Supersonic flight has captivated humanity‘s imagination since Chuck Yeager first broke the sound barrier in 1947. In the decades since, aviation engineers have pushed the limits of speed ever higher through advanced aerodynamic designs and materials.
The development of these incredibly fast jets has been driven primarily by military requirements for reconnaissance, interception and research. Spy planes need speed to evade defenses, while rocket-boosted experimental craft probe the edges of high-speed flight.
Civilian planes have also gone supersonic, most famously with the Concorde airliner. And new startups aim to bring supersonic passenger travel back in coming years.
Let‘s look at 6 of the fastest-ever aircraft in aviation history and the stunning speeds they reached.
1. North American X-15
Top Speed: 4,520 mph (Mach 6.7)
The North American X-15 looks more like a rocket than a plane. That‘s because it needed a giant rocket engine to push it to a world record top speed of Mach 6.7 – over 4,500 mph or 7,300 km/h!
This Cold War research plane used a Reaction Motors XLR-99 rocket providing 57,000 lbs of thrust. Its purpose was pioneering extreme high-speed and high-altitude flight. The X-15 still holds the record for fastest manned aircraft.
Only 199 flights were made by the three X-15 aircraft built. This limited program was due to the extensive maintenance required between each flight at the edges of space. The exotic fuel and materials needed also made it enormously expensive per mission.
The X-15 launched off a NB-52 carrier plane before firing its rocket. It then glided unpowered back to land on a dry lakebed. Because of the limited glide range, precision timing was critical for the test pilot to make it back.
On one flight, test pilot William "Pete" Knight reached a staggering Mach 6.7 – over 4,500 mph. This set the record for aircraft top speed that remains unbroken over 50 years later. It was an immense technological achievement to control stable flight at velocities and dynamic pressures far beyond other jets.
The X-15 made major contributions to developing technology for the Space Shuttle orbital vehicles soon to come. Even today it represents the cutting edge of jet-powered atmospheric flight.
2. Lockheed SR-71 Blackbird
Top Speed: 2,200 mph+ (Mach 3.2+)
No military aircraft was ever built faster than the SR-71 Blackbird spy plane. Capable of cruising over 3 times the speed of sound (Mach 3.2+) at 85,000 feet, it remains the fastest jet ever flown operationally.
Its extreme performance was essential to safely overflying hostile territory for reconnaissance. Flying high and fast at up to 85,000 feet, Soviet air defenses struggled to target the Blackbird.
What made these blistering speeds possible was Lockheed‘s clever use of titanium alloy. Steel or aluminum jets would melt at the Blackbird‘s Mach 3+ extremes. The titanium gave it the necessary heat resistance. Up to 1,000°F at the nose and cockpit edges was endured.
The SR-71 first flew in 1964. It remained the world‘s fastest and highest-flying operational aircraft for decades through the Cold War until retirement in 1998. Over 3,500 missions were flown without an aircraft loss, solid proof of Kelly Johnson‘s genius engineering for the CIA.
3. Lockheed A-12 & YF-12
Top Speed: Mach 3.35
Preceding the famous SR-71 Blackbird was Lockheed‘s A-12 for the CIA. This single-seat version pioneered design concepts used in the SR-71.
Hand-built by Lockheed‘s Skunk Works team, it was called Archangel and flown secretly. It used the same titanium alloy, streamlined shape and powerful engines allowing over 2000 mph speeds.
The A-12 couldn‘t carry sensors making it unsuitable for the needed overflight spy role. It saw brief use photographing missile sites in Vietnam and the Chinese mainland. After serving as an aerodynamic testbed it was retired in 1968 once its descendant SR-71 arrived.
There was also a proposed interceptor version called the YF-12 able to reach Mach 3.35 matching the SR-71. But with no air combat need seen this variant stayed experimental-only with just 3 built.
