Flight, June 1929

BRITISH AIRCRAFT AT OLYMPIA

THE CIERVA AUTOGIRO CO., LTD.

   THE most unorthodox aircraft to be seen at Olympia will be the Cierva "Autogiro" or "windmill" 'plane, in which lift is obtained not from rigid stationary wings as in the normal aeroplane, but by four windmill or airscrew blades which, by their rotation, exert lift and carry the machine. The visitor to this stand should be careful not to confuse the "Autogiro" with the helicopter type of aircraft. In the latter, the rotating wings are driven by the engine, while in the "Autogiro" the four blades are free to rotate around a nearly vertical shaft, their rotation being entirely due to the air forces upon them, and not to any direct drive from the engine.
   The particular machine to be exhibited at Olympia will be a type C. 19, with Armstrong-Siddeley "Genet" engine, designed as a private owner's two-seater light 'plane. The machine is a development of the "Autogiro" C. 8 Mark II (Armstrong-Siddeley "Lynx"), which successfully completed 3,000 miles without any major replacements during a tour of Britain in August, 1928, a flight from Croydon to Paris in September, of 1928, and a tour of 1,500 miles from Paris to Berlin, via Brussels, Cologne, Dortmund, Hanover and Dessau, and return to Paris via Magdeburg, Hanover, Munster, Rotterdam and Brussels in October, 1928.
   The fuselage of the "Autogiro" C.19 is of welded steel tube construction, and is supported on a split undercarriage of very wide track and incorporating oleo legs with a stroke of 12 in., which should give excellent shock-absorbing qualities. Bendix brakes and wheels are fitted, and as the "Autogiro" alights with very low forward speed, the brakes should reduce the landing run to a few feet. Thus it should be possible to land the "Autogiro" in almost any field.
   The mast which supports the rotating wings is in the form of a pyramid of steel tubes with conical platform, welded and riveted. The hub of the rotor is a steel forging incorporating radial and thrust ball bearings, and a system of braking. The wings themselves are of the mono-spar type, with spars of steel tube and box ribs. The covering is a planking of mahogany. The stabilising planes are of mixed construction, with front and rear spars of box section in wood, while the aileron spars are steel tubes.
   A biplane tail is fitted, composed of top and bottom tail plane, of which the top plane acts as the elevator while the bottom plane is fixed, and two rudders and fins. The construction of the tail is in steel-welded tube.
   The equipment and instruments fitted as standard are :- 2 air-speed indicators, 2 cross levels, 2 safety belts, 1 altimeter, 1 engine revolution counter, 1 rotor revolution counter, 1 oil thermometer and one tele-level.
   A standard fuel capacity of 23 gallons is provided, which gives the machine a cruising range of 280 miles at a speed of 80 m.p.h.
   The main dimensions, areas, etc., of the "Autogiro" C. 19 are :- Length, o.a., 30 ft.; span, 30 ft.; height, 10 ft.; rotor chord, 1 ft. 3 3/4 in.; total rotor area, 25-74 sq. ft.; stabilising plane chord (average), 2 ft. 6 1/2 in.; total stabilising plane area, 42 sq. ft.
   With a tare weight of 750 lbs., and a disposable load of 550 lbs,, the "Autogiro" C. 19 has a gross weight of 1,300 lbs., which gives a rotor loading of 45-5 lbs./sq. ft. and a stabilising plane loading of 3-1 lb./sq. ft.
   A top speed of 95 m.p.h. is claimed, and a cruising speed of 80 m.p.h. The initial rate of climb is 500 ft./min., and the landing speed 10 m.p.h. In still air the take-off run is 30 yards, and the landing run 10 yards.

