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).
Appendix page with calculations for vehicle lap speed and windage drag based on horsepower and test results.
| Identifier | ExFiles\Box 90a\2\ Scan191 | |
| Date | 22th August 1934 | |
| Appendix. (3) EV.{Ivan Evernden - coachwork}1/KW.22.8.34 If we had 118.5 H.P. at 4300 R.P.M. on B-23-AE instead of 92.5 at 4150 R.P.M. there would be available 26 H.P. more for windage because - V ∝ ³√P. Lap Speed = 95 x { (106.35) / (80.35) }^(1/3) = 95 x 1.1 = 104.5 M.P.H. B-35-AE (Hall's Car). Tests 2 & 4. As originally tested by Hs{Lord Ernest Hives - Chair}/Hn.{F. C. Honeyman - Retail orders} on Brooklands with 92.5 H.P. at 4150 R.P.M. the lap speed was 90 M.P.H. This corresponds to Test 2. The windage drag was 344 lbs. at 90 M.P.H. If we had 118.5 H.P. the lap speed would have been 90 x { (107.3) / (82.5) }^(1/3) = 98.0 M.P.H. Windage drag = 344 x 98² / 90² = 406 lbs. In the final test tim (test 4) the drag is reduced to 406 x 406 / 425 = 389 lbs. Because V₂³ = V₁² P₂ x 375 / R₁ V₂ = { (98² x 107.3 x 375) / 389 }^(1/3) = 99.7 M.P.H. This car (Test 4) actually lapped at 99.5 M.P.H. EV.{Ivan Evernden - coachwork} | ||