Evolution of the Airplane

Evolution of the Airplane

Evolution of the Airplane
Reading Level

	edHelper's suggested reading level:	grades 5 to 7
	Flesch-Kincaid grade level:	9.99

Vocabulary

	challenging words:		airflow, airfoil, autogiro, auxiliary, biplane, chain-driven, conventional, convertiplane, convertiplanes, dependence, fuselage, gyroplane, horsepower, propellers, stability, supersonic
	content words:		Wright Brothers, V-22 Osprey, Falklands Islands, Most STOL

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Evolution of the Airplane
By Trista L. Pollard

¹     Since that fateful day in December of 1903, airplane design has changed dramatically. The Wright Brothers built a biplane with two propellers that were chain-driven by a gasoline motor. Their first engine weighed a whopping twelve pounds (5.4 kilograms) per horsepower. Today's airplanes have engines that weigh one pound or less per horsepower. They also use shorter wings because they depend less on the lift that is produced by those wings. Our dependence on air travel over the years has forced airplane design to catch up with the times.

²     Now that aircraft use jet engines which have helped to increase the average speed of airplanes, aircraft wings have been shortened to produce less drag. This is extremely important for aircraft that travel at supersonic speeds. On some airplanes there is a delta wing which is a single triangular lifting surface that is bisected by the airplanes' fuselage. These types of wings are swept back and shortened to produce less drag. Engineers have also designed variable-sweep or swing wings. The wings are extended as the aircraft is taking off or landing for maximum lift. Once the craft is in the air, the wings swing back to their original position for traveling at high speeds. This design improvement helps to keep airport runways at reasonable lengths. Aeronautical engineers have also altered the vertical and horizontal surfaces of the tail assembly to help decrease drag. The need for aircraft to use shorter runways has shifted the focus of airplane design. Engineers are now working on two approaches called the vertical takeoff and landing (VTOL) approach and the short takeoff and landing (STOL) approach. The goal of both approaches is to produce aircraft that can operate on shorter runways.

³     The VTOL approach focuses on aircraft that can takeoff and land like helicopters, but can also fly faster than helicopters. VTOL aircraft should be able to rise and descend vertically from and to the ground. This type of aircraft requires no runways. Balloons and airships are VTOL crafts; however, they do not move parallel to the earth's surface at high speeds. The autogiro, along with the helicopter, is one type of VTOL aircraft. The autogiro or gyroplane is an aircraft that is supported in the air by a horizontally mounted airfoil that is similar to a helicopter but isn't powered. This aircraft was invented and flown successfully in January of 1923 by Spanish scientist Juan de la Cierva. The majority of the autogiro's lift comes from the airfoils that are mounted above the aircraft. These airfoils are rotated by the airflow that is produced as the autogiro moves forward. Its wings are fixed and smaller than those found on an ordinary airplane.

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