Flight, January 1930

THE AUTOGIRO
Flown by Sir Sefton Brancker

   ON January 7 a demonstration flight of the Autogiro C.19 Mark II was made at Heston Air Park. The pilot was Flight-Lieut. A. H. C. A. Rawson, and the second seat was occupied by Sir Sefton Brancker, Director of Civil Aviation. The machine was fitted with dual control, and for part of the flight the D.C.A. himself piloted the machine and made one take-off and one landing.
   The appearance of the machine is best described by the photographs. It is one of the tiniest two-seaters ever seen since the second Lympne meeting. The Moths which were on and over the aerodrome at the same time looked quite large aeroplanes beside it. The front seat is directly under the four uprights of the pylon which supports the vanes, and Sir Sefton had to make himself very slim to get in and out.
   The pylon inclines somewhat to the right side of the machine, and after landing it is as well to draw up with this side opposed to the wind. The wings on each side are not merely booms to support ailerons, but actually give about 20 per cent, of the lift at full speed. At the end of each is a keel surface set at a pronounced dihedral angle. The undercarriage has a very wide track, and the oleo leg gives an 8-in. travel. A great deal is apt to be asked of this undercarriage, and on this occasion it did its work well.
   The empennage constitutes the most notable feature of this type of autogiro. The fins and rudders are double. Between them are arranged the tail plane and elevator in biplane formation. The chord of the tail plane is equal to the gap between the two. A simple control in the cockpit raises these two surfaces to a vertical position, so that they present a wall, flanked by the fins, to the slipstream of the propellor, and deflect it upwards on to the rotor blades and set them in motion. In practice it is usual to start them off with a gentle push of the hand, but on this occasion they actually commenced to rotate when the machine moved, before a hand had been laid on them.
   While the machine is still standing still, the deflected slipstream will work the rotor blades up to 95 r.p.m., but when the pilot commences to taxi forward their speed increases rapidly. When they reach 140 r.p.m. it is safe to take off. Their normal speed in the air is 160 r.p.m., but when the engine is shut off they work up to 170 r.p.m. The best take-off made has been after a run of 30 yards.
   The top speed of the machine is given as 95 m.p.h., and the minimum speed at 28 m.p.h. Flight-Lieut. Rawson said that the normal way of landing was to approach the aerodrome at 40 m.p.h. and when about 20 ft. off the ground to jerk the nose up and pancake down. The machine stops dead where it lands, but wheel brakes are also provided.
   The engine is an Armstrong-Siddeley 100 h.p. "Genet Major." When we arrived on the aerodrome it was suffering from magneto trouble, which gave an opportunity to see how very quickly the engine cowling can be taken off and put on. However, the engine was not giving its full revolutions, and this somewhat detracted from the performance of the autogiro.
   The first run was rather a long one, and the machine climbed somewhat laboriously. Slow flying, however, is one of the attractions which the autogiro offers the pleasure-seeker, and this quality was emphasised by the Moths which flashed past it and round it as though it were a candle. Quite apart from the rotors, the tiny fuselage, the wide undercarriage, the turned-up wing tips, and the double fins, make this machine one of the weirdest fowls ever seen in the air, at least since the days of the box kite.
   The eerie effect was increased when the pilot pointed the machine towards the spectators, and allowed it to sink towards the earth. Actually it was moving forwards as well as downwards, but this was not apparent from the end-on view. The appearance was that of an abnormally steady parachute. After losing two or three hundred feet, the pilot opened up the engine and flew on once more.
   The first landing looked like a very heavy pancake, from a generous 20 ft., but the undercarriage took it easily. The machine pulled up, but before the blades lost flying speed Sir Sefton took the joystick and took off again. This time the engine was warmer, and the run was shorter. Sir Sefton also made the second landing, and put the machine down quite gently. Then the test pilot took charge again and made a couple more landings.
   When Sir Sefton had extricated himself from the pylon struts, he said that he had found the autogiro very easy to fly - in fact, anyone could fly it. He said it was very comfortable, and, though it was quite a bumpy day, the bumps had far less effect upon the autogiro than upon an ordinary aeroplane. He said that the machine gave him a feeling of complete confidence. He felt that nothing could go wrong. He found no unpleasant sensation from the rotors whirling above his head.
   Then, turning to the inevitable microphone, Sir Sefton said that when Mr. de la Cierva first lectured on his invention to the Royal Aeronautical Society, he at once became a very strong advocate of the principle of the autogiro. The experiences of this afternoon had confirmed him in his conviction that the autogiro had a great future - especially for citizens of a great city like London, in enabling them to get out quickly into the country or to the aerodromes where airways start and finish. He congratulated the inventor and the company on their progress.
   Striking as were the words of the D.C.A., it was almost more striking to hear a private owner-pilot who was present say that he looked forward to the time when the autogiro should be fully developed. He lived in a distant county, and he had frequent business in London. He liked to fly to and fro, but, though he enjoyed flying by night, he never felt quite safe in doing so. With an autogiro he would feel quite safe, and he would not mind a bit if he got home half an hour later in the evening. If he were forced to land, he was sure that he could put an autogiro down anywhere with safety and probably without damage.

