Hufton, P.A. et al. General Investigation into the Characteristics of the C.30 Autogiro. London, Aeronautical Research Committee, 1938. 70pp, illus with photos and graphs, 9x12", wrps, tied with cord. Good, one cover chip, normal light soil and wrinkles. Unusual report of full-scale testing of a Cierva Gyroplane in British colors!