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 memorandum discussing vehicle suspension dynamics, specifically the ratio K²/ab, to minimize pitching in various car models.
| Identifier | ExFiles\Box 43\2\ Scan236 | |
| Date | 12th December 1927 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} BY.{R.W. Bailey - Chief Engineer} c. to OY. X3900 Hs{Lord Ernest Hives - Chair}/Rn{Mr Robinson}3/LG2.12.27. SUSPENSION. X5440 X8410 X3900 In OY13/E111026, a figure was given for the ratio K²/ab of the Phantom and Silver Ghost. The condition at present thought to be ideal to avoid pitching is that K²/ab should equal 1. OY. found that for Phantom and Silver Ghost cars with closed bodies and 143.5" wheelbase K²/ab lay between .455 and .53. We find that for the Landaulet 20 HP. with a spare wheel at the back, K²/ab = .73. This gives a reason for the better riding of the 20 HP. We have not previously carried out this test on the 20 HP. because, though we anticipated this result, we could see no way of causing the Phantom to approach the ideal other than by carrying the spare wheel and luggage as far out at the back as possible, which we have been striving for a very long time. The only points that occur from a superficial consideration of the problem are that flywheel and gearbox weights are in the worst position for producing pitching also that pushing the engine forward as on EAC.14. should be very desirable if not combined with short bodies as on 12-EX. Bumpers, while highly objectionable in a number of ways, are in an ideal position for increasing K². The Lancia with its short engine and gearbox under the bonnet and its spare wheel far out at the rear is clearly fundamentally in a very good position for pitching. Additionally, the mass which on a normal car constitutes the front axle contd:- | ||