N.O. Brantly began designing B-1 coaxial helicopter 1943, flown 1946. Replaced by simpler B-2, flown 21 February 1953, since mass-produced together with 5-seat Model 305. Successively became division of Lear Jet Industries, ARDC (Aeronautical R&D Corp), Brantly Operators Inc. and, on 1 January 1975, Brantly-Hynes.