General Dynamics – Grumman F - 111B The General Dynamics / Grumman F - 111B was developed as a long - range carrier - based interceptor follow - on to the F - 4 Phantom II . It was developed in the 1960s by General Dynamics in conjunction with Grumman for the United States Navy ( USN ) as part of the joint Tactical Fighter Experimental ( TFX ) with the United States Air Force ( USAF ) to produce a common fighter across services for a variety of missions . The F - 111B incorporated innovations such as variable - geometry wings , afterburning turbofan engines , and the long - range AWG - 9 / AIM - 54 Phoenix weapons system . Designed in parallel with the F - 111 " Aardvark " , which was adopted by the Air Force as a strike aircraft , the F - 111B suffered development issues and changing Navy requirements for an aircraft with maneuverability for dogfight ing . The F - 111B was not ordered into production and the F - 111B prototypes were used for testing before being retired . The F - 111B would be replaced by the smaller and lighter Grumman F - 14 Tomcat , which carried over the engines , AWG - 9 / Phoenix weapons system , and similar swing - wing configuration . Development . Background . The F - 111B was part of the TFX program , an ambitious early - 1960s project to combine the U . S . Air Force requirement for a fighter - bomber with the U . S . Navy ' s need for a long - range carrier - based Fleet Air Defense fighter . The USAF ' s Tactical Air Command ( TAC ) was largely concerned with the fighter - bomber and deep strike / interdiction roles . The aircraft would be a follow - on to the F - 105 Thunderchief . In June 1960 the USAF issued a specification for a long - range interdiction / strike aircraft able to penetrate Soviet air defenses at very low altitudes and very high speeds to deliver tactical nuclear weapons against crucial targets . Meanwhile the U . S . Navy sought a long - range , high - endurance interceptor to defend its carrier battle groups against long - range anti - ship missile s launched from Soviet jet bombers and submarines . The Navy needed a Fleet Air Defense ( FAD ) aircraft with a more powerful radar , and longer range missiles than the F - 4 Phantom II to intercept both enemy bombers and missiles . Tactical Fighter Experimental ( TFX ) . The Air Force and Navy requirements appeared to be different . 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 . In June 1961 , Secretary McNamara ordered the go ahead on TFX despite Air Force and the Navy efforts to keep their programs separate . The USAF and the Navy could only agree on swing - wing , two seat , twin engine design features . The USAF wanted a tandem seat aircraft for low level penetration , while the Navy wanted a shorter , high altitude interceptor with side by side seating . Also , the USAF wanted the aircraft designed for 7 . 33 g with Mach 2 . 5 speed at altitude and Mach 1 . 2 speed at low level with a length of approximately 70 ft ( 21 . 3 m ) . The Navy had less strenuous requirements of 6 g with Mach 2 speed at altitude and high subsonic speed ( approx . Mach 0 . 9 ) at low level with a length of . The Navy also wanted a 48 - inch ( 122 cm ) radar dish for long range and a maximum takeoff weight of 50 , 000 lb ( 22 , 700 kg ) . So McNamara developed a basic set of requirements for TFX based largely on the Air Force ' s requirements . He changed to a 36 - inch ( 91 . 4 cm ) dish for compatibility and increased the maximum weight to approximately for the Air Force version and for the Navy version . Then on 1 September 1961 he ordered the USAF to develop it . A request for proposal ( RFP ) for the TFX was provided to industry in October 1961 . In December of that year Boeing , General Dynamics , Lockheed , McDonnell , North American and Republic submitted their proposals . The proposal evaluation group found all the proposals lacking , but the best should be improved with study contracts . Boeing and General Dynamics were selected to enhance their designs . Three rounds of updates to the proposals were conducted with Boeing being picked by the selection board . Instead Secretary McNamara selected General Dynamics ' proposal in November 1962 due to its greater commonality between Air Force and Navy TFX versions . The Boeing aircraft versions shared less than half of the major structural components . General Dynamics signed the TFX contract in December 1962 . A Congressional investigation followed , but could not change the selection . Design phase . The Air Force F - 111A and Navy F - 111B variants used the same airframe structural components and TF30 - P - 1 turbofan engines . They featured side by side crew seating in escape capsule as required by the Navy . The F - 111B ' s nose was shorter due to its need to fit on existing carrier elevator decks , and had longer wingtips to improve on - station endurance time . The Navy version would carry an AN / AWG - 9 Pulse - Doppler radar and six AIM - 54 Phoenix missiles . The Air Force version would carry the AN / APQ - 113 attack radar and the AN / APQ - 110 terrain - following radar and air - to - ground armament . Lacking experience with carrier - based fighters , General Dynamics teamed with Grumman for assembly and test of the F - 111B aircraft . In addition , Grumman would also build the F - 111A ' s aft fuselage and the landing gear . The first test F - 111A was powered by YTF30 - P - 1 turbofans and used a set of ejector seats as the escape capsule was not yet available . It first flew on 21 December 1964 . The first F - 111B was also equipped with ejector seats and first flew on 18 May 1965 . To address stall issues in certain parts of the flight regime , the F - 111 ' s engine inlet design was modified in 1965 – 66 , ending with the " Triple Plow I " and " Triple Plow II " designs . The F - 111A achieved a speed of Mach 1 . 