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| R-4360 | |
|---|---|
| Name | Franklin R-4360 |
| Caption | Radial engine installation |
| Manufacturer | Curtiss-Wright Corporation |
| Country | United States |
| First run | 1944 |
| Type | 28-cylinder, four-row, air-cooled radial piston engine |
| Displacement | 4,362 cu in (71.5 L) |
| Power | 3,000–4,300 hp (2,240–3,210 kW) |
R-4360 The R-4360 was a 28-cylinder, four-row, air-cooled radial piston aircraft engine developed in the United States during the World War II era. It became one of the most powerful piston engines of its time and powered heavy United States Army Air Forces and commercial aircraft into the early Cold War period. The engine influenced designs at companies such as Pratt & Whitney, Wright Aeronautical, and General Electric and was integral to projects at Boeing, Consolidated Aircraft, Lockheed, and Curtiss-Wright.
Design work began under the auspices of Curtiss-Wright Corporation engineers alongside research at National Advisory Committee for Aeronautics facilities and testing at Wright Field. The concept evolved from earlier multi-row radials such as the Pratt & Whitney R-2800 and Wright R-3350, incorporating lessons learned from development efforts at Fairchild, Douglas Aircraft Company, and the United Aircraft Corporation supply chain. Prototype runs were bench-tested at Naval Air Station Patuxent River and evaluated in flight on Boeing B-17 Flying Fortress and Boeing B-29 Superfortress testbeds, with further trials conducted by United States Navy and United States Army Air Corps squadrons. The engine program coordinated with the Arsenal of Democracy industrial mobilization and benefited from metallurgy advances from firms like Carpenter Technology Corporation and research at Massachusetts Institute of Technology.
The engine used four rows of seven cylinders arranged in a radial configuration, producing roughly 4,362 cubic inches of displacement. Each cylinder featured single-stage, two-speed supercharging derived from developments at General Electric and lubrication systems influenced by work at Shell Oil Company laboratories. Cooling was air-based, assisted by cowling developments similar to those on Republic P-47 Thunderbolt installations, and materials included high-strength alloys from Alcoa and Timken Company. Ignition systems used dual magnetos with designs comparable to Bendix Corporation products. Fuel delivery utilized multiple carburetors and, in later variants, fuel injection elements reminiscent of work at Lucas Industries and Sunstrand Corporation. The power-to-weight ratio competed with the Rolls-Royce Merlin and Napier Sabre in output, and accessory drives accommodated generators and superchargers used by airframe manufacturers like Lockheed Corporation and Convair.
After introduction in 1944, the engine entered service with long-range Boeing B-50 Superfortress and transport aircraft such as the Douglas C-74 Globemaster I and later the Douglas C-124 Globemaster II prototypes. Flight operations involved crews drawn from Strategic Air Command units and testing by Air Materiel Command engineering groups. The engine saw civilian use in postwar airliners operated by carriers including Pan American World Airways and Trans World Airlines, and it was evaluated for use in North American Aviation projects and Grumman designs. Operators contended with maintenance-intensive schedules influenced by manuals from Army Air Forces Technical Service Command and logistics practices at Elmendorf Air Force Base and Wright-Patterson Air Force Base. The engine’s high power enabled record attempts by pilots associated with Howard Hughes and engineering teams from National Aeronautics and Space Administration predecessor programs, but it was gradually supplanted by turboprop and turbojet developments from General Electric and Rolls-Royce guided by policy from Department of Defense planners.
Multiple series were produced to fit various propeller and reduction gear requirements for airframes supplied by Hamilton Standard and Curtiss Propeller Division. Factory variants included models tuned for high-altitude operation, naval adaptations with corrosion-resistant finishes used by United States Navy, and merchant variants for freighters operated by Matson Navigation Company. Experimental conversions tested water-methanol injection systems with assistance from Oak Ridge National Laboratory research, and some civil retrofit programs incorporated components from Pratt & Whitney and Continental Motors Company workshops. Wartime subcontracts involved suppliers such as Lockheed Vega and Vultee Aircraft subcontract plants coordinated through War Production Board directives.
Airframes powered by the engine encompassed strategic and transport types from major manufacturers: Boeing B-50 Superfortress, Convair B-36 Peacemaker prototypes, Douglas C-74 Globemaster I, Douglas C-124 Globemaster II trials, Lockheed Constellation experimental installations, and long-range seaplane designs evaluated by Martin Company and Sikorsky Aircraft. The engine was also installed in prototypes and special projects at Northrop Corporation, Fairchild Republic, and civil conversions for Howard Hughes-backed record attempts. Testbeds and demonstrators appeared at airshows organized by Experimental Aircraft Association and were displayed in expositions hosted at Smithsonian Institution and National Air and Space Museum venues.
Several examples remain in museums and collections, conserved by organizations such as the National Museum of the United States Air Force, Museum of Flight, Henry Ford Museum, Pima Air & Space Museum, and regional institutions including New England Air Museum and Commemorative Air Force detachments. Restoration projects often involve specialists from Aviation Restoration shops and parts sourced through networks tied to Experimental Aircraft Association chapters and volunteer groups at EAA AirVenture Oshkosh. Static displays and occasional ground-runs are managed under oversight from curators at Smithsonian Institution National Air and Space Museum affiliates and local historical societies like Collings Foundation preservation teams. Examples are preserved in collections in the United States, United Kingdom, and Australia, with documentation archived at repositories such as National Archives and Records Administration.
Category:Aircraft engines