OKB-1 EF-140 - Soviet Union, 1948
Detailing the development and operational history of the OKB-1 EF-140 Jet-Powered Tactical Fast Reconnaissance / Bomber Prototype.
Entry last updated on 4/5/2016; Authored by Staff Writer; Content ©www.MilitaryFactory.com
The Soviet OKB-1 EF-140 jet-powered bomber prototype emerged from work immediately done after the close of World War 2.
The EF-140 was a Soviet post-World War 2 jet-powered tactical bomber design continuation of the line begun with the capture of the German Junkers Ju 287. The Ju 287 was one of the more unique of the German wartime jet-powered aircraft in development before the close of the war in 1945 - particularly in its use of advanced swept-forward wings as well as jet propulsion technology. The Junkers product was furthered into the local Soviet "EF-131" which completed a hasty first flight in 1946 with more formal testing had in 1947. Though the project was terminated in 1948, the second airframe of the EF-131 made up the basis for the evolved EF-140.
The EF-140 initially existed as a tactical bomber like the EF-131 before it. However, whereas the EF-131 relied on now-obsolete German Junkers Jumo turbojets (a total of six such systems powered the original aircraft), the EF-140 introduced Soviet engines of a more advanced, capable nature. Design of the new aircraft commenced in 1947 and the EF-131 was modified to carry 2 x Mikulin AM-TKRD-01 axial flow turbojet engines. The forward-swept wings remained in play with the engines slung underneath and the crew of three was increased to four. Dimensions included a length of 62 feet, a wingspan of 71.8 feet and a height of 18.5 feet. Fixed armament became four guns (largely defensive in nature) with two guns held in a dorsal barbette and two guns fitted to a ventral barbette. Both barbettes would be remote-controlled and aimed by way of periscopes. An internal bomb bay would hold several thousand pounds of conventional drop ordnance.
The initial EF-140, born from the second EF-131 prototype while carrying the Mikulin engines, was made ready for September 1948 and completed its first flight on September 30th. From this, thought came to rework the EF-140 as a tactical fast-reconnaissance platform and this produced the "EF-140R" model in turn. Engines were changed to 2 x Klimov VK-1 units (5,950lb thrust each) and wingtip fuel tanks were added to increase operational ranges. Other refinements were enacted on the overall design including revised turrets.
Flight testing at GOZ-1 revealed issues with wing flutter which brought the design back to the engineering boards. The final iteration of the line came in the proposed "EF-140B/R" which was to be a fast-reconnaissance platform with bombing capability as secondary. The engines remained the same Klimov units as in the earlier model and the program progressed enough to begin ground testing before the end. However development was terminated on both prototypes in June of 1950 in favor of more advanced, capable bomber / reconnaissance platforms.