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).
Table of critical air temperatures for Phantom III, Bentley, and 20/25 HP cars under various test conditions.
| Identifier | ExFiles\Box 149a\3\ scan0188 | |
| Date | 24th September 1936 guessed | |
| Critical Air Temperatures for Phantom III, Bentley and 20/25 HP. Cars. Note: The critical air temp. given in the case of Bentley & 20/25 HP. is the critical air temp. obtained under the worst of the test conditions. Critical Air Temp. 20/25 (3½ litre) 53°C. Bentley (3½ litre) 48°C. Ph.III { (1) Mk.VI type matrix, 40 M.P.H. { shuttered bonnet. 26°C. full throttle { (2) Mk.VI type matrix, { louvred bonnet. 29°C. Ph.III - { Mk.VI matrix, Max. speed { louvred bonnet. 31°C. full throttle. { | ||