With the military converting to jet fighters and bombers, it was inevitable that jet aircraft would also be developed for airline use. When this did occur, the first jets were British-built, not American, which is rather surprising since United States aircraft had dominated the airlines since World War II. There are two types of jet propulsion, turboprop and "pure" jet. Both types use a gas turbine engine, the difference being that in a turboprop the gas turbine is fastened to a propeller that is used to propel the aircraft. There is some thrust provided by the jet exhaust, but the propeller provides most of the power. In a "pure" jet, all of the thrust is provided by the jet exhaust.
The turbopropeller, or turboprop engine, is basically derived by gearing a conventional propeller to the shaft of a gas generator composed of a compressor, burner, and turbine. The turboprop engine may therefore be thought of as a turbojet engine that transmits power to the air by means of a propeller rather than through the jet exhaust. turboprop engine is light and relatively simple as compared with the large high-power reciprocating engines. For example, a modern turboprop engine may develop between 2 and 3 horsepower per pound of weight, as compared with a maximum of about 1 horsepower per pound for a reciprocating engine. The specific fuel consumption of the turboprop engine, however, is somewhat higher than that of the best reciprocating engines. turboprop engine has been used in a number of highly successful transport aircraft and is still in fairly widespread use, particularly for short-haul, commuter-type transports.
The British developed both the first turboprop and the first turbojet airliners. The first civil airliner to be equipped with turboprop engines was the Vickers Viscount. The Viscount first flew in July 1948 and went into commercial service in 1953. The Viscount employed four Rolls-Royce Dart turboprop engines of 1600 horsepower each and had a gross weight of about 60 000 pounds. Depending upon the configuration, 40 to 59 passengers could be carried in the pressurized cabin. The cruising speed of the Viscount was 334 miles per hour at 25,000 feet. The aircraft employed double-slotted flaps and was equipped with a tricycle landing gear.
The very considerable success of the Vickers Viscount in airline service was due to the smoothness, economy and reliability of its turbine engines. In one enormous leap it had raised cruising speed almost 100% by comparison with the piston-engined Vickers Viking; it carried two or three times as many passengers (according to type) and offered increased range. The Viscount was used by airlines all over the world. There was a total of 444 [441?] Viscounts produced in three series. The first series carried 47 passengers. This was increased to 75 in later models. The Viscount had a cruising speed of about 350 mph and a range of about l,700 miles.
Undetected ice on the horizontal stabilizer of a Continental Airlines Vickers Viscount 810 caused the airplane to pitch down during an attempted night landing in freezing precipitation at Kansas City on 29 January 1963. The aircraft struck the ground short of the runway, causing eight fatalities. Research into the problem of tailplane icing had first been undertaken during the late 1970s and early 1980s by a Swedish-Soviet working group in the wake of the crash to a Linjeflyg Vickers Viscount on 15 January 1977, near Stockholm. Their wind tunnel and flight tests that studied the tailplane stall phenomenon failed to produce definite results, but had provided insights that would assist later researchers.
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