In 1962, the British and French governments signed an agreement to develop a supersonic transport aircraft (SST). The plane was built jointly by British Aerospace (BAe) and Aerospatiale. Two prototypes were built, and the first flight took place in 1969. A total of 20 Concordes were made. The planes were flown by British Airways and Air France. The 30th anniversary of the Concorde took place on March 2, 1999.
The American and Soviet governments also had plans to build an SST. In the United States, Boeing contracted to build a prototype. However, the program was killed in 1971 after a federal report stated that it would be too costly to continue. The Russians built an SST similar in design to the Concorde, called the Tupolev Tu -144, nicknamed the "Konkordski."
In 1973, a Tu -144 crashed at the Paris Air Show. The crash was probably caused by pilot error. However, the Tu -144's use for passenger flights was suspended (see Nova: Supersonic Spies for details on the Tu -144 and events surrounding the crash). The Tu -144 was modified and used for air-mail service. Several Tu -144s have been donated to museums, and one is being used now in a joint aeronautic project between the Russian government and NASA for supersonic-flight research.
At the time of its decommissioning, the Concorde was the only SST in commercial service. However, the Concorde had its share of problems. On July 25, 2000, an Air France Concorde flight en route from Paris to New York crashed] just moments after takeoff, killing all passengers and crew as well as several people on the ground. Investigations into the crash have centered on a loose strip of metal that was lying on the runway. It is believed that the metal caused one of the Concorde's tires to blow out. Debris from the tire was sucked into the engine and/or fuel tank and caused a fire on the portside (left) engine, yielding 200-foot-long flames. The aircraft stalled, tumbled, and crashed on a hotel in nearby Gonesse. Both British Airways and Air France immediately grounded their Concorde fleets.
Now that we know some of the history of the Concorde and other SSTs, let's look at the details of these aircraft.
The Concorde vs. Other Passenger Jets
The Concorde flew faster and higher than most commercial jets. For example, a Boeing 747 aircraft cruises at about 560 mph (901 kph, or Mach 0.84) at an altitude of 35,000 ft (10,675 m). In contrast, the Concorde could cruise at 1,350 mph (2,172 kph, or Mach 2) at an altitude of 60,000 ft (18,300 m). Because the Concorde traveled faster than the speed of sound and almost twice as high as other commercial jets, it had several features that set it apart from other aircraft:
As any aircraft approaches the speed of sound (1100 ft/s, 343 m/s), the air pressure builds up in front of the aircraft, forming a "wall" of air. To punch through that wall of air, planes must be streamlined. To streamline the Concorde, the following designs had to be implemented:
Swept-back delta wing
Vertical tail design
The fuselage (body) of the Concorde was only 9.5 ft (2.7 m) wide (for comparison, a 747 is 20 ft (6.1 m) wide). The length of the Concorde was about 202 ft (61.7 m), just slightly shorter than a 747. The long, narrow shape of the Concorde reduced the drag on the plane as it moves through the air.
The wing of the Concorde was thin, swept back and triangular, whereas a 747's wing is swept back but rectangular. Also, there was no space between the fuselage and the wing of the Concorde as there is in the 747. The Concorde's wing was called a delta-wing design and did the following:
Reduces drag by being thin and swept back (55 degrees with the fuselage)
Provides sufficient lift for takeoff and landing at subsonic speeds
Provides stability in flight so that no horizontal stabilizers are needed on the tail
The Concorde had a longer, needle-shaped nose compared to most commercial jets. The nose helped penetrate the air, and can be tilted down upon takeoff and landing (13 degrees) so that the pilots can see the runway. (Delta-winged aircraft have a steeper angle of attack during takeoff and landing than other types of aircraft.) Also, the Concorde's nose had a visor to protect the windshield when flying at supersonic speeds.
As mentioned above, because the delta wing provided stability to the aircraft, the Concorde did not require a horizontal stabilizer on the tail like most other aircraft.
These designs in the body and wings of the aircraft allowed it to move easily through the air at high speed.
The engines on the Concorde provided the thrust necessary for takeoff, cruising and landing. The Concorde had four Rolls Royce/Snecma Olympus 593 turbo jet engines. Each engine generated 18.7 tons (180 kN) of thrust. Together, the four engines burned 6,771 gallons (25,629 liters) of fuel per hour.
