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|Avro 671 Rota Mk 1 at Imperial War Museum, Duxford|
|Designer||Juan de la Cierva|
|First flight||April 1933|
Design and development
Before the experimental Cierva C.19 Mk V, autogyros had been controlled in the same way as fixed-wing aircraft, that is by deflecting the air flowing over moving surfaces such as ailerons, elevators and rudder. At the very low speeds encountered in autogyro flight, particularly during landing, these controls became ineffective. The experimental machine showed that the way forward was a tilting rotor hub fitted with a hanging stick extending to the pilot's cockpit with which he could change the rotor plane. This was known as direct control and was fitted to the C.30. The production variant, called C.30A in England, was preceded by several development machines.
The first production design in the series was the C.30, a radial-engined autogyro with a three-blade, 37 ft (11.3 m) rotor mounted on an aft-leaning tripod, the control column extending into the rear of the two cockpits. The engine was the five-cylinder, 105 hp (78 kW) Armstrong Siddeley Genet Major I used in the C.19 series. The fabric-covered fuselage carried an unbraced tailplane, without elevators but with turned-up tips. The port side of the tailplane had an inverted aerofoil section to counter roll-axis torque produced by the propeller. As with most autogyros, a high vertical tail was precluded by the sagging resting rotor, so the dorsal fin was long and low, extending well aft of the tailplane like a fixed rudder and augmented by a ventral fin. The wide-track undercarriage had a pair of single, wire-braced legs and a small tail wheel was fitted. This model flew in April 1933. It was followed by four improved machines designated C.30P (P here for pre-production) which differed in having a four-legged pyramid rotor mounting and a reinforced undercarriage with three struts per side. The rotor could be folded rearwards for transport. The C.30P used the more powerful (140 hp, 104 kW) seven-cylinder Armstrong Siddeley Genet Major IA radial engine.
The production model, called the C.30A by Avro, was built under licence in Britain, France and Germany and was similar to the C.30P. The main alteration was a further increase in undercarriage track with revised strutting, the uppermost leg having a pronounced knee with wire bracing. There was additional bracing to the tailplane and both it and the fin carried small movable trimming surfaces. Each licensee used nationally built engines and used slightly different names. In all, 143 production C.30s were built, making it by far the most numerous pre-war autogyro.
Between 1933 and 1936, de la Cierva used one C.30A (G-ACWF) to test his last contribution to autogyro development before his death in the crash of a KLM Douglas DC-2 airliner at Croydon Airfield in England on 9 December 1936. To enable the aircraft to take off without forward ground travel, he produced the "autodynamic" rotor head, which allowed the rotor to be spun up by the engine in the usual way but to higher than take-off r.p.m at zero rotor incidence and then to reach operational positive pitch suddenly enough to jump some 20 ft (6 m) upwards.
Avro obtained the licence in 1934 and subsequently built 78 examples, under their model designation, fitted with an Armstrong Siddeley Genet Major IA (known in the RAF as the Civet 1) 7-cylinder radial engine producing 140 hp (100 kW). The first production C.30A was delivered in July 1934.
Of the 66 non-RAF aircraft built in the UK by Avro, 37 appeared at least for a while on the UK register. Some (maybe a dozen) were sold abroad, but others were flown by wealthy enthusiasts and by flying clubs who offered autogyro training. By the end of the decade, private flyers were moving back to the comforts and economies of fixed-wing aircraft and more C.30s moved abroad leaving the Autogyro Flying Club at London Air Park, Hanworth as the major UK user. 26 aircraft were directly exported by Avro. These went both to private owners and to foreign air forces who wish to investigate the autogyro's potential.
In September 1935, five members of the Lithuanian Aero Club flew C.30A in the "air train" together with the glider Schneider Grunau Baby and the airplane de Havilland DH.60 Moth over the Baltic sea states: Kaunas, Riga, Tallinn, Helsinki.
Twelve C.30As built by Avro for the Royal Air Force (RAF) entered service as the Avro 671 Rota Mk 1 (Serials K4230 to K4239 and K4296 & K4775). The twelve were delivered between 1934 and 1935. They equipped the School of Army Co-operation at RAF Old Sarum near Salisbury.
Many of the surviving civil aircraft were also taken into RAF service between 1939 and 1940. In 1940 they equipped 1448 Flt. at RAF Duxford. Later they equipped 529 Sqn. at RAF Halton on radar calibration work, disbanded in October 1945, the twelve survivors were sold on to civilian owners.
Most of these did not last long, although two were used for pilot rotary wing experience by Fairey in their Fairey Gyrodyne helicopter programme. Rota Towels kept one ex-RAF Rota airworthy G-AHTZ until an accident in 1958. G-ACUU, the Imperial War Museum's C.30A exhibit at Duxford had one of the longest active lives. It joined Air Service Training Ltd in 1934, was impressed (as Rota HM580) in 1942, serving with 529 Squadron and returning to civil use by G.S. Baker based at Birmingham's Elmdon airport with its original registration plus the nickname Billy Boy and was not withdrawn from use until 1960.
