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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Summary of research on the three phases of spark plug discharge connected to a magneto.

Identifier  ExFiles\Box 58\2\  Scan145
Date  1st August 1934
  
COPY.

81812.a.

I.A.E. RESEARCH AND STANDARDISATION COMMITTEE.

Research Department,
5, Bolton Road,
Chiswick, W.4.

No. 7228, Class 222, 220.
August, 1934.

Sparking Plug Research
R.Anthouard, L'Aeronautique, March, 1934, p. 29.
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A study has been made of the spark discharge obtained from sparking plugs connected to a magneto. Current and voltage were measured with oscillographs, and the diagrams are reproduced. Three successive phases were noticed in the discharge; (1) a period of about 10^-4 sec. in which the tension at the gap builds up to several thousand volts, while there is a slight variable brush discharge of several milliamps.; (2) a short period of less than 10^-6 sec. during discharge, the voltage drops to zero and the current rises to nearly 100 milliamps.; and (3) a period of arcing which dies away rapidly. A short analysis of the results is given, and the effects of increased pressure and of radio interference are mentioned. In conclusion, it is suggested that sparking plug and magneto construction have only been studied from the point of view of obtaining the high tension discharge, and that improvements could be effected by considering the earlier and later phases of the spark.

A.D.B.
  
  


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