Eventually adopted as the front-line fighter by all three US Services and exported to eleven other countries, the McDonnell Aircraft Company's classic F-4 Phantom stood at the forefront of fighter development in the 1960's. Though it was originally designed as a Mach 2 fleet interceptor for the Navy, the Phantom became the workhorse of the Vietnam war, performing many types of missions. Its weaknesses were relatively poor maneuverability and the lack of an internal cannon but its sheer ruggedness and high engine power made it a successful aircraft. In the 1950s, many military aircraft designers were creating fighters to oppose Soviet supersonic strategic bombers, and in this mission it was thought that cannon were not needed. That limited judgement was probably correct, but during the Vietnam War it became clear that the missile technology of the day was not sufficient to deal with the tightly-maneuvering MiG fighters the Phantoms found themselves facing in air combat. The AIM-9 Sidewinder was reasonably effective, but only from the rear and was subject to signal interference from the sun or light reflected off the ground. The AIM-7 Sparrow, though touted as a medium-range missile, was rendered ineffective by launching problems and the Air Force's own rules of engagement which required visual identification of the enemy before firing, thus negating any beyond-visual-range advantage the missile would have conferred. Added to this is the fact that neither missile could be launched at extremely close range, where a cannon would be most effective. These disadvantages made Phantom pilots keenly aware of their lack of a cannon, but they developed tactics to compensate. One was to send a single aircraft into a high-speed pass through a group of bandits, acquiring a visual identification and allowing his fellow pilots behind him to open fire with radar-guided AIM-7 missiles. Once the combat closed to dogfight range, the F-4s would shy away from the 'classic' dogfight because they could not turn as nimbly as the MiGs. Instead they would take advantage of the Phantom's impressive engine power and use the vertical, climbing too quickly for the underpowered MiGs to follow, and then descending upon them from a position of advantage.
