Cierva C.19

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Contents

Type Description

• C.19 Mk.I
• The first Cierva machine to be designed from the outset as an autogyro, rather than adaption of a fixed wing design, the two seat C.19 featured an all new fuselage of fabric covered, welded steel tube construction with wooden stringers to create a rounded shape, supported on a split undercarriage of very wide track and incorporating oleo legs with a stroke of 12 in. The cable braced four blade rotor was supported above the forward cockpit by by a pyramid of steel tubes, faired to an aerodynamic profile. the rotor blades themselves were of a new form of construction, with two layers of mahogany planking at 90 degrees. A box deflector biplane tail with two rudders and fins was fitted, which could be pilot-adjusted to deflect the propeller slipstream up into the rotor for pre-spin, after which, in normal flight, the top plane acted as the elevator while the bottom plane was fixed. Strut braced stub wings with upturned wingtips were similar to that of the C.17, fabric covered, with front and rear spars of box section in wood, while the aileron spars were steel tubes. One 80 h.p. Armstrong Siddeley Genet II powerplant.

• C.19 Mk.II
• As C.19 Mk.I but featuring a 105 h.p. Armstrong Siddeley Genet Major I powerplant.

• C.19 Mk.IIA
• As C.19 Mk.II but featuring increased fuel tankage, a longer stroke undercarriage and an improved rotor hub.

• C.19 Mk.III
• Similar to the C.19 Mk.IIA with greater diameter rotor blades of new construction. The main spar was of high tensile steel tube, 1-3/4 in. diameter, running the length of the blade (except at the extreme tip) at quarter chord. The ribs were of wood, consisting of a mahogany core 5/32 in. thick, faced on each side with 1/16 three-ply, closely spaced at 3 in. apart and riveted to a flanged clip on the main spar. An auxiliary spar of 1/4 in. thick spruce was fitted at approximately midway between the main spar and the trailing edge. The trailing edge was a strip of duralumin, doubled back over the ribs and riveted to each. The nose portion of the blade was covered with 1/16 in. 3-ply extending back to the centre of the main spar. The whole blade is fabric covered. The rotor blade tip was an aluminum fairing. A machined fork end bolted to the root end of the main spar, formed an attachment to the articulation joints in the rotor hub. The rotor blades were inter-braced with cables which carried damper loads from one blade to another. Thus, the blades were free to lead-lag as a group, but motion relative to each other was restricted.. A suspension, or 'droop', cable fitted at the top of the rotor hub was attached to a bracket on the main spar at 6 ft. 6-1/2 in. from the centre line of the rotor hub. One 105 h.p. Armstrong Siddeley Genet Major I powerplant.

C.19 Mk.III Specification
Rotor Dia	Length	Span *	Disc Area	Empty Wt	Max AUW	Minimum Speed	Maximum Speed	Range	Service Ceiling
3 ft 6 in	18 ft 3 in	20 ft 6 in	962 sq ft	930 lb	1400 lb	25 mph/ 22 kn	82 mph/ 71 kn	175 mi	7500 ft
1.07 m	5.56 m	6.25 m	89.37 m2	422 kg	635 kg	40 kph	132 kph	282 km	2286 m

Span * = span of stub wing

• C.19 Mk.IVP
• As C.19 Mk.III but fitted with a folding three blade cantilever (i.e., unbraced) rotor, requiring the use of a "droop stop," projecting out from the hub, provided a resting spot for the blade flapping hinge assembly (and thus the blade spar) when not rotating. The blade was constructed around a tubular steel spar at approximately quarter chord, with light spruce ribs, an ash leading edge and spruce strip trailing edge, the whole being fabric covered. This construction, however, was replaced by one one consisting of a fabric covered solid balsa wood fairing attached to a tubular spar with spruce core. A direct drive from the engine to the rotor was fitted, through which the rotor could be accelerated up to speed; the system was then declutched for the commencement of the take-off run. This removed the need for the box deflector tail, being replaced by a conventional strut braced monoplane tail unit with elevators, attached to the fuselage upper longerons. A rudder was attached to the stern post, plus a small dorsal fin, though the latter was later increased in size. One 105 h.p. Armstrong Siddeley Genet Major I powerplant.

• C.19 Mk.IV
• Production C.19. As C.19 Mk.IVP.

• C.19 Mk.V
• An experimental single seat autogyro, the forward cockpit being faired over, fitted with a direct control rotor hub, a universally mounted rotor hub that could be tilted in all directions by the pilot through a control column linked to the tilting head by two rods. The stub win, ailerons, tailplane and elevators were all dispenced with, only the rudder remaining, with a larger dorsal fin. It was exprimentally fitted with a variety of tailplanes during its lifetime. In 1933, the control column and linkages were replaced by a simple hanging stick directly connected to the rotor tilting head. One 105 h.p. Armstrong Siddeley Genet Major I powerplant.

Production Details - All UK Built Aircraft

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Non-UK Production

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Production Summary

Notes

1. Brooks [1] gives G-ABUE as going to Germany as D-EKOT, but this would appear to be a confusion with the Focke-Wulf built C.19 D-EXOT. There seems to be some uncertainty as to whether Focke-Wulf built their own C.19 prototype or simply modified G-ABUE with a new powerplant.

Production References

1. Cierva Autogiros - The Development of Rotary-Wing Flight, Peter W. Brooks (Airlife, 1988)
2. Introduction to Autogyros, Helicopters, and Other VSTOL Aircraft Volume I - Overview and Autogyros, Franklin D. Harris (NASA Center for AeroSpace Information, May 2011)
3. The K File, The Royal Air Force of the 1930s, J.J. Halley (Air-Britain Publications, 1995)
4. BARG Roundel Aug 1996
5. Via posts on the Air Britain Information Exchange (AB-IX) forum, August 18 and 19, 2024 (https://groups.io/g/AB-IX)