3 in February 1965 with an interim intake design . F - 111B . The weight goals for both F - 111 versions proved to be overly optimistic . Excessive weight plagued the F - 111B throughout its development . The prototypes were far over the requirement weight . Design efforts reduced airframe weight but were offset by the addition of the escape capsule . The additional weight made the aircraft underpowered . Lift was improved by changes to wing control surfaces . A higher thrust version of the engine was planned . Requirements for the F - 111B had been formulated before air combat over Vietnam in 1965 showed the Navy had a need for an aircraft which could engage fighters at close range . The Navy desired a fighter with more performance than the F - 4 Phantom II , yet in trials , the maneuverability and performance of the F - 111B was decidedly inferior to the Phantom . During the 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 ! " With the F - 111B program in distress , Grumman began studying improvements and alternatives . In 1966 the Navy awarded Grumman a contract to begin studying advanced fighter designs . Grumman narrowed down these designs to its Model 303 design . With this the F - 111B ' s end appeared near by mid - 1967 . 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 . A total of seven F - 111Bs were delivered by February 1969 . Replacement . The F - 111B ' s replacement , the Grumman F - 14 Tomcat , which derived from Grumman ' s initial Model 303 design , reused the TF30 engines from the F - 111B , though the Navy planned on replacing them with an improved engine later . Although lighter than the F - 111B , it was still the largest and heaviest U . S . fighter to takeoff and land from an aircraft carrier . Its size was a consequence of the requirement to carry the large AWG - 9 radar and AIM - 54 Phoenix missiles , both from the F - 111B , while exceeding the F - 4 ' s maneuverability . While the F - 111B was armed only for the interceptor role , the Tomcat incorporated an internal M61 Vulcan cannon , provisions for Sidewinder and Sparrow air - to air missiles , and provisions for bombs . While F - 111B did not reach service , land - based F - 111 variants were in service with the U . S . Air Force for many years and with Australia until 2010 . Design . The F - 111B was an all - weather interceptor aircraft intended to defend U . S . Navy carrier battle groups against bombers and anti - ship missiles . The F - 111 features variable geometry wings , an internal weapons bay and a cockpit with side by side seating . The cockpit is part of an escape crew capsule . The wing sweep varies between 16 degrees and 72 . 5 degrees ( full forward to full sweep ) . The airframe consisted mostly of aluminum alloys with steel , titanium and other materials also used . The fuselage is a semi - monocoque structure with stiffened panels and honeycomb sandwich panels for skin . 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 . 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 . The F - 111B would carry six AIM - 54 Phoenix missiles , its main armament . Four of the Phoenix missiles mounted on wing pylons and two in the weapons bay . Operational history . Flight testing . Flight tests on the F - 111B continued at Point Mugu and China Lake even after the program had been terminated . In July 1968 the pre - production F - 111B serial number 151974 was used for carrier trials aboard USS " Coral Sea " . The evaluation was completed without issue . Hughes continued Phoenix missile system development with four F - 111Bs . In all two F - 111Bs were lost in crashes and a third seriously damaged . The F - 111B ' s last flight was with " 151792 " from California to New Jersey in mid - 1971 . The seven F - 111Bs flew 1 , 748 hours over 1 , 173 flights . Variants . F - 111B numbers 1 to 3 were initial prototypes , and No . 4 to 5 were prototypes with lightened airframes . No . 6 – 7 had lightened airframes and improved TF30 - P - 12 engines and were built to near production standard . These are also approximately longer due to an added section between cockpit and radome . The first five aircraft included the Triple Plow I intakes . The last two had Triple Plow II intakes . The first three B - models were fitted with ejection seats and the remainder included the escape crew capsule . Specifications ( F - 111B pre - production ) . For pre - production aircraft # 6 & # 7 :