Cierva C.19

https://en.wikipedia.org/wiki/Cierva_C.19

The Cierva C.19 was a 1930s British two-seat autogyro, designed by Spanish
engineer Juan de la Cierva. It was built by Avro as the Avro Type 620. It proved
to be the most successful and widely produced of the early de la Cierva designs.

De la Cierva's first successful autogyro, the Cierva C.6, used an Avro 504
fuselage, and this led to a long and close collaboration between de la Cierva
and Avro from 1926 onwards, with de la Cierva providing the rotor design, and
Avro the airframe from designs that often appeared as both fixed-wing and rotary
aircraft. There was a long series of such autogyros, developing the rotary wing
concept. However the 1929 C.19, was a de la Cierva design, owing nothing to
existing Avro aircraft, though it was built by Avro at Hamble.

Like the earlier aircraft, the C.19 had a conventional airframe, a two-seat
fuselage carrying a small-span wing with ailerons (to relieve rotor loads in
level forward flight), and a single radial engine in the nose. The unpowered,
free-spinning rotor had four wire-braced blades, or three cantilever blades in
the Mk IV, and was mounted on four struts over the forward cockpit which met
together to form a pyramid. The C.19 Mk I – IV did not have the tilting rotor
head and associated hanging control column of later autogyros like the Cierva
C.30. Instead, control was by the ailerons, elevators and rudder via a
conventional column, a system that only worked effectively when the airspeed was
high enough.

A major engineering refinement in the C.19 was the means to mechanically start
the main rotor spinning; in earlier de la Cierva designs, the rotor had to be
turned by hand or by pulling a rope, unless there was space for a takeoff run.
In the C.19 Mk I, this was done aerodynamically. The tail unit of this mark was
a biplane structure with endplate fins and rudders. To start the rotor,
elevators and tailplanes were fixed in a near vertical position and the engine
started. The wash from the propeller was deflected upwards by the tail unit
through the rotor, rotating it. For the first time, this made the autogyro
independent of ground crew when starting, and private ownership was a practical
proposition.

The 80 hp (60 kW) Armstrong Siddeley Genet II made the Mk I machine
underpowered, and it was replaced in the C.19 Mk II by a 105 hp (78 kW) Genet
Major I. The C.19 Mk IIA, introduced in 1930, had a longer undercarriage and
improved rotor head. Landings were often made at high angles of attack, so the
rudders of the C.19 Mk III were reshaped to slope sharply upwards to avoid
damage; this variant also had a 5 ft (1.52 m) increase in rotor diameter.

In the C.19 Mk IV, the rotor was started directly from the engine via a clutch
mechanism, as in all future autogyros. This allowed the elaborate biplane
empennage to be replaced by a more conventional monoplane tailplane. The single
central fin was low and of correspondingly deep chord, to avoid being struck by
the rotor. The C.19 Mk IV had a three-bladed, 34-foot-diameter (10 m) cantilever
rotor. The designation C.19 Mk IVP was also used, the "P" standing for
production, that started in 1931.

The final variant was the solitary C.19 Mk V, G-ABXP. The aircraft-style
controls of earlier autogyros depended on airflow past ailerons, rudders and
elevators; during the slow forward speed phases of takeoff and landing, these
were ineffective, and accidents resulted. The C.19 Mk V lacked the small wing
and all-moving control surfaces, relying instead on a tilting rotor head. Using
a long control arm that reached to the rear cockpit, the pilot could direct the
aircraft by tilting the plane of rotation of the rotor. After a period of
experimentation, the C.19 Mk V flew with a small fixed tailplane and a
two-bladed rotor. This control system was adopted for the Cierva C.30.


Role
Utility autogyro

Manufacturer
Cierva

Designer
Juan de la Cierva

First flight
1929

Number built
30

Some thirty examples were built in England, with licences acquired by Focke-Wulf
to produce it in Germany (as the C.20) and by Lioré et Olivier in France (as the
C.21), although no actual French production took place.

Initially, all fifteen C.19 Mk IVPs appeared on the British civil register. One
was used in an attempted flight to South Africa, although it only reached Tunis.
Later, it flew with Alan Cobham's Circus. Another went to an autogyro flying
school at London Air Park, Hanworth. Several machines were reregistered abroad:
in Australia, Germany, Japan, Singapore, Spain (one for the Spanish Air Force)
and Sweden.

During the early 1930s, the Royal Air Force operated two C.19 Mk IIIs for
evaluation of the autogyro concept (serials K1696 and K1948).

Variants

C.19 Mk.I – The original three prototypes, powered by a 60 kW (80 hp) Armstrong
Siddeley Genet radial piston engine. (three built)
C.19 Mk.II – This variant was powered by a 78 kW (105 hp) Armstrong Siddeley
Genet Major radial piston engine. The Genet Major engine was used on all further
variants. (three built) C.19 Mk.IIA – Mk.II with improved rotor head. (one
built)

C.19 Mk.III – (six built)
C.19 Mk.IV – The definitive production version, the basis for foreign licences.
(15 built)
C.19 Mk.V – One-off experimental aircraft, tilting rotor head development
machine. (one built)
C.20 – Focke-Wulf licence-built version with Siemens Sh 14 engine.
C.21 – Lioré et Olivier licence-built version. (not built)

Specifications (Mk.II)

General characteristics
Crew: one pilot
Capacity: one passenger
Length: 18 ft 0 in (5.49 m)
Main rotor diameter: 30 ft 0 in (9.15 m)
Height: 10 ft 0 in (3.05 m)
Wing area: 708 ft2 (65.8 m2)
Empty weight: 850 lb (386 kg)
Gross weight: 1,400 lb (635 kg)
Powerplant: 1 × Armstrong Siddeley Genet Major I five-cylinder radial, 105 hp
(78 kW)

Performance
Maximum speed: 95 mph (153 km/h)
Range: 300 miles (483 km)
Rate of climb: 500 ft/min (2.5 m/s)





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