targets at about , and was able to track eight targets at a time in its track while scan mode at up to . The radar also broadcast midcourse corrections to the missiles, and was in charge of calculating their lofted trajectories. The range of the AN/APQ-81 meant the Eagle could not be fired at its maximum effective range of , but the Eagle also had a home-on-jam capability that allowed it to attack targets at its maximum range, although this was reduced in practice as it did not use midcourse corrections and flew directly at the target at lower altitudes. To support the fighters, an improved early warning radar aircraft was needed, and Grumman won the contract with the W2F Hawkeye. It was equipped with the AN/APS-125 radar, which had a search range of . This allowed a single Hawkeye to cover an area serviced by several of the fighters. Operators on these aircraft would pass information to the pilots of the interceptors, who would then use their own radars to lock on to the targets. Finally, in July 1960, Douglas Aircraft won the contract for the aircraft itself, being selected over designs from North American Aviation and McDonnell Aircraft. They proposed using the relatively new turbofan engine design to improve fuel economy, and thus loiter time. Pratt & Whitney was selected to start development of the TF30 to fill this role. Other than that, the F6D design was typical of subsonic designs of years earlier, like their Douglas F3D Skyknight. 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. Cancellation In order for the F6D "system" to work, a large number of technologies had to work at the same time. Among these were the new engines, radar, missiles, and the supporting early warning aircraft. Development of the F6D itself was highly likely to be successful and low cost, but the system as a whole was very risky and expensive. Throughout the program, others in the Navy questioned the entire concept. They argued that, once the Missileer had fired its missiles, it would be completely unable to defend itself, and would