One of the Navy's ongoing concerns is defense of its ships from attacks by aircraft and/or missiles. The Chinese anti-ship missile threat is only the latest. In the 1950s, it was long-range, high-performance missiles launched from Soviet bombers. The first solution was the Sparrow air-to-air missile carried by fighters whose development had begun in the late 1940s. The F4H Phantom was the first Navy fighter specifically designed for the mission and was also armed with the Sparrow. However, the Navy continued to fret about a combination of faster bombers and longer range air-to-surface missiles that the Phantom/Sparrow approach was not capable of adequately addressing.
The solution from operational analyses was the Missileer concept. The Operational Requirement was issued on 11 July 1955. The "fighter" would simply be a subsonic platform that loitered out on a station on the threat axis, lugging a huge, long-range radar and up to eight very long-range air-to-air missiles. The missile's range requirement necessitated that it be provided with its own radar for terminal guidance. That and fuel required range that it was a very big missile indeed. It was to be called Eagle.
Work on the missile and engine design definition began first, because they would take much more time to develop and qualify than the airframe. The Bendix Corporation was selected as the prime contractor for the Eagle, including the airborne radar and missile control system, in December 1958. Grumman (airframe and flight test), Westinghouse (aircraft radar), Litton (tactical computer), Sanders (missile active pulse doppler seeker), and Aerojet (propulsion) were subcontractors.
The Pratt & Whitney TF30 engine was one of the first turbofan-type engines, desired for its benefit on endurance. It was based on an engine that Pratt was developing for airlines.
The invitation to bid on the aircraft wasn't requested until 11 December 1959. Bids were received at the end of February from Chance Vought, Douglas, Grumman, McDonnell, and North America. Douglas was selected. The decision was announced on 21 July 1960.
The Navy's press release was explicit about the F6D's role: "The EAGLE-MISSILEER weapon system employs the concept of building long range and high performance into the missile, rather than into the launching aircraft." The 50,000-lb takeoff-gross-weight airplane was to be capable of operating from Essex-class carriers and loiter on station for four hours at 35,000 feet.
The bulbous nose was necessary to accommodate the Westinghouse AN/APQ-81 radar dish, which was five feet in diameter. (Big as the radar was, the missile's maximum range could only be utilized with the Bendix home-on-jam option.) The two-man crew sat side-by-side, surrounded by avionics. The normal missile load was six, all carried under the wings. Two additional missiles could be carried under the fuselage, increasing the takeoff gross weight by 4,800 lbs.
Unfortunately, the incoming Secretary of Defense, Robert McNamara, decided that it would be cost effective to combine two nascent "fighter" programs, the Navy's carrier-based, subsonic, 35,000-ft loiter Missileer and the Air Force's land-based, supersonic, tree-top ingress, nuclear-strike TFX. Strictly speaking, neither was a fighter and what's worse, two more different tactical airplane requirements would be difficult to imagine. The F6D program was formally terminated in April 1961 (it had been on hold since December 1960 awaiting the Kennedy administration's DoD programs review); Hughes took over the development of the radar/missile program, which was appropriately renamed Phoenix.
The F-111 train wreck, particularly given the Navy's outrage at being subservient to Air Force program management and subsequent passive-aggressive cooperation, was inevitable. For more on the F-111B program history, buy my F-111B monograph HERE.