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How Concordes Work
by Craig C. Freudenrich, Ph.D.

Do you need to get from London to New York in a hurry? No problem! Just hop onboard the world's fastest passenger airplane, the Concorde, and you will be there in less than four hours! How can you cross the Atlantic in such a short amount of time? Simple: The Concorde travels faster than sound!


Photo courtesy British Airways
Concorde supersonic passenger jets

In this edition of HowStuffWorks, we will show you how this amazing vehicle works.

A Little History
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, of which 13 are still in service. The planes are flown by British Airways and Air France. The 30th anniversary of the Concorde took place on March 2, 1999. Ten of the Concordes have flown more than 920,000 hours.

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."


Photo courtesy NASA
The Russian Tu -144LL landing

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.


Photo courtesy British Airways
A flight engineer installs a Kevlar liner to a Concorde's fuel tank for its return to flight.
Today, the Concorde is the only SST in commercial service. However, the Concorde has 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.

The Concordes are undergoing modifications. These modifications include installing Kevlar linings to the fuel tanks, to prevent them from rupturing in the event that the wing is punctured, and strengthening the wiring in the undercarriage. The Concordes are projected to be back in commercial service in September 2001.

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 flies 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 cruises at 1,350 mph (2,172 kph, or Mach 2) at an altitude of 60,000 ft (18,300 m). Because the Concorde travels faster than the speed of sound and almost twice as high as other commercial jets, it has several features that set it apart from other aircraft:

  • Streamlined design
    • Needle-like fuselage
    • Swept-back delta wing
    • Moveable nose
    • Vertical tail design
  • Engine design
  • Main and auxiliary fuel tanks
  • High-reflectivity paint


Structural diagram of a Concorde
Move your mouse over the color options to see where each component is located on the Concorde.

Let's look at these features in detail.

Streamlined Design
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 have been implented:

  • Needle-like fuselage
  • Swept-back delta wing
  • Moveable nose
  • Vertical tail design
The fuselage (body) of the Concorde is only 9.5 ft (2.7 m) wide (for comparison, a 747 is 20 ft (6.1 m) wide). The length of the Concorde is about 202 ft (61.7 m), just slightly shorter than a 747. The long, narrow shape of the Concorde reduces the drag on the plane as it moves through the air.


Photo courtesy British Airways
Drawing of the Concorde in flight: Note the wide, triangular wing structure and lack of horizontal tail.

Photo courtesy British Airways
A Boeing 747 in flight: Note the thin, rectangular wing structure and horizontal stabilizer on the tail.

The wing of the Concorde is thin, swept back and triangular, whereas a 747's wing is swept back but rectangular. Also, there is no space between the fuselage and the wing of the Concorde as there is in the 747. The Concorde's wing is called a delta-wing design and does 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 has a longer, needle-shaped nose compared to most commercial jets. The nose helps 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 has a visor to protect the windshield when flying at supersonic speeds.

As mentioned above, because the delta wing provides stability to the aircraft, the Concorde does not require a horizontal stabilizer on the tail like most other aircraft.

These designs in the body and wings of the aircraft allow it to move easily through the air at high speed.

Engines
The engines on the Concorde provide the thrust necessary for takeoff, cruising and landing. The Concorde has four Rolls Royce/Snecma Olympus 593 turbo jet engines. Each engine generates 18.7 tons (180 kN) of thrust. Together, the four engines burn 6,771 gallons (25,629 liters) of fuel per hour.

The location and type of engines on the Concorde's are different from on other jets.


Photo courtesy British Airways
Concorde in flight: Note that the engines are attached directly underneath the wing without struts.

Photo courtesy British Airways
Airbus 320 in-flight: Note that the engines are attached underneath the wing with struts.

The Concorde's engines are attached directly to the underside of the wing without engine struts. This design reduces 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 use 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 are several components that enable and support the speed and power achieved by the Concorde.

Fuel Tanks
The Concorde has 17 fuel tanks that can hold a total of 31,569 gallons (119,500 liters) of kerosene fuel. The main tanks are located in each wing (five on each side) and fuselage (four).

The Concorde also has three auxiliary or trim fuel tanks (two in front and one in the tail). Here is what the trim tanks are used for:

  • As the Concorde reaches supersonic speeds, its aerodynamic center of lift shifts backward.
  • This shift drives the nose of the aircraft downward.
  • To maintain balance, fuel is pumped backward into the trim tanks.
  • The redistribution of fuel balances the aircraft by making its center of gravity match the center of lift.
  • When the plane slows down, the center of lift shifts forward.
  • Fuel is then pumped forward into the trim tanks to compensate.
So, unlike other jets, the Concorde uses fuel not only for the engines, but also for aerodynamic stability.

High-reflectivity Paint
Because the Concorde moves faster than sound, the air pressure and friction (collision with air molecules) really heat up the plane. The temperature of the aircraft's skin varies from 261 degrees Fahrenheit (127 degrees Celsius) at the nose to 196 F (91 C) at the tail. The walls of the cabin are warm to the touch. To help reflect and radiate this heat, the Concorde has a high-reflectivity white paint that is about twice as reflective as the white paint on other jets.

The heat encountered by the Concorde causes the airframe to expand 7 inches (17.8 cm) in flight. To minimize the stress on the aircraft, the Concorde is made of a special aluminum alloy (AU2GN) that is lightweight and more heat-tolerant than titanium.

Now that we have seen the technical features that make the Concorde special, let's look at a typical flight from London to New York.

A Trip on the Concorde

Photo courtesy British Airways
The Concorde's cabin
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 30 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!


Photo courtesy British Airways
A typical in-flight meal on the Concorde

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.


Photo courtesy British Airways
A Concorde landing

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!

Future SSTs
As of 2000, plans are to improve the Concorde in terms of safety and comfort. New seats and cabin lighting are being installed to improve the passenger's experience onboard the plane.

In addition to the Concorde, other supersonic planes are currently under design. 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.


Photo courtesy NASA
One concept of the National Aerospace Plane

Photo courtesy NASA
Another concept of the National Aerospace Plane
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.

For more information on SSTs and related topics, see the links on the next page.

Lots More Information!

Related HowStuffWorks Links

Other Great Links

General Information

Technical Information

Other SSTs

Future of SSTs

Aeronautics

 

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