July, 1931 AIRCRAFT ENGINEERING 181 Vickers Showrooms—A New Noise Measuring Device— Carburising in Electric Furnaces Vickers Show Rooms A New Company purpos e of the test a standard engine selected by th e Air Ministry was installed in the Bristol N May 28 Vickers, Ltd., opened show rooms Messrs. Gibbons Brothers, Limited, Dibdale typ e 109 machine, a large single-engined biplane of a t Vickers House, Broadway, Westminster, Works , Dudley, in conjunction with Messrs. Wild- 50 ft. span and designed to carry a maximum all-up in order that customers may be able to Barfield Electric furnaces, Ltd., Elecfurn Works, weight of 9,000 lb. inspect examples of th e many branches of th e firm's Nort h Road, Holloway, London, N.7, have acquired Th e machine was stationed a t Famborough and manufactures, without the necessity of leaving from Messrs. Rudge-Whitworth, Ltd., Birmingham, throughou t the test was flown by Royal Air Force London. as from February 1, the sole manufacturing and pilots nominated by the Air Ministry. As a check selling rights of the Carburising Compound When it is remembered that the Vickers organi on the possible replacement of components the "Eternite. " sation comprises more than twenty companies with engine was scaled by officials of the Aeronautical I n connection with the above, and also the their works spread over the British Isles in more Inspectio n Directorate in numerous places. acquisition of the manufacturing and selling rights than eighteen towns, it will be realised what an advantage it must be to a prospective customer to of Hevi Duty Electric type mechanically-operated Th e aircraft was delivered to the Royal Aircraft be able to visit one central show room. furnaces (under agreement with the Hevi Duty Establishmen t on September 12, 1930, and flying The exhibits themselves range from a 75 mm. Electric Co., Milwaukee, U.S.A.), Messrs. Gibbons wa s carried out daily on all possible occasions in mobile anti-aircraft gun with a maximum vertical Brothers, Ltd., and Messrs. Wild-Barfield Electric periods • varyin g from to two to twelve hours. range of 30,300 ft., to a complete set of steel-shafted Furnaces, Ltd., are forming a new Company under Throughou t the test, apart from taking off and golf clubs. th e title of G.W.B. Electric Furnaces, Ltd. landing , the machine was flown at a constant throttl e setting giving 90 m.p.h. and 1,850 r.p.m., Many items manufactured are, of course, too unde r which conditions the power output of the large to exhibit, and of these beautifully-made Case-hardenin g in an Electric Furnace engine was approximately 350 b.h.p. models are shown. A large portion of a Vickers A new method of carburising has been introduced, "Viklebeest " is exhibited, comprising the front Thre e hundred hours flying time was completed in America by The Hevi Dut y Electric Co., whose' half of the fuselage, complete with engine and lower in March this year, and during this time the only Europea n patent rights are controlled by Wild- wings, to which are attached other products of seals broken were on a magneto after 232 hours, in Barfield Electric Furnaces, Ltd., and G.W.B. Vickers Ltd. , such a s th e Vickers-Berthier observers' orde r to replace a defective automatic timing Electri c Furnaces, Ltd., respectively. gun, Scarff ring gun mounting and Constantinesco coupling and to replace a set of valve-rocker gear Th e charge to be treated is loaded in a basket, synchronising gear. an d details due to a broken tie rod. an d although no special attempt is made to keep Under the wings, bombs and bomb racks of Throughou t the test the engine ran smoothly th e components of the charge from touching each various sizes are fitted, while a 1,610 lb. Whitehead an d well, both when cruising and at full throttle. other, they should be so placed to allow the circu torpedo, fitted with an eight-cylinder radial engine, Standar d Shell aviation petrol, without the addition lation of the carburising medium to take place is slung in its correct place between the under of dope or benzol, and a standard grade of Shell throughou t the charge. In this way maximum carriage legs. minera l oil were used exclusively, the average fuel uniformity in penetration and structure is obtained. Other types of aircraft, such as the Supermarine consumptio n working out at 20·6 gallons per hour, Th e loaded basket sits inside a heat-resisting alloy. 5.6, are shown in the model form. an d the oil consumption at 6·9 pints per hour. retor t inside the furnace chamber. In place of a Thi s fuel consumption may be regarded as excep basket , plates suspended on a vertical rod can be Stri p Steel Construction tionall y low, especially as the condition of the used for bevel and other gears and camshafts cylinders and valves a t the end of the test gave no The Bristol Aeroplane Company send an inter suspended inside the retort, which is fitted with a indicatio n of injury from running on too weak esting booklet, entitled "Bristol Steel Aircraft special cover making a sealed working chamber. a mixture. Construction," in which the question of weight/ A motor-operated paddle fan incorporated in the cover circulates the carburising gases throughout strength ratio of various materials—such as spruce, A t the end of the 300 hours, the aeroplane