Ka-22 "Vintokryl" Hoop

N.J.Kamov, a Soviet rotorcraft pioneer, started work on rotary wing aircraft in the 1920s. In 1945 he began construction of the Ka-8 which eventually led to the production of the Ka-15 HEN for the Soviet Navy. This helicopter is reported to have been produced in large quantities and is credited with two world speed records, in 1958 and 1959. Following successes with the Ka-18 HOG and Ka-20 HARP (a turbine powered helicopter), Kamov's introduction of the Ka-22 HOOP was the highlight of his career. It was a complex aircraft, powered by twin 5,495 SHP turbines mounted on the wing tip pods. Although the HOOP never entered production, it was capable of carrying 70 to 100 fully equipped troops. In 1961 it set eight world records of performance.

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 jump from Ka-15 to Ka-22 was huge. The Ka-15 has a flight weight of 1200–1300 kilograms, and the Ka-22 has 35 tons. The speed of the first is 150, the second is 350 kilometers per hour. The search for only one control system required enormous efforts. No one has ever wondered: how to make a reliable transition from airplane to helicopter control.

The rotors were not only huge, but also fast. The speed of the air flowing around the ends of the blades approached the speed of sound. If the load on the blade of the Ka-15 was 18 kg / m2 , then the Ka-22 - 45 kg / m2. The wing was located under the rotors. They blew it and thereby reduced the thrust of the screws in hover mode. It was necessary to somehow reduce this blowing. And then they made flaps deflectable 90 degrees. Their length was approximately half the wingspan. They significantly reduced traction loss.

The Ka-22 load-bearing circuit consisted of a wing with rotor helicopter rotors at the ends, as well as two turboprop engines as in an airplane. Due to this feature, the Ka-22 could fly both at low speeds and at high speeds. When taking off with the help of rotors, the wing on the rotorcraft did not play a special role, however, when the flight speed increased, the wing took up up to 90% of the lifting force, freeing the rotors from work.

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 17 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. On July 19, the rotorcraft hovered already five to seven meters from the ground. After that, it took several months of hard work to bring the car to a state guaranteeing reliable flights.

Raising after a small machine such a giant as a rotorcraft is honorable, but also very responsible. It is necessary to go not only technically difficult, but also psychologically difficult barrier. Though still full of problems the Vintokryl was demonstrated on 11 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. Hundreds of thousands of Muscovites and foreign visitors saw on May 9, 1961, at an air festival in Tushino, as a rotorcraft at high speed, like an airplane, approached the airfield, made a small circle. And then, like a helicopter, it hovered at an altitude of twenty - twenty-five meters exactly above the place indicated in advance, turned around and began a slow and smooth descent to a given point. After spending one or two minutes on the ground, Efremov picked up the car again, dispersed it and left the field at high speed.

Here is what the Soviet Russia newspaper reported about the rotorcraft: “A real miracle flies over Tushin: a huge winged car. At the ends of the planes - propellers, like a helicopter, and in front, like an airplane, propellers. So it seems that the Ka-22 flew from a fairy tale." The newspaper Izvestia wrote: “An unusual rotary-wing aircraft is an ingenious combination in the aerodynamics of an airplane and a helicopter, it does not need special airfields ...”

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.

Further, everything only got worse. Engines and gearboxes were changing, the Ka-22 tried in every way to modify, but all to no avail. He remained difficult to manage and unpredictable. Several rotorcraft incidents led to the abandonment of the project. 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.