VFAX for Naval Fighter Attack Experimental was actually two specifications for two US Navy fighter projects. The first was for a low cost lightweight complement for the General Dynamics–Grumman F-111B which could replace the McDonnell F-4 Phantom II for air superiority, escort, and ground attack missions in the early 1960s. This role was dropped in favor of the VFX aircraft, which emerged as the F-14 Tomcat. The second VFAX evolved when the VFX proved too costly to replace all existing USN fighters and attack aircraft, and the Navy was invited to take part in the USAFs Lightweight Fighter Program (LWF). The Navy chose the YF-17, the loser of the LWF contest as its Navy Air Combat Fighter, as it was inherently more suitable to naval operations than the winning General Dynamics F-16 Fighting Falcon; it was redesigned to become the McDonnell Douglas F/A-18 Hornet.
Overview
VFAX was essentially the Navy counterpart to the Air Force's FX study which eventually led to the F-15 Eagle air superiority fighter. The F-111B had no rear visibility and was found to be too heavy and ungainly in a dogfight. It was not even slated to carry a simple gun or AIM-9 Sidewinder normally carried by air superiority fighters like the F-8 Crusader. Even the F-4 Phantom II did not achieve the success that the US enjoyed over Korean MiGs. It was thought that a mix of F-111B and lighter advanced fighter bombers could handle all anticipated threats in close and long range combat.
As a company project, Grumman was well aware of the limitations of the F-111B, but their approach to the VFAX was the Grumman 303 design. It essentially transplanted the engines and AWG-9/AIM-54 Phoenix weapons system of the F-111B into an agile airframe with the same tried and proved components of the A-6 Intruder, such as the landing gear and primary attitude reference. It would have to be capable of defeating the Soviet MiG-17 'Fresco' and MiG-19 'Farmer' fighters encountered by Navy pilots after 1965 over Vietnam. After 1967, it would also have to defeat the next generation Soviet fighters as well. By 1966, the Navy had been persuaded that a single VFAX could meet the specification if it were large enough to carry the AWG-9/Phoenix weapons system. The VFAX was quickly dropped in favor of a hastily rewritten VFX specification which was largely built around the 303. The VFX, it was thought, was a better and cheaper alternative to a fleet of F-111B FADF (fleet air defence) dedicated interceptors and lighter fighter bombers. Needless to say, this greatly accelerated the need to cancel the now superfluous F-111B.
When the final classifications of the VAFX/VFX was released it was composed of the following, with Air Superiority (Visual maneuvering close combat) as the first priority, ahead of FADF.
Air superiority
Fleet Air Defence FADF
Attack Escort
Air to Ground Attack
Long loiter time
Range
Approach speed to the carrier
Maneuverability
In order to avoid being forced to accept the F-X specification then being developed by the USAF, the Navy insisted on an airplane uncompromised by the air superiority requirements. This was actually a code phrase which meant retaining the primary FADF capability of the relatively heavy Phoenix missile. If the F-14 was created to shoot down bombers, and it was not optimized for maneuvering air combat as the primary design goal, it has even been suggested that the F-14's extraordinary maneuverability is due to the accident of a low approach speed requirement.
However, the Grumman design was able to create a design in which the FDAF and AS requirements did not significantly compromise each other. The F-14 would use a wing sweep program to optimize lift and drag at all combat speeds, twin tails for stability, greatly reduced weight through extensive use of titanium to achieve a better thrust to weight ratio than the F-4, a pancake fuselage for increased lift, a raised tandem cockpit for reduced drag and increased visibility, a gun for close-in fighting, and widely spaced engines for weapons carriage and survivability. Though as the first of a new generation of air superiority fighters, it would be criticized for not possessing the desired 1:1 combat thrust to weight ratio as was intended in the proposed upgraded F-14B and F-14C, it would prove to be competitive in training against a variety of competitors throughout its service life, especially at low speeds with a fully forward wing at full afterburner.