Laboratory test results for a modified aero battery ignition changeover switch.
| Identifier | ExFiles\Box 163\7\ img303 | |
| Date | 1st December 1936 | |
| Rm {William Robotham - Chief Engineer} /Wat.10/JH.1.12.36. R.R. Aero Battery Ignition. Laboratory tests of changeover switch to R.R.Sch. 895 with modifications to D.7475/6/7/8/9. These modifications were designed to reduce the lag in the operation of the switch when changing back to the battery on a glide and they have been successful as the switch is a great improvement over the original design. Before commencing the test the switch was adjusted as follows :- Ignition contact gap .022". Battery negative contact gap .040". " posative " .040". Air gap in the off position .125". Tests were carried out with the equivalent of two and four coil loadings representing the MerlinAero Engine VultureExperimental 6 CYL OHV LONG STROKE / Aero Engine and ExeAero Engine engine conditions respectively. Two coil loading :- Temperature of switch 20°C. Changeover from battery to dynamo occurs at 12.4 volts. Reversion to battery occurs at 10.25 volts showing a volt lag of 2.15 volts. Temperature of switch. 40°C. Changeover from battery to dynamo 13.8 volts. Reversion to battery 10.5 volts. Volt lag 3.3 volts. | ||
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).