Flight, April 1930

AIRCRAFT FOR THE PRIVATE OWNER

AUTOGIRO

   THE Autogiro stands quite alone in the aircraft market, as it is the most unorthodox.
   The lift in this machine is obtained not from the usual stationary type of wing or wings, but from four rotating wings which, through the aerodynamical action of their rotation exert the necessary lift to fly the machine. They are not driven in any way except at the start and their rotation is a natural function of their aerodynamical characteristics, hence the name "auto-giro," and once they are started they continue to rotate until the machine comes to rest on landing. For starting this rotation the latest method which has been designed is to utilise the slipstream from the engine which is deflected on to the blades by means of the tailplane and elevators which are locked together and then set at the requisite angle so that the slipstream coming aft is caught and deflected upwards on to the blades.
   Many engines have been fitted to these machines and for the private owner those advocated are the Armstrong-Siddeley "Genet" or the "Cirrus III."
   The chief advantages of this peculiar design are its ability to fly very slowly and to land almost vertically. The initial rate of climb is not very good, being only 500 ft./min., but the advantage of being able to land in a small space is very great indeed. Anyone can easily learn to fly this type, and even those who have never flown it before find that they can, with the help of the wheel brakes, land with a run of only a few yards.
   Don Cierva, the designer, is a Spaniard, and to build his machines in this country he has formed the Cierva Autogiro Co., with offices at Bush House, London, W.C.2, while the works are at Hamble.
   The actual fuselage is of normal construction and is fabric covered. The undercarriage is worthy of especial note as it has had to be designed to stand the stress of the almost vertical landings which the Autogiro is capable of. The track is very wide and the compression legs are oleo shock absorbers with a travel of some 12-in. Bendix wheel brakes are fitted which not only decrease the landing run still further but also allow very easy manoeuvring.
   The Autogiro can hardly be said to be an established private owner's machine, but its qualities make it one which should be very safe to fly.
   One of these machines was, the year before last, flown round the continent on a demonstration flight of over 3,000 miles without any mishap, during which it visited most of the capitals of Europe, so that it cannot be said to be untried.

Flight, November 1932

British Aircraft

The Cierva Autogiro Co., Ltd.
Bush House, London, W.C.2

   CENOR JUAN DE LA CIERVA is a Spanish engineer who several years ago conceived the idea of a non-stalling aircraft in which the lift was obtained not from one or more fixed wings but from a rotor with blades free to revolve under the action of the air forces on them. He has had a long and difficult fight to convince the world of the soundness of his ideas, but with a persistence which must receive the most unstinted admiration he has continued to experiment, and it can now be said that the experimental stage is passed and the commercial stage has arrived. The various problems met with in the earlier machines have been overcome, and the Cierva Company feel justified in placing their machines on the market.
   Two models of the Autogiro are available at present in Great Britain, the type C.19 Mark IV and the C.24.

The C.19 Mark IV

   Fitted with an Armstrong-Siddeley Genet engine of 100 h.p. this machine is an open two-seater with steel tube fuselage and three-bladed rotor. The fixed wing is mainly of wood construction. The rotor blades have steel tube spars, while the aerofoil section used is formed by solid Balsa wood having a Spruce core. The rotor hinges have been so designed that for housing the machine two of the blades can be folded back, when the space occupied by the machine is reduced to that required to accommodate the fixed wing.
   The undercarriage is of wide track and of the "split" type, incorporating oleo legs of 9 1/2-in. travel. Dunlop wheels are fitted and low-pressure tyres. The wheel brakes are Bendix.
   The normal petrol tankage is of 16 gallons (72,7 litres), which gives a range of 230 miles (370 km.).
   The main data are :-
   Rotor diameter 34 ft. (10,4 m.)
   Span of fixed wing 21 ft. (6,4 m.)
   Tare weight 1,075 lb. (490 kg.)
   Normal gross weight 1,450 lb. (660 kg.)
   Max. gross weight 1,550 lb. (705 kg.)
   Maximum speed 102 m.p.h. (164 km./h.)
   Cruising speed 90 m.p.h. (145 km./h.)
   Minimum speed 25 m.p.h. (40 km./h.)
   Rate of climb 630 ft./min. (3,2 m./sec.)