was th e charge. duralumin, elektron, and various classes of steel— hande d over to the R.A.E. Experimental Flying are discussed and tabulated. The reasons for the Th e furnace and charge are brought up to heat Departmen t for Certificate of Airworthiness trials, adoption by this firm of steel strip construction wit h the fan running; which gives a rapid and an d was the n flown back t o Bristol, where th e engine are clearly explained and the problem of spar uniform rise t o th e carburising temperatur e of about wa s removed for calibration prior to stripping and design gone into. Thereafter the typ e of construc 940 deg. C , depending upon the type of steel used detailed examination. tion adopte d and methods of assembly are described. an d the kind of case structure required. The Th e calibration tests on th e Froude Dynamometer This is done in a historical manner so tha t th e reader carbona l is then introduced into the hot retort by revealed tha t the engine had maintained its power learns how and why the present-day methods have mean s of a drip-feed attachment mounted on the outpu t exceptionally well, the full-throttle power been evolved. The booklet is very fully illustrated retor t cover. a t normal r.p.m. being within 2 per cent of that with informative photographs and graphs. On entering the retort, the carbonal, which is developed by the engine prior to the 300 hours' mad e up of a vegetable base, very rich in hydro flight test. carbons, is forced outward against the hot walls by A Simple Method of Measuring Noise Finally , the seals were removed and the engine th e centrifugal action of the circulating fan, where wa s stripped for inspection under A.I.D. supervi London noises were measured some eighteen i t is immediately cracked up into hydrocarbon sion. It was found to be in very satisfactory con months ago by Dr. A. II. Davis, of the National gases, which circulate through the charge, thus dition, with the minimum of wear on the major Physical Laboratory, Teddington, by a novel exposing it to a very active carburising agent. component s and a marked freedom from gumming method which is surprisingly simple. He described Th e forced circulation assures fresh uniform gas u p of piston rings. his procedure on June 19, during a discussion on being brought to the work continuously. "Audition " held by the Physical Society of Carburising proceeds very rapidly, a penetration London, in which various British and Continental of from 12 t o 15 thousandth s of a n inch a t 930 deg. C. Shor t Floats for Canada authorities took part. A tuning fork having a takin g place per hour. After the carburising cycle pitch in the third octave above the middle "C " General Aircraft Builders, Ltd., of Montreal, is complete, the retort is lifted out of the furnace on the piano was struck in a standard manner and hav e come to an arrangement with Short Bros., b y an overhead gear, and cooled in th e air, while a placed to the ear. Observation was then made of Ltd. , of Rochester, whereby Short floats will bo second loaded retort is placed in the furnace. the time which elapsed before the loudness of the manufacture d in Canada. General Aircraft Builders I n some cases the carburised work is quenched fork fell to the loudness of the observed noise or, hav e specialised in the production of metal floats from the carburising temperature or a little under, alternatively, until the sound of the fork was no of standardised pattern suitable for all types of air thi s being accomplished by removing the cover and longer audible in the presence of the noise. On craft and have a practical knowledge of Canadian handlin g the charge direct t o the quench by means this scale,' sounds become painful at about 120 conditions. The floats will be made a t the G.A.B. of the basket containing the charge. decibels above the threshold of hearing, where factory at Ville le Salle. each decibel is th e least change of loudness percep A n Engine Flight Endurance Test tible to the ear. In descending order of loudness Italia n World Flight Dr. Davis placed the noises of acro-engines (110 Following upon th e series of 100 hour s full-throttle I t is understood tha t preparations are being made decibels), pneumatic drills (90), busy traffic (70), benc h tests carried out on the geared F-type side streets in London (50), rustling leaves (30), b y the Italian Air Force for a flight round the world. Bristol Jupiter engines, the Bristol Aeroplane suburban quiet (20), an d silence (0). The loudness Th e all-metal Savoia S. 55, M. type seaplane, Company, Ltd., decided to submit one of their of ordinary conversation was about 50 decibels described on anothe r page, will be used, the greater standar d 490 b.h.p. Jupiter XI. F. engines to an above threshold. This simple method has been enduranc e resulting from the lighter structure extende d endurance flight test, in order to demon found to give results consistent with those obtained makin g the crossing from the Azores to Bermuda strat e the reliability, smoot h running, an d economy with much more elaborate apparatus. of these engines under flight conditions. For the possible.
Aircraft Engineering and Aerospace Technology – Emerald Publishing
Published: Jul 1, 1931
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