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).
Graph showing the effective insulation resistance versus temperature for a Champion R-II-V sparking plug.
| Identifier | ExFiles\Box 35\4\ scan 013 | |
| Date | 19th March 1928 | |
| DRG.NO. E.E.1671 Issued by:- Directorate of Technical Development. AIR MINISTRY DEPT. ELECTRICAL DRAWN S.J.Goodman TRACED L.E.B 19.3.28 CHECKED [Signature] APPROVED C.C.S. 19.3.28 S.P.402. EFFECTIVE INSULATION RESISTANCE (MEGOHMS) CURVE SHOWING INCREASE OF EFFECTIVE RESISTANCE WITH TEMPERATURE RISE. E.E.1671. FIG.4. CHAMPION SPARKING PLUG. TYPE R-II-V.{VIENNA} EX FALCON XI ENGINE. TEMPERATURE t°C. PLUG N° 4. NOTE:- EFFECTIVE RESISTANCE WAS GREATER THAN 2 MEGOHMS AT 180°-190°C & AFTER COOLING DOWN TO ATMOS. TEMP. | ||