Category FLIGHT and M ОТІOIM

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

Business boomed as World War II pro­gressed. At peak production in 1944, Boeing’s Seattle plant rolled out sixteen new planes in twenty-four hours. During World War II, B-17s flew day­light bombing raids, relying on their armament of thirteen machine guns for defense against enemy fighters.

The B-17 was succeeded in 1942 by the B-29. The B-29 was twice as heavy; it had a top speed of 358 miles per hour (576 kilometers per hour) and a range of 3,250 miles (5,230 kilometers). The manufacture of the B-29 was spread all around the nation. Thousands of subcontractors supplied the airplane’s components to four production plants: Boeing at Renton, Washington, and Wichita, Kansas; Bell at Marietta, Georgia; and Martin at Omaha, Nebraska.

From the B-17, Boeing developed the 307 Stratoliner (1938), the first pressurized airliner, which seated thirty – three passengers. The B-29 gave rise to a cargo plane, the 367 (1944), and a passenger carrier, the 377 Stratocruiser.

This was Boeing’s last, big, piston – engine airliner. In the 1940s and early 1950s, the 377 carried 117 passengers from New York City to London at 340 miles per hour (547 kilometers per hour).

Instruments in an aircraft’s cock­pit show the pilot what is hap­pening to the aircraft and how well it is flying. The instruments are especially important when a pilot cannot see the ground because of cloud, fog, or dark­ness. They enable a pilot to keep an aircraft flying safely in the right direction. The instruments also can warn pilots of dangers, such as fire in an engine or flying too close to the ground.

Glass Cockpits

Modern cockpits often have several screens, like computer screens, which combine the functions of many separate instruments. This kind of cockpit is called a glass cockpit.

There are three types of screens in a glass cockpit. The first is the primary
flight display, which shows the airspeed, altitude, heading, and vertical speed. There is a primary flight display in front of each pilot.

The next screen is the navigation display, which shows the aircraft’s posi­tion and course. The picture from the aircraft’s weather radar also can be

TECH^TALK

There are seven basic flight instru­ments in an airplane:

• Airspeed indicator shows an aircraft’s speed compared to the surrounding air.

• Altimeter shows an aircraft’s height above sea level, or altitude.

• Attitude indicator shows an aircraft’s attitude (the way it is pointing) compared to the horizon.

• Magnetic compass shows an aircraft’s heading (direction).

• Heading indicator also shows heading but works in a different way from the magnetic compass.

• Turn and bank indicator shows if an aircraft is turning correctly.

• Vertical speed indicator shows how fast an aircraft is climbing or descending.

The magnetic compass works by sensing the direction of Earth’s mag­netic field. It works fine in steady flight, but it can be unreliable if the plane is climbing, diving, or turning.

The heading indicator (which is based on a gyroscope) is used to double-check it.

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shown on this screen. A small business jet might have one navigation display in the middle. A larger airliner may have a separate navigation display in front of each pilot.

The third type of screen is linked to the engine indicating and crew alerting system (EICAS). It shows engine infor­mation and emergency warnings. In addition, an aircraft’s flight computer has its own small screens.

A glass cockpit can greatly reduce the number of instruments and controls. The glass cockpit of the Boeing 747-400 has 365 instruments and switches – about 600 fewer than the cockpits in earlier 747s. A glass cockpit also has a basic set of old-style instruments to provide an emergency backup if the cockpit screens fail.

Glass cockpits have proved to be so reliable and effective that spacecraft now have them as well. The Space Shuttle and Soyuz spacecraft are fitted with their own glass cockpits.

BOAC showed its loyalty to the Comet by ordering Comet 4s in 1955, but the

LESSONS LEARNED

Airplane manufacturers learned les­sons from the Comet. All modern airplanes are very strongly built. Their structures (body, wings, tailplane, and everything else) are tested extensively to see how long it takes for cracks to appear. Further tests are made during an aircraft’s working life, to check for any signs of structural failure (some­times called metal fatigue). If inspec­tions show even minute cracks in any part of the structure, airplanes are taken out of service for repair, or they are permanently retired.

