Pratt & Whitney R-4360 Wasp Major

The U.S. Pratt & Whitney R -4360 Wasp Major was one of the largest aircraft radial engines that were developed and built during the Second World War. Its engine capacity was 71.25 liters or 4,360 cubic inches; Therefore, the type designation. He is the last of the P & W " Wasp " series and the culmination of the piston engine development by Pratt & Whitney, but came only after the end of the war for installation. Then he drove to the last generation of large propeller aircraft before the jet engines were used.

R -4360 was an air-cooled four-row radial engine with 28 cylinders, each level to improve the cooling air supply to the individual cylinder banks was arranged slightly offset. So this was not a row radial engine, but a multiple radial engine. A running at six times crankshaft speed compressor provided for the charging of the intake air, while a 2:1 gear reduced the propeller speed in order not to let the blade tips run at supersonic speed.

The four 7- stars were each offset by 12,857 °, so that the rear cylinder levels between the front and looked through each abbekamen effective possible air flow for cooling. Its one-piece, five -bearing crankshaft had four cranks were successively offset by 192.857 ... ° - ie the Hubzapfenversatzwinkel were 0 ° ( 1 crankpin ), 192.857 ° ( second crank pin ), 25.714 ° ( crank pin 3 ) and 218.571 ° ( crank pin 4 ). A uniform firing order was guaranteed ( 25.714 ° per crankshaft revolution ignition ). For a quiet running the oscillating masses were balanced to the crank pin by two fixed and two bifilar counterweights. As zweiventiliger the Wasp Major engine had a total of 28 intake and exhaust valves 28, which were controlled bumper. The ignition took two spark plugs per cylinder.

The first series developed nearly 2210 kW (3000 hp) take-off power, while they were able to give ( 4300 PS) at the end of the construction period already 3160 kW. The immense weight 1580-1755 kg belies the fact that it was very efficient engines with a low power to weight ratio, as was achieved by only a few engines.

This type of engine was produced from 1944 to 1955 in a total number of 18 679 pieces. They were originally planned B-29 Superfortress for Boeing, but these were then renamed when using the R -4360 in B-50. The R -4360 also drove the Convair B-36, the Fairchild C -119 Flying Boxcar, the Hughes H-4, the Boeing 377, as well as a number of other aircraft to. In the past yet in service extinguishing Martin JRM Mars flying boats they continue to come to the regular use.

The engine had because of its appearance and the nickname "corn cob " ( maize). The only other example of such a quadruple Star Motors is the Soviet Shvetsov ASch -2K, which also has 28 cylinders and air cooling.

Specifications

  • Type: Air-cooled 28 -cylinder radial engine quad ( 4-stroke ) with charge
  • Stroke: 152 mm
  • Bore: 146 mm
  • Displacement: 71.25 liters
  • Compression ratio: 6.7:1
  • Power: 3160 kW ( 4300 hp) at 2700/min
  • Maximum speed: 2800 rpm
  • Mass: 1755 kg
  • Diameter: 1.397 m
  • Length: 2,451 m
  • Specific power: 44.4 kW / l
  • Power to weight ratio: 0.56 kg / kW
  • Specific fuel consumption: 265 g / kWh
Engine displacement Bifilar coil Power-to-weight ratio Fairchild C-119 Flying Boxcar Hughes H-4 Hercules Wright R-3350 Duplex-Cyclone List of aircraft engines
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