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Aviation History
1938
1938 - 1602.PDF
558 FLIGHT. JUNE 2, 1938. erosion caused by the additional capacity of the screened cable. On this account high resistances of the same value as suppressor resistances were used, but, although these were successful in their object, certain effects peculiar to aero engines made them impracticable. The heavy fouling of the plug insulators, caused by the leaded fuel used and the high temperature, made it undesirable to reduce the spark energy below that necessary to cope with the electrical leakage caused by the fouling. A certain minimum of spark energy is also necessary to burn the deposit off the points, as otherwise the gap slowly closes up and short-circuits the plug. In addition, it was no easy matter to design a resistor of reasonable dimensions able to cope with the high voltage which appeared across it and the other arduous conditions of use. These results led to the abandon- ment of the attempt, until the writer's researches into spark phenomena led him to try the effect of reducing the rate of the capacity discharge, without affecting the total energy of the spark or attempting to suppress oscillation (oscillation has not been included in the above explanation of spark discharge as it does not affect the conclusions reached; both high- and low- frequency oscillations exist in a spark discharge). Judging from the average resistance of the ionised gap, the additional resistance necessary to produce a considerable re- duction in the Tate of discharge would be much less than ten •thousand ohms and, in fact, it was found that a resistance of one thousand ohms cancelled out completely the effect of the screening and reduced the point erosion to the same rate as was given by plain cables. There was no measurable reduction in the total spark energy, and prolonged engine tests showed no tendency to "building-up" of the gap. The optimum value of resistance would vary slightly with cable capacity and plug voltage, but there is no gain in reducing it below one thousand ohms, and increasing it would tend towards the dangerous region without any useful increase in efficiency. The voltage across the resistor being much lower than with the suppressor type, it became an easy matter to incorporate it in the screened cable elbow terminals, this method being pre- ferred to that of building it into the plug, and terminals of this type are about to be put into production by K.L.G. Sparking Plugs, Ltd., who have acquired the patent covering this work. The real value of the reduction in point erosion lies not in the saving in cost through increase in plug life, though this is worth having, but in the extension of time between removal of the plugs for servicing and the increased reliability in flight. The research on the problems referred to above was carried out in the laboratories of D. Napier and Son, Ltd., Acton, in collaboration with K.L.G. Sparking Plugs, Ltd. The writer's thanks are due to the former company for permission to pub- lish the results. AIR MINISTER at R.A.F.F.C. DINNER First Public Appearance WHEN 70-odd R.A.F. officers get togetheron an auspicious occasion, as theydid for the R.A.F. Flying Club'sfifth annual dinner last Friday, an excel- lent spirit of camaraderie and at least a. modicum of revelry may be taken for granted. But when the same very delightful and informal spirit con- tinues to pervade the party in the distinguished presence of a new Secretary of State for Air making his first public appearance since his ap- pointment, it speaks very highly for the per- sonality and understanding of that Minister. Sir Kingsley Wood had consented to attend at only a few hours' notice on a busy day, and everyone felt his presence a personal honour; F/O. W. A. Hammerton (the chairman), Fit. Lt. Robert Brittain (the club's founder), Sir Harry Brittain and Mr. Handley Page each expressed that feeling. There were no official speeches, but if more speakers at dinners were to model their efforts on the brilliantly witty sentiments of those who addressed the company the jokes about postprandial oratory would soon become meaningless. F/O. W. A. Hammerton said a few words about the club, its three aeroplanes stationed at Hatfield and its past year, and thanked the officials, in particular F/O. R. G. Weighill, the hon secretary. Then Fit. Lt. Robert Brittain, who founded the club before going out East, spoke of its growth. He was pleased to see that the office was '' No longer a suit- case under his bed," and mentioned the Egyptian Branch, which is in the able hands of Fit. Lt. J. N. Tomes, at the moment on leave and present at the dinner. ROYALAIR FORCE FLYINGCLUB Sir Harry Brittain thought it splendid to have the Secretary of State present, and took the opportunity of mentioning his past achievements in popularising the Post Office and vitalising the Ministry of Health. Sir Kingsley Wood himself was persuaded to say a word or two. He recalled a vote of thanks in which he had been described as no ornament to the House of Commons, but, nevertheless, a good hard-working member. He was content to be described thus. Sir Kingsley expressed his pleasure at his reception there. He also added, : r.-:,*:r m answer to a possible hint from a previous speaker, that Mr. Handley Page was much better able to meet the Club's demand for more machines than was the Secretary of State, who was limited by the Chancellor of the Exchequer. Mr. Handley Page said that Sir Kingsley's nicely rounded frame offered very little resistance to his forward political pro- gress, and suggested that it was the true type of angelic fuse- lage. There were, of course, two kinds of angels. He did not think there were black angels in the S.B.A.C., though perhaps they were not white—possibly they were camouflaged. It was a great compliment to be a guest and good to hear Sir Kings- ley talking thus familiarly down from the pedestals of the great. Concluding, Mr. Handley Page said that were his products more suitable for the R.A.F.F.C., and not so much needed by the Secretary of State, he would be only too delighted to let them have «5me (cries of "Why not ? ")—to give them "some of certain type equalled by few and bettered by none, and equipped with a certain device." Napier Appointmentr is announced that Mr. C. W. Reeve, chairman and man- aging director of the Associated Equipment Co., Ltd., has been elected a director of D. Napier and Son, Ltd. Mr. T. B. Keep MR. T. B KEEP, M.I.Mech.E., M.I.A.E., managing direc-tor of Petters, Ltd., of Yeovil, has accepted an additional appointment—that of managing director of the Brush Elec- trical Engineering Co., Ltd., Loughborough. Deekay ChangesT HE Deekay Aircraft Corporation Ltd., announce that Major E. L. Cower, A.F.C., has joined the Board, while the com- pany's address has been changed to 39-40, Albemarle Street, London, W.i. ModelsO WING to pressure on space, caused by the coincidence oi several important events, we are compelled to hold over the monthly "Models" page until next week. NEW COMPANIES AIR COURIERS LTD.—Private company, registered May 20. Capital. £100 in100 shares of £1 each. Objects : To carry on the business of aircraft engineers, consultants, contractors and suppliers, and carriers of passengers and goods by air.The directors are: Wm. F. Griffith and Geo. G. Glanville. Registered office: Croydon Aerodrome, Croydon. LONDON SAILPLANES LTD.—Private company, registered May 24. Capital,£100 in 100 shares of £1 each. Objects : To promote and encourage gliding, soaring and aviation in all its forms, etc. Subscribers : Henry A. Petre and Edward A. St°r?yBarnard. The directors of the company shall be members of the Committee of the London Gliding Club. Solicitors : Blount Petre & Co., 8, Carlos Place, GrosvenorSquare, London, W.I. BRUCE DOUGLAS MOTORS (BRISTOL) LTD.—Private company, registeredMay21. Capital, £10,000 in 10,000 shares of £1 each. Objects: To carry on busniess as mechanical, aeronautical, motor, electrical and general engineers, etc. * *directors are: Bruce Douglas and Jack Douglas. Solicitors: Cooke, Painter Spoflorth and Co., 2fi, Broad Street, Bristol. SOUTHERN MOTORS AND AIRCRAFT (CROYDON) LTD.—f?™*company, registered May 25. Capital, £100 in 100 shares of £1 each. Objects. To carry on business as aeronautical experts and consultants, dealers in aeroplanes,airships, motors, cycles and vehicles generally. The subscribers are: Dona 10 a. Middleton and Doris E. Davies. D. E. Middleton signs documents » diiMOT-Solicitors : Good, Good and Co., Fairfax House, Fulwood Place, London, W-UI' AEROPATENTS LTD.—Private company, registered May 18. Capital, £1W>in 100 shares of £1 each. Objects: To carry on the business of aeronaoi^ mechanical, constructional, railway, electrical and motor engineers. 1 ?e,directors are : Louis S. Armandias (permanent) and Spence Sanders. Solicuc F. R. Stephen and Co., 34, Bishopsgate, London, E.C.2.
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