G.Swanborough, P.Bowers United States Navy Aircraft Since 1911 (Putnam)

STANDARD H-4-H

The Standard Aero Corporation was formed in 1916 in anticipation of America's eventual participation in World War I. First products at the company's Plainfield, NJ, plant were Model H-3 reconnaissance-trainers derived from earlier Sloan Aircraft models designed by Standard's chief engineer, Charles H. Day. First sales by Standard to the Navy were three Improved H-4-H seaplane trainers (A137-A139) delivered in 1917. Power plant, 125 hp Hall-Scott A-5.

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The Standard H-4-H (H for Hydro). The exact serial which can be seen is A137, making it the first of a series of three (A137-A139) ordered by the US Navy.
   There were two earlier Standard seaplane models ordered by the US Navy, that is A91 [ Standard seaplane ] and A92 [Standard Twin seaplane], the order of which was cancelled.