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 detailing the determination of air resistance coefficient 'C' and comparing performance data for rail cars, highway buses, and trucks.
| Identifier | ExFiles\Box 161\1\ scan0021 | |
| Date | 31th May 1936 guessed | |
| 6. DETERMINATION OF "C" IN EQUATION HPH_a = H C ((KAV^3)/575) RAIL CAR K = .00059 A = 96.2 HIGHWAY BUS K = .0006 A = 64 HIGHWAY TRUCK K = .001 A = 86 | | RAIL CAR | | HIGHWAY BUS | | HIGHWAY TRUCK | | M.P.H. | % | H.P. | Hrs. | H.P.H. | % | H.P. | Hrs. | H.P.H. | % | H.P. | Hrs. | H.P.H. | |-----------|----|------|------|----------|----|-------|------|---------|----|-------|------|---------| | 90 | 1 | 112 | 30 | 3351 | | | | | | | | | | 80 | 5 | 78 | 150 | 11700 | | | | | | | | | | 70 | 9 | 52 | 270 | 14040 | | | | | 3 | 28.7 | 90 | 2565 | | 60 | 22 | 33 | 660 | 21780 | 1 | 22.1 | 30 | 663 | 20 | 14.6 | 600 | 8960 | | 50 | 35 | 19 | 1050 | 19950 | 5 | 12.8 | 150 | 1823 | 40 | 6.2 | 1200 | 7428 | | 40 | 20 | 9.7 | 600 | 5820 | 42 | 6.5 | 1260 | 8217 | 30 | 1.8 | 900 | 1647 | | 30 | 7 | 4.1 | 210 | 861 | 27 | 2.8 | 810 | 2236 | 5 | .23 | 150 | 36 | | 20 | 1 | 1.2 | 30 | 36 | 18 | .8 | 540 | 432 | 2 | .03 | 60 | 2 | | 10 | | | | | 5 | .1 | 150 | 15 | | | | | | 5 | | | | | 2 | .01 | 60 | 1 | | | | | |-----------|----|------|------|----------|----|-------|------|---------|----|-------|------|---------| | | 100| | 3000 | 87538 | 100| | 3000 | 13387 | 100| | 3000 | 20638 | AVERAGE | V | H.P. | Hrs. | H.P.H. | V | H.P. | Hrs. | H.P.H. | V | H.P. | Hrs. | H.P.H. | |------|-------|------|--------|------|------|------|--------|------|------|------|--------| | 52.2 | 21.86 | 3000 | 65580 | 32.2 | 3.42 | 3000 | 10260 | 28.1 | 5.09 | 3000 | 15270 | INCREASE OVER AVERAGE | 21958 | 3127 | 5368 | PER CENT INCREASE | 33.4 | 30.6 | 35.1 | Fig. 10 The air resistance coefficient, K, is the resistance which the equipment offers to the air divided by the product of the air's velocity, squared, and the frontal, or projected, area of the equipment. K = R / (A V^2) and R = K A V^2. The air coefficients of the component parts of a train are determined separately by suspending the component part only from the wind tunnel balance, with the rest of the train in correct position at the same time - since there is aerodynamic interaction between any component part and the train as a whole. Thus the air resistance coefficient of a train = K_t = R / (AV^2), where K_t = K_L + K_1 + nK_2 + K_E, in which equation K_L is the coefficient of air resistance loco. & tender K_1 is the coefficient of air resistance 1st car K_2 is the coefficient of air resistance intermediate car K_E is the coefficient of air resistance end car and n is the number of intermediate cars (K_2). | ||