The gear box ratios for the Goshawk II and Goshawk III engines.
| Identifier | ExFiles\Box 57\1\ Scan072 | |
| Date | 12th February 1925 | |
| X5440 12.2.25. GEAR BOX RATIOS. GOSHAWK(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II. Reverse 57/35 x 37/14 = 4.304 First 57/35 x 37/19 = 111/35 = 3.171 Second 57/35 x 28/28 = 57/35 = 1.629 Third = Direct drive. GOSHAWK(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) III. Reverse = 57/35 x 19/29 x 39/13 = 3.201 First 57/35 x 39/17 = 3.736 Second 57/35 x 33/23 = 2.337 Third 57/35 x 27/29 = 1.516 Fourth = Direct Drive. EFC. {E. Fowler Clarke - Electrical Engineer} | ||
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).