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 report comparing chassis features, booming issues, and design differences between Phantom I and Phantom II models.
| Identifier | ExFiles\Box 182\M19\ img046 | |
| Date | 21th March 1931 | |
| - 3 - of these combinations. (b) Though vibration in the front seats is reduced when the central rear engine support is mounted on rubber, booms are not affected. We have confirmed this result some dozen times. With regard to (a) we believe that this is better for steering shocks than the diamond engine mounting owing to the torsional inertia of the engine helping the frame to resist axle tramping. Unless we find another avenue of escape, we may have to try and get a good steering with combination (a). P.I. & P.II. So far, we have been unable to put our finger on any chassis feature which distinguishes P.I from P.II in the matter of booming. We have not tried a great many P.I cars some of those we have tried have a slight boom at 50 - 60 M.P.H. which can be picked out with difficulty, but there is no resonance in the body and therefore it is hardly noticeable. The main differences we note between P.II & P.I bodies are - (1) The rake on the column on P.I's is less and so the driver is not looking into the scuttle armature but seated well above the mouth of the loud speaker. (2) The subframe has made more rigid scuttle armatures possible. (3) Divided windscreens have with P.II ceased to exist. Single piece windscreens present an excellent drumming surface. (4) Cast dashboards, rigid steering column fixings, less flexible attachment of the scuttle to the dash, all tend to increase the diaphragm effect of the front of the body. We are still trying. - (1) To find a P.I. with a similar type of body to those complained of on P.II. (2) Trying to reproduce P.I conditions in P.II. Cars complete with bodies. All the results we have ever obtained at the Works indicate that a boom usually follows the body and not the | ||