Aircraft to Come

Airplanes, only 50 years old this year, have grown up quickly from the feebly powered box kites of the Wright brothers into rocket planes that fly more than twice as fast as sound. In such a fast-changing field, crystal-gazing is risky, but last week at a Manhattan meeting of the Institute of Aeronautical Sciences, Dr. C. C. Furnas, director of the Cornell Aeronautical Laboratory, prophesied about aviation's next 50 years.

Dr. Furnas does not think much of nuclear power for aircraft. It will be used for specialized military purposes, he predicts, but not in commercial transportation. Chief obstacle: weight of the shield needed to protect the crew and passengers from nuclear radiation.

The future of aircraft, Dr. Furnas believes, belongs to jet engines, but the turbojets so popular at present will not be the only type. They have the disadvantage of moving a small amount of air at very high speed, and so are really efficient only at the speed of sound and above. Below this speed range, turboprop engines, or the "ducted fans" now being developed, may take over (TIME, Nov. 10). For really high speeds (above Mach 2), ram-jets will be the thing. Old-fashioned reciprocating engines may hang around for a long time, but mostly in marginal fields such as light puddle-jumpers.

Ramjet speeds will be attained, all right, but Dr. Furnas does not think that they will be common. He points out that evolution, whether of animals or machines, often overdoes things. Ocean liners, for instance, are not growing bigger; the biggest ones (Queens Mary & Elizabeth) have not proved as economical as smaller and newer competitors. For similar reasons, not all the airplanes of the future will fly even at today's highest speeds.

Speed is costly and must be bought by sacrificing other attributes. The best military aircraft of the future may fly rather slowly and rely on air-to-air guided missiles for both attack and defense.

Dr. Furnas thinks that commercial airliners will seldom fly faster than sound; the time saved would not be worth the cost. Long-range aircraft will probably settle for 600 m.p.h., and short-range planes for a prosaic 300 m.p.h. For hops below 200 miles, helicopters will take over as the quickest means of traveling between the cluttered centers of large cities.

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