Continental XR-1740-2, Sleeve Valve, Radial 14 Engine

Type: Reciprocating, 14 cylinders, 2 rows, radial, air-cooled, direct fuel injection, single-speed centrifugal supercharger

Power rating: 652 kW (875 hp) at 2,600 rpm

Displacement: Not available

Bore and Stroke: Not available

Weight: 630 kg (1,388 lb)

In 1925, Continental, a successful manufacturer of automotive engines, purchased the rights for a Burt-McCollum single-sleeve valve engine design. Believing this technology might replace poppet valves in aircraft engines, Continental announced the R-790 engine in 1927, incorporating single-sleeve valves initially installed on a Wright 9-cylinder engine. It was never fully tested, but followed by the 7-cylinder R-794, for which five engines were ordered by the U.S. Navy in 1934. It was tested, but did not go into production.

The Navy later sponsored a number of unconventional engine designs; however, few entered production. In the case of the 1939 XR-1740-2 development, the outcome was apparently typical of single-sleeve valve history. For example, Bristol’s Roy Fedden, one of history’s great aircraft engine experts, was unable to mass produce single-sleeve engines. Continental only became successful after reverting to poppet valves, and this artifact represents a seemingly simple new concept that could not compete with older, conventional technology better developed for practical application.