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).
Investigation into the cause of failure of Champion sparking plugs removed from a Falcon XI engine using doped fuel.
| Identifier | ExFiles\Box 35\4\ scan 001 | |
| Date | 17th March 1928 | |
| D/4/11. E.E.344. ROYAL AIRCRAFT ESTABLISHMENT. Report No. E.E.344. Investigation of the Cause of Failure of Champion Sparking Plugs Type R.11.V. Removed from Rolls-Royce "Falcon" XI Engine using Doped Fuel. -by- The Staff of the Ignition and Electrical Department. A.M.Reference:-739999/27/R.D.E.3. R.A.E.Reference:-S.P.402. 17th March,1928. "D". Summary. 1. Introductory (Purpose of Investigation). Six Champion sparking plugs type R.11.V. which had been removed as defective from a Rolls-Royce "Falcon XI" engine fitted in the "Wizard", were forwarded to the R.A.E. by AD/R.D.S. Air Ministry for examination and report. 2. Range of Investigation. (a) General examination and tests for sparking under pressure. (b) Measurements of effective ohmic resistance of plugs at various temperatures. (c) Engine tests. 3. Conclusions. (a). Four of the six plugs examined were defective as regards insulation resistance; the remaining two sparked satisfactorily under air pressure of 200 lb/sq.in. (cold). (b). The failure of the four plugs is attributable directly to the effects of T.E.L. dope used in the fuel. At moderate temperatures the deposit on the plug insulator was found to be of a highly conducting nature and formed a low resistance path to earth for the H.T. current. (c). The tests show that taking the plugs through a temperature cycle changes completely their effective insulation resistance. Plugs which as received were virtually short-circuited by deposit on the insulator were found on heating to a critical temperature in the region of 150°C to lose | ||