- Powered by a 105 hp (78 kW) Armstrong Siddeley Genet Major I radial piston engine.
- Improved model, powered by a 140 hp (104 kW) Armstrong Siddeley Genet Major IA radial piston engines
- Main production model, powered by a 140 hp (104 kW) Armstrong Siddeley Genet Major IA radial piston engine.
- Rota Mk I
- RAF designation of the Cierva C.30A.
- Lioré et Olivier LeO C-30
- 59 license built Cierva C.30, powered by 175 hp (130 kW) Salmson 9Ne engines, were supplied to the French Air Force and French Navy. All LeO C-30 autogyros were destroyed or captured by German forces during the invasion of France in 1940.
- Lioré et Olivier LeO C-30S
- Construction number 26 was completed as the sole C-30S.
- Lioré-et-Olivier LeO C-301
- Improved C-30s with uprated Messier oleo-pneumatic shock absorbers, flotation devices to facilitate ditching at sea and tripod main rotor support. Six aircraft were delivered to the French Navy by early June 1940.
- Lioré et Olivier LeO C-302
- Early autogyros suffered from relatively long take-off runs. To reduce the take-off length two C-301 aircraft were fitted with the equivalent of Cierva's "Jump" head allowing the aircraft to leap vertically after only a very short run. The C-302s were used extensively for testing rotor and undercarriage components but development was eventually abandoned in 1949/1950.
- Focke-Wulf C 30 Heuschrecke
- (Heuschrecke (Grasshopper)): 40 aircraft built, each with a 140 hp (104 kW) Siemens Sh 14A 7-cylinder radial engine.
Aircraft on display
- Cierva C.30A LV-FBL is on display at the Museo Nacional de Aeronáutica de Argentina.
- Cierva C.30A VH-USR is on display at the Powerhouse Museum, Sydney.
- Leo C-302 F-BDAD is on display at the Musée de l'Air et de l'Espace, Paris.
- Cierva C.30 I-CIER is on display at the Museo della Scienza e della Tecnologia "Leonardo da Vinci", Milan.
- Cierva C.30A SE-AFI is on display at the Aviodrome.
- Cierva C.30A XVU.1-1 flyable reproduction with a Siemens engine is on display at Museo del Aire, Madrid.
- United Kingdom
- Avro Rota I K4232 on display at the Royal Air Force Museum, London, England.
- Cierva C.30A AP506 (smashed wreck) on display at the Helicopter Museum, Weston-super-Mare, England.
- Cierva C.30A AP507 on display at the Science Museum in London, England.
- Avro Rota I HM580 the former G-ACUU is on display at the Imperial War Museum Duxford, England.
- United States
- Cierva C.30A K4235 on display at Fantasy of Flight, Polk City, Florida.
- Crew: 1
- Capacity: 1 passenger
- Length: 19 ft 8 in (6 m)
- Height: 11 ft 1 in (3.38 m)
- Empty weight: 1,220 lb (553 kg)
- Gross weight: 1,600 lb (726 kg)
- Powerplant: 1 × Armstrong Siddeley Genet Major IA 7-cyl. air-cooled radial piston engine, 140 hp (100 kW)
- Main rotor diameter: 37 ft 0 in (11.28 m)
- Main rotor area: 1,100 sq ft (100 m2)
- Maximum speed: 96 kn; 177 km/h (110 mph)
- Cruise speed: 83 kn; 153 km/h (95 mph)
- Range: 248 nmi; 459 km (285 mi)
- Rate of climb: 700 ft/min (3.6 m/s)
- Jackson 1973, p. ?.
- Thetford 1957, p. ?.
- Orbis & 1982-1985, p. ?.
- Smith 1973, p. 94.
- La Cierva and the Transportable Station of Naval Aeronautic (in Spanish) Archived 2008-06-15 at the Wayback Machine
- Lithuanian Aviation History 1919-1940. Air train (in Lithuanian)
- MOULIN, Jacques (2003). Les autogires LeO C.30 & C.301. France: Editions Leila Presse. ISBN 9782914017152.
- Danish Air Museum
- Jackson, A.J. British Civil Aircraft 1919-72: Volume II. London: Putnam and Company, 1973. ISBN 0-85177-813-5
- Munson, Kenneth. Helicopters and other Rotorcraft since 1907 (Blandford Colour Series). London: Associate R.Ae.S., 1973. ISBN 0-7137-0610-4.
- Pacco, John. "Cierva C-30A" Belgisch Leger/Armee Belge: Het militair Vliegwezen/l'Aeronautique militaire 1930-1940. Artselaar, Belgium, 2003, p. 92. ISBN 90-801136-6-2.
- Smith, J. Richard. "C 30 Heuschrecke" Focke-Wulf, an Aircraft Album. London, Ian Allan, 1973. ISBN 0-7110-0425-0.
- Thetford, Owen. Aircraft of the Royal Air Force 1919-57. London: Putnam and Company, 1957.
- The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.
- Moulin, Jacques (2003). Les autogires LeO C.30 & C.301. France: Editions Leila Presse. ISBN 9782914017152.
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