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 car performance metrics including windage, braking, and engine efficiency against a 20 HP model and an Austro-Daimler.
| Identifier | ExFiles\Box 21\7\ Scan036 | |
| Date | 23th October 1925 | |
| R.R. 493a (50 H) (D.D. 31, 12-6-25) J.R.D. EXPERIMENTAL REPORT. -5- Expl. No. REF Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG231025 The windage of the body we should say was slightly less than that of a R-R 20 HP. Comparison of 20 HP. RR. and Austro-Daimler. Graph with Y-axis 'Accn Ft/sec2' from 0 to 3, and X-axis 'Road speed M.P.H.' from 10 to 60. Displacement/ton/wheel rev. approx. R-R / Austro-D.{John DeLooze - Company Secretary} = .92 or Austro-Daimler 8.5% better off. BRAKING. As we have previously indicated, this was the worst feature on the car. GENERAL IMPRESSION. "We consider that the only point which we are likely to gain useful information on this car is its engine. This is certainly more efficient than the 20 HP. R-R.{Sir Henry Royce}, but this efficiency has been gained at the expense of a certain amount of sweet running. A 20 HP. R-R engine fitted with two carburetters and a higher compression ratio, would not be very much inferior to a the overhead camshaft unit of the Austro-Daimler. Possibly, however, contd :- | ||