Thread by @heatloss1986

For a long time, I've derided the AIM-54 as being a poor anti-fighter missile. However, I've stumbled across some information that makes me reconsider what I've said. A short🧵

While reading old congressional hearings, I found this passage. There are three major portions to this performance that I think are worth touching on. Increased energy, autopilot efficiency, and control efficiency and design.

The first should be pretty self-explanatory. The motor on Phoenix propels it to speeds higher than Sparrow could dream of, at ranges of over 100 nautical miles, about double the aerodynamic range of AIM-7F.
At short ranges, this means vastly increased available missile energy.

The second, autopilot efficiency, is a little bit more complicated. Phoenix was one of the first applications of an "adaptive gain" system.
This refers to a system of automatic adjustment of the autopilot control input gain based on target parameters.

In the case of the AIM-7E Sparrow, the gain was managed by target speed alone. This proved to be inadequate to deal with sharply maneuvering targets.

In Phoenix, I suspect target average angular rate data, in combination with closing velocity, was used to determine the magnitude of autopilot gain, as it did not track in range, and therefore range could not be used to influence the autopilot gain.

The final point to touch on is the control systems. Wing control, a system used in the Sparrow, is quite reactive to inputs but requires high wing area due to its proximity to the center of gravity of the missile.
For numerous reasons, wing control missiles are high-drag.

One of the primary reasons wing control was used in the Sparrow was likely proximity to the seeker and control systems due to the narrow width of the missile body.
The Phoenix, with a much larger missile body, took advantage of a much more efficient system: Tail control.

Though tail control requires higher angles of attack to make hard maneuvers, it tends to provide lower drag than comparable wing control systems in maneuvers, meaning that the Phoenix could achieve longer ranges against maneuvering targets than Sparrow.

For these reasons stated above, I believe that the Phoenix was a much more effective anti-fighter missile than I gave it credit for, at least on par with the later versions of the AIM-7 Sparrow (7F/M).