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).
Proposed modifications and allowances for engine components including metal thickness and throat area.
| Identifier | ExFiles\Box 134\2\ scan0175 | |
| Date | 20th December 1937 | |
| -2- 20.12.37. sizes and slopes and valve size. The following allowances should, however, be made - (a) Metal thickness on face. This should be at least .400" thick, as there is then ample metal to machine off for increasing the compression ratio. The first ratio tried should be 6.4, which could later be increased to 7.5 or more by machining of the head. If necessary two heads could be made, to give a direct comparison. (b) Throat Area. The initial throat area should be 1.500 sq.in. which would automatically be reduced by an increase in C.R. If sufficient metal were left this could then be machined out if necessary and useful and definite information on throat size obtained. (2) New cylinder block and T.H. c'case. As was stated earlier on, the variable timing mechanism has fulfilled its mission, and could now be deleted. We therefore see no objection to making a cast iron cylinder and T.H.crankcase as near as possible to the main engine design, incorporating a complete main engine valve mechanism. The design of this would not be unduly complicated, and if a really serious effort were made to make the unit as much like a main engine in every detail as possible, some very valuable information would be obtained for a relatively low cost. Whilst we appreciate that this programme looks a little formidable, it appears that so far as High Power develop- ment goes, the existing unit has outlived its usefulness, as there are so many variations between it and the proposed main engine that no results obtained will be really convincing. In addition, after some 1300 hours running, the unit is beginning to show signs of wear, and really requires a thorough overhaul, which in itself would be quite an expensive item. Taking these points into consideration, therefore, and the fact that a new field of investigation is opened up, we think that the proposed expenditure would quite definitely be justified. Rm{William Robotham - Chief Engineer}/Ed.{J. L. Edwards} | ||