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).
Letter discussing race strategy for the Le Mans race, covering fuel, weight, and engine compression.
| Identifier | ExFiles\Box 90a\4\ Scan041 | |
| Date | 16th June 1936 | |
| Bentley Motors Ltd. Derby........ Rm.{William Robotham - Chief Engineer} Levallois Sr3/ET.16.6.36 Dear "Rm{William Robotham - Chief Engineer}", I am glad that "Sg{Arthur F. Sidgreaves - MD}" has now agreed to run at Le Mans and that you are "sitting up and taking notice". I, on my side, as you well know, will be only too pleased to give you all possible assistance and work at all the hours, days and nights necessary. FUEL TO BE CARRIED - I have been very carefully into this question with Geo Lefèvre in the absence of Charles Faroux and, as you know, Geo runs this race with Faroux and is therefore fully qualified. Geo Lefèvre, after working the whole problem out with me, considers that there is not too much to be gained by carrying more petrol than is necessary for the 24 laps. Let us presume that you will average 125 Kms. an hour and that your tank holds 32 gallons. This gives you a range of 300 miles (487 Kms.) and represents 32 laps. In other words, you will have to stop seven times during the race. If on the other hand you were to carry strictly the fuel necessary for 24 laps, you would have to stop 10 times. This means to say three more stops would be necessary and if we calculate each stop as representing 2 minutes, you would only gain 6 minutes during the race. Your men at the wheel would each have to put up with greater strain and the extra weight carried would probably affect your speed, especially at the beginning after refuelling. Geo Lefèvre therefore does not think there is any advantage to be gained, unless of course you are so sure of your peak speed, with a complete load of petrol and a full tool kit. This latter weight must be taken into consideration, also your spare wheels, whether you carry one or two. As you know, one has to accomplish 24 laps prior to refuelling, in other words 24 times 13.5 Kms. = 324 Kms. Therefore, according to you, if you fitted a 32 gallon tank, you would have a range of 300 miles or 487 Kms., which makes it apparent that, without any extra tanks, you would have ample fuel on board. Re: COMPRESSIONS - On this point Geo Lefèvre is very clear. He stipulates that as long as the cylinder head has the same exterior shape, and is made of the same material as the standard cars, your "taux de compression" can be anything you like. In other words it can be much more than you generally use on the T.T., there being no hard and fast rule about this. | ||