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).
Comparing crankshaft details and torsional periods of the company's engines against those of Alfa Romeo.
| Identifier | ExFiles\Box 179\3\ img063 | |
| Date | 15th March 1932 | |
| P. From Ha/Gry.{Shadwell Grylls} c. to SS.{S. Smith} Wor.{Arthur Wormald - General Works Manager} c. to RS.{Sir Henry Royce's Secretary} E.{Mr Elliott - Chief Engineer} c. to Ry. ORIGINAL x634 Ha/Gry.{Shadwell Grylls}1/W.A.15. 3. 32. CRANKSHAFT TORSIONAL PERIODS. We have compiled a list of crankshaft details of all our engines and the Alfa Romeo. On J.lll we found the speed of the half period to be 2.25 R.P.M. From this figure and the measured inertia of the crankshaft assembly we can deduce the crankshaft stiffness. We therefore also know similar particulars for Peregrine since this is scaled lineally from J.lll. The inertia varies as (L)⁵, the stiffness as (L)³ and the speed of the master period as (L)⁻¹. We find that the Alfa Romeo four bearing shaft is nearly twice as stiff as the Peregrine crankshaft for a smaller engine. The stiffness of the Alfa shaft is derived in 3 ways; having only 3 instead of 9 bearings (2 for the flywheel), having very stiff webs and lastly being of a short stroke. The total length of this shaft is only just less than the Peregrine crankshaft, and the journals and pins are smaller. Ha/M.Grylls. Attached: One Print. | ||