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DE
LA CIERVA
CIERVA C.4 / C.5 |
CIERVA C.4
CIERVA C.5
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Al experimentar con los tres modelos anteriores, De la Cierva descubrió que el secreto de un vuelo correcto residía en la flexibilidad de las palas, para compensar la diferencia de sustentación entre la pala que avanza y la pala que retrocede. El C.4 basado en esta teoría fue construido en 1922, con un rotor de cuatro palas articuladas en la raíz. Al principio no tuvo éxito, pero luego de algunas modificaciones realizó su primer vuelo el 9 de enero de 1923 al comando del teniente Alejandro Gomez Spencer, el cual realizó un "vuelo" de 183 metros. A finales del mismo mes , el C.4 recorrió en cuatro minutos un circuito cerrado de 4 Km.a una altura de 30 metros. El C.4 estaba equipado con un motor Le Rhone 9JA de 110 HP. En julio de 1923, con el mismo motor del C.4, voló el C.5, este constaba de un rotor tripala. A partir de este modelo De La Cierva comenzó a contar para el desarrollo de sus proyectos con el apoyo del gobierno español. |
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The
new design, later identified as C.4, but known at the time as Autogiro
No. 4, had a single four-blade rotor, 8 m (26 ft 3 in) in diameter. The
rotor blades were of Eiffel 101 symmetrical section 70 cm (28 in) wide
and were articulated at their roots and braced downwards with cables and
upwards by rubber shock absorbers allowing them a vertical flapping
motion. These restraints prevented the blades rising too high or
dropping too low while at rest or when rotating at less than flying
speed. The flapping hinges were below the plane of the blades with bent
blade roots so that the blades flew flat rather than coned. Blade
construction was of tubular steel spars, wooden ribs, and fabric
covering. Normal speed of rotation was about 140 rpm. As in the C-3, the
fuselage probably came from a Sommer monoplane; indeed, the fuselage,
the Le Rhone 9C engine-even the tail surfaces and landing gear (in
modified form)-may have been the very ones used in the C-3. The C-4 had
only an elevator and no fixed stabilizer. Lateral control was to be
provided by a sideways-tilting rotor hub. The C-4
was completed in
April/May 1922. Jose Maria Espinosa Arias tested it at Getafe from June
onward, for many months. It crashed several times and was tried in fifteen
different forms, plus three or four lesser modifications. Changes included
shortening the fuselage, increasing the track of the landing gear, and
substituting a larger 9.75 m diameter rotor with blades of Eiffel 106
section. The last change was made after a hinge had failed on one of the
blades of the original rotor, fortunately without catastrophic results. The freely flapping blades
were found to have overcome the problem of the unbalanced lift of the
advancing and retreating blades. The rising advancing blade automatically
reduced its incidence to the relative airflow, and hence its lift, while
the retreating blade did the opposite. Because the centrifugal forces
acting on the blades were about ten times the lift that they generated,
the blades took up a mean coning angle of about one in ten with the plane
of rotation. Articulation of the blades had also completely removed any
gyroscopic effect from the rotor. These tests established,
however, that the pilot's lateral control by tilting the rotor head, as
then designed, was too heavy to be practical. The pilot was unable to
restrain violent oscillations of the control column transmitted from the
rotor. Therefore, as the fifth modification of the CA, the rotor hub was
fixed. At a later stage still, despite Cierva's reluctance to use
airplane-type controls, ailerons on outriggers were added to provide
control in roll. Actually, the C-4 was found to fly quite well in calm
conditions without any lateral control at all, although the rotor head had
to be permanently offset somewhat to prevent the aircraft from rolling
over on the ground. Ailerons were needed in certain circumstances and
these lateral control surfaces were to remain a feature of all Cierva's
designs until 1932. Later they were incorporated into fixed wings. In its
final configuration, the C-4 had a fixed, slightly offset rotor head and
ailerons. It had its first tests in this form on January 10, 1923, when,
encouragingly, it rolled over on the ground the opposite way to all
previous accidents. It took a week to repair the damage. There is some controversy
about the first flight date of the C-4
but the most reliable evidence is
that on January 17, 1923, in its latest form the C-4
made the first
controlled gyroplane flight in history, a flight which has been described
as the most significant since the first flight of the Wright brothers. Piloted by Cavalry lt
Alejandro Gomez Spencer, a flying instructor at the Spanish Flying Corps
flying school at Getafe and "a Spanish gentleman whose surname and
appearance both indicate an English ancestry,' it made a steady straight
flight of 600 ft at a height of about 13 ft across Getafe airfield. A
further wries of similar flights after engine trouble on January 20 were
repeated before official military and Aero Club observers on January 22.