4. Mikoyan-Gurevich MiG-25 Foxbat
Top Speed: 2,170 mph (Mach 3.2)
In March 1961 an immense aircraft was spotted over Moscow setting no less than 7 new world records. Western observers were shocked – it was apparently faster than the in-development SR-71 Blackbird!
The MiG-25 "Foxbat" seemed a highly advanced fighter able to outrun anything NATO had. But what NATO didn‘t then realize – it was largely hollow threat. Built mostly of heavy but cheap nickel steel with vacuum tube electronics, its performance was badly compromised.
The MiG-25 unable to supercruise lacked sustained Mach 3 speed. It was an interceptor not air superiority fighter. The high fuel usage also gave it extremely limited range.
Eventually a MiG-25 pilot defected to Japan with his plane. When examined West experts were almost disappointed to discover how unsophisticated it was. But it remained dangerously fast – up to Mach 3.2.
The Foxbat was soon reassigned from high prestige air defense duties to simpler reconnaissance missions. This fast-climbing interceptor was best at what the Soviets had likely intended all along – catching the SR-71 to prove who had the world‘s fastest jet.
5. Bell X-2 Starbuster
Top Speed: 2,094 mph (Mach 3.196)
Breaking the Mach 3 barrier took an advanced successor to Bell‘s previous pioneering rocket plane: The X-2 Starbuster.
Shaped like a giant supersonic rifle bullet, it carved out a family of exotic aircraft combining rocket and jet propulsion technology. A Volkswagen Beetle-sized rocket motor boosted it up to 3400 mph for sustained high-speed research.
Like so many experimental aircraft, tragedy struck the ambitious X-2 program. Both internal explosions and loss of control took lives, halting further flights by 1956.
But major strides in aviation progress also came at the price of these test pilots‘ sacrifices. The X-2 successfully bridged the gap between early primitive rocket planes and controlled practical high-speed designs.
Soon aviation would master triple supersonic speeds as aircraft pushed Mach 3 in the 1960s. Technology from the X-2 helped make this reality.
6. Aerospatiale-BAC Concorde
Aircraft like the SR-71 Blackbird and XB-70 Valkyrie made sustained speeds above Mach 2 routine. Traveling from New York To London in under 4 hours became possible across the Atlantic.
But for 3 decades air travelers didn‘t get to directly experience these thrilling supersonic voyages. As the Vietnam War wound down focus moved to a more optimistic purpose – transporting the public abroad faster than ever.
The Concorde airliner proved turbojet engines could power Mach 2 commercial flights starting in 1976. For 27 years it served as the ultimate luxury long-distance transport before economic factors forced retirement.
Passengers checking-in for the distinctive "rocket-ship" Concorde witnessed an amazing spectacle. That pointy white fuselage would swiftly swing upward during takeoff revealing its true delta-wing shape – the emblem of supersonic aviation.
Reaching 60,000 feet cruising altitude in barely 10 minutes, the view outside then darkened. Accelerating past 1,300mph, numbers on the Machmeter soon blurred. In just 3 hours, the Atlantic Ocean was traversed!
No commercial aircraft has matched the Concorde‘s speed records since. But its legacy continues to inspire civil supersonic prototypes for radical new sub-4 hour travel times.
Summary
This list shows how tiny changes make the difference between aircraft falling just short of Mach 3, or streaking 50% faster in the high Mach 3s:
- North American X-15 – Mach 6.7
- Lockheed SR-71 Blackbird – Mach 3.2+
- Lockheed A-12 & YF-12 – Mach 3.35
- Mikoyan-Gurevich MiG-25 Foxbat – Mach 3.2
- Bell X-2 Starbuster – Mach 3.196
- Aerospatiale-BAC Concorde – Mach 2
Afterburning turbojets and hydrozene rocket boosting enabled manned flight up to mind-bending velocities. Half a century later aviation now stands ready to apply these lessons to resurrect rapid global travel.
What stunning new heights of speed remain for tomorrow‘s planes? Aviation visionaries continue to explore this frontier.
