Airplanes have evolved from slow-moving wood and canvas biplanes to the first supersonic jet. Once the Bell X-1 pierced the sound barrier in October 1947 with Chuck Yeager at the controls, engineers soon developed many other supersonic aircraft.
Most of the world’s fastest-ever supersonic planes are military jets. Supersonic flight has more advantages for fighters, bombers, and spy planes than passenger jets or cargo aircraft. It’s also easier for engineers to build the necessary streamlined aerodynamics into a smaller, single-seat or two-seater aircraft. The bulky fuselage of a passenger or cargo plane is cheaper to build for subsonic speeds. However, at least one honorable mention from the civilian world, too – the famous Aerospatiale/BAC Concorde.
1. North American X-15
The Bell X-1 was the first in a series of experimental X-planes commissioned and tested by NACA. The X-1’s breaking of the sound barrier in 1947 encouraged more ambitious research. By the time engineers developed the X-15, the goal was to surpass Mach 5, or five times the speed of sound.
A slim, dart-shaped aircraft with rear winglets, the X-15 was born from specifications set out in late 1954. North American Aviation, the P-51 Mustang’s developer, worked on the project with liquid-fuel rocket engine maker Reaction Motors, Inc.. The two companies started work in 1955 and readied the first X-15 by 1959. The needle-like single-seater was 50 feet long with a 22-foot wingspan.
The X-15 mounted under the wing of a modified B-52 bomber like a missile to be launched. Because of its design, it couldn’t take off from the ground. The two modified B-52s built to carry it received the nicknames “Balls 8” and “The High and Mighty One.” The aircraft’s chief engineer, Harrison Storms, described the X-15 as “the beginning of man’s most advanced assault on space.”
North American Aviation built three X-15s in all. Each was taken to a height of 45,000 feet by one of the NB-52s and launched at 500 mph. Between the first flight on June 8th, 1959 and the last on October 24th, 1968, the three aircraft made 199 flights. Just one year before the X-15’s retirement, William “Pete” Knight reached 4,520 mph, or Mach 6.7, setting its top speed record.
2. Lockheed SR-71 Blackbird
In 1960 former USAF major and CIA operative Gary Powers took his Lockheed U-2 Dragon Lady spyplane over the USSR. Flying in the stratosphere at 70,000 feet, Powers was believed to be safely above the range of Soviet attacks. But a swarm of 14 S-75 Dvina missiles rose like angry hornets from launchpads across the Soviet Union, targeting his aircraft. One destroyed a MiG-19 jet fighter also trying to intercept Powers. Another hit Powers’ U-2. Powers successfully ejected but was captured and eventually freed in a prisoner exchange. US intelligence knew they needed a more elusive aircraft to photograph Soviet military installations.
The now-famous Lockheed SR-71 Blackbird stepped up to fill the role. Born at Lockheed’s top secret “Skunkworks” research facility, the SR-71 made its maiden flight three days before Christmas 1964. The Blackbird was the final development of the experimental YF-12 featuring bigger fuel tanks and a two-man cockpit.
The SR-71’s speed and altitude would protect it from sharing the same fate as Gary Power’s slower U-2. The aircraft operated at 16 miles altitude, or above 85,000 feet, meaning the pilot and reconnaissance officer onboard wore pressure suits. It flew at 2,200 mph, Mach 3.4 to 3.5. Blasting through even the super-thin air at 16 miles created huge friction. An aluminum or steel aircraft would melt with wing edges reaching 1,000° F at these speeds. Lockheed’s engineers made the Blackbird’s skin from titanium, bought from the USSR through shell companies.
The result was a complete success. Even the Soviets’ Mach 3.2 MiG-25 Foxbat couldn’t catch the SR-71. The Soviet Air Forces used the Blackbird to train Foxbat pilots, however. MiG-25 trainees would wait on the Kamchatka Peninsula for an SR-71 overflight to practice their supersonic pursuit skills.
3. Lockheed A-12 and YF-12
The SR-71 Blackbird didn’t spring out of anywhere, and the Lockheed A-12 and YF-12 were the aircraft it was developed from. Just a little slower at Mach 3.35, the earlier Blackbirds were the brainchildren of Skunkworks engineer Clarence “Kelly” Johnson and his team. The A-12 shared the SR-71’s sleek, flowing outlines and titanium skin, but was a single-seat aircraft with less fuel.
The USA had stopped USSR overflights following Gary Power’s U-2 incident, using early spy satellites instead. Instead, the Oxcart saw service during the Vietnam War. The CIA used three aircraft flying out of an Okinawa airbase to conduct recon over North Vietnam during Operation Black Shield.
Thanks to its blistering speed and ability to fly above 90,000 feet, the A-12s remained invisible to the North Vietnamese for three months. At that point, the Vietnamese air defense radar picked up pilot Dennis Sullivan’s A-12 as he flew over Hanoi. The Vietnamese fired six surface-to-air missiles, one of which blew up within 300 feet of the Oxcart. A few small pieces of shrapnel struck it, enough to cause the CIA to stop flights for several months.
