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).
Development and testing of car demister and defroster systems using hot air from the bonnet versus dedicated heaters.
| Identifier | ExFiles\Box 137\3\ scan0036 | |
| Date | 3rd February 1939 | |
| - 2 - Cx{Major Len W. Cox - Advertising Manager}8/KW3.2.39. probable that an efficient defroster might at the same time be effective in acting as a demister as well. On this subject you refer to utilising a supply of hot air taken from under the bonnet to the outside of the screen. Of course, it is impossible for us at this stage to make any comments on this so far as its appearance goes, but that is a point which we must not lose sight of. We are assuming, therefore, that you would propose to use suitably shaped and positioned openings in the scuttle allowing the hot air to impinge on the outside of the windscreen. We feel that if these openings are of a controlled type, that is they could be closed and therefore out of sight when not needed, the scheme may be a very desirable addition to our cars, and we shall be interested to learn the results of the tests you are carrying out with 1.B.50 as regards the utilisation of the hot air under the bonnet. If this is found to be effective as a demister as well as a defroster, then the interior heater need only be concerned with heating and ventilation. In that event we would like to ask you whether you would still take the view that the more expensive R-R heater is desirable. It may be that if only heating and ventilation are sought by this fitting the A.C.Sphinx, which costs less, would do the job just as well. We realise that much depends upon the result of your further experiments, but this perhaps is a point we have to bear in mind. We think in any case that it would be undesirable to rely on the admission of cold air to demist the inside of the screen as you describe at the top of Page 5, because when this misting occurs the weather conditions are usually such that it is desired to exclude cold air in the interests of comfort. Sg{Arthur F. Sidgreaves - MD} is anxious I should emphasize the fact that when this scheme is developed and is ready to be used, it must first be on R-R cars. Sg.{Arthur F. Sidgreaves - MD} is asking whether his new Wraith could be fitted up with whatever scheme it is necessary to try out, as this might be a useful opportunity of an additional car in use to gain some further experience of the respective merits of this device. Cx.{Major Len W. Cox - Advertising Manager} | ||