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).
Calculation of the air resistance coefficient 'K' for a standard 4-door Bentley saloon.
| Identifier | ExFiles\Box 160\2\ scan0137 | |
| Date | 6th July 1933 guessed | |
| TO OBTAIN K.{Mr Kilner} FOR STANDARD 4 DOOR BENTLEY SALOON. N.SCH.3685. PROJECTED AREA - 28.38 SQ.FT. Road Wheel H.P. at 86 M.P.H. = 4150 Revs. = 92.5 Ø Rolling Resistance 30 lbs/ton. Weight 1.5 Tons. Total constant tractive resistance 45 lbs. /126 H.P. due to Constant T.R. at 86 M.P.H. = 130 ft/sec. = 10.7 ∴ H.P. due to Windage = 92.5 - 10.7 = 81.8 Lbs. Resistance = (81.8 x 550) / 130 = 345. R = K.AV² K = 345 / (28.38 X 7400) = .00165 A = Projected area Sq.Ft. K = A Coeff: of air resistance in lbs/sq.ft projected area per M.P.H² R = Total air resistance force Lbs V = M.P.H speed, still air Ø Measured road wheel HP 90, to which is added 2.5 HP for the power absorbed due to rolling resistance of the tyre on the drum. Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} | ||