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Aviation History
1946
1946 - 1292.PDF
FLIGHT JULY 4TH, 1946 CIERVA "AIR HORSE" under all conditions of hovering and translational flight, and it absorbs but some 2 per cent of the take-off b.h.p. Transmission drive to three rotors presented something of a problem, but, all things considered, that evolved is not unduly complicated. It is divided into primary and secondary transmissions. The primary transmits power from the engine to secondary gear boxes, which form units with the three rotor heads. The standard Merlin XXXII is fitted with a modified Borg and Beck type single-plate clutch. This clutch, the main function of which is to start the rotors, is capable of transmitting 150 h.p. only. At a predetermined number of revs the centrifugal ratchets of the positive dog clutch become engaged, thus relieving the clutch of further duty. The automatic ratchet type dog clutch also acts as a free- wheel or over-riding device in case of engine failure, and allows the rotors to autorotate in gliding flight. As the rotors are geared together, adequate control is retained. A simple arrangement of bevel gears distributes the torque ', to the rotor transmission shafts and thence to the rotor hubs. The standard Merlin airscrew reduction gear ratio of 2.095 • * has been retained. Rotor Drives Large-diameter hollow universally-jointed shafts trans- mit the torque from the primary gear box to the secondary gear boxes under the rotor hubs. The shafts, are supported at about mid-point by bearings in the outriggers and, to keep the gears within reasonable proportions, the oppor- tunity has been taken to introduce a double-xeduction gear. The gear ratio between primary and secondary is 6.55:1, which gives an overall ratio between engine crankshaft and rotors of 13.7 : 1. The normal flying controls are a spade-grip column and rudder pedals. The clutch lever, combined with the brake for the rotors, is mounted at the side of the pilot's seat, the lever operating on a common drum at the rear of the primary transmission gear box. Connected with the con- trol distribution box is the overriding collective pitch con- trol, together with 'a visual indication of the blade pitch setting. In a helicopter such as the "Air Horse," the rotors and their transmission system are all-important, and it may be said that the primary aircraft structure is of secondary importance. In this particular machine the fuselage and inner half of the outriggers are of welded tubular construc- tion. The forward end of the fuselage is so designed that it can take different forms of cabin to suit any specific operational duties. The outer portions of the three out- riggers are of stressed-skin construction. Spraying Gear As for the special equipment needed for pest destruc- tion, Pest Control, Ltd., proposed a main stainless steel tank of 500 gallons capacity, provided with ample vent pipes and fillers so as to permit of rapid "refuelling." A special three-stage centrifugal pump with an additional low-pressure stage is capable of delivering to the spraying system at a rate of 100 gallons per minute, and at a pres- sure of 350 lb/ sq in. The spraying gear is so arranged that the liquid can be sprayed into certain sections of the slipstreams. The whole equipment, including the 500 gallons of pest-destroying liquid, will, it is estimated, weigh about three tons. It is calculated that with a three-ton payload (including equipment and personnel) the loaded weight of the machine will be 15,000 lb, but greater loads could be lifted. At 15,000 1b the power required to hover at one rotor dia- meter from the ground is 980 b.h.p., which leaves a take- off power reserve of 620 b.h.p. This should give a rate of vertical ascent of 1,440 ft/min, but this rate is consider- ably increased if a certain amount of forward speed can be employed. Under still-air conditions the maximum weight that can lifted from the ground when using full take- off power is estimated to be approximately 20,000 lb. For pest destruction, as already mentioned, forward speed is of small importance, but the cruising speed should be about 88 m.p.h., and the maximum speed something like 115 m.p.h. The work on design and construction has now begun, and the performance of the machine will be awaited with great interest. The project is an ambitious one, but the Cierva company has had long experience. SUBMARINE SINKINGS QOME interesting figures appear in the official booklet **J issued by the Admiralty giving the particulars of the destruction of enemy submarines. Out of 781 German U-boatssunk, aircraft, eithei on their own or in conjunction with ships, were employed in the attack on no fewer than 415of them. The figure for those sunk by aircraft alone is 369. The Italian and Japanese figures, however, show a preponder-ance of successes for ship attacks. Italy lost 85 submarines, of which 13 were sunk by aircraft, and of the total Japaneselosses in U-boats of 130, aircraft were responsible for only 15. The following is an analysis of German U-boat sinkings. SUBMARINE SINKINGS Sinkings aided Sinkings by by ships or Type of a'rcraft s/c only other a/c Sunderland ... ... ... ... 25 6 Swordfish 13 Unidentified (R.A.F.) 24 M Hudson , 19 J Whitley ... 4 I Unidentified (N.A.A.) I Catalina 15 4 Blenheim ... ... ... ... . _ I Wellington 24 * Lancaster _ I Liberator 58 I Fortress ... ... ... ... U I Wellesley | Albacore II Bisley ... | Unspecified a/c (by mines) 16 2 Hampden | _ Halifax 9 | Beaufighter 6 —• Cams (French) | Brazilian — | Mosquitoes... ... ... ... ... 8 I Avenger Wildcat _ | Ventura I By American aircraft 105 - 28 . 'German, Italian and Japanese U-boat casualties during the war. H.M.Stationery Office, 6d. PUBLIC'S USE OF RUBBER DINGHIES TV/TORE than 100,000 surplus rubber dinghies of various typesJ-*-*- have been disposed oi to the public, and the Air/ Sea Rescue Service asks that care shall be taken, when thesedinghies are used on bathing beaches, that they shall not be allowed to drift out to sea. This has already happened on a number of occasions with theresult that false alarms of "ditched" aircrew have put the Service to unnecessary trouble. Moreover it is pointed outthat such false alarms might send aircraft and marine craft on wild goose chases just when their services were genuinelyrequired elsewhere. Privately owned dinghies, it is recommended, should have their owners' names and addresses clearly marked by means of ^-^^ a securely attached tag, and, __X^> if a dinghy does accidentallyescape, it should be reported at once. " Hullo—Air/Sea Rescue Service ? 'I
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