Douglas XB-42
| Douglas XB-42 Mixmaster | |
|---|---|
 XB-42 in flight |
|
| Type: | Prototype of a bomber |
| Design country: | |
| Manufacturer: | |
| First flight: |
May 6, 1944 |
| Commissioning: |
Flight tests ended in 1948 |
| Number of pieces: |
2 |
The Douglas XB-42 Mixmaster was an experimental American bomber of the Second World War . With two counter-rotating pusher propellers at the stern, it should reach high speed.
Development and history
The development started in early 1943 by Edward Burton and Carlos Wood was initially financed privately and should result in a medium-sized bomber with high speed, low production time and less crew than previous models. The aim was to find a bomber that could reach the range of a B-29 Superfortress , but without its size and cost. To reduce aerodynamic drag, the design had a very unusual drive. Two motors located behind the cockpit in the fuselage drove two counter-rotating, coaxially one behind the other pusher propellers . The free wings and the fuselage could be optimized aerodynamically. Only two prototypes were built. The end of the Second World War and the advent of jet engines finally caused series production to fail.
The design was presented to the USAF in May 1943. The US Air Force's procurement department in Wright Field then ordered two prototypes worth three million US dollars on June 25, 1943, which were initially classified as attack aircraft with the designation XA-42 .
The aircraft received two water-cooled 1,800 HP -12-cylinder- Allison V-1710-125- in- line engines behind the flight cabin, one each via a long-distance shaft almost nine meters long and divided into five segments and a 2.77: 1 gearbox the counter-rotating pusher propellers from Curtiss Electric at the stern. The air inlets for the engines and the tanks were integrated into the wings. These were attached in a middle-decker version, which also made a large bomb bay possible. The landing gear consisted of a nose wheel and a main landing gear that could be retracted to the rear and to the side. The cross-shaped tail unit prevented damage to the propellers during take-off and landing. The part located behind the tail unit, including the propeller and gearbox, could be blown off in an emergency to enable the crew to leave the aircraft safely. The pilot and the copilot sat under double glass cabin roofs, the bombardier in the front glassed-in nose of the aircraft. The aircraft had a defensive armament of six 12.7 mm machine guns, which could be sunk into the wings.
The first prototype of the XB-42 (43-50224) took off earlier than scheduled on May 6, 1944 with test pilot Bob Brush on board for its maiden flight, which brought it from Clover Field near Santa Monica to Palm Springs , where the actual flight tests should take place. The performance was excellent; so could z. B. the speed of the De Havilland DH.98 Mosquito can be reached or exceeded - and this with twice the bomb load. The glazed booths turned out to be design flaws and created some instabilities and vibrations. When the landing flaps were extended and the bomb bay was open, there was turbulence that caused the propellers to vibrate. The poor engine cooling was another problem; however, the problems were seen as solvable.
On August 1, 1944, the second prototype (43-50225) took off on its maiden flight. It was equipped with the intended self-protection armament of two remote-controlled 12.7 mm machine guns in the wing trailing edge between the flaps and the ailerons, which were covered by flaps during flight. This machine was soon retrofitted with a one-piece cockpit canopy to improve communication between the pilots.
The US Air Force took over the machines at the end of 1945 and set a new speed record on December 8, 1945 with the XB-42 on the flight from Long Beach to Bolling Field (Washington) at 697.8 km / h. On December 16, 1945, a machine was destroyed in an accident. The reason was that the landing gear of the aircraft could not be fully retracted after take-off from Bolling Field and the engines later failed due to a lack of fuel. The pilot Fred Asconi then gave the order to jump and triggered the mechanism to blow off the propellers. Due to the loss of weight, the machine tilted steeply downwards; however, the three men managed to take off at a low altitude.
However, with the end of the Second World War, development was cut back in order to advance the development of jet bombers.
The second machine was tested further. This resulted in the XB-42A with better piston engines and two Westinghouse 19XB-2A jet engines, each with 7.11 kN of thrust under the wings. Its maiden flight took place on May 27, 1947 in Muroc. In this configuration it reached 785 km / h. It was damaged in a hard landing in 1947 after 22 flights and then repaired; but she never flew again.
In 1949 the machine was handed over to the National Air and Space Museum without having been exhibited before. It stood there together with the XB-43 until the end of 2010 in the warehouse of the museum in Silver Hill. It was then transported to the National Museum of the United States Air Force in Dayton to be restored.
An enlarged, civilian version of the XB-42 for up to forty passengers was developed under the project name 1004 or DC-8 (which was later reused for the well-known passenger jet), but not realized.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 3 |
| length | 16.4 m |
| span | 21.5 m |
| Wing area | 51.6 m² |
| height | 5.7 m |
| Empty mass | 9,475 kg |
| Takeoff mass | 15,060 kg |
| Top speed | 660 km / h |
| Service ceiling | 8,960 m |
| Range | 2,900 km (combat mission), 8,700 km (transfer flight) |
| Engines | 2 × Allison V-1710 -125 in-line engines with 1,300 kW (1,800 PS) each |
| Armament | 6 × 12.7 mm machine guns, 3,600 kg bombs |
Web links
- Douglas XB-42. In: US Air Force Fact Sheet. National Museum of the United States Air Force , July 7, 2009, archived from the original on September 27, 2013 ; accessed on May 6, 2019 .
Individual evidence
- ↑ Bryan R. Swopes: December 8, 1945. In: This Day in Aviation. December 8, 2018, accessed May 6, 2019 .
- ↑ Dynamic duo - Douglas XB-42 and XB-43. In: FlugRevue . September 2011, pp. 82-85.