Under the initial designation Douglas XA-42 for an attack bomber, redesignated subsequently XB-42 as a bomber, Douglas designed and built two prototypes and one static test airframe under a contract received from the US Army Air Force on 25 June 1943. Named Mixmaster by the company, this unusual aircraft had a mid-set cantilever monoplane wing, cruciform tail surfaces and tricycle landing gear, whose main units retracted aft to be housed in the sides of the fuselage. The broad and deep fuselage provided accommodation for a crew of three, consisting of a bomb-aimer/navigator in the nose, with the pilot and co-pilot in a side-by-side cockpit well forward on the fuselage, each beneath an individual canopy; the fuselage also incorporated a large internal bomb bay, as well as housing the twin-engine powerplant in a compartment immediately to the rear of the pilot's cockpit. The two Allison V-1710 engines were used to drive, via shafting and a reduction gearbox in the tailcone, two three-bladed contra-rotating pusher propellers to the rear of the tail unit.

Despite its unusual features, when first flown on 6 May 1944 the Mix-master more than lived up to expectations. The second prototype was flown for the first time on 1 August 1944, soon afterwards being modified by the addition of a single canopy over the pilot/copilot cockpit. This prototype was destroyed in a crash during December of that year, but by that time the USAAF had decided not to proceed with production of this design, awaiting instead the development of higher-performance turbojet-powered bombers. As an interim step to allow evaluation of turbine power, the first prototype was given a mixed powerplant comprising two 1025kW Allison V-1710-133 piston engines to drive the propellers, plus two 726kg thrust Westinghouse 19XB-2A turbojets mounted in underwing nacelles. Redesignated XB-42A, this aircraft was used for performance testing over several months before being retired at the end of June 1949.

3-View

A three-view drawing (550 x 777)