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).
Performance data and theoretical conclusions for the 48.4 HP (Silver Rogue) model.
| Identifier | ExFiles\Box 20\6\ Scan014 | |
| Date | 12th October 1908 | |
| Test 47/R (F.H.R.) 12th Oct. 1908 (2) 48.4 H.P. Rolls-Royce (Silver Rogue). Consumption over 2000 miles (2000 miles International Touring Car Trial) at an average speed of about 19 m.p.h........... 20.1 m.{Mr Moon / Mr Moore} per gl.{G. Linnett} or.... 40.98 ton miles per gall. Total running weight................. 4560 lbs. Wind resistance of body.............. 19 3/4 sq. ft. Speed at 1000 r.p.m. (on 4th gear)...... 46 m.p.h. The following are theoretical conclusions deduced from what data I have by me. - Wind resistance is assumed to vary directly as the resisting area and directly as the square of the velocity. Therefore, for constant velocities, energy absorbed by wind resistance varies directly as the windage area. Force of wind at 20 m.p.h. is about 2 lbs. per sq.ft. Therefore energy absorbed by 10.4 sq. ft. of windage area at 20 miles per hour - 1.12 H.P. And energy absorbed by 19.75 sq. ft. of windage area at 20 miles per hour - 2.12 H.P. Approximate speed of engine is 500 r.p.m. Consumption by brake test at this speed is 10.9 B.H.P. hours per gallon. | ||