Since the dawn of aviation with the Wright brothers‘ first powered flight in 1903, the speed of airplanes has been a major focus for engineers and pilots alike. Breaking the sound barrier and flying faster than the speed of sound, known as supersonic flight, has long been seen as a key milestone. The first piloted aircraft to achieve supersonic flight was the Bell X-1 experimental rocket plane in 1947.
Supersonic flight brings with it many challenges though. When planes exceed the speed of sound, they generate loud sonic booms – thunder-like noises caused by shockwaves. This limits supersonic planes to flying primarily over oceans to avoid disturbing people on the ground. The aerodynamic forces and air friction generated at such high speeds also require stronger airframes, special materials, and powerful engines, all of which drive up costs substantially. High fuel usage is another major issue for supersonic aircraft.
These factors have meant supersonic flight has remained limited to fairly niche military and research applications. On the commercial side, the Anglo-French Concorde and Soviet Tupolev Tu-144 airliners that flew in the 1970s-2000s have been the only supersonic passenger jets to date. Let‘s take a look at some of the most expensive supersonic planes ever developed.
The Concorde is probably the most famous supersonic plane to many people. Jointly developed by British and French companies, only 20 of the sleek, delta-winged airliners were built. With a cruising speed of around Mach 2 (1,354 mph; 2,180 km/h), the Concorde could cross the Atlantic in under 3.5 hours – less than half the time of other airliners. However, its sonic booms limited it to flying over water on routes like London and Paris to New York.
With a total program cost estimated at $2.8 billion (not adjusted for inflation) spread over fewer than 20 aircraft, the Concorde was fabulously expensive. That worked out to a cost per aircraft of around $150-200 million – several times the price of a conventional widebody jet of the time like a Boeing 747. Ultimately, a combination of limited routes, high operating costs, low passenger capacity, safety concerns after a fatal 2000 crash, and a slump in air travel after 9/11 led to the Concorde‘s retirement in 2003.
The Tupolev Tu-144 was the Soviet Union‘s rival to the Concorde. It actually beat the Concorde into service by a few months in 1977, earning the nickname "Concordski" in the West, but had a brief and troubled career. The Tu-144‘s development costs aren‘t fully known but likely exceeded $1 billion given the USSR‘s vast defense spending. After one fatal crash at the 1973 Paris Air Show and another crash with no fatalities in 1978, the Tu-144 was restricted to cargo service and used for research flights in its later career before being fully retired in 1999.
Military fighter jets have continued to push the envelope on supersonic flight in recent decades. At the expensive end of the spectrum, the U.S. Air Force‘s Lockheed Martin F-22 Raptor has a unit cost of around $350 million. With a top speed of Mach 2.25 (1,500 mph; 2,410 km/h), it was one of the first jets with "supercruise" – the ability to maintain supersonic speeds without afterburners. However, its high costs and maintenance needs, as well as a lack of air-to-air combat missions, led to the F-22‘s production being halted after fewer than 200 aircraft and its retirement in 2011.
The F-22‘s successor, the Lockheed Martin F-35 Lightning II, is a bit slower with a top speed of Mach 1.6 (1,200 mph; 1,930 km/h) but has proven more versatile and affordable at a unit cost of around $251 million as of 2022. The F-35 is being adopted by air forces in over a dozen countries, with the U.S. military alone planning to procure over 2,000 of the multi-role stealth fighters.
Beyond crewed military jets, NASA has used unmanned supersonic vehicles for aeronautical research. The X-43 experimental plane, of which only three were made in the early 2000s, was a unique "waverider" design that rode its own shockwaves for improved efficiency. Powered by a supersonic-combustion ramjet (scramjet) engine and launched from a rocket, the X-43 reached a record speed of Mach 9.6 (7,000 mph; 11,200 km/h) in its final flight in 2004. The X-43 program had a total cost of around $230 million.
One of the most legendary spy planes ever built, the Lockheed SR-71 Blackbird first flew in 1964 and was capable of cruising at speeds of Mach 3.2+ (2,200 mph; 3,540 km/h) at altitudes of 80,000 ft (24 km). Used by the U.S. Air Force and NASA for reconnaissance and research until 1998, the SR-71 cost around $34 million per plane when built in the 1960s – equivalent to over $200 million today.
So when will we see supersonic passenger jets taking to the skies again? Prospects are looking up as a new generation of startups like Boom Supersonic, Hermeus, Spike Aerospace, and others are developing more efficient and environmentally-friendly supersonic aircraft using the latest technologies. Boom‘s Overture airliner, planned to carry up to 88 passengers at speeds of Mach 1.7, has already attracted sizable orders from United Airlines and American Airlines, showing that major carriers are willing to bet on supersonic being commercially viable again.
These new supersonic hopefuls will still have to overcome the same challenges around costs, fuel efficiency, and sonic boom noise that constrained planes like the Concorde. But with more advanced designs and engine technology at their disposal, they stand a better chance of making supersonic passenger travel more practical and accessible than ever before. The renewed competition in the supersonic space makes it likely that we‘ll see some of the most impressive and expensive planes ever take to the skies before long.
