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).
Technical notes and sketches with feedback regarding piston design modifications.
| Identifier | ExFiles\Box 77\1\ scan0011 | |
| Date | 28th January 1920 | |
| Contd. -2- (3) The information of the piston as in sketch, cuts out the awkward piston ring pin shewn in section 00, N. scheme 234. The bosses for the other pins are thought to be too short, and should be made .300" in length. (4) Owing to the lower compression ratio is it thought that the thickness of the crown might be reduced, and at the same time Mr. Royce would like it to be made uniform in thickness, and he would also like more metal behind the rings to the dimensions given in the sketch also below - [Handwritten text next to sketch]: SIDE WALLS ALSO below [Sketch with dimensions]: .200, .150, .350 (5) The thickness of the piston webs should be graduated into the gudgeon pin bosses over a longer distance, as shewn in sketch, and the diameter of the gudgeon pin bosses should be increased all over by .050". (6) The corss webs of the piston should be of constant thickness instead of increasing in thickness towards the crown. This latter is thought to be unnecessary since the load becomes more distributed as the webs approach the crown. (7) The clearance diagram used by Ricardo for slipper piston is as shewn in the sketch. - [Handwritten text next to sketch]: about twice this (8) Mr. Royce thinks it is most important to calculate the weight of this piston as unless it promises to be substantially lighter he does not think it worth while to make the experiment. The weight of the model piston we are sending, increased in proportion to the cube of diameter comes out rather heavy - (415 lbs.) compared with the weight of the existing "Condor". Contd. | ||