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).
Optimal radiator tube size for the 40/50 HP chassis.
| Identifier | ExFiles\Box 38\2\ Scan019 | |
| Date | 20th January 1919 | |
| To R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to EH. c. to DA.{Bernard Day - Chassis Design} c. to EFC. 20th January 1919. E12/G20119. X.3456 - RE RADIATORS FOR 40/50 H.P. CHASSIS We are informed by Mr. Day that the statement by the Air Board that the 10 mm. tubes have been found to be the most efficient size for cooling is now considered incorrect, and the most preferable dimension is really 7 mm. Mr. Royce prefers the 7 mm. tubes because he thinks the matrix is stronger, and in view of Mr. Day's information he is inclined to favour the 7 mm. still more. He thinks that the small tubes can have expanded ends, while the big tubes should have ferrules, the latter on account of increasing the strength of the matrix made up of big tubes. The length of the soldered joint to be used for the expanded 7 mm. tubes should be .200". E.{Mr Elliott - Chief Engineer} | ||