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).
Blueprint showing a diagram plotted on a grid.
| Identifier | Morton\M7\ img064 | |
| Date | 5th May 1921 guessed | |
| 84 69 | ||