The world of experimental and prototype aircraft throws up many interesting and unusual machines, and the aircraft manufacturers of the USA were no exception. Within a few years of the Wright Brother's first flight in 1903, World War I greatly accelerated the development of aircraft as the fighting machines of all sides were pushed to the limits to gain more speed, altitude and firepower. This book, the first of a two-volume history of the USA's 'X' and 'Y' experimental planes from the earliest years of aviation to the present day, covers the period from the Wright Brothers to the end of World War Two.