Category FLIGHT and M ОТІOIM

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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The science of aerodynamics was slow to develop compared to other sciences. Long before people began to unravel the secrets of aerodynamics, they could see that birds use their wings to create and control the forces needed for flight. They were unable to see exactly how a bird’s wings work, however, because the wings moved too fast to see clearly. Until high­speed photography was developed at the end of the nineteenth century, there was no way to freeze the action of a bird’s wing so it could be studied. Without this understanding, early attempts to build flying machines failed.

One person did try to analyze the forces involved in flight more accu­rately. George Cayley was the first person to study airplane flight scientifi­cally. He experimented with different wing shapes and measured how well they worked. Cayley discovered the four forces that act on an aircraft: lift, drag, thrust, and weight. Other inventors learned from Cayley and expanded upon his work. In time, they learned how to use aerodynamics to create the forces needed to lift and steer flying machines.

THE FIRST HEAVIER-THAN – AIR FLIGHT

The founder of the science of aero­dynamics was the Englishman Sir George Cayley (1773-1857). He worked on a wide variety of engi­neering projects, but is best known for his aero-dynamic research. By 1804, Cayley was building model gliders with the same layout as a modern airplane—they had fixed wings, a body, and a small tail at the back. He also built gliders capable of carrying people. In the 1840s, Cayley built a small glider that carried a ten-year-old boy. Cayley went on to build a full-size glider. In 1853, it carried his coachman, John Appleby, across a valley on the first heavier – than-air flight by an adult. When the glider landed, the terrified Appleby said, "Please, Sir George, I wish to give notice [quit]. I was hired to drive and not to fly!"

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Modern aerodynamics really began with the Wright brothers. Several years of aerodynamic research and experi­ments with wings, kites, and gliders enabled them to build the first success­ful powered airplane in 1903.

arth is surrounded by a blanket of air called the atmosphere. Air is a mixture of gases. It supports life, soaks up energy from the Sun, and moves water around the planet. The atmosphere protects us from harmful rays from space.

Gases and Gravity

Air is made mainly of nitrogen and oxy­gen with small amounts of other gases. The weather, winds, and air currents keep the gases mixed up together. The gases in dry air are 78 percent nitrogen, 21 percent oxygen, and 0.9 percent argon. The remaining 0.1 percent is a mix of carbon dioxide, neon, helium, methane, krypton, hydrogen, and all other gases. The atmosphere also con­tains varying amounts of water vapor.

Gravity pulls the atmosphere down toward the ground, which means the atmosphere has weight. In fact, the atmosphere weighs about 5,500 trillion tons (about 5,000 trillion metric tons).

This great weight presses down on Earth’s surface. At sea level, it presses against everything with a force of about 14.22 pounds on every square inch (98 kilopascals). This pressure is known to scientists as “1 atmosphere.”

ommercial aircraft carry passen­gers and cargo or perform other paid work in the field of general aviation. Fleets of large commercial air­planes are owned by airlines. Many smaller commercial aircraft are owned by small businesses and private pilots.

Airplanes used for commercial air transportation include the huge, wide­bodied airliners able to carry more than 400 passengers. Today’s freight carriers can take loads of cargo weighing more than 155 tons (140 metric tons). These large aircraft fly for thousands of miles across continents and oceans. Cargo planes carry goods-such as perishable foods, mail, and money-that are rela­tively small or of high value and that need to be moved quickly.

General purpose aircraft include small airplanes with special tasks, such as farm crop dusters. Helicopters are also
useful for business travel and on large farms and ranches.

n aircraft carrier is a warship built to carry airplanes. It is also a floating airfield: aircraft can take off and land on aircraft carriers. Aircraft carriers have been nicknamed flattops for their long, flat decks.

History of Carrier Flying

The first vessel to carry any form of air­craft was a coal barge. The George Washington Parke Custis was converted during the American Civil War (1861-1865) to carry observation bal­loons for the Union Army. Experiments in naval aviation began before World War I. In 1910 Eugene Ely piloted a plane from a platform built on the deck of the cruiser USS Birmingham. In 1911 Ely successfully pioneered a system used to land airplanes on carrier decks when he landed on the deck of the battleship USS Pennsylvania. In 1918 U. S.-born Stuart Culley, flying with the British Royal Navy, made the first combat take­off from a moving ship (a converted barge towed by a British warship). He climbed to a height of 18,000 feet (5,485 meters) and shot down a German Zeppelin airship.

The U. S. and British navies began converting more ships to carry air­planes. In 1918 the British modified a merchant ship into a carrier, HMS Argus. The U. S. Navy’s converted coal ship USS Langley launched its first fighter plane in 1922. The navy then gained two converted battle cruisers,

Lexington and Saratoga, in 1927. The USS Ranger was built in 1934 as the first purpose-built flattop.

The planes flown from early carriers were biplanes, such as the Boeing F3B-1 of 1928. Some aircraft were fighters, while others were designed to carry

HELLCAT

The Grumman F6F-3 Hellcat entered U. S. Navy service in 1943. A single-seat carrier-based fighter, its top speed was 376 miles per hour (605 kilometers per hour). The Hellcat was armed with six Browning 0.5-inch (12.7-millimeter) machine guns. During World War II, U. S. Navy ace pilot David McCampbell shot down thirty-four enemy planes from his Hellcat, including nine on a single mis­sion over Leyte Gulf on October 23, 1944.

