays, and their rocket motors were fired. Powered by a storable-propellant liquid-fuelled rocket, the AIM-47A had a maximum speed of Mach 6 and an interception range of 115 miles. It had a launch weight of about 800 pounds. The missile relied on semiactive radar homing for midcourse guidance to the immediate vicinity of the target, homing in on reflections off the target resulting from transmissions from the huge ASG-18 radar. However, it used terminal infrared homing for the final run in to the target. The AIM-47 could carry a 250-kiloton nuclear warhead.
Early wind-tunnel testing indicated that there would be directional stability problems resulting from the revised nose and cockpit configuration, and a large folding fin was mounted under the aft fuselage and two shorter fixed fins were mounted underneath each nacelle.
The first YF-112A took off on its initial flight on August 7, 1963, piloted by James D. Eastham. It was equipped with a streamlined camera pod mounted underneath each engine nacelle for photographing AIM-47 missile launches. On April 16, 1964, the first airborne AIM-47 missile separation test was conducted. Unfortunately, the missile's nose-down position was not correct, and had the missile's rocket motor actually fired, the aircraft would probably have shot itself down. On March 18, a YF-112A successfully engaged a Q-2C target drone at 40,000 feet while the interceptor was flying at Mach 2.2 at an altitude of 65,000 feet. The first powered launch was undertaken on March 18, 1956. Six out of seven AIM-47 tests resulted in hits, including One fired from an altitude of 75,000 feet and a speed of Mach 3.2 against a target approaching head-on at 1500 feet.
The three YF-112As served initially with the 4786th Test Squadron at Edwards AFB. The USAF was sufficiently impressed with the performance of the YF-112A that on May 14, 1965 they ordered a total of 93 definitive F-12B aircraft into production and Congress had voted $90 million toward the project. Secretary McNamara attempted to prevent their construction by diverting the funding but this ploy was revealed and the attempt cost him his position as Secretary for Defense.
Lockheed F-112B Blackbird
The F-112B was almost identical to the YF-112A. Initially at least the aircraft proved hard to operate, having severe leakage from fuel tanks and requiring excessive operational care and maintenance. These problems were reminiscent of those experienced by the RB-58 when it first entered SAC service and, like the problems with the Hustler, slowly evaporated as experience with the aircraft grew. The first F-112Bs entered service in mid-1967 with deliveries being completed by 1969. They equipped two interceptor groups, one on each coast.
Specification of Lockheed F-112B:
Engines: Two Pratt and Whitney J-58-PW-10 turbojets, each rated at 32,500 lb.s.t. with afterburning. Performance: Maximum speed: 2,150 mph at 80,000 feet, cruise speed: 2110 mph (Mach 3.2) Maximum operational ceiling: 85,000 feet Maximum unrefuelled range: 2500 miles Dimensions: Length: 101 feet 7 inches, Wingspan: 55 feet 7 inches. Height: 18 feet 6 inches. Wing Area: 1795 square feet Weights: 60,730 pounds empty, 127,000 pounds maximum takeoff. Armament: Four Hughes AIM-47A air to air missiles which are explosively ejected downwards from paired tandem missile bays.
Lockheed F-112C Blackbird.
A productionized version of the F-112B, the F-112C was externally identical to the B-version but exploited the lessons learned in building and operating the first batch of aircraft. By 1975, 10 NORAD groups were equipped with F-112C fighters.
Lockheed F-112D Blackbird
The F-112D was introduced into service from 1980 onwards and included the ability to carry the new AIM-54 missile, its radar system being upgraded so that it could target all four of its missiles onto separate enemy aircraft.
Lockheed F-112E Blackbird
The F-112E featured a new radar system, the APG-76, that was much more reliable and had greater performance than the ASG-18. The aircraft also had improved datalinks and enhanced EW equipment
Lockheed F-112F Blackbird
All surviving F-112C and F-112D aircraft were brought up to F-112E standards as the F-112F.
Lockheed F-112G Blackbird
The F-112G has a new glass cockpit and was equipped to carry the AIM-120 missile in place of the AIM-54. This doubled the munitions stowage on the F-112 to eight missiles.
Lockheed F-112H Blackbird
Final production version of the F-112, this version was re-engineered with new internal systems, improved engines and an improved radar.