The A-12 didn’t see much more action before it was retired. The aircraft sat in military storage for two decades before they were sent to museums, including one to the CIA HQ. While the A-12 and YF-12 didn’t make many headlines, they provided the tech and research leading directly to the SR-71.
4. Mikoyan-Gurevich MiG-25 Foxbat
Constructed as a bluff, the USSR’s MiG-25 Foxbat had a nominal speed of Mach 3.2. The Soviets designed the MiG-25 as an interceptor to take on fast American nuclear bombers like the XB-70 Valkyrie. The result was a gigantic jet fighter 78 feet long with a 45-foot wingspan, weighing well over 40 tons.
The Soviets must have soon realized they had a “white elephant” on their hands with the MiG-25. However, the Soviets cleverly used the Foxbat as a deception. They showed their Western adversaries lightened reconnaissance variants of the aircraft while pretending these were full-on, heavily-armed interceptors. Disarmed and stripped down to the airframe and engines, the MiG-25 could achieve Mach 3.2.
The USA and its allies were tricked and treated the MiG-25 as a massive threat. The Americans abandoned their fast nuclear bomber plans and developed the McDonnell Douglas F-15 Eagle as a countermeasure.
When Soviet pilot Viktor Belenko defected to Japan in 1976, just four years after the MiG-25 went into service, he revealed the Foxbat was a paper tiger. The Soviets lacked the technology to make a light, heat-resistant titanium fuselage, so the aircraft was made from nickel steel. This made it massively heavy, unable to climb above 60,000 feet or exceed Mach 2.35 if armed for combat. The designers used cruise missile engines to propel the Foxbat, capable of only a limited range. The engines also wore out quickly and needed to be replaced after 150 hours of use.
The lumbering MiG-25 needed runway three-quarters of a mile long to get its massive 81,000-lb bulk airborne at 180 mph. It was eventually retired and given away to Egypt and other Soviet client countries, where it saw some use as a recon aircraft.
5. Bell X-2 Starbuster: Mach 3.2
The Bell X-1 was the first aircraft to go supersonic, exceeding Mach 1 on October 14th, 1947 with Chuck Yeager at the controls. The small, bright orange aircraft, modeled after a .50 machine gun bullet, eventually surpassed Mach 2. However, despite many tweaks, it could never reach Mach 3 before its use ended.
The Bell X-2 Starbuster, its successor, operated at speeds of Mach 2 to Mach 3. The design featured a sharp nose and swept wings, unlike the X-1’s straight wings. Like the X-1, designers made the X-2 purely as a research aircraft meant to collect detailed data at high speeds. A modified Boeing B-50A bomber served as the X-2’s mothership, carrying it to launch height. The X-2 then flew under its own power and, following its powered flight, glided back to the ground.
Bell only built two X-2s in total. One of these exploded when its liquid oxygen system caught fire while still attached to the B-50A mothership. The explosion killed the pilot Skip Ziegler and a B-50A crewman, Frank Wolko. The shattered remains of the Starbuster fell into Lake Ontario and sank irretrievably.
Pilot Milburn Apt set the X-2’s maximum speed record of Mach 3.2 when he blasted past 2,000 mph on September 27th, 1956. Apt thus became the first human to surpass three times the speed of sound. However, pilot error followed almost immediately as Apt banked the X-2 too sharply at too high a speed. He lost control of the aircraft and jettisoned from it, using the nosecone capsule Bell had designed for the X-2. Apt could not escape the sealed capsule to parachute and was killed when it crashed into the ground at terminal velocity. His death marked the end of the X-2 program.
6. Honorable Mention: Aerospatiale/BAC Concorde
The Concorde is approximately the 17th or 18th fastest aircraft ever built, depending on the source. However, it arguably deserves to feature on the list of top-speed aircraft because it’s the fastest civilian jet to date.
With its bird-beak nose and slim “fighter jet” style wings, the Concorde was immediately recognizable among standard, portly passenger jets. Initial design started in 1956 with a partnership between England’s British Aircraft Corporation and France’s Sud Aviation. The English and French governments agreed to fund the project in 1962, and Charles de Gaulle named the jet “Concorde” the following year.
The Concorde’s engineers included many features in its design that have since become standard in subsonic passenger jets. These include a fly-by-wire interface, computerized intakes, and carbon fiber brakes. The jet first took off on October 1st, 1969, though years of extensive testing followed. Its first commercial flight took place in 1976. In the following two and a half decades, British Airways and Air France operated 14 Concordes, halving the time needed for transatlantic flights. Many routes across the ocean took just three and a half hours for a flight. The jets carried around 100 passengers.
Flying on the Concorde was always expensive, and the program’s cost drew criticism. The interior was cramped, but the blastoff-like takeoff and premium service made the trip a memorable experience. All the jets were grounded following a fatal July 2000 crash, the airframe’s only lethal accident. The Concorde returned briefly to service but was retired in 2001 as too inefficient and expensive. Richard Quest of CNN paid tribute to the Concorde by saying the jet was “extremely noisy, but I challenge anybody not to have a smile from ear to ear when they got on it.”