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 balancing and material selection for an enlarged face shield on a Type BD gun.
| Identifier | ExFiles\Box 175\3\ img305 | |
| Date | 31th January 1941 | |
| To Rm.{William Robotham - Chief Engineer} from Ev.{Ivan Evernden - coachwork} [strikethrough]c. to Ve.[/strikethrough] [strikethrough]or to Rm{William Robotham - Chief Engineer}/HH[/strikethrough] SECRET. Ev.{Ivan Evernden - coachwork}3/JH.31.1.41. Enlarged Face Shield - Type BD.{Mr Berend} Gun. We are told that 30 lbs. weight of lead in the armrest would balance the gun, but that when the armrest is filled with lead its weight is increased by 14 lbs. To have equal effect to the 16 lbs. weight deficit at the armrest 23.8 lbs. weight has to be added to the Face Shield. This is an added area of 170.2 sq.in. of .500 P.B. plate or 138.87 sq.in. of 14 m.m. B.P. Plate or 65.77 sq.in. of .750 B.P. Plate. On QPL.168 (original attached to Rm{William Robotham - Chief Engineer}/HH's. copy of this memo.), we shew these proposals for enlarged shields for each plate thickness. Unfortunately the shield cannot be carried over the gun body, because in that position it would foul the Recoil Shield in the open position. We do not know how the cradle will like the increased weight and overhang of the shield and rather fear that the shield will vibrate transversely due to the elastic nature of the cross-section of the cradle. We suggest that the better solution might be to use .750 ins. thick B.P. Plate or better still to move forward the trunnions on the gun cradles. to Ve. Will Rm{William Robotham - Chief Engineer}/HH. please send two prints of QPL.168 We return to Rm{William Robotham - Chief Engineer}/HH. the original detail of the Face Shield EU(M).2/8. Ev.{Ivan Evernden - coachwork} Original QPL.169 and EU(M)2/8 to Rm{William Robotham - Chief Engineer}/HH. Prints to Ve. (2 off) Ev.{Ivan Evernden - coachwork} Rm{William Robotham - Chief Engineer}/HH. Ashby. | ||