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).
Technical letter discussing fuel gauge variations due to liquid surge and potential pipe obstructions.
| Identifier | ExFiles\Box 44\3\ Scan037 | |
| Date | 19th October 1928 | |
| Messrs. Rolls-Royce, Ltd., Date 19.10.28. Page 2 variations in the gauge due to surge, and was introduced in your particular instance owing to the possibility of the danger with a completely full tank, of the surge of the liquid itself from the back to front tube at maximum accelerations on the lower gears. If you will recollect, this is one of the points which the writer asked you to test in connection with the balanced type of gauge, as we have now returned to the 2 1/4" scale, and with the tank completely full of benzole mixture, we do not know whether there would be a sufficient safety factor at the top of the glass to prevent liquid passing into the pressure balance line. It is very easy to test this point, as if the liquid does not disappear from view with a tank full of ordinary petrol, then there is a sufficient factor of safety when the heavier gravity fuels are used, which will give a higher reading. It may be possible that in the particular instance of the gauge you are observing, there is some small obstruction in the pipe which is causing higher resistance than merely the length of the capillary which we have introduced, as the figure of five minutes is rather in excess of what we should expect. We fully expect 60 secs. for even a standard gauge to come to rest, | ||