Aviation

Wanganui Chronicle, Volume 76, Issue 122, 26 May 1933, Page 5

Aviation

Notes by “Airscrew’’

When the order for two high-flying -planes was negotiated the Everest expedition organisers stipulated that the machines should attain in trial flights a height above sea level with full load on board of at least 34,000 feet, thus providing an adequate margin over the 1’9.000 feet of Everest. All military gear, and fittings such as vrheel fair ings and wheel brakes, were removed to save weight in order that the re quired heights might easily be reached with the heavy load which was to be airborne during the flights over the mountains. Essential load included pilot and observer, ninety gallons of fuel, oxygen-breathing and electrical heating apparatus, camera, kinecamera, and many special instruments. In each aeroplane the observer's cockpit was enclosed to protect the occupants against the terrible cold of the great heights. Sliding windows are provided for work with the cameras. An “Air Yacht.” Though the Spartan “Cruiser” trimotored monoplane is fitted primarily for commercial flying it is sufficiently near the luxurious touring class for it to be worth consideration by the re latively wealthy private flyer who desires to transport himself and his friends in comfort greater than is obtainable in a light aeroplane. Priced at around £4OOO, the aeroplane provides accommodation with fuel for 650 miles cruising, for pilot and five passengers. The price is not far beyond the cost of a luxury automobile, while the mobility and speed of the air vehicle are incomparably greater. The aircraft is a low-wing monoplane, designed for installation with three engines <)f 120 or 130 h.p. During test flights with full load on board the macsine ~as proved its ability to climb even at a height of 6000 feet on the power of any two engines. In one demonstration, over Athens, a fully-laden “Cruiser” attained a height of more than 9000 feet on two engines only. During the same flight it travelled a distance of no less than forty miles from a height of 6000 feet on the power of one engine. Up to 6000 feet it will fly level on any two engines, with full load, at normal cruising revolutions. Obviously the machine has a large safety margin and should be practically immune from forced landings away from an aerodrome. Fuselage is of metal and the full cantilever wing is covered with plywood—an exceptionally robust combination. It has a wide split-axle undercarriage, wheel brakes and tail wheel. Wing span is 54 feet, the length overall two inches more than 39 feet, and the height ten feet. Tare weight of rhe aeroplane, when it is fitted for passenger carrying, is 3500 or 3550 pounds, according to the engines installed; laden weight is 5600 pounds. When equipped for use as a freighter, the tare weight is 3410 or 3460 pounds, and pay-load in the form of freight is 1020 or 970 pounds. Performance figures arc impressive. With three 120 h.p. “Gipsy” engines maximum speed is 135 m.p.h. and cruising speed 110. With three 130 h.p. “Gipsy Major” units the high speed goes un to 140 m.n.h. and the cruising speed to 118 m.p.h. “Ceiling” of a]] types is 15,000 feet. The stalling speed is 57 miles an hour.

Head of the Industry. Mr Herbert J. Thomas last week succeeded Sir John biddcley in the oihee of chairman of the Society of British Aircraft Constructors. Sir John Siddeley, chairman for the past two years, retired in accordance with the regulations of the society, and Mr. Thomas, who is assistant-managing director of the Bristol Aeroplane Company, was unanimously elected in his place. He will be supported by Mr. ‘U. C. Walker, of the de Havilland Company, who was elected deputay chairman (aircraft) and by Mr. A. F. Sidgreaves, managing-director of Rolls Royce, Ltd., elected deputy-chairman (engines). The new chairman began his association with flying as long ago as 1909, when he was engaged in France on ex perimental and constructional work with balloons. The following year he joined, at its inception, the Bristol Company, and has occupied since then nearly every one of the chief positions in the firm, being successively pilot, head of the flying school, chief inspector, assistant works manager, works manager, and assistant manag ing-director. He took his pilot’s “ticket” in 1910, when he was eighteen years old, and was at that time the world’s youngest certificated pilot. His Royal Aero Club certificate is numbered 51, which places Mr Thomas right among the pioneers of aeroplane flight. Another Scottish Order, Work is going forward in the Avro factory at Manchester on four special “Cadet” biplanes ordered by fhe Scottish Motor Traction Company for “juy-riding” use. When delivered, towards the end. of this month, they will bring up to twenty-four the number of new aeroplanes ordered by this concern within the past twelve months. This summer, in addition to pleasure-flying, special charter work and newspaper services, the company proposes to inaugurate regular air-line services through Scotland and much ot northern England. Normally, the “Cadet” is a twoseater craft, designed in the first place for the inexpensive and efficient train ing of military pilots. Those ordered by the Scottish company will carry two passengers in an enlarged cockpit forward of the pilot. Power will be supplied by an inverted 130 h.p. air-cooled engine. The “Cadet” follows standard Avro practice in construction and design. It is a single-bay staggered biplane of which the wings are built mainly of wood, with the compression struts and trailing edge of duralumin tube. The fuselage is a welded steel tube structure; the tai] unit is wood. Fabric covering is employed. Normally the power is supplied by an Armstrong-Sid-deley 136 h.p. “Genet Major” radial engine. Every pilot who has flown the “Cadet” is enthusiastic about its handling qualities; lightness and sureness of the controls give a feeling of confidence and pleasure similar to that obtained in driving a first-class sporting motor

