Avro 501

The Avro Type H, Type 501 and Type 503 were a family of early British military seaplanes developed from the Avro 500 and originally conceived as amphibious, with one large wheeled main float under the fuselage and two outrigger floats under the wings. Tests were held on Windermere in January 1913, after which the prototype was converted to twin floats, bought by the British Admiralty, found too heavy and converted again to a landplane. An improved 503 earned an order for three from the Inspector of Naval Aircraft, and the prototype was bought by the Imperial German Navy and became the first aircraft to fly across the North Sea, from Wilhelmshaven to Heligoland, in September 1913. Gotha built the type under licence as the WD.1.