Why Fighter Jets Haven’t Gotten Faster in 50 Years

Have you ever wondered why an older fighter jet like the F-4 Phantom is faster than the modern F-35? Surprisingly, fighter jets haven’t increased in speed over the last five decades, and there’s a strategic reason for that.

Speed vs. Combat Reality

During the Vietnam War, the U.S. Air Force and Navy deployed the F-4 Phantom against Vietnam’s MiG-21s. Both planes could theoretically reach speeds of Mach 2.2, but in practice, they rarely flew that fast.

Analysis of thousands of flight records from the conflict revealed that F-4s hardly ever reached Mach 1.8 in combat. Most flights were conducted at Mach 1.2, with only brief moments at Mach 1.4.

The Missile Factor: No Need to Outrun the Enemy

Historically, speed was crucial for evading enemy fire, especially during World War I and II. However, the advent of air-to-air and surface-to-air missiles (SAMs) dramatically shifted this need for speed.

Modern missiles like the AIM-120 can reach Mach 4, while Russia’s S-300 variants can hit Mach 7, far outpacing any manned fighter jet. In this environment, trying to outrun a missile is futile.

Speed Sacrifices Range and Efficiency

You might assume that more speed means arriving at the target faster, but supersonic speeds have major drawbacks.

Flying faster uses up fuel at a much higher rate, drastically reducing a fighter jet’s combat range. A Northrop Grumman study showed that increasing an F-4 Phantom’s speed from subsonic to Mach 1.5 could cut its combat range by up to 70%.

As a result, fighter pilots typically aim for the speed that allows them to maximize their turn rate, which is around Mach 0.7, rather than going supersonic.

Stealth Over Speed

Modern fighter jets prioritize stealth over raw speed. Supersonic flight generates a significant heat signature, making planes easy targets for infrared-guided missiles and SAMs.

Afterburners and high-speed air resistance heat the aircraft’s body, further increasing its detectability. For example, the F-22’s maximum sustained speed was reduced from Mach 1.8 to 1.6 specifically to manage the heat load on its composite wings and avoid detection.

New Priorities for Modern Fighters

Older jets like the F-104 Thunderchief could fly at Mach 2, but at the cost of reduced combat range and limited payload capacity. In contrast, modern jets like the F-35 may top out at Mach 1.6, but they are far stealthier, can carry more weapons, and have greater endurance in combat.

Simply put, modern fighter jets are designed for long-range, survivable missions rather than high-speed sprints. While faster jets could be built, their effectiveness in today’s missile-dominated battlefield would be severely limited.