JETS

Development

During the 1950s jet aircraft replaced slower, propeller-driven planes. In the military the change was swift; in civilian aviation it took place more slowly. World War II forced the United States government to accelerate research and development of high-performance jet aircraft in order to counter the German air force's jet fighters. While American pilots never flew jets during the war, the air force tested a number of jet-and rocket-powered planes from 1942 onward.

Background

The jet age arrived on 27 August 1939 when Erich Warsitz flew a turbojet-powered Heinkel 178 aircraft at Marienehe airfield in Nazi Germany. German officials shrugged indifferently. In the United States, Bell Aircraft's XP-59 Airacomet jet made its debut on 1 October 1942 over Muroc, California. Neither plane was substantially faster than its piston-engine counterpart, and while both aircraft served as prototypes and training models for later, more-advanced jet aircraft, early jet engines only hinted at the possibilities of super-sonic flight.

Mach-1

Attitudes changed on 14 October 1947 when a Bell X-1 rocket plane, piloted by Capt. Charles ("Chuck") Yeager, reached a speed of 964 miles per hour (Mach 1.06) in level flight at an altitude of 42,000 feet over California's Muroc Air Base. The Bell X-l demonstrated that aircraft could fly faster than the speed of sound (760 miles per hour at sea level) without disintegrating. But jet aircraft still lacked the range and engine life of propeller aircraft. Although the United States Air Force and the National Advisory Council on Aeronautics (the forerunner to the National Aeronautics and Space Administration) successfully tested and operated American jet-fighter aircraft early in the decade.

Korean War

During the Korean War the United States Air Force and Navy employed large numbers of both jet and propeller aircraft. Most American fighters were jets, but none of them, including the Lockheed P-80 "Shooting Star," the North American F-86A "Sabre," or the Grumman F9F-2 "Panther," could fly at the speed of sound in level flight. American bombers were either piston engine or turboprop (basically a jet turbine driving a high speed propeller). The only American multiengine jet bomber of the Korean War was the B-45 "Tornado." The large strategic jet bombers, the Boeing B-47 and B-52, became operational in 1951 and 1952 but did not see combat in Korea. These huge bombers provided research information vital to the design of the American passenger jets.

Early Misgivings

Despite Boeing's technical advancements in jet bombers, airline companies in the United States did not have a great deal of faith in the reliability of jet-powered aircraft. C. R. Smith, president of American Airlines, stated that America would be ready for high-speed commercial jet transport after the British Rolls-Royce Nene jet engine proved it could operate for five hundred hours. There was the further complication of negative publicity generated by Great Britain's de Havilland aircraft company, which operated the first commercial jet passenger aircraft, the DH.106 "Comet L" Early models suffered from structural problems involving stress fractures in the fuselage from the pressurized passenger cabin. The "Comet I" first flew successfully on 27 July 1949 after the disastrous midair crack-up of an earlier prototype research plane, the de Havilland DH.108. Two "Comet I's" crashed into the Mediterranean Sea on 10 January and 8 April 1954, forcing de Havilland to ground the plane temporarily so that diagnostic technicians could discover the flaws.

Boeing and Douglas

In the United States the Boeing and Douglas aircraft companies tried to sell their respective jet-transport aircraft designs to the air force before approaching the commercial airline industry. Like other defense contractors, these two aircraft-design firms minim ized their financial risk when they competed for military contracts since the air force subsidized a significant portion of the research and production.

Boeing 707

But Boeing invested its own money in developing what would eventually become the first American passenger jet, the Model 707. The Boeing 367-80, the first variant of the 707, and the Air Force's KC-135 airborne refueling aircraft flew on 15 July 1954. During its October nonstop flight from Seattle to Washington, D.C., the Boeing 367-80 flew at an average speed of 592 miles per hour. On the return trip the aircraft averaged 567 miles per hour for four hours and eight minutes. The commercial airline industry signaled its confidence in the plane when Pan American Airways purchased thirty 707s on 8 November 1955.

DC-8

The earliest jet competitor to the 707, the Douglas DC-8, competed for commercial contracts in 1955. On 13 October 1955 Pan Am ordered twenty DC-8s and twenty Boeing 707s. On 25 October 1955 United Airlines ordered thirty DC-8s for their new nonstop transatlantic flights. Although the Boeing 707 was available, it was not yet capable of flying the Atlantic nonstop. The DC-8 it did not make its first flight until 30 May 1958. In the interim Boeing continued to improve and modify the 707 with numerous variants for the air force and civilian airlines.

Decade's End

By the end of the decade jet transports, supersonic fighters and bombers, and transcontinental jet passenger aircraft were the norm in aviation. Scientists, designers, technicians, and pilots worked together to improve the reliability, fuel efficiency, power, and overall flying performance of all types of jet aircraft. During the 1950s jet aircraft carried out numerous military missions as well as civilian transport of people and goods on a scale not previously imagined.