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 report on the Spectre Gearbox oil feed to the 3rd motion shaft, detailing modifications and results using high pressure heavy oil.
| Identifier | ExFiles\Box 94\1\ scan0269 | |
| Date | 13th December 1935 | |
| To E.{Mr Elliott - Chief Engineer} Hdy.{William Hardy} File +328 Hs{Lord Ernest Hives - Chair}/WB.{Mr Brazier/Mr Bell}34/KW.13.12.35. SpectreCodename for Phantom III Gearbox - 1-HS.{Lord Ernest Hives - Chair} N. Sch.4668 Oil Feed to 3rd Motion Shaft, and Modifications to Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}9/KW.31.10.35. Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}12/KW22.11.35. All Tests performed in Direct Drive, using Wakefield's High Pressure Heavy Oil. Originally, the subtended angle of the scoop - i.e. from the leading edge of the scoop to the centre line of the feed pipe - was 60° and the protrusion of the feed pipe into the shaft .200" - see N.Sch.4668. Tests taken at 2,000, 3,000 & 4,000 R.P.M. showed a maximum delivery at the open end of the 3rd motion shaft of 200 c.c's/hr. at 4,000 R.P.M., the rate of delivery decreasing rapidly with the speed, the minimum pumping speed being 1,500 R.P.M. approximately. As directed in Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}9/KW.31.10.35, the scoop angle, and the protrusion of the feed pipe, were reduced by 50% - i.e., 30° and .100" respectively. The delivery at 4,000 R.P.M. was increased considerably, the maximum registered being 750 c.c's/hr., the deliveries at 3,000, and 2,000 R.P.M. being also increased. The initial pumping speed, however, was still between 1,000 and 1,500 R.P.M. Generally, in the course of these experiments, the gearbox was allowed to generate its own heat - no external heating or cooling being applied - but during this series of tests, deliveries were also measured with the box artificially cooled to obtain a reasonable temperature level at all speeds. Plotting the deliveries against temperatures for the various speeds indicated that the delivery decreased with increasing temperature up to approximately 2,500 R.P.M., whilst above this speed the results were reversed. This characteristic admirably suits running conditions. The scoop was still further shortened to .250" - see Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}12/KW. 22.11.35, the .100" feed pipe protrusion being retained, but the tests showed the delivery to be reduced at high temperatures and speeds, remaining approximately the same at low speeds and temperatures. Naturally, with a scheme of this nature, consistent results cannot be obtained, the delivery being dependent upon speed, temperature, oil level, and the frothing characteristics of the oil. | ||