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helicopter Autogyro TsAGI - 3A-1
TsAGI 3-EA - Experimental helicopter built in 1933 for training pilots. Identical to the 1-EA, except for a strut that replaces the rear wheel on the original layout. Their TsAGI 1-EA helicopter was able to fly in low altitude testing in 1931-32, with Cheremukhin flying it as high as 605 meters (1,985 ft) by mid-August 1932.
TsAGI is a transliteration of the Russian abbreviation for (ЦАГИ) "Tsentralniy Aerogidrodinamicheskiy Institut", the Central Aerohydrodynamic Institute. It was founded in Moscow by the pioneer of Russian aviation, Nikolai Yegorovich Zhukovsky on December 1, 1918.
Since 1925 and into the 1930s, TsAGI developed and hosted Tupolev's AGOS (Aviatziya, Gidroaviatziya i Opytnoye Stroitelstvo, the "Aviation, Hydroaviation, and Experimental Construction"), the first aircraft design bureau in Soviet Union, and at the time the main one. In 1930, two other major aircraft design bureaus in the country were the Ilyushin's "unsystematic" TsKB (Tsentralnoye Konstruksionnoye Byuro, the "Central Design Bureau") and an independent, short-lived Kalinin's team in Kharkiv.
In 1935 TsAGI was partly relocated to the former dacha settlement Otdykh (literally, "Relaxation") converted to the new urban-type settlement Stakhanovo. It was named after Alexey Stakhanov, a famous Soviet miner. On April 23, 1947, the settlement was granted town status and renamed to Zhukovsky. The Moscow branch of the institute is currently known as MAGI, or Moscow complex of TsAGI.
In 1965 in Zhukovsky an Aeromechanics faculty of MIPT was established under TsAGI; it has been preparing young specialists able to solve complex problems of the aircraft industry.
Among latest TsAGI developments are the rocket Energia and the Space Shuttle Buran. In 2013 TsAGI developed a testbench for high-speed compound helicopters with propellers.
Autogyro
An autogyro (from self-turning), also known as gyroplane, gyrocopter, or rotaplane, is a type of rotorcraft which uses an unpowered rotor in autorotation to develop lift, and an engine-powered propeller, similar to that of a fixed-wing aircraft, to provide thrust. While similar to a helicopter rotor in appearance, the autogyro's rotor must have air flowing through the rotor disc to generate rotation. Invented by the Spanish engineer Juan de la Cierva to create an aircraft that could fly safely at slow speeds, the autogyro was first flown on 9 January 1923, at Cuatro Vientos Airfield in Madrid. De la Cierva's aircraft resembled the fixed-wing aircraft of the day, with a front-mounted engine and propeller in a tractor configuration to pull the aircraft through the air.
Under license from Cierva in the 1920s and 1930s, the Pitcairn & Kellett companies made further innovations. Late-model autogyros patterned after Etienne Dormoy's Buhl A-1 Autogyro and Igor Bensen's designs feature a rear-mounted engine and propeller in a pusher configuration. The term Autogiro was a trademark of the Cierva Autogiro Company, and the term Gyrocopter was used by E. Burke Wilford who developed the Reiseler Kreiser feathering rotor equipped gyroplane in the first half of the twentieth century. The latter term was later adopted as a trademark by Bensen Aircraft.
An autogyro is characterized by a free-spinning rotor that turns because of passage of air through the rotor from below. The vertical (downward) component of the total aerodynamic reaction of the rotor gives lift for the vehicle, and sustains the autogyro in the air. A separate propeller provides forward thrust, and can be placed in a tractor configuration with the engine and propeller at the front of the fuselage (e.g., Cierva), or pusher configuration with the engine and propeller at the rear of the fuselage (e.g., Bensen).
Whereas a helicopter works by forcing the rotor blades through the air, drawing air from above, the autogyro rotor blade generates lift in the same way as a glider's wing by changing the angle of the air as the air moves upwards and backwards relative to the rotor blade. The free-spinning blades turn by autorotation; the rotor blades are angled so that they not only give lift, but the angle of the blades causes the lift to accelerate the blades' rotation rate, until the rotor turns at a stable speed with the drag and thrust forces in balance.
Because the craft must be moving forward (with respect to the surrounding air) in order to force air through the overhead rotor, autogyros are generally not capable of vertical takeoff or landing (unless in a strong headwind). A few types have shown short takeoff or landing.
Pitch control of the autogyro is by tilting the rotor fore and aft; roll control is by tilting the rotor laterally (side to side). Three designs to affect the tilt of the rotor are a tilting hub (Cierva), swashplate (Air & Space 18A), or servo-flaps. A rudder provides yaw control. On pusher configuration autogyros, the rudder is typically placed in the propeller slipstream to maximize yaw control at low airspeed (but not always, as seen in the McCulloch J-2, with twin rudders placed outboard of the propeller arc).
The early Russian TsAGI autogyros were strongly influenced by the work of Juan de la Cierva and their 1931 designed A-4 was broadly similar to the Avro-built 1929 Cierva C.19, with a pylon mounted rotor, forward tractor configuration engine, small wings with ailerons and a conventional tail. It first flew on 6 November 1932 but it took about a year before rotor vibrational problems were solved and successful tests completed.
The flat sided fuselage of the A-4 was built around four tube steel longerons with internal tube bracing and covered with a mixture of fabric and plywood. A 220 kW (300 hp) M-26 (KIM) 7-cylinder radial engine was mounted in the nose, cowled in a Townend ring and with its output shaft pointing downwards at an angle of 4.5°. Its small, low wings were rectangular plan, wooden structures, each built around a pair of spars and braced from above by a pair of parallel struts, one from each spar to the upper fuselage longeron. They had 5° of dihedral but their semicircular tips were inclined upwards by a further 35°. Conventional ailerons occupying almost 30% of the overall wing area provided roll control. There were two open cockpits in tandem, the forward, passenger seat ahead of the wing trailing edge and close to the rotor axis. Dual control was fitted. At the rear the fin was long, rounded at the front but with a flat top. It mounted an unbalanced rudder, roughly rectangular though rounded at the rear corners, which extended to the keel. Small like the wing, the tailplane was braced from below and had swept leading edges; its elevators were more generous, with rounded tips and a large cut-out for rudder movement.
The A-4's four blade rotor was mounted at the top of a three legged pylon. The two rear legs were based on the upper fuselage longerons and the forward on the upper central fuselage. They positioned the rotor hub directly over the wing centre line and 96 mm (3.78 in) behind the centre of gravity. The 13 m (42 ft 8 in) rotor had blades with an aspect ratio of less than 14. They were of mixed construction, with steel main spars, two wooden subsidiary spars and covered in a mixture of ply and fabric. Their section was the airfoil used by the Cierva C.19. The blades were wire braced from above from an extension of the rotor axis, which leaned forwards with respect to the aircraft's axis by 2°. These wires were steel but contained rubber dampers. Hinges (double Cardan shafts) provided both upwards and in-plane movement, the latter damped by springs; normally such deflections were about ±7°.
Like a fixed wing aircraft, the A-4 was controlled with ailerons and elevators connected to a control column and the rudder to pedals. To the pilot's right there was a lever which enabled the rotor to be connected to the engine via reducing gears for jump starts and to ease heavy landings. The drive shaft followed the single forward rotor pylon strut, enclosed within a streamlined fairing. The A-4's fixed undercarriage had wheels on pairs of hinged V struts from the lower fuselage longerons with vertical legs, fitted with faired rubber shock absorbers, to the forward wing spar immediately below the wing strut. The tailskid also included a shock absorber.
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