R-4360 Wasp Major

Pratt & Whitney R-4360 Wasp Major

The R-4360 was a 28-cylinder four-row air cooled radial engine. Each row of pistons was slightly offset from the previous, forming a semi-helical arrangement to facilitate efficient airflow cooling of the successive rows of cylinders. A mechanical supercharger geared at 6.374:1 ratio to engine speed provided forced induction, while the propeller was geared at 0.375:1 so that the tips did not reach inefficient supersonic speeds.

Although reliable in flight, the Wasp Major was maintenance intensive. Improper starting technique could foul all 56 spark plugs, which would require hours to clean or replace. As with most piston aircraft engines of the era, the time between overhauls of the Wasp Major was about 600 hours when used in commercial service.

Engine displacement was 4,362.50 cubic inches (71.5 L), hence the model designation. Initial models developed 3,000 hp (2,240 kW), but the final models delivered 4,300 hp (3200 kW) using two large turbochargers in addition to the supercharger. Engines weighed 3,482 to 3,870 lb (1,579 to 1,755 kg), giving a power to weight ratio of 1.11 hp/lb (1.83 kW/kg), which was matched by very few contemporary engines.

Wasp Majors were produced between 1944 and 1955; 18,697 were built.

A derivative engine, the R-2180-E Twin Wasp E, was essentially the R-4360 "cut in half". It had two rows of seven cylinders each, and was used on the postwar Saab 90 Scandia airliner.

STATISTICS - R-4360-51VDT

Manufacturer:

Pratt & Whitney

Model:

R-4360

Engine Type:

Air Cooled Supercharged Four Row Radial Engine

Cylinders:

28

Bore:

5.75 in. (146.0 mm)

Stroke:

6 in. (152.4 mm)

Displacement:

4,362.5 cubic in. (71.49 L)

Diameter:

55 in. (1.397 m)

Dry Weight:

3,870 lbs. (1,755 kg)

COMPONENTS

Valvetrain:

Poppet, Two Valves per Cylinder

Fuel System:

Stromberg Four-Barrel Pressure Carburetor

Supercharger:

Gear-Driven Single-Stage Variable Speed Centrifugal Type

Turbocharger:

General Electric CHM-2

Fuel Type:

108/135 Octane Gasoline

Oil System:

 

Cooling System:

Air-Cooled

PERFORMANCE

Power Output:

4,300 hp

Compression:

6.7:1

PRODUCTION MODELS

Variant

Horsepower Rating

Airframe Application

R-4360-4

2,650 hp

Goodyear F2G-1 Super Corsair
Goodyear F2G-2 Super Corsair
Martin AM Mauler
Martin XP4M-1 Mercator

R-4360-4A

3,000 hp

Hughes H-4 Hercules Spruce Goose

R-4360-8

3,000 hp

Douglas TB2D Skypirate

XR-4360-8A

3,000 hp

Curtiss XBTC-1

R-4360-10

3.000 hp

Boeing XF8B-1

R-4360-13

3,000 hp

Republic XP-72
Vultee XA-41

R-4360-17

3,000 hp

Northrop YB-35

R-4360-20

3,500 hp

Fairchild C-119 Flying Boxcar

R-4360-20A

 

Martin P4M-1 Mercator

R-4360-21

3,000 hp

Northrop YB-35

R-4360-25

3,000 hp

Convair XB-36 Peacemaker

R-4360-30

 

Fairchild C-119B Flying Boxcar
Fairchild XC-120 Packplane

R-4360-31

3,000 hp

Hughes XF-11
Republic XF-12 Rainbow

R-4360-33

3,000 hp

Boeing XB-44 Superfortress
Lockheed R6V Constitution

R-4360-35

3,500 hp

Boeing B-50A Superfortress
Boeing B-50B Superfortress
Boeing B-50D Superfortress
Boeing KB-50 Tanker
Boeing RB-50B

R-4360-41

3,500 hp

Convair B-36B Peacemaker
Convair B-36D Peacemaker
Convair RB-36D Peacemaker
Convair GRB-36D FICON
Convair XC-99

R-4360-49

3,250 hp

Douglas C-74 Globemaster

R-4360-51VDT

4,300 hp

Boeing YB-50C Superfortress

R-4360-53

3,800 hp

Convair B-36F Peacemaker
Convair RB-36F Peacemaker
Convair B-36H Peacemaker
Convair NB-36H Airborne Reactor
Convair RB-36H Peacemaker
Convair B-36J Peacemaker
Douglas C-124 Globemaster II

R-4360-59

3,500 hp

Aero Spacelines Pregnant Guppy
Aero Spacelines Mini Guppy
Republic RC-2 Rainbow

R-4360-B6

3,500 hp

Boeing 377 Stratocruiser
Boeing C-97 Stratofreighter

R-4360-B13

3,500 hp

SNCASE S.E.2010 Armagnac