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).
Calculations for spring deflection and pitching frequency on Phantom II and 25 HP models.
| Identifier | ExFiles\Box 19\3\ Scan362 | |
| Date | 15th May 1930 | |
| x7772. To: Rm.{William Robotham - Chief Engineer} From: Oy. c. Srn. Oy1/DM.{D. Munro}15.5.30. P.II and 25 HP. Springing. ------------------------ In Hs{Lord Ernest Hives - Chair}/Rml/EJ.14.5.30 you say (page 4) that 85/min pitching speed is equivalent to 5" spring deflection. This is only so if k² / ab = 1. In actual practice with k² / ab = about .5 a pitching frequency of 85/min corresponds to about 7" deflection. For example front springs of 3½" deflection which should give a pitching frequency of 100/min, if k² / ab were equal to one, actually give 120/min with k² / ab = .5. In the same way 5" deflection on our front springs (P.II) which have a frequency of 85/min under direct load would actually give 102/min. The importance of this I think is that it illustrates why greater spring deflections have to be used on larger cars in which the moment of inertia becomes increasingly "inadequate". Front P.II 120/min Oy. Maurice Olley | ||