Douglas XB-42 Mixmaster

XB-42A

Douglas designed and built two bomber prototypes and one static test airframe under a contract received from the US Army Air Force on 25 June 1943. This was based on two 1800-hp (1342-kw) Allison V-1710-25 inline engines located in tandem in the fuselage to drive a pair of contra-rotating propellers behind the cruciform tail unit. Named Mixmaster by the company, this 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 fuselage provided accommodation for a crew of three. A bomb-aimer/navigator in the nose, and 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 an 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. Opening the bomb doors in flight interrupted the airflow to the propeller and caused excessive vibrations. The bomber version had six machine guns. The four on the wing trailing edge were aimed by the copilot, whose seat could turn to face aft. An attack version armed with 16 machine guns or a 75mm cannon and two machine guns, or two 37mm cannon was proposed.
Designated XB-42, the Mixmaster was first flown on 6 May 1944.

A 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. The XB-42A is now in storage for the National Air and Space Museum. Somewhere along the way its wings were removed for transport and haven't been seen since.

 

XB-42
Engines: 2 x Allison V-1710-125, 1800-hp (1342-kw)
Max take-off weight: 16193 kg / 35700 lb
Empty weight: 9475 kg / 20889 lb
Wingspan: 21.49 m / 70 ft 6 in
Length: 16.36 m / 53 ft 8 in
Height: 5.74 m / 18 ft 10 in
Wing area: 51.56 sq.m / 554.99 sq ft
Max. speed: 660 km/h / 410 mph
Cruise speed: 502 km/h / 312 mph
Ceiling: 8960 m / 29400 ft
Range: 2897 km / 1800 miles
Armament: 4 x 12.7mm machine-guns, 3629kg of bombs

XB-42A
Engines: 2 x Allison V-1710-25, 1800-hp (1342-kw) & 2 x turbojets.