In 1919, Dayton-Wright built a limousine version of the DH-4, the single-seat Messenger, and a three-seater. In 1920, Milton C. Baumann designed the RB-1 racer, with solid balsa wood wing,John Wegg, General Dynamics Aircraft and Their Predecessors (London: Putnam, 1990), , 38. enclosed cockpit, and retractable landing gear linked to rod-operated leading and trailing-edge camber-changing flaps.David Mondey, ed.; Michael Taylor, rev. The New Illustrated Encyclopedia of Aircraft (London: Greenwich Editions, 2000), ), 560.
