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).
Testing the 'SS' engine mounting, detailing challenging road conditions and the resulting radiator wobble and directional instability.
| Identifier | ExFiles\Box 17\7\ Scan029 | |
| Date | 2nd March 1929 | |
| To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to SG.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} X7810 E1/M1.2.3.29. SS.{S. Smith} ENGINE MOUNTING ETC. X.W005 X.7810 X.7830 X.7850 At the risk of repeating a little of what has already been reported the following notes are intended to shew the line of procedure adopted in connection with the above. CONDITIONS OF TESTING. The testing of the SS.{S. Smith} engine mounting has been greatly hampered by the difficulty of finding a suitable stretch of rough road on which it is possible to drive at 70 m.p.h., and also by unfortunate climatic conditions which rendered high speeds absolutely unsafe and out of the question e.g. snow, ice and fog. The early testing was done on more or less main roads and a set of values was established for different arrgts. of mounting. Eventually however the Expt: Dept: found a long straight bye-road possessing a surface which did not appear to be very bad but brought up evident periodic wobbles of the radiator and front of the frame at 65/75 m.p.h., the same cars behaving in a comparatively normal manner on ordinary main roads. These radiator wobbles were not associated with a steering wobble although the steering was affected directionally, and it was necessary to hold the wheel very tightly to keep the car on the road. This directional instability persisted also on the better roads in a minor degree. This test which proved to be the ultimate one was by no means abnormal as we found that 12-EX an open touring Phantom would traverse the course at full speed with the radiator remaining perfectly steady, and there is no doubt that in France this condition would be frequently met. In passing it should be mentioned that the road in question had to be used with caution and economy to avoid giving objection to the local road users before the tests were brought to a successful conclusion. It was noticed that the behaviour of a car on good and ordinary roads is not necessarily a criterion of what it will do on bad. One of the examples tested on the main road gave the impression of incipient unsteadiness, but in the ultimate test behaved very much better than expected, and went through with comparatively little periodic bouncing. This peculiarity necessitated a contd :- | ||