[6][13] He worked closely with Glenn Curtiss on the controversial 1914 flying tests of the (substantially rebuilt and modified) Langley Aerodrome in an attempt to show that Langley's machine had been capable of powered flight with a man aboard before the Wrights' glider was.

[14] Zahm testified that earlier experimental gliders and glider designs and publications, before those of the Wrights, had included a variety of monoplane and biplane designs, with horizontal and vertical rudders, and steering concepts of ailerons and wing warping.

There were complex technical issues, notably whether Curtiss's airplanes used a vertical rudder and ailerons in ways that closely matched the patented design of the Wrights.

In the end judge John R. Hazel ruled in Feb. 1913 for the Wrights, and on appeal a higher court agreed with this decision in 1914.

[13] Zahm became the chief research engineer of Curtiss Aeroplane Company in 1914-1915 and then the director of the U.S. Navy's Aerodynamical Laboratory, 1916-1929.