The General Dynamics–Grumman F-111B was a long-range carrier-based interceptor aircraft planned as a follow-on to the McDonnell Douglas F-4 Phantom II for the United States Navy (USN).

It incorporated innovations such as variable-geometry wings, afterburning turbofan engines, and a long-range radar and missile weapons system.

The planned F-111B was replaced by the smaller and lighter Grumman F-14 Tomcat, which carried over the AWG-9 radar/Phoenix missile system, engines, and a similar swing-wing configuration.

In June 1960, the USAF issued a specification for a long-range interdiction and strike aircraft able to penetrate Soviet air defenses at very low altitudes and very high speeds to deliver tactical nuclear weapons against crucial targets.

However, on 14 February 1961, the new U.S. Secretary of Defense, Robert McNamara, formally directed that the services study the development of a single aircraft that would satisfy both requirements.

Early studies indicated the best option was to base the Tactical Fighter Experimental (TFX) on the Air Force requirement and a modified version for the Navy.

[3] In June 1961, Secretary McNamara ordered the go ahead on TFX despite Air Force and Navy efforts to keep their programs separate.

[3][5] The Navy also wanted a 48-inch (120 cm) radar dish for long range and a maximum takeoff weight of 50,000 pounds (23,000 kg).

In December of that year Boeing, General Dynamics, Lockheed, McDonnell, North American and Republic submitted their proposals.

Instead Secretary McNamara selected General Dynamics' proposal in November 1962 due to its greater commonality between Air Force and Navy TFX versions.

[8] Lacking experience with carrier-based fighters, General Dynamics teamed with Grumman for assembly and test of the F-111B aircraft.

[15][16] During March 1968 congressional hearings for the aircraft, Vice Admiral Thomas F. Connolly, then Deputy Chief of Naval Operations for Air Warfare, responded to a question from Senator John C. Stennis as to whether a more powerful engine would cure the aircraft's woes, saying, "There isn't enough power in all Christendom to make that airplane what we want!

"[17] By May 1968 both Armed Services committees of Congress voted not to fund production and in July 1968 the DoD ordered work stopped on F-111B.

The F-111B was an all-weather interceptor aircraft intended to defend U.S. Navy carrier battle groups against bombers and anti-ship missiles.

[27][28] The F-111B was powered by two Pratt & Whitney TF30 afterburning turbofan engines and included the AN/AWG-9 radar system for controlling the AIM-54 Phoenix air-to-air missiles.

[30] The F-111 offered a platform with the range, payload, and Mach-2 performance to intercept targets quickly, but with swing wings and turbofan engines, it could also loiter on station for long periods.

[10] In July 1968, the pre-production F-111B Bureau Number 151974, was used for carrier trials aboard USS Coral Sea.

[35] For pre-production aircraft #6 & #7: Data from Thomason,[40] Miller,[41] Logan[42][43]General characteristics Performance Armament Avionics