a new airframe of light alloy stressed skin with a lifting aerofoil wing set at zero incidence, completed in 1947 but only limited test flying due to excessive wing flexure. Bratukhin B-9 - An ambulance derivative of the 'B-5' with a larger fuselage housing four stretchers in two layers with an attendant. The wing was changed to a symmetrical section set at positive incidence. One example completed in 1947 but never flown due to the wing flexure problems identified by flight testing of the 'B-5'. Bratukhin B-10 - With a new fuselage this slightly enlarged version of the "B-9" introduced bracing struts from the fuselage through the wings at the main spar and up to the rotor head. An observation cupola was fitted at the extreme nose, above the pilots cockpit, and a gunners position was provided at the aft end of the fuselage. Power was supplied by fully boosted AI-26GRF engines. A twin-finned variable incidence tail unit was also introduced. The new fuselage allowed the "B-10" to fulfill all the envisaged roles without building separate versions. One example was built in 1947 and underwent successful flight testing. Later the "B-10" was flown with single ShKAS machine guns in the nose and tail positions. Bratukhin B-11 - To provide data for comparison with Yakovlev and Mil helicopters two examples of the "B-11" were authorized and underwent flight testing to measure their performance from April 1948. Single-engined flight, auto-rotation and a marked reduction in vibration were all demonstrated. Problems identified included; a persistent hydraulic leak and rotor stalling due to lack of lift from the fixed wing at high speeds. Many modifications were proposed before the first prototype was destroyed, and the pilots killed, after the right hand rotor shed a blade in flight. A general disillusionment with helicopters in general and superior handling and performance from single rotor designs led to termination of the twin lateral rotor Bratukhin helicopters. Bratukhin AK - Ten AK (Artilleriskii Korrektirovshchik – artillery correction) production G-3 helicopters ordered but manufacture and/or delivery is uncertain. Bratukhin VNP (Vozdushnii Nabludatyelnii Punkt - aerial observation point) - Alternative designation for "B-10". Specifications See also Focke Achgelis Fa 223 McDonnell HJD Whirlaway Platt-LePage XR-1 References Notes Bibliography Apostolo, Giorgio. The Illustrated Encyclopedia of Helicopters. New York: Bonanza Books, 1984. . Gunston, Bill. The Osprey Encyclopaedia of Russian Aircraft 1875-1995. London: Osprey, 1995. . Taylor, Michael J. H. Jane's Encyclopedia