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).
Confidential memorandum discussing engine performance, chassis gearing, and modifications for the 20/25HP model.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan272 | |
| Date | 22th November 1929 | |
| FROM R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} (crossed out) HS.{Lord Ernest Hives - Chair} DA.{Bernard Day - Chassis Design} (crossed out) Copy to SG{Arthur F. Sidgreaves - MD} (crossed out) Copy to WOR.{Arthur Wormald - General Works Manager} Copy to BY SECRET AND CONFIDENTIAL. ORIGINAL 20/25HP. CHINA, & JAPAN. So far we think there is not sufficient advantage in changing China 1. for a town carriage, and that we shall make no changes until we come to 'Japan'. This engine is distributing better, not firing in the exhaust, filling up better at all speeds, and peak HP. considerably greater. We cannot get much advantage for a town carriage until we can gear this chassis somewhat lower, say between 5% and 10%. We have decided to get a 9/44 hypoid (i.e. 4.87 instead of 4.55 - actually 7.6% lower.) We have at present a 25HP. chassis, which, although good, is not beyond criticism when it comes to comparative performance, and we must remove this disadvantage as soon as possible, so as to get more sales for this chassis, which may prove our best bread and butter. It is assumed that with the stiffer crankshaft and low inertia damper, the above gear ratio will not bring us on to the master period with ordinary town carriage bodies. It is the nearest way of taking full advantage of a 'Japan' engine. The alternative is an easier available, and more silent third gear, such as we are making for Phantom 2. | ||