Douglas XB-42 Mixmaster

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Douglas XB-42 Mixmaster

The Douglas XB-42 Mixmaster was an American experimental bomber designed for very high speed. Its unusual design put the two engines inside the fuselage, driving a pair of contra-rotating propellers mounted at the tail in a pusher configuration, keeping the wing and fuselage free of drag-causing protrusions.

Two prototypes were built. The first flew on May 6, 1944. The idea was to achieve Mosquito-like speed but with heavier bomb load and longer range. The engines were two Allison V-1710-125 V-12s placed behind the crew, with air intakes in the wing leading edge. The aircraft used tricycle landing gear and a four-surface cruciform tail with a ventral fin; a tailwheel helped prevent the propellers from striking the ground. The pilot and co-pilot sat under twin bubble canopies, while the bombardier sat at the front behind a plexiglass nose.

Armament varied. The wing trailing edge housed two 0.50 in machine guns on each side for defense, which retracted into the wing when not in use. Some early plans (the XA-42) proposed heavy armament, including many guns or a 75 mm cannon. An emergency system could sever the tail propellers to protect the crew if needed.

The first prototype, 43-50224, flew at Palm Springs, showing fast performance and a large bomb load for its size. However, the twin bubble canopies created communication problems, so a single canopy was adopted after the second prototype’s first flight. The XB-42 also showed stability problems (yaw), propeller vibration, and cooling issues, and it required careful handling on the ground because the ventral tail was close to the ground. A shock absorber was added to reduce tail stress.

With World War II ending, the U.S. Army Air Forces decided to wait for jet bombers rather than continue with the XB-42, and the program was canceled in 1948. In December 1945, the second prototype (43-50225) set a transcontinental speed record, flying from Long Beach to Washington, D.C. in about 5 hours and 17 minutes at 433.6 mph. The aircraft crashed later that month during a routine flight; the crew survived after bailouts and jettisoning the tail propellers, while observers speculated about fuel or other issues.

The remaining prototype was used to test an uprated engine concept named the XB-42A, which added underwing Westinghouse jet engines for propulsion. It first flew in May 1947 and reached about 488 mph in testing, but after a hard landing the ventral tail was damaged. It never flew again and was removed from U.S. Air Force inventory in 1949.

The program cost about $13.7 million (including the related B-43 project). The first prototype is kept by the National Museum of the United States Air Force in Dayton, Ohio, with the wings reportedly removed for transport and later reassessment. The fuselage (along with the XB-43 Jetmaster) has been moved to the National Museum of the United States Air Force for display in the Experimental Aircraft Hangar.