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| Wright R-1670 | |
|---|---|
| Name | Wright R-1670 |
| Type | Radial aircraft engine |
| Manufacturer | Wright Aeronautical |
Wright R-1670
The Wright R-1670 was a piston radial aircraft engine developed by Wright Aeronautical Corporation during the interwar period as part of a lineage that included the Wright R-1820, Wright Cyclone, and engines used by United States Army Air Corps and United States Navy aircraft. Designed amid developments in radial engine technology influenced by designers linked to Charles Lawrance, Lloyd Stearman, and corporate interactions with Pratt & Whitney, the R-1670 aimed to balance power, weight, and reliability for civilian and military applications in the late 1920s and early 1930s. Although overshadowed by larger designs adopted by Boeing, Douglas Aircraft Company, and Lockheed Corporation, the R-1670 contributed to experimental installations and served as an engineering stepping stone within Curtiss-Wright's consolidation of American aero-engine production.
The R-1670 emerged from Wright Aeronautical's response to competition from Pratt & Whitney R-1340 Wasp, Bristol Jupiter, and European designs such as those by S. E. Saunders and Royce-era firms, with engineering influenced by personnel who had worked under Glenn Curtiss and Orville Wright. Development emphasized a compact seven- or nine-cylinder radial configuration derived from lessons learned on the Wright J-5 Whirlwind and Wright R-975, incorporating innovations in aluminum alloy casting, sodium-cooled valve technology, and improved carburetion introduced around the same time as experiments at National Advisory Committee for Aeronautics facilities. Test programs involved prototype runs at Wright plants near Dayton, Ohio, coordination with United Aircraft and Transport Corporation affiliates, and bench testing alongside engines destined for Boeing 247 testbeds and Lockheed Vega experiments.
Specifications varied among prototypes and early production examples but generally reflected Wright practice of the era: a single-row radial layout with a displacement near 1,670 cubic inches, producing power in a bracket competitive with contemporary Pratt & Whitney outputs for light transport and liaison aircraft. Construction employed forged steel crankshafts akin to those used in Hispano-Suiza installations and retained Wright's emphasis on reliability found in engines used by Transcontinental Air Transport. The R-1670 featured direct-drive or gear-reduction options to suit propeller types developed by Hamilton Standard and Sensenich, with cooling fins and baffling derived from studies conducted at Langley Research Center. Lubrication systems reflected advances tested by Rolls-Royce and General Motors engine divisions, while ignition systems paralleled developments at Bendix Corporation and Delco.
Several experimental and factory variants were recorded, reflecting changes in compression ratio, supercharging, and accessory equipment to meet the needs of air mail contracts, naval liaison duties, and commercial transports. Variant designations paralleled Wright's internal nomenclature used for the Wright R-790 and Wright J-6 families, with some versions fitted with single-stage superchargers inspired by Svenska Flygmotor practices and others adapted for cold-weather operations tested in Alaska by operators tied to Pan American Airways affiliates. Military evaluation versions incorporated fittings compatible with United States Army Air Corps procurement standards and assessed against competing types in trials overseen by Mitchell-era advocates within air-service procurement circles.
The R-1670 saw limited operational use, largely in prototype installations, company demonstrators, and a handful of light aircraft serving in transport, trainer, and utility roles for operators including corporate flight departments linked to Standard Oil interests and early commercial carriers such as Transcontinental and Western Air affiliates. It was evaluated during procurement competitions where engines like the Pratt & Whitney R-1690 Hornet and Wright R-1820 Cyclone achieved broader adoption by manufacturers including Douglas, Boeing, and Martin. Comparative endurance trials occurred at facilities associated with Wright Field and in civilian trials promoted by National Air Races participants, influencing Wright's later strategic decisions during corporate mergers culminating in Curtiss-Wright consolidation.
Installations of the R-1670 were primarily experimental and retrospective: demonstrator airframes built by Stinson, Waco, and boutique builders evaluated the engine for light transport and utility roles, while some conversions were fitted to Travel Air and Ryan designs for cross-country record attempts and exhibition flying in events promoted by Smithsonian Institution-affiliated demonstrations. Naval evaluations saw bench and shipboard testing coordinated through yards and bureaus linked to United States Navy Bureau of Aeronautics, though the engine did not enter wide carrier-based service, where competing engines from Pratt & Whitney and foreign manufacturers dominated.
Surviving examples of the R-1670 are rare and typically held in the collections of institutions with extensive aviation holdings such as the National Air and Space Museum, the National Museum of the United States Air Force, and regional museums in Ohio and California. Museum exhibits, private collections, and restoration workshops associated with organizations like Experimental Aircraft Association sometimes display R-1670 components alongside contemporaneous Wright engines, where they serve as reference artifacts for restoration projects and scholarly study by historians connected to Smithsonian research, university engineering departments, and preservation groups.
Category:Aircraft engines