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torpedoes or bombs. Faster monoplane fighters came into service in the late 1930s. New carrier aircraft had adap­tations such as hydraulically operated folding wings. These wings were first tried on the Douglas TBD Devastator (1935), the U. S. Navy’s first carrier – based monoplane torpedo bomber.

Early airships were all nonrigid, which meant that their balloons collapsed without gas inside. An all-metal airship, called Metallballon, was tried in Germany in 1897, but it flew only once.

The next big step forward in airship design came in 1900. German engineer Ferdinand von Zeppelin built a rigid air­ship that kept its shape with or without gas inside it. It had a strong internal frame, or skeleton, made of metal gird­ers and wires. A fabric skin stretched over the frame. Inside were gas bags, known as ballonets, that were filled with hydrogen gas to lift the airships, which soon became known as Zeppelins, into the air.

BLIMPS

The 1884 La France was not rigid; it was simply a bag of gas, like a balloon, with a cabin and engine fastened beneath. Without gas to inflate it, the airship became limp. In 1917, American sailors gave the nickname blimp, short for "B-limp," to the U. S. Navy’s B-class, nonrigid airships. The blimps were 160 feet (48.8 meters) long and had a speed of 45 miles per hour (72.4 kilometers per hour). The U. S. Navy continued to use blimps until the 1960s. Non­rigid airships are still called blimps. Modern blimps, usually carrying advertising logos, are sometimes seen flying over cities. These aircraft, because they can remain fairly still, also make useful platforms in the sky for television and film cameras. Blimps are popular, too, for tourist flights over city landmarks.

Zeppelin’s first rigid Luftschiff Zeppelin, LZ-1, flew well, and the Germans went on to build bigger rigid airships to carry passengers on regular flights. The Zeppelin Deutschland began the world’s first commercial airship pas­senger flights in 1909. It seemed that airships might dominate aviation.

To leave the Moon in the early hours of July 21, Armstrong and Aldrin used the descent stage of the lunar module as a launchpad. Squeezed inside the upper ascent stage, the two astronauts blasted off and successfully rejoined Michael Collins in Columbia. The lunar module was then discarded, and a blast from a rocket in the service module sent the astronauts on their homeward course.

Before reentering Earth’s atmosphere, the astronauts seated themselves inside the cone-shaped command module. This was the only part of the Apollo
spacecraft with tough, outer insulating layers. The insulation would shield the crew from the searing heat, caused by air friction, that makes a spacecraft glow red-hot as it plunges back into the atmosphere.

The command module carried three large parachutes that opened during the final stage of descent, dropping the spacecraft safely into the Pacific Ocean. Apollo 11 splashed down on July 24,

1969. The astronauts, hailed as heroes, received a huge welcome. First, how­ever, they had to spend more than two weeks in isolation in a sealed medical chamber in case they had brought back any harmful infections from space. Fortunately doctors found none.

balloon is a sack filled with gas. Large balloons filled with gas can rise and stay in flight because of the gas inside the balloon.

How Balloons Stay Up

Archimedes (AR-key-MEE-dees), a Greek scientist of the third century b. c.e., real­ized that an object will float when its weight equals, or is less than, the weight of the fluid (gas or liquid) it displaces, or pushes away. His discovery explains why a ship floats. It also provides an explanation of why a balloon flies, because air displaces in the same way as water. This force is called buoyancy.

A small balloon filled with air is light, but it is not buoyant. It will naturally sink to the ground because the weight of the balloon skin makes it heavier than the air around it. In the 1700s inventors began to experiment with “floating flight.” They were possi­bly inspired by watching smoke from a fire rise into the air. Hot air seemed to hold the key to flight.

This was proved in 1709. In Portugal a priest named Bartolomeu de Gusmao demonstrated a small paper balloon filled with hot air. A small fire, lighted in a dish tied beneath the balloon, heated the air. The balloon rose 12 feet (3.66 meters) toward the ceiling of a room. Nothing more came of this experiment, but it proved that hot air, being lighter than the air around it, can enable an object to rise and stay afloat.

Biplanes can still be seen flying today. They are useful as general aviation workhorses, doing such jobs as crop dusting, geological surveying, and air photography. Some are flown by vintage airplane enthusiasts. They enjoy the sen­sation of piloting a plane with an open cockpit and listening to the roar of the engine and the humming of the wires and struts in the wind. Biplanes are also superb for aerobatics because of their

TECH

Boeing/Stearman Model 75

Type: Two-seat basic trainer. Construction: Wood and fabric wings, metal frame body.

First flight: 1933.

Engine: One radial piston engine. Primary use: Training.

Top speed: 124 miles per hour (200 kilometers per hour).

strength and their stability at low speeds. One outstanding aerobatic plane is the Pitts Special, a design first flown in 1947. Today, it remains one of the most powerful, agile aerobatic stunt planes, thrilling crowds at air shows around the world.

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SEE ALSO:

• Aerobatics • Kitty Hawk Flyer

• Lift and Drag • Lilienthal, Otto

• World War I • World War II

•

Wright, Orville and Wilbur