Eincient Power Unit. me “Gipsy -Major” 130 h.p. eu gine, latest and most powerful in the iange of four-cylinder-in-liue aircuoied engines built by the de Haviliand Company, has swept into fa void on a tide ot successful long-distance flights. Both Mr. and Mrs. Mollison employed these engines on their recent record-breaking Hights, by Mr. Moll l sou across the bouih, Atlantic Ocean aud by his wife between Bngiand and Capetown. Fr«m start to finish er each of these great endeavours the engine was run at nearly full throttle, at speeds considerably in excess or the normal rate of revolution recoin mended by the makers. Yet not the slightest trouble hindered either fliglu. Performance of this order is sufiicieut proof of the trustworthiness aud efficiency of the engine and is not believed by its behaviour m more normal flying. An inverted unit, the “Gipsy Major” possesses many effective features of design which contribute to low oil and fuel consumption and long “life.” Parts which might need ad justmeut are easily accessible, and maintenance is at ouce easy and inex pensive. Particularly interesting is the lubrication system. Oil is drawn from a separate tank by a gear-type pump located on the timing cover and driven by a gear which meshes with the cam shaft wheel. The oil pressure is regulated at 40/451b. per square inch by an adjustable relief valve in the covei of the pump casing. From the pump the oil flows under pressure through a Tecalemit felt filter, which ensures removal of even the finest particles of foreign matter before the oil passes into the engine. This filter is affixed on the timing gear cover and is easily removed for cleansing or renewal of the element. From the filter the main supply is taken to an external gallery, along the side of the crankcase, connected by drillings to the five main bearings. Tehnce the oil passes into the crankshaft and so through the hollow journals and crank pins to the big ends.

