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).
Page of calculations for determining vehicle lap speeds from horsepower and drag.
| Identifier | ExFiles\Box 160\2\ scan0165 | |
| Date | 4th December 1933 guessed | |
| (2) To calculate lap speeds at 92.5 H.P. at road wheel given the drag at 86 M.P.H. P = RV / 375 & V^2 = R / KA P = V^3 / 375KA or P = RV P1 = H.P. due to windage at V1 which is 86 M.P.H. P2 = Max. H.P. available for windage = 81 H.P. V1 = 86 M.P.H. V2 = Max. speed at max. horsepower (81 H.P.) in M.P.H. R1 = Drag in lbs. at V1 R2 = Drag in lbs. at V2 Now V1^3 / V2^3 = P1 / P2 = (R1 V1) / (R2 V2) V2^3 = (V1^3 P2) / P1 Since P1 = (R1 V1) / 375 V2^3 = (V1^3 P2 x 375) / (R1 V1) = (V1^2 . P2 . 375) / R1 V1, P2, & R1 being known, V2, the max. lap speed can be calculated. | ||