Science: Electricity from Plane Engines

Like the oldtime housewife who used to hitch the cradle to her rocking chair, letting the motion of the chair rock the baby, U.S. airplane motormakers last week were harnessing airplane engines to generators—thus just about licking the serious wartime shortage in electricity. One Midwest motor plant is generating several million kilowatt hours a month, more than half the power needed to run the plant at capacity.

Airplane engines (unlike automobile engines) are not broken in by actual use, but must furnish maximum power at the first takeoff. This means that airplane engines have to be broken in by running them on the ground at the factory for at least twelve hours without stopping.

The waste in such motor tests is prodigious. A 2,200 h.p. engine burns up some 2,000 gallons during a twelve-hour test. And plane engines cannot burn anything but precious 100 octane gas.

Engineers have long wanted to use the engine tests to generate power, but there were too many hitches. For one thing, test runs of motors in the past have been sporadic. With quantity production of high-powered engines, tested on schedule, power production becomes possible. More important was the difficulty of coupling a high-speed engine to a low-speed generator, of obtaining uniform, dependable voltage regardless of the ups & downs in speed and number of the engines under test. Now a variable-speed dynamo unit replaces the propeller, produces power instead of wind.

Last week General Electric (which provides many of the generators) reported that present generator installations number 163, include Pratt & Whitney, Ford, Buick, Chrysler.