The location and type of engines on the Concorde's was different from on other jets.
The Concorde's engines were attached directly to the underside of the wing without engine struts. This design reduced air turbulence and makes for a more stable engine. At supersonic speeds, engine struts would be overstressed and likely to break.
The Concorde's engines used afterburners to gain additional thrust to reach supersonic speeds. Afterburners mix additional fuel with the exhaust gases from the primary combustion chamber and burn it to get more thrust. Afterburners are typically used on supersonic military jets.
Other Special Components
There were several components that enabled and supported the speed and power achieved by the Concorde.
The Concorde had 17 fuel tanks that could hold a total of 31,569 gallons (119,500 liters) of kerosene fuel. The main tanks were located in each wing (five on each side) and fuselage (four).
The Concorde also had three auxiliary or trim fuel tanks (two in front and one in the tail). Here is what the trim tanks were used for:
As the Concorde reached supersonic speeds, its aerodynamic center of lift shifted backward.
This shift drove the nose of the aircraft downward.
To maintain balance, fuel was pumped backward into the trim tanks.
The redistribution of fuel balanced the aircraft by making its center of gravity match the center of lift.
When the plane slowed down, the center of lift shifted forward.
Fuel was then pumped forward into the trim tanks to compensate.
So, unlike other jets, the Concorde used fuel not only for the engines, but also for aerodynamic stability.
Because the Concorde moved faster than sound, the air pressure and friction (collision with air molecules) could really heat up the plane. The temperature of the aircraft's skin varied from 261 degrees Fahrenheit (127 degrees Celsius) at the nose to 196 F (91 C) at the tail. The walls of the cabin were warm to the touch. To help reflect and radiate this heat, the Concorde had a high-reflectivity white paint that was about twice as reflective as the white paint on other jets.
The heat encountered by the Concorde caused the airframe to expand 7 inches (17.8 cm) in flight. To minimize the stress on the aircraft, the Concorde was made of a special aluminum alloy (AU2GN) that was lightweight and more heat-tolerant than titanium.
Now that we have seen the technical features that made the Concorde special, let's look at a typical flight from London to New York.
A Trip on the Concorde
Imagine traveling back in time to take a trip on the Concorde. You arrive at London Heathrow airport for the 10:30 a.m. flight, check in, check your luggage and wait in the Concorde Lounge of British Airways. When it comes time, you board the airplane. The Concorde can hold 100 passengers, with two seats on each side of the aisle. The crew consists of the pilot, co-pilot, flight engineer and six cabin crew members. You sit in your seat and await the takeoff.
As the plane taxis to the runway and begins takeoff; its nose is down. The engines fire with 38,000 pounds of thrust, and you go from zero to 225 mph (362 kph) in just three seconds -- so fast that you are pushed back into your seat by the acceleration. The noise of the engines roars through the cabin. You quickly reach your cruising altitude (11.3 mi/18.3 km) and pass the sound barrier. The plane's nose is now up. A sign inside the cabin displays the Mach number continuously. As you look out the window, you can see the Earth's curvature. You are at the edge of space between the stratosphere and the ionosphere -- you can see the colors of the stratosphere!
While you are in flight, you can enjoy a gourmet meal with wine or champagne. The flight does not take long, only about three-and-a-half hours. As you approach New York, the plane slows down, descends and the plane's nose comes down. You touch down in New York at 9:30 a.m., one hour before you left London.
More than 2.5 million people have flown on the Concorde. The cost of your Concorde flight from London to New York is about $5,100 (£3,521 British) one way!
For a time, it seemed as though the air travel industry was headed in the direction of more supersonic options. For example, President Ronald Reagan called for a program to develop a hyperspace transport or National Aerospace Plane capable of going from New York to Tokyo in two hours.
Such planes would have to enter outer space in a suborbital flight. They would have to develop the air-breathing rocket engines necessary to achieve the appropriate speeds and deal with the intense heat of re-entry, much like the space shuttle.
However, none of these options ever became commercially viable, making the Concorde and the the Tu-144 the only SSTs that made commercial flights. For more information on SSTs and related topics, check out the links on the next page.