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).
Ratios of connecting rod length to crank radius for various engines and discussing piston acceleration.
| Identifier | WestWitteringFiles\L\Jan1924-March1924\ Scan168 | |
| Date | 1st March 1924 | |
| TO R.{Sir Henry Royce} FROM E.{Mr Elliott - Chief Engineer} SECRET. E1/M7. 3. 24. Copy to - GS. " HS.{Lord Ernest Hives - Chair} E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. re.CONNECTING ROD LENGTH. X9030 The following table shews the ratio of con. rod length to crank length of various of our own engines, in response to your query. We have not the proportions of the Hispano. It will be seen that the EAC. is slightly longer than the Goshawk ll. We should require connecting rods 1.4" longer to bring the EAC. engine up to the 40/50. proportions. ENGINE. CON. ROD LENGTH L. / CRANK RADIUS R.{Sir Henry Royce} (L/R) Condor lll. - - - - - 3.46 Goshawk ll. - - - - - 3.53 E.{Mr Elliott - Chief Engineer} A.{Mr Adams} C. - - - - - - - 3.64 Goshawk l. - - - - - - 3.78 Hawk. - - - - - - - - 3.83 Present 40/50. - - - - - 4.15 We also attach curves shewing the expressions (1 + R/L) & (1 - R/L) for piston acceleration plotted against different values of L/R with the ratios of the above engines indicated thereon. These curves shew the amount of distortion produced by the obliquity of the rods on the acceleration at each end of the stroke and give some guide as to the disturbance produced by the variation in kinetic energy of the pistons and con. rods. It will be seen that all of the engines enumerated (1) | ||