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).
Performance issues with radiator shutters on Bentley cars and considerations for the upcoming Spectre model.
| Identifier | ExFiles\Box 39\4\ Scan341 | |
| Date | 29th December 1933 | |
| File (handwritten) X3499. (handwritten) To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to Dy.{F R Danby} c. to Ev.{Ivan Evernden - coachwork} Radiator Shutters. ================== When the Bentley was produced it will be remembered that we got rid of radiator shutters, on the grounds that they were technically undesirable. Subsequently it was decided that the appearance of the radiator with the alternative to shutters was unsatisfactory, and therefore they were replaced. Since then we have run into a further difficulty with these shutters owing to the fact that the Bentley is equipped with water heated hot spots for the carburetters. The difficulty experienced on the shutters is that in order to ensure good snap opening up under Winter conditions in England, the radiator temperature must be at least 80º C. If we fit a thermostat of the ordinary size, which opens the shutters at 80º C, it has not a very strong action at 80º C. (curve attached). This means that as the friction of the shutters increases, coupled with wind pressure at high speeds, the radiator temperature will sometimes reach 90º before the shutters start working. Even with the modified leverage which takes full advantage of the thermostat stroke this is likely to happen. Again, on the closing side due to friction of the shutters, the temperature may fall as low as 75º, with consequent disadvantage to the pick-up. We know from the results of the first 15 cars that in actual practice these deficiencies are not very noticeable, but the point we wish to make is that the thermostat in the water system, owing to its having less work to do, has a much more precise temperature control, and this is an advantage with any water heated throttle. are (handwritten) We are raising this point because the SpectreCodename for Phantom III will have water heated hot spots, which are of course desirable if the carburetion will permit of their being used. | ||