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).
Report analyzing power savings achieved through streamlining vehicles like trains, buses, and trucks.
| Identifier | ExFiles\Box 161\1\ scan0017 | |
| Date | 31th May 1936 guessed | |
| 2. In this service the saving in fuel per month due to decreased air resistance is (2 x $177.80) - $40.50, or $355.60 - $40.50 = $315.10. This saving represents actual conditions with the conventional trains using coal and the Zephyr using Diesel fuel. A better comparison would be on a basis of total cost per H.P.hour instead of fuel cost per H.P.hour, in which case the balance would be even more in favor of the streamlined equipment. The above saving, large as it is, is not the entire amount to credit to the lowered K value. Saving in first cost of equipment, due to decreased air resistance, must also be added. The cruising speed of the Zephyr is 85 m.p.h. for a substantial portion of its run. If its K value were the same as that for the steam trains it would require a power plant of 1875 rated H.P. instead of 660 rated H.P., which it now has, in order to maintain 85 m.p.h. cruising speed. At $100 per horsepower, including all power items, this increase in power would add $121,500, or approximately 60%, to the cost of the train for increased power alone. Increased weight, also, would add substantially to the cost. In the following table, Fig. 1, the cost of overcoming air resistance in conventional and streamlined highway trucks and busses operating in interurban service is shown, at a power cost of 2 cents per horsepower hour and for a 1000 hour period. POWER SAVINGS BY STREAMLINING BUSES and TRUCKS per 1,000 HOURS at $0.02 per H.P.H. | Type of Equipment | | Average V.{VIENNA} | A | K | H.P.H. | Dollars per 1000 Hrs. | Saving per 1000 Hrs. | |---|---|---|---|---|---|---|---| | Highway Bus | 1 Streamline | 32 | 64 | .0006 | 4444 | 88.88 | 161.96 | | | 2 Conventional | 32 | 72 | .0015 | 12542 | 250.84 | | | Highway Truck | 3 Streamline | 28 | 86 | .0010 | 6689 | 133.78 | 95.24 | | | 4 Conventional | 28 | 92 | .0016 | 11451 | 229.02 | | Fig. 1 Outline drawings of the streamlined truck and bus are shown in Figs. 2 and 3. The air resistance coefficients, K, in the above table, Fig. 1, were determined from wind tunnel tests made by the writer at New York University on models built to conform to these drawings. The horsepower required to overcome air resistance is shown below in Fig. 4. | ||