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).
The investigation into different mounting projects for a 40mm Type BD gun.
| Identifier | ExFiles\Box 175\3\ img049 | |
| Date | 6th August 1940 | |
| SECRET 3 To Rm.{William Robotham - Chief Engineer} c. to Rm.{William Robotham - Chief Engineer}/HW. c. to Ve. c. to Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} Ev.{Ivan Evernden - coachwork}7/JH.6.8.40. re Projects of Mountings for 40 m.m. Gun Type BD.{Mr Berend} Considerable investigation work has been carried out on the problems of providing a non elevating mounting with the gunner in a chair. On Q.PL.103 we show an attempt at a manual operation by the gunner for elevating both himself and the gun as a unit around the trunnion, the traversing being done by a handle and layer. The mass of the gun plus the gunner is balanced by a weight, whilst the gunner elevates the gun by means of a foot pedal operating pump and hydraulic ram. We were lead to consider such a mounting because we were told that type BD{Mr Berend} gun might frequently be used on craft where power would not be available. We have been considering power mountings used on Nash & Thompson hydraulic gear. On Q.PL.101 we show our first effort. It will be noticed that the sights move in respect to their distance from the gun barrel during elevation. We had noticed such a sight equipment on one of the Nash & Thompson turrets. It soon became apparent, however, that it was possible to so place the sights and the gunner relative to the trunnion that the sights themselves could be fixed to the gun cradle. Our final conclusion in this matter is Q.PL.102. We have sent a print of Q.PL.102 to Cpt.Frazer Nash who has since sent us an elaborated scheme and is now engaged on the full scale project and details. All the hydraulic mechanism is standard and can be bought "off the shelf". No new design technique is involved. We attach the originals to Rm{William Robotham - Chief Engineer}/HH's. copy of P.T.O. | ||