Britain's Bid

The world's commercial airplane business is now almost wholly dominated by U.S. manufacturers, but the 'British hope soon to get their share. Last week Vickers-Armstrong showed off its Viscount 700, in most respects a conventional-looking craft. The novelty was the four engines. They carried ordinary propellers on their noses, but instead of being blunt and thick, the Viscount's engines stuck out ahead of the wing like half-cigars (see cut). On these slender "turboprop" engines Britain is pinning her commercial airplane hopes.

Turboprops are a sort of halfway mark between piston engines and the turbojets that drive fighter airplanes. Their inside works are very like the jets', but instead of putting all their propulsive energy into a blast of hot gas shot out the tailpipe, they extract some of it by means of a turbine set in the blast and use it to drive a conventional propeller. This compromise gives turboprops some advantage. They are simpler and lighter than piston engines, and they burn cheap, nonexplosive kerosene instead of high-octane gas. Unlike turbojets, they do not have to fly at extremely high speeds to operate efficiently. At the speeds practical for present-day airliners (300-plus m.p.h.), the jet's high velocity blast wastes much of its energy in merely pushing air backward.

More Payload. Vickers-Armstrong claims that the Viscount 700, the first turboprop airliner to pass its structural aerodynamic tests, has already proved itself superior to comparable airplanes powered with piston engines. It burns more fuel, but it carries a ton of extra payload because of the lightness of its engines. It cruises at 325 m.p.h. with 40 passengers, and is designed for short or medium runs, such as London-Paris and London-Rome.

The Rolls-Royce Dart engines vibrate hardly at all, so the Viscount's designers are hoping for low maintenance costs. None of the plane's 200 instruments, for instance, had to be replaced after its tests. With normal vibration a lot of them would have gone out of whack. The engines are rugged too. Rolls-Royce engineers tossed two buckets of ice cubes into the nose of one, and the only result was a loud clatter and a puff of steam out the exhaust.

More Peace & Quiet. The Viscount 700 takes off with little noise. Inside the cabin, it is no noisier than in a passenger automobile. The vibration is so slight that coins can be stood on their edges and pencils on their ends for 20 minutes at a time. Vickers is counting heavily on the public's reaction to the Viscount's peace & quiet. "Once a passenger has had a ride on a turboprop," said a spokesman, "he won't go back to the noise and vibration of piston engines."

Vickers does not hope to deliver Viscount 7005 before 1952, but there seems to be no great need for hurry. U.S. manufacturers have given comparatively little attention to the turboprop. Their attitude has been that commercial airliners will jump directly from piston engines to turbojets, but not soon. The problems of the 600 m.p.h. jet airliner are far more difficult than those of the intermediate airplane driven by turboprops.

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