Cierva C-30 Rota
Avro 671 Rota
The Cierva C.30A marked a major step forward in rotorcraft development, being the first production autogiro in which the engine was geared directly to drive the rotor blades for take-off. The degree of direct control was increased still further by having the control column, which acted directly on the rotor, suspended from the pylon so that the rotor head could be tilted in any direction to produce the manoeuvre desired. The new-style control system was first installed in G-ABXP, a Cierva C.19 designated Mk.V with a 100hp Genet Major I engine. This was basically a C.19 Mk.IV modified to have a clutch and transmission shaft, a tilting rotor head and (later) a small, fixed tailplane.
The prototype C.30 (G-ACFI) differed chiefly in having a tripod rotor pylon and dihedral on the tailplane tips; the fuselage was modified by Airwork from a standard Cierva C.19, and assembly was undertaken by National Flying Services at Hanworth, where G-ACFI made its maiden flight early in April 1933. Take-off run of the C.30 was about 30 yards (27.43m), while the landing was achieved in about 3 yards (2.74m) with the rotor blades autorotating. Another 1933 prototype was G-ACKA, the first C.30P, with 140hp Genet Major 1A, folding rotor blades and other improvements.
First customer for the production C.30A was the Royal Air Force, for whom the type was built by Avro and given the name Rota. One twin-float Sea Rota and ten standard Rotas with wheeled undercarriages were completed to Specification 16/35, and were delivered to the School of Army Co-operation at RAF Old Sarum from December 1934. By the outbreak of the Second World War they had been allocated for use by a highly secret unit engaged on ground radar calibration duties. One other military C.30A was K4775, a Civet Major-engined machine sent to the Royal Aircraft Establishment in 1935 for blade-flexing tests.
Nearly 150 were built under licence in the UK (Avro and Airwork), Germany (Focke-Wulf) and France (Lioré-et-Olivier). Airwork produced the C.30 and C. 30P, and Avro the C.30A and C.30P. The C.30A was built by A. V. Roe as the Avro Type 671 Rota for RAF and civil market.
The C-30A was the most widely produced Cierva autogyro design. Avro built the type under licence, as the Avro Type 671 Rota.
Avro production of C.30 types was in the region of seventy aircraft, three of which were C.30P's. Thirty-seven C.30A's appeared on the pre-war British civil register, and others were completed for customers in Europe, India, China, Australia and South Africa. In Britain the C.30A, like the C.19 before it, was used for traffic reporting duties at major sporting and similar events, and one aircraft (G-AGUT) was used for filming the 1936 F.A. Cup Final.
During 1933 the C.30 prototype, G-ACFI, was converted for jump-start trials with a modified rotor head, and in 1936 a perfected form of this was fitted to G-ACWF when it made the first genuine vertical take-off by an autogiro, by keeping the engine and rotor system engaged throughout the take-off sequence. This machine was, in effect, the prototype for the C.40, five of which were ordered for the R.A.F. as the Rota II to Specification 2/36. These were built by the British Aircraft Manufacturing Co., having side-by-side seats, wooden semi-monocoque fuselages and 175hp Salmson 9NG engines. Two of the original five Rota II's were diverted to civilian customers, replacements being built in 1938-39. The R.A.F. C.40's served with No.1448 Flight (later 529 Squadron). On the outbreak of World War 2 over a dozen civil C.30A's were impressed for military service; these and the surviving Rota I's were allocated singly to R.A.F. radar stations in the United Kingdom for calibration duties.
C.30A G-AHMJ was used by Fairey Aviation in the 1940's for research that led to the Fairey Gyrodyne design. After retirement, it was moved to the rear of TS Broke, North Hyde Road, Southall, Middlesex, in the care of the Sea Cadet unit based there. In the early 1950's it was aquired by the Shuttleworth Trust and restored in the 1970's to it's wartime camouflage scheme and serial number as an Avro Rota. It is now in the Fantacy of Flight Museum in Florida.
Concerning license manufacture of the type by Focke-Wutf, it is to be noted that Focke-Wulf did not obtain rights to produce the C 30 under license in 1933 as has claimed. License negotiations began in February 1935, initially with the "Hamburger Flugzeugbau G.m.b.H", however these collapsed for financial reasons. Focke-Wulf entered the negotiations in July 1935. The start of license construction by Focke-Wulf was delayed on account of currency exchange difficulties until December 1935, when the exchange rate was guaranteed for 36 examples of the C 30.
Preliminary shipboard trials with the C 30 autogiro began on November 10, 1936 at E-Stelle See (Naval Test Station) Travemünde. The trials ended unsatisfactorily as a result of the type's inadequate performance, its less than satisfactory handling characteristics in gusts and the poor view offered the pilot during deck landings on small platforms. Further development of the C 30 for military use was therefore abandoned.
Engine: 1 x Armstrong Siddeley Civet 1, 140 hp
Main rotor diameter: 37 ft
Fuselage Length: 19 ft. 8.5 in
Loaded weight: 1,900 lb Empty weight:
Max speed: 100 m.p.h
Ceiling: 8,000 ft
Range: 250 miles at 85 m.p.h
Avro Rota Mk I.