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The Douglas F6D Missileer was a proposed carrier-based fleet defense fighter designed by Douglas Aircraft Company in response to a 1959 United States Navy requirement. It was designed to be able to loiter for extended periods at a relatively long distance from the Navy's aircraft carriers, engaging hostile aircraft away with its powerful radar and long-range missiles. Since the enemy would be fired on long before they reached visual range, the aircraft had little dogfighting capability and was strictly subsonic. When doubts were expressed about the Missileer's ability to defend itself after firing its missiles, the value of the project was questioned, leading to its cancellation. Some of the Missileer's systems, primarily the engines, radar, and missiles, continued development in spite of the cancellation, eventually emerging on the ill-fated General Dynamics–Grumman F-111B and successful Grumman F-14 Tomcat years later.
Development
Background
Through the later part of the 1950s and into the 1960s, military air planners increasingly believed that future air combat would be carried out almost entirely by long-range missile fire. This changed the basic requirements for a fighter design considerably. The pilots would be expected to fight primarily through their radar and fire control systems, hopefully never even seeing their opponent. Because of this, the emphasis was on "head down" combat and an all-round view was considered unimportant. Radar systems were so complex that a pilot could not be expected to operate both the aircraft and the radar, so a second crewman, the "radar intercept officer", or "RIO", became a common fixture.
In the case of the Navy, the primary threat to their air operations would be high-speed aircraft attacking their aircraft carriers, potentially with long-range anti-ship missiles that were assumed to have nuclear warheads. They envisioned a large aircraft with loiter times on the order of six hours, supported by a dedicated radar aircraft providing early warning. In order to get the loiter times they wanted, the aircraft had to carry a large fuel load and was thus very large. The complex radar required dedicated operators, which resulted in a three-man crew. Additionally, they specified a side-by-side layout so both the pilot and co-pilot could concentrate on a single, centered radar display, avoiding duplication of equipment and helping reduce communications errors that could occur if they were looking at different screens. Since dogfighting was out of the question, the aircraft was strictly subsonic and did not require all-round visibility, suggesting a cockpit layout similar to the Grumman A-6 Intruder.
thumb|Artist's conception of the AAM-N-10 Eagle missile
The process formally started in December 1958 when Bendix was awarded a contract to develop the AAM-N-10 Eagle missile system After launch, the Eagle was boosted to Mach 3.5 by a large solid-propellant rocket booster, and then after a glide period, a long-burning sustainer motor slowly increased speed to Mach 4.5.
At the same time, Westinghouse won the contract to develop the AN/APQ-81 radar for the aircraft. Douglas Aircraft won the contract for the aircraft itself, being selected over designs from North American Aviation and McDonnell Aircraft. It featured a large cockpit area well forward on the aircraft, above the large radar and avionics section in a somewhat bulbous arrangement with windows on the front area only. The two engines were mounted on the side of the aircraft under the straight wings, and the rest of the fuselage and tail section were very simple. When the F-111B ran into intractable problems in terms of aircraft performance as an air-to-air fighter and operational difficulties as a sea-based aircraft aboard aircraft carriers, the same systems were instead fitted to the F-14 Tomcat.
The Missileer's lasting contribution was not only its systems, but its engines. The TF30, with an afterburner, was used on both the F-111 and F-14, and turbofans are now commonplace in military jets. But while the TF30 was well-suited to the land-based fighter-bomber performance parameters of the F-111s and FB-111s operated by the U.S. Air Force and the Royal Australian Air Force, it was highly susceptible to compressor stalls in high angle-of-attack flight regimes and proved to be a marginal powerplant for the U.S. Navy's air superiority fighter-oriented F-14A Tomcat. Later versions of the F-14, the F-14B and F-14D, would replace the problematic TF30s with two General Electric F110 afterburning turbofan engines.
Design
The F6D-1 would have weighed approximately . It would have been powered by two Pratt & Whitney TF30-P2 non-afterburning turbofan engines which were more fuel efficient than the turbojets common at the time. It would have had subsonic performance, Of conventional design with straight wings, and the engines in pods at the root, it resembled a larger version of the company's earlier F3D Skyknight. The Missileer's radar was to be the Westinghouse AN/APQ-81 pulse Doppler set, with a range of and "track while scan" capability.
Specifications (XF6D-1, as designed)
thumb|right|Three-view silhouette
See also
References
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