Category FLIGHT and M ОТІOIM

propeller is a set of long blades attached to a hub in the center. The job of a propeller is to change the turning force, or torque, of an engine into thrust. Thrust is the force that moves an aircraft through the air.

Propellers and Engines

More than 100 years ago, the first air­planes were powered through the air by propellers. When the jet engine was invented, it looked like the propeller’s days might be over. Even in the age of jets and rockets, however, propellers are still widely used. A piston engine driv­ing a propeller is still the best way to power a small plane today.

There also are many turbine-powered planes with propellers. A turboprop engine runs a lot faster than the best speed for the propeller it controls, so the engine and propeller are connected by a gearbox. Just as a car’s gearbox lets its engine and wheels run at different speeds, a turboprop’s gearbox allows the engine to run at its ideal speed and the propeller to spin more slowly.

Rocket-powered airplanes are rare, because the propellants that power them are often poisonous, explosive, or have to be kept super-cold. The German com­pany Messerschmitt built a rocket-pow­ered fighter, the Me163 Komet, in the 1940s. It could climb amazingly fast, but was could only stay airborne for about 8 minutes.

Rocket-powered planes have been used for research in high-speed flight. On October 14, 1947, the first supersonic flight was made in the rocket-powered Bell X-1 aircraft with Chuck Yeager at the controls.

Rockets are sometimes used to help heavy aircraft take off. This is called rocket assisted takeoff (RATO) or jet assisted takeoff (JATO). The solid-fuel
rockets used for this are called JATO bottles because they look like big bottles.

Other Uses

Small rockets are used for a variety of purposes. Fighter pilots sit in rocket – powered ejection seats. If a pilot has to leave an aircraft in an emergency, rock­ets blast the seat clear of the aircraft. Rocket flares for signaling an emergency at sea use a rocket to launch a bright flare, which may then descend slowly by parachute. Scientists use small rockets called sounding rockets to carry instru­ments into the upper atmosphere. Lightning researchers also use rockets to trigger lightning for study.

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SEE ALSO:

• Apollo Program • Bell X-1

• Ejection Seat • Engine • Fuel

• Jet and Jet Power • Spaceflight

• Space Shuttle

The U. S. military signed a contract with Sikorsky Aircraft in 1943 to buy helicop­ters. The company began producing the R-4, the first mass-produced helicopter. The machines had little impact during World War II, but by the Korean War (1950-1953), they were in constant use.

During the 1950s, Sikorsky opened a new plant dedicated to making helicop­ters. Along with making the flying machines, he helped promote their use. A New York company used helicopters
to carry passengers between the city’s different airports. The aircraft also were used to rescue people caught in disasters or to bring supplies to places difficult to reach in other ways. In 1950, the Collier Trophy was awarded to the entire heli­copter industry. Sikorsky, who had pio­neered the field, had the honor of accepting the award.

Sikorsky retired in 1957. He remained active in aviation and was elected to the Aviation Hall of Fame in 1968. On October 25, 1972, he was still working at his desk. He died the next day.

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SEE ALSO:

• Aircraft Design • Da Vinci,

Leonardo • Flying Boat and Seaplane

• Helicopter • World War I

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