The Physics
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Speed of a Commercial Jet Airplane

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"747 Jumbo Jet." Microsoft Encarta Encyclopedia. CD-ROM, 2000. "This Boeing 747, commonly called a jumbo jet, makes a cargo-transport flight. The 747, the first of the wide-bodied commercial jets, had its inaugural flight in 1970. Four jet engines propel the plane, which reaches cruising speeds of 885 km/hr (550 mph)." 245 m/s
Air Transportation. Aerospace Industries Association of America, 1997: 316. "Such aircraft generally cruise at speeds of approximately 540 mi/h or 870 km/hr and at altitudes high enough that aircraft pressurization is required." 241 m/s
747 Family. Boeing. "Cruising speed: 570 mph
Range: 3,110 miles
Ceiling: 36,100 feet
Power: Three 14,000-pound-thrust P&W engines
Accommodation: 131 passengers"
250 m/s
"And, the 747 continues to be the world's fastest subsonic jetliner, cruising at Mach 0.85 -- or 85 percent of the speed of sound. Along with the popular Boeing 777, the 747 is a key element of the Boeing long-range market strategy." 260 m/s
Beichner, Robert J., and Raymond A. Serway. Physics for Scientists and Engineers. 5th ed. Orlando: Harcourt College, 2000. 52. "A plane is traveling at 100 m/s…." 100 m/s

Modern large commercial-airplane manufacturers, such as The Boeing Company and Airbus Industries, a conglomerate of European manufacturers from Britain, Germany, France, and Spain, offer a wide variety of aircraft with different capabilities. Today's jet airliners carry anywhere from 100 passengers to nearly 600 over short distances and great lengths. The 747 the first in its class of wide bodied "jumbo" jets, which would later become the premier transcontinental jet in the world went into service in the early 1970s and seated as many as 490 passengers. Other "jumbo jets"include the 717, 757, 767 and 777, which are used as cargo or passenger jets.

All four models uses the jet engine which operates on the principle of Newton's third law of motion, which states that for every action, there is an opposite but equal reaction. A jet sucks air into the front, squeezes the air by pulling it through a series of spinning compressors, mixes it with fuel, and ignites the fuel, which then explodes rearward with great force out through the exhaust nozzle. This great rearward force is balanced with an equal force that pushes the jet engine, and the airplane attached to it, forward. Thrust is the force that propels an airplane forward through the air. It is provided by the airplane's propulsion system in this case by a jet engine.

Drag is a force acting on all airplanes. Drag is created by any object moving through a fluid, or in this case an airplane through air, which produces friction as it interacts with that fluid because it must move the fluid out of its way to do its work. A high-lift wing surface, for example, may create a great deal of lift for an airplane, but because of its large size, it also creates a significant amount of drag. When thrust is greater than drag, an airplane will accelerate forward. All four jets have four jet engines to propel the plane, which allows the plane to attain cruising speeds of 500 to 900 km/hr (or 150 to 250 m/s). Traveling at approximately Mach 0.80 to 0.85 (or 80 to 85 percent of the speed of sound) these jets make themselves to be the world's fastest set of subsonic (less than the speed of sound) jetliners.

Joby Josekutty -- 2002