The latter included General Francisco Echagüe Santoyo, director of Air
Services, and Don Ricardo Ikuiz Ferry, president of the Spanish Royal Aero
Club Commission. The C-4 was then transported to Cuatro Vientos military
airfield and on January 31 was flown again by Spencer on an officially
observed circular flight of 4 km (21/2 mi) in 31/2 minutes at a height of
more than 25 m (80 ft). The speed range of this aircraft in level flight
was estimated at between 65 and 95 km/hr (40 and 60 mph) and the rate of
descent, at low forward speed without power, at 2 to 3 m/s (6 to 10
ft/sec), aithough it was, in fact, almost certainly considerably higher
than this. The excellent low-speed
characteristics of the Autogiro were effectively demonstrated on January
20 when the C-4 accidentally got into a steep nose-up atititude (nearly 45
degrees to the horizontal) after engine failure at a height of about 8-10
m (25-35 ft). The Autogiro's reaction to this situation was to descend
vertically quite slowly, and to land undamaged without running more than
1m. most significant since the first flight of the Wright brothers.
Piloted by Cavalry 'lieutenant Alejandro Gomez Spencer, a flying
instructor at the Spanish Flying Corps flying school at Getafe and "a
Spanish gentleman whose surname and appearance both indicate an English
ancestry,' it made a steady straight flight of I S3 rn (600 ft) at a
height of about 4 m (13 ft) across Getafe airfield. A further wries of
similar flights after engine trouble on January 20 were repeated before
official military and Aero Club observers on January 22. The latter
included General Francisco Echagüe Santoyo, director of Air Services, and
Don Ricardo Ikuiz Ferry, president of the Spanish Royal Aero Club
Commission. The C-4 was then transported to Cuatro Vientos military
airfield and on January 31 was flown again by Spencer on an officially
observed circular flight of 4 km (21/2 mi) in 31/2 minutes at a height of
more than 25 m (80 ft). The speed range of this aircraft in ievel flight
was estimated at between 65 and 95 km/hr (40 and 60 mph) and the rate of
descent, at low forward speed without power, at 2 to 3 m/s (6 to 10
ft/sec), aithough it was, in fact, almost certainly considerably higher
than this. The excellent low-speed characteristics of the Autogiro were effectively demonstrated on January 20 when the C-4 accidentally got into a steep nose-up atitude (nearly 45 degrees to the horizontal) after engine failure at a height of 25-35 ft. The Autogiro's reaction to this situation was to descend vertically quite slowly, and to land undamaged without running more than 1 m (3 ft). |
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Characteristics |
Information |
Characteristics |
Information |
First
Flight Primer Vuelo |
1923 | Engine Motor |
1 LE RHONE |
Seating
Capacity Plazas |
1 |
Power Potencia |
110 HP |
Empty
Weight Peso Vacío |
Lb |
Hover
Ceiling O.G.E. Estacionario O.G.E |
Ft |
Maximum
Weight Peso Máximo |
Lb |
Hover
Ceiling I.G.E. Estacionario I.G.E |
Ft |
Vel.
Cruise Vel. crucero |
Kt |
Service
Ceiling Techo de Servicio |
Ft |
V.N.E. V.N.E |
Kt |
Maximum
Range (Std) Alcance (Std) |
NM |
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