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).
Test results and performance graph for a Watford Magneto Type EW6.
| Identifier | ExFiles\Box 65\3\ scan0086 | |
| Date | 16th August 1927 | |
| DRG No.- 638-1 WATFORD MAGNETO Type EW6 Extended POLE SHOES 60° A-R TESTS ON FINISHED MAGNETO Mag No.- 99802 After endurance run at 3,500 RPM Graph: Y-Axis: Degrees retard X-Axis: Speeds. Graph annotations: Regular sparking over 5.5 m/m 3 point gap. The penciled curve & figures are the results on magneto N° 99171 Text to the right of the graph: HIGH SPEEDS. MAGNETO RUN GRADUALLY UP TO 6,000 R.P.M. & EXAMINED OVER FULL RANGE Ad. to Retard. CONSTANT SPARKING UNDER ALL CONDITIONS UP TO 6,000 R.P.M. UTILITY TEST. ONE 3 POINT GAP WAS REPLACED BY AN ANNULAR GAP .325 Dia. CENTRAL ELECTRODE 'OB7' DIO THIS GAP WAS SHUNTED BY A LEAK OF 320,000 OHMS. CONSTANT SPARKING AT 520 RPM. OVER FULL RANGE 60° OK FROM 520 RPM UP TO 4,200 RPM WHEN MISSING COMMENCES ON FULL ADVANCE. LEAK TESTS REPEATED WITH POLARITY OF SPARK REVERSED. | ||