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).
Piston design modifications for the Phantom engine to address knocking and improve performance.
| Identifier | ExFiles\Box 66\1\ scan0133 | |
| Date | 5th March 1927 | |
| To R.{Sir Henry Royce} c. to BJ. Hs.{Lord Ernest Hives - Chair} RG.{Mr Rowledge} PHANTOM PISTONS. In reply to your enquiry re: proposal to introduce another slot in the std. piston, the modification appeared to me to be a safe one if the slot is not carried too far, but I do not think it is premature to put in hand standardisation tests without further experiment. One gains the impression from experimental reports that the knocks occur mostly at the bottom of the stroke, and this suggests that we ought to try lengthening the cyl. skirt .750" so that the piston does not run out at all. The object of this is threefold :- (1) To maintain the oil cushion. (2) To maintain max: control of piston at moment of changeover. (3) To avoid overhand of spring skirt and concentration of load possibly leading to breakdown of oil film. Regarding point No.3. this may lead to piston dragging on one side and clicking on the changeover. Also we want to push on with hollow top pistons which give longer controlling surface. The present standard pistons have cone tops. E.{Mr Elliott - Chief Engineer} | ||