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).
Weight comparison between a 'Square engine' and the 'Phoenix' engine.
| Identifier | ExFiles\Box 83\3\ scan0043 | |
| Date | 19th May 1937 | |
| Square engine of the same capacity as the Phoenix would weigh 5% lighter (accessories excluded) or 25 lbs. (Phoenix without access. 500 lbs.) ROLLS-ROYCE, LTD. PR.{Percy H. Rose} MAY 19 1937 DERBY. | ||