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).
Design and development of an experimental compression ignition two-stroke engine.
| Identifier | ExFiles\Box 179b\1\ img220 | |
| Date | 6th December 1932 | |
| E.G. FROM R.{Sir Henry Royce} C. to S.G. W.R. H.S. UD ORIGINAL R1/6.12.32. Sent off 9. 12. 32. X4433 re. COMPRESSION IGNITION TWO STROKE EXPERIMENTAL UNIT. Referring to your letter to the Air Ministry of the 30. Nov., this seems to have developed into a design which promises to be useful. We cannot expect it to entirely compete with the petrol engine, but we do expect that it will still be useful even if it comes out 50% heavier, on account of its other merits, especially in connection with the heavier type of aircraft. I think the Air Ministry will do well to let us make a trial of this as suggested, so I strongly endorse your letter of the 30. Nov. In the casual inspection I have made of the drawings I should like to see the upper bevel drive, and the camshaft, a little more robust. In fact, we might make the valve gear a little more substantial in one or two places where we think the stress is high. Your memo. does not say what type of blower we are thinking of using. I suggest we arrange to have one of the Roots type ready, but we must realise that even this does not give much boost pressure at slow speeds owing to the rate at which the air leaks back past the rotors, but if the engine can be started, and will run light slowly, we are really only interested in a limited speed range. As regards the pattern of the complete engine I think it would be better to say very little about this, as we may find the Vee type too difficult for stresses and strains, especially about the con. rods. The engine I had in mind for minimising these forces was the opposed type which utilises the inertia of the pistons to minimise the crankpin maximum pressure, and reverse the crankpin loading. I think we have done well in sticking closely to my suggested 1500 RPM. for any type of two stroke engine of these dimensions, owing to gas speeds, and the time in which the valves can be open, etc. (1) | ||