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).
Analyzing various gun sizes and weights, comparing the Hispano and Oerlikon 20mm guns.
| Identifier | ExFiles\Box 176\1\ img029 | |
| Date | 17th July 1940 | |
| To Rm.{William Robotham - Chief Engineer} from Ve/NP. Ve/NP.2/CB.17.7.40. In reply to your memo Rm.{William Robotham - Chief Engineer}2/JMS.13.7.40, Ev.{Ivan Evernden - coachwork} was handed the installation drawing of the 13.2 on Saturday morning. Attached herewith is the analysis of gun sizes, ammunition, weights and number of guns you called for. The curves are based on figures which are correct to the best of our knowledge, but are, of course, mean curves approximated from the various weights of guns of varying calibre; consequently the weight for the 20 mm. gun reads 95 lbs. from the curve, whereas the actual weight of the Hispano 20 mm. is 109 lbs. without magazine. Against this the Oerlikon 20 mm. F.F.S. weighs 86 lbs. Ve/NP. | ||