Ka-22 "Vintokryl" Hoop
The Kamov Ka-22 Vintokryl (screw-wing) Hoop was a compound helicopter. The Ka-22 had side-by-side rotors, instead of Kamov's usual coaxial ones. In 1960, the Ka-22 prototype made its maiden flight, and later set a number of world records, including maximum speed (356 km/h) and payload (16,500 kg) records. Several more designs of this configuration were later developed to provide for the transportation of heavy payloads over long distances.
The Mi-6 helicopter was designed simultaneously in transport, troop-carrying and medevac versions. For the first time the carriage of underslung loads was envisaged from the outset. At the same time, the design bureau headed by N.I.Kamov was allotted the task of designing the Ka-22 rotary-wing aircraft of approximately the same class.
The Ka-22 combined a square fuselage with a 20m wing span. The fuselage was similar in size to the Antonov An-12 transport and could carry 100 passengers or a 16000kg load [other accounts report is could carry 36,400 lb of cargo or 80 seats, although this was never done. The fuselage housed a loading ramp that could be used for freight or vehicles, and. The tricycle landing gear was fixed and the entire nose area was glazed for good visibility, especially in landing. The high flight deck accommodated two pilots, a radio operator and engineer.
At the tips of the wings were two nacelles containing Ivchenko TB-2 engines delivering over 5600shp each of which could power a 20m four-blade rotor or four-blade tractor propeller. Other accounts report that at each end of the high, straight wing, was a 6,500 shp Soloviev D-25VK engine which powered a four-bladed rotor for vertical flight and a four-bladed propeller for cruise. The rotors apparently autorotated during horizontal flight. Each engine was progressively clutched between the two systems to transition between the two modes of flight. The engine was a nine-stage single spool turboshaft modified from the 5,500 shp D-25V engine used on the Mil Mi-6, Mi-10, and V-12 helicopters. The final turbine stage was a free-wheel that drove the gearbox.
Much attention was paid to the problems associated with the compound rotorcraft's stability and controllability. Kamov's engineers succeeded in corroborating the results of theoretical methods of calculation through the use of numerous models, test rigs and special devices, as well as in the process of flight tests.
The Ka-22 itself first lifted from the ground on 17th June 1959, and made its first untethered flight on 15th August 1959, the test crew being led by pilot D. K. Yefremov. Serious control difficulties were encountered, and the Kamov team were joined by LII pilots V.V.Vinitskii and Yu.A.Garnayev. Though still full of problems the Vintokryl was demonstrated on 11th October 1959 to MAP Minister P.V.Dement'yev and VVS C-in-C K.A.Vershinin. In July 1960 an order was received to manufacture three more Ka-22s at GAZ No.84 at Tashkent, with D-25VK engines.
The first public appearance was at the 1961 Tushino airshow. The world registered records of altitude and speed of flight on a straight route for convertoplanes belong to the Soviet aircraft Ka-22 "Vintokryl" by the Kamov design bureau. On October 7, 1961, the aircraft set a speed record of 356.3 km/h over 15 km distance. On November 24, 1961 at Bykovo airport , Ka-22 set an altitude record of 2588 m with a 15000 kg payload.
The fate of the Ka-22 was sealed by two tragic crashes, on 28th August 1962 and 12th August 1964, the cause of which could not be determined beyond doubt at the time. After that, the Air Force leadership could not overcome the mistrust that had arisen towards this flying machine and never gave the OKB a chance to complete development. By this time the Mi-6 heavy helicopter was in wide service, and the Ka-22 was ultimately abandoned. Nevertheless, the design, construction and testing of such a complex and large rotorcraft took the company's specialists to a new, higher scientific and technical level.
Apart from prolonged dissatisfaction with the engines, the problems with the Ka-22 were mechanical complexity, severe losses in the gearboxes and drives and the fact that each lifting rotor blew straight down on top of the wing. Similar charges could be levelled against today's V-22 Osprey.
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