The F-4 was designed with the assumption that air-to-air missiles would make guns obsolete. However the state of development of missiles at the time did not match the assumption. When I was flying F-4s from Korat RTAFB in 1970-71 we were still flying with AIM-4 missiles (this was in the F-4E with a gun). The AIM-4 had a small cryo tank which released cooling gas to the IR seeker to provide the sensitivity needed. There was a switch on the lower left instrument panel which had to be momentarily activated to provide cooling to the missile. This lasted for two minutes after which time the switch had to be activated again. As it turned out two minutes was just about enough time to get into the firing envelop at which time you missile went “dead” and you were not thinking about that $%&* switch. The AIM-9 was much better but the early versions had limited firing aspect. By the way we tried to not fire the gun in the F-4E in our air-to-ground missions since it shook the radar and created issues. We used the radar for dive bombing using the “Dive Toss” mode which was an early automated release.
Given that the F-4 was designed as an interceptor, it did a remarkable job in the fighter role. Two things relative to its performance against the Mig-21: it could indeed turn with a Mig-21 at low speeds if approach flaps deployed (a trick not normally taught or condoned at the time). The Mig-21 could not accelerate out of the slow speed situation and it was possible to actually turn in front but above the Mig-21 in a turning fight with ½ flaps as he could not get the nose up to get a shot. Secondly if you could keep the Mig-21 at bay for any length of time you would run it out of gas. There were many times when I logged only 25 minute flights in the MiG-21 if I used afterburner extensively. The other issue is the pilots that were flying the F-4 over the course of the Vietnam war. With one tour of duty being the norm, some of my squadron mates in SEA were newly minted F-4 drivers coming from bombers or transports. It takes more than a 3 month course to become truly proficient as a fighter pilot. In addition, as has been mentioned also, we were unable to use the one advantage we had which was better avionics and missiles (from the fleet defense mission) because of the requirement to visually identify the target. This generally put us into a dog fight position at the start.
As has been mentioned the F-14 was also designed as a fleet air defense fighter – basically an interceptor. As a fighter its biggest issue was its lack of thrust. The TF30 engines were compressor stall prone and the solution to that issue was to bleed air which reduced thrust. The final version F-14D had two General Electric F110 engines and was a much better fighter. The AIM-54, Phoenix, missile was a complicated missile and the F-14 actually had a cooling fluid reservoir on board that pumped coolant to the missiles to keep the electronics cool prior to launch. While I was at VX-4 in 1984 we were just testing the AIM-54C which was a “dry” missile. Although the AIM-54 had an advertised range of over 100 miles, it you launched at that range you still had to keep the target on the radar to provide updated guidance to the missile. This resulted in an F-pol (the distance between you and the target at missile intercept) of about 40 miles. Also, although the F-14 could carry six Phoenix missiles it had to get rid of two of them to get down to carrier landing weight, and given the cost of the missile that load was very seldom seen.
The VX-4 XO was an F-8 driver and had sticker that showed an F-8 being tossed into a wastebasket and said; “When you are out of F-8s you are out of fighters”.