Holes are drilled iu the big-end beamings aud connecting rod caps, frou\ which oil is thrown on to the cylinder walls and pistons. This arrangement is especially useful at starting, as proper lubrication of the pistons is established during the earliest revolution>- of the engine. Further, the supply . of. lubricant to the cylinder walls is maintained irrespective of wear and clearance in the main bearings. The spray thus created inside the crankcase lubricates the camshaft bearings, cams and tappets and, 'be cause a considerable amount of it comes into contact with the walls of the top cover, a useful cooling effect is obtained. Two connexions are provided, at the rear end of the oil gallery, one supplying oil to the timing gears, th© other linking up with an oil pressure gauge. ( After passing through the engine, rhe oil collects in the space formed by the extension of the .cylinders iu me crankcase, when it is returned by external pipes to the tank. There the oil settles and cools before being pumped back into the engine. The whole of the valve gear i? totally enclosed and is lubricated by splash, from the rockers dipping in an oil bath provided in the valve casing covers. Largely because of the excellent lubrication thus provided and the 1 total exclusion of dust, wear of the moving parts is exceptionally small even after prolonged -running. Navigation and Observation. Instruments for use in flights ovet the world's highest mountains plainly must possess certain important qualities. Nothing must be left to chance. The equipment must work with accuracy even in the extreme cold and low atmospheric ' pressure prevailing -it heights up to 35,000 feet. Before Smith’s Aircraft Instruments supplied the necessary equipment, every instrument was tested in the laboratory in conditions simulating those imposed by flight at great heights. Ihe problem before the experts was to provide that the instruments should be entirely trustworthy and work correctly over a range of temperatures down to sixty degrees below zero centigrade and over pressure varyiug from 30 inches of mercury down to 8.5 inches. Probably the most important single item was the altimeter. Two were to be fitted in each aeroplane, one in either cockpit. After consideration Smith'-s technicians decided to use I’ype Av. 5G3 altimeters, calibrated in accord with the isothermal Jaw from zero to 35,000 feet, in conjunction with Type Av. 660 strut-fitted air temperature thermometers calibrated from minus 60deg. C. to plus 50deg. C. and Type Av. 907 height computers covering a range from zero to 40,000 feet and from minus 60dcg. C. to plus 20deg. C. for temperature. This latter method enables corrections to be made for the indicated height in the conditions actually met. Certain of the instruments w’ere especially chosen to meet conditions of heat and humidity which prevail in India near ground 'level. These included the Type Av. 548 air speed indicator (metal diaphragm), calibrated from 40 to 170 m.p.#., used together with the Type Av. 552 trapped pressure head. Type Av. 90S air speed computer was supplied to correct indicated air speeds at indicated heights. Type Av. 722 cross level, which incorporates a special device to compensate for extremes of temperature, was adopted. Type Av. 448 mercury-in-steel oil thermometers were cali brated from zero to 120 deg. C. to meer the high temperatures which are reached in the oil system at great heights. The possibility of a forced landing through fracture of the oil pipe lead ing to the oil pressure gauge was avoided by fitting a special Type Av 449 gauge. In this instrument a nonfreezing liquid is substituted for oil in the pipe connecting the oil system to the pressure gauge. This liquid is separated from the oil by n floxibb* container, mounted in a small brass rasing fitted directly to the oil pump. Should the connecting pipe to the oil gauge break there is no loss of oil. because the flexible contained collapses and seals oft’ any possible e\H for the oil. Alcohol-filled thermo meters were fitted in each cockpit (<■ measure temperatures inside the

machine. The remainder of the equip ineut—engine speed indicators, time of flight clocks, and so forth—was of standard pattern, but each instrument was specially tested unaer conditions similar to those likely to be met during the flights over the Himalayas. Couise and Drift. Two Type Av. 772 “Husun” aperiodic compases, of the kind employed on many record-breaking flights, and Type Av. 917 floor drift signs coin pleted the equipment. These drift sights consist in a rotatable grid ring carrying seven parallel drift wires and engraved with a drift scale of thirty degrees in each direction, port and starboard. Three wind scales enable thf. observer to determine wind speed and direction while in flight. A special negative lens gives a wide field of view and a flexible remote control is fitted in a convenient position iu the. cockpit. “Blind” Plying Extraordinary. “Blind’’ flying of an order of skill which would have seemed magical only a few years ago gained for Mr. C. Wilson the trophy awarded annually by Air Service Training Limited to the pupil who does best iu the process of acquiring the fascinating, but dif licult, art of flying »y instruments alone. The final test requires every pupil to make a triangular cross-coun try flights of seventy miles in length; the pupil is given all the essential information about prevailing wind and the course to be followed and is placed on the aerodrome w T ith his machine facing into wind. The hood is then lifted over his cockpit, completely blanketing all outward vision, and he is left to take-off, to ffy over the course at constant height of 2000 feet and to arrive at a point within easy gliding distance of the home aerodrome without any direction other than that given by his instruments. An instructor flics with him in the other cockpit, which naturally is left open, to take over control In emergency and to observe all deviations from the proper course. In a wind blowing at 25 miles an hour Air. Wilson kept an exceptionally steady course and finally put uj the hood at a point oniy a quarter of a mile from the aerodrome. The trophy, which is a model in silver of an Avro “Tutor” biprane, had been worthily won.

Learning to fly by instruments, gen erally styled “needle-chasing,” is n task which usually takes a pupil nine hours. At the end of tnat time he can .perform all normal evolutions, includ ing spin loops and rolls, and can steel “ blind D over a predetermined course Most difficult lesson of all to mash'; is expressed in five won*s, “The in struments are always right.”