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Aviation History
1932
1932 - 0516.PDF
FLIGHT, MAY 27, 1932 Shfi ftvAu/rtfo. SCINTILLA AIRCRAFT MAGNETOS 'THE PARTICULAR technical feature of the Scintilla aircraft magneto—the type associated with most of the successful Atlantic flights and so many notable long-distance flights throughout the world, including the recent Atlantic crossing by Miss Amelia Earhart—is its inverse system, which causes its permanent magnet and most robust part to rotate, and its delicate parts, such as the contact breaker with contact points and the coil, to remain stationary. This system results in the magneto successfully withstanding the worst vibration and giving a regular and efficient output at high speeds. In these days, with high compression ratios, supercharging and ground boosting, the magneto has to be de signed in many cases for speeds of 7,000 r.p.m. for short-life racing en gines, and 5,500 r.p.m. for a duration of more than 500 hr. Scintilla magnetos are manufactured for engines ranging from 2 to 24 cylinders, and of small dimensions and minimum weight. They can be sup plied with substantial flanges for flange fitting to either British or Conti nental standards. Bonding or screen ing to prevent interference with the wireless apparatus can be incorporated in all types, and provision is made for any degree of automatic advance and retard. An automatic spark control pro duced for Scintilla magnetos is arranged between the magnet poles, and is a satisfactory means of giving an engine the correct spark advance in relation to its speed. As the normal running speed of an aero engine is always in excess of 1,300 r.p.m. and the idling speed not more than 500 r.p.m., the spark advance has to take place between 600 and 1,200 r.p.m. The characteristic curve of the spark advance can be altered by using dif ferent governor springs. In this way it is possible to provide a fully re tarded spark for starting and idling speed, also a fully advanced spark for the normal running speed. Scintilla magnetos with automatic spark ad vance are of the same overall dimen sions as the normal machines, as the automatic device is incorporated in the rotating magnet ; no special provision need therefore be considered by en gine designers desiring to fit magnetos with this device. A Scintilla magneto for hand start ing is produced, mounted on the instrument board. For starting the engine with this type the ignition system is switched off and the pro peller turned to suck in a charge into the cylinder. Ignition is then switched on and the handle of the starting mag neto turned, causing sparks in the cylinder which is on the firing stroke. This hand-starter magneto is cased in bakelite and is therefore very light. Other equipment produced by the Scintilla Company includes switch boards which enable the pilot to switch off either magneto in order to test the working of the magneto still in operation, and further, to check the firing of each series of plugs. In connection with the screening of magnetos to reduce interference to the wireless there is an interesting device in the nature of a small choke fitted directly to the plugs, which has no detrimental effect on the sparking at the plug points. Scintilla aircraft dynamos are manu factured for various capacities, i.e., 300 to 1,225 watts, 12 to 24 volts. Special louvres and holes to ensure cool running are provided in the housing. A large range of flexible couplings for magneto driving are also made. Mounting and dismantling is thereby simplified, axial as well as radial fric tion eliminated, and ample protection Scintilla Magneto TypeGNS-D sectionalised. against vibration is provided. Varia tions in timing can be made without slipping back or removing the mag neto, and accurate setting is obtained by means of a Vernier adjustment screw. The London office of Scintilla, Ltd., is 14, Clerkenwell Close, E.C.I. C.F.S. TO CHANCERY LANE CLT. LT. W. E. P. JOHNSON, whom • everyone in aviation has known for many years as the acknowledged authority on instrument flying, and also for his amazing displays of in verted flying at many of our flying meetings, has now joined the firm of F. J. Cleveland & Co., Bank Cham bers, 29, Southampton Buildings, Chancery Lane, London, W.C.2 (Hol- born 5876), as a Patent Agent. Mr. Cleveland himself was actively in terested in flying as far back as 1910, when he was connected with the design of an aircraft shown by Hum- bers at .Olympia in 1911. Fit. Lt. Johnson qualified as a Patent Agent 476 before he joined the R.A.F. in 1925, and his knowledge, therefore, of this business, together with his unique ex perience in the R.A.F., should stand him in good stead in helping his firm to specialise to a certain extent in aeronautical cases, particularly those of a consultant nature, in which Mr. Johnson's qualification as a pilot will be useful, as, for example, in matters where expert evidence is required. The amount of business which is done in aircraft patents is growing very rapidly, and just as in 1895 the intro duction of the pneumatic tyre and the combustion engine caused an unprece dented rise in the number of patents taken out for road transport work connected with these two matters, so the present-day growth of aircraft for transport will cause yet another similar rise. DISENGAGED 1V/IR. H. VV. GRAVENELL, who has lvi been employed by Saunders-Roe, Ltd., for the past six years in the organising of their Marine Service Station and for sales and publicity of the aircraft and boat-building section of their business, has now severed his connection with that firm. He is, therefore, open to consider any other appointment. Mr. Gravenell's many years' experience in aviation publicity should be of great value, particularly to some of the firms whose activities are of comparatively recent date and may not, therefore, be as au fait with the inner workings of the aviation business as is Mr. Gravenell. L. & P. CHANGE ADDRESS THE LONDON & PROVINCIAL 1 AVIATION CO., which has been started by Mr. S. J. Gilbert, has now moved to larger and more convenient premises at 3, Thackeray Street, Ken sington Square, London, W.8 (Western 4354/5). An arrangement has been come to with the Kensington Square Garage, of 7/11, Ansdell Street, W.8, for repair work of all descriptions to be undertaken, and a booking office has been established whereby seats on the ordinary air lines may be booked or air taxis ordered at short notice. Another attraction will be a showroom containing a wide selection of acces sories of all types, and arrangements can be made for the cash or hire-pur chase of new and secondhand aircraft or motor cars. Aircraft and general insurance can also be arranged at very low terms. Among the particular lines handled at the moment are L. & P. Aviation suits, Orpi cleaning com pounds and the aircraft light equipment of the Hendon Lamp & Accessories Co., Ltd.
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