Comparison of front axle weights between the 40/50 HP and the Goshawk II models.
| Identifier | ExFiles\Box 107\4\ scan0005 | |
| Date | 11th September 1922 guessed | |
| COMPARISON OF 40/50 AND GOSHAWK(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine)) II. FRONT AXLE WEIGHTS. 40/50 H.P. | Goshawk(Aero Engine)(Codename for 20HP Car / Aero Engine after Kestrel(Aero Engine))-II. Weight of axle, wheels springs, all unsprung weight. 330 lbs. | 260 lbs. Average sprung weight on front axle. 1900 to 2400 lbs. | 1150 to 1400 lbs. Total 2230 to 2730 " | 1410 to 1660 " Weight of wire wheel and tyre complete. 87 lbs. | 72 lbs. | ||
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).