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company had to wait until 1958 for these new airplanes to be delivered. That year, Comet 4s began operating passen­ger flights between London and New York. The Comet 4 was bigger than the Comet 1; it was 18.5 feet (5.6 meters) longer and could seat eighty to 100 pas­sengers. Its Rolls-Royce Avon engines were twice as powerful as the De Havilland Ghost engines used in the Comet 1. The Comet 4 cruised at 503 miles per hour (809 kilometers per hour) at 42,000 feet (12,800 meters) and had a longer range than the original Comet. It also had a strengthened fuselage and stronger windows. The Comet 4 proved to be a perfectly safe and easy airplane to fly and travel in.

By this time, however, airlines— especially large airlines in the United States—were lining up to buy new, U. S.-built jet airliners. The Comet had lost its lead in world jet travel to the U. S. Boeing 707 and the Douglas DC-8. These airplanes were faster and carried more passengers than the Comet, and they sold in much greater numbers.

The Comet, as the world’s first jet airliner, never achieved the success that its designers had hoped for. The Comet airframe was later used as the basis for the British Aerospace Nimrod maritime patrol aircraft, first flown in 1967.

SEE ALSO:

• Aerospace Manufacturing

Industry • Aircraft, Commercial

• Aircraft Design • Jet and Jet

Power • Materials and Structures

Flying takes a lot of energy. When a bird flies, it uses about fifteen times more energy than when it is still. The fuel that supplies this energy is the bird’s food, which is stored as fat until it is needed.

When a bird takes off and flies, it needs the chemical energy stored in its fatty fuel. The energy is released by chemical reactions that use oxygen from the air. A lot of oxygen is needed to keep

a bird’s muscles supplied with enough energy to keep flying.

Airplanes and rockets have energy needs similar to those of a bird. They carry energy stored in their fuel, and they have to combine the fuel with oxy­gen to burn it and release the energy. When a jet plane or rocket takes off, chemical energy in the fuel changes to heat energy in the engines. Heat energy changes to the kinetic energy of the hot gas that shoots out of the engines.

Other Forms of Flight Power

There are other ways than using jet fuel to obtain the energy needed for flight. There are electric airplanes powered by propellers driven by electric motors. The electricity is produced by solar cells on top of the wings. Solar cells change solar energy into electrical energy.

There have been experimental nuclear-powered aircraft, too. In the 1950s, nuclear-powered military planes seemed attractive because they could stay in the air for weeks or months. Nuclear-powered jet engines were built, and at least one nuclear-powered air­craft did fly. These planes never went into production, however. It proved to be too hard to protect the crew from the dangerous radiation produced by the fuel. If one of these planes had crashed, it also could have spilled radioactive fuel over a wide area.

In the 1920s, the German firm of Dornier built the Whale, which set the pattern for later passenger flying boats. It had four engines set on top of the wing and a boat-shaped hull, with airfoil-shaped sponsons (float-like attachments to the hull) that kept the craft stable on water.

The Whale cruised at 112 miles per hour (180 kilometers per hour) for a distance of 1,243 miles (2,000 kilometers) and could carry up to nineteen passengers. Whales and the bigger Super Whales made many record-breaking flights and opened up new commercial services, such as flights from Germany to Brazil.

Pan American Airways started the first regular mail and passenger service across the Pacific Ocean in 1935, using the Martin 130 China Clipper, a flying boat. The Clipper could carry forty-eight passengers on daytime flights and eight­een passengers in a night sleeper layout. Britain also built flying boats for long- haul routes: The Short Empire flying boats (1936), for instance, flew to Africa and India.

Flying Boats at War

During World War II, navies of warring nations used flying boats and other sea­planes to attack shipping and patrol supply routes. The British built the Short Sunderland, a heavily armed patrol flying boat, to hunt Nazi submarines in the Atlantic Ocean. The Sunderland remained in service until 1959.

Probably the most famous seagoing airplane of World War II was the U. S. PBY Catalina. Built by Consolidated and first flown on March 28, 1935, the twin – engine Catalina carried a crew of up to nine people. It had a cruising speed of 117 miles per hour (188 kilometers per hour) and a range of 2,500 miles (4,023 kilometers). The Catalina offered greater range and load-carrying capacity than

earlier flying boats. It flew with the British, Canadian, and Australian forces and also was built in Russia.

As well as flying patrol and bombing missions, Catalinas rescued many pilots whose airplanes had crashed into the ocean, dropping lifeboats into the water or landing to pick up fliers from the water. Most Catalinas were amphibious airplanes-they had wheels and so could land on a runway, too. Consolidated also built the larger, four-engine PB2Y Coronado, a flying boat bomber that saw service during World War II.