W.H. McAvoy and North American O-47

NACA's second research lab was established in 1939 at Moffett Field in Sunnyvale, Calif. (It's now known as NASA's Ames Research Center.) Here, in November 1940, test pilot W.H. McAvoy steps out of a North American O-47, the first test airplane at Ames. Research flights by McAvoy and fellow pilot Lawrence Clousing included looking into the problem of ice buildup on aircraft.

Those flights often were done in a two-engined Lockheed 12 airplane. "McAvoy and Clousing...flew the little transport plane into some of the worst weather they could find on the West Coast," according to a NASA account. "Ice would sometimes form on the windows so thickly that they could not see whether the wings were ice-free or not, the radio would cut out due to icing, and ice would sometimes form on the tail surfaces, which were only partially protected by an inflatable rubber shoe."