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 the performance and accuracy requirements for vehicle instruments at different temperatures and for a 20 HP chassis.
| Identifier | ExFiles\Box 50\4\ Scan182 | |
| Date | 17th March 1928 guessed | |
| -2- Contd. You will see therefore that these two instruments are reading correctly at slightly above 26.0°C and at approx. 27.0°C, respectively. Further, that the variation between readings at 18 and 30°C is 5%. This performance, though reasonably good, is not yet quite as good as we would like to have. We are desirous that the instruments should read correctly at 30°C. and have an increase of m.p.h. reading, in dropping to 18°C., not exceeding 4%. Would you please let us know what you can do, if anything, to improve the instrument indications to our requirements as stated. We trust that you will also endeavour to apply these requirements to the smaller instrument for our 20 HP. chassis, for which the approved figures corresponding to the axle ratio of 11/50 are 48.6 m.p.h. at 600 revs. per min. and 740 revs. per mile. Yours faithfully, A.M.I.E.E. Electrical Experimental Engineer. ROLLS-ROYCE LIMITED. | ||