Capable of sustaining flight over a fifty-per-cent greater range than any gasoline engine, a lightweight Diesel airplane motor was recently tested before U. S. army officials and is ready for production. Developing 310 horsepower, the nine-cylinder radial air-cooled engine weighs only 653 pounds, little more than two pounds per horsepower. It burns fuel oil costing around six cents a gallon. The engine, designed by S. A. Guiberson, Jr., of Dallas, Tex., is the only American built Diesel approved by the Civil Aeronautics Authority. A test flight indicated it could take a plane to an altitude of 21,000 feet, while the same plane had a 17,000-foot ceiling with a gasoline engine. The Diesel, however, costs about five times as much as the gas engine.