The Fastest Fighter Jet in History: The NASA X-43

The X-43, an experimental aircraft, holds the distinction of being not only the fastest fighter jet but the fastest aircraft ever built period, having achieved a top speed of Mach 9.6.

As part of a $230 million Hyper-X program, the National Aeronautics and Space Administration (NASA) developed the X-43 to explore hypersonic flight. In doing so, the U.S. agency shattered speed records and pushed the limits of aerospace engineering.

Technical Difficulties

Because of the X-43's design, NASA had to release it from a B-52 for it to fly. Once airborne, however, the flights were short-lived.

NASA destroyed the first jet in 2001 when it malfunctioned during a test. In 2004, each of the remaining two jets flew for just 10 seconds (achieving Mach 6.8 and then Mach 9.6, respectively) during test flights, then crashed into the ocean after 10 minutes of gliding.

Technically Disqualified?

Some argue the X-43 doesn't count as a fighter jet, given it was an experimental, unmanned aircraft focused on speed rather than dogfighting.

However, given the project's federal backing and the military implications of what it achieved, others consider this supersonic aircraft to be the fastest fighter jet of all time.

The X-15, a joint project between NASA and the United States Air Force (USAF), was another groundbreaking aircraft in the pursuit of speed and a predecessor to the X-43. Capable of reaching speeds over Mach 6, the rocket-powered jet was in development during the 1950s and '60s.

Fastest Flight in a Manned Aircraft

Like the X-43, the X-15 had to hitch a ride into the sky on a B-52, but unlike the X-43, it was a manned aircraft. In 1967, pilot Pete Knight made history by flying Mach 6.72, or 6.72 times the speed of sound, in the X-15, marking the fastest flight in a manned aircraft ever recorded.

An Honorable Retirement

The high-speed aircraft underwent 199 test flights before NASA and the USAF retired the X-15 in 1968. A famous USAF photo from the 1960s shows an X-15 flying over Edwards Air Force Base during a supersonic flight.

No discussion of fast fighter jets would be complete without mentioning the legendary SR-71 Blackbird.

Developed during the Cold War era, this reconnaissance aircraft boasted a top speed of Mach 3.30 at more than 16 miles (85,000 feet or 25,908 meters) above the earth. Because of the danger of a sudden loss in cabin pressure, the Blackbird's crew members wore pressure suits similar to astronaut suits.

The U.S. military had needed a fighter jet that could out-maneuver interceptors and other surface-to-air missile systems, and in the Blackbird the USAF found the speed it was looking for.

The aircraft's sleek, all-black profile and unmatched speed capabilities earned it a reputation as the pinnacle of aerospace technology and a symbol of American air superiority.

In the early days of supersonic flight, the Bell X-2 Starbuster emerged as a pioneering aircraft, leading the way for future jets, including the X-43 and the X-15.

The X-2 was the result of a 1945 collaboration between Bell Aircraft Corporation, the USAF and the National Advisory Committee for Aeronautics (NACA).

Glory and Tragedy

In 1956, Capt. Milburn G. "Mel" Apt broke the sound barrier when he reached a top speed of Mach 3.20 in the X-2, making him the first person to fly faster than Mach 3.

Unfortunately, after setting this record, the jet went into a tumble. Although Apt jettisoned the escape capsule in which he was riding, he was unable to deploy his parachute before the capsule crashed.

The USAF developed the Lockheed YF-12 as a prototype interceptor in the 1960s because it needed a jet that could fly at a high altitude while also defending military assets from an enemy's supersonic bombers.

Lockheed and the military made three of these aircraft, and at least one of them reached a maximum speed of Mach 3.20 during testing.

Unfortunately, the USAF ultimately ran out of funding for the YF-12 program, instead diverting funds to other needs related to the Vietnam War. Although the U.S. never put this jet fighter into full production, the performance of this impressive aircraft led to the development of other high-speed military aircraft.

The only surviving plane is on display at the National Museum of the USAF in Ohio.

The Soviet Union developed the MiG-25, also known by its NATO code name "Foxbat," during the Cold War. A formidable interceptor aircraft, known for its blistering high speeds, the MiG-25 had a top speed of Mach 2.83 and entered service in 1970.

Enemy Intel

When the Soviet fighter pilot Victor Belenko defected to Japan in 1976, he flew there in a MiG-25. As a result, the U.S. military was able to gain a wealth of information on the Foxbat.

The Soviet Union had designed the fighter jet to counter the threat of high-altitude reconnaissance aircraft and bombers. Equipped with advanced radar systems and four air-to-air missiles, the MiG-25 posed a significant challenge to Western air forces.

A Prolonged Legacy

The Soviet Union stopped producing MiG-25s decades ago, but that didn't stop them from playing a part in subsequent global conflicts. For example, Iraq flew MiG-25 aircraft during the Iran-Iraq War and the Persian Gulf War.

Building upon the legacy of the MiG-25, the MiG-3, or "Foxhound," emerged as a successor for intercepting and engaging high-speed targets. With a maximum speed of Mach 2.83, this fighter jet first appeared in the skies in 1975, and the Russian air force, called VVS, still uses it.

Featuring a classic fighter jet silhouette, the MiG-31 is a formidable adversary in aerial combat. While a pilot controls the airspeed and altitude, a weapon system officer (WSO) focuses on operating the radar and deploying weapons.

In comparison to the MiG-25, the Foxhound features enhanced radar capabilities and improved avionics, making it able to fly fast with good stability at low altitudes — something its predecessor couldn't do nearly as well.

This article was created in conjunction with AI technology, then was fact-checked and edited by a HowStuffWorks editor.