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).
Specifications and mounting of an ammunition box tray for a 40mm gun.
| Identifier | ExFiles\Box 175\3\ img054 | |
| Date | 6th August 1940 | |
| SECRET. To Rm.{William Robotham - Chief Engineer} from Ev.{Ivan Evernden - coachwork} o.{Mr Oldham} to Ve. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} Blackstone. Rm{William Robotham - Chief Engineer}/HH. re Ammunition Box Tray 40 m.m. Gun Type BD.{Mr Berend} 1st. 36 sets. On QPL.113 (original attached to Rm{William Robotham - Chief Engineer}/HH's copy) we shew a sheet steel ammunition tray which will be used in conjunction with the first 36 guns Type BD.{Mr Berend} fitted to the Oerlikon Mounting Type 3.SL. We have measured a standard ammunition box, the weight of which when empty is 35 lbs. With 30 rounds at approx: 3 lbs. each the full weight would be approx. 125 lbs. With this load the heaviest loaded fixing bolt is stressed to 3,000 lbs.in.sq. in shear. The factor of safety to guard against the possibility of rough usage appears to be adequate. It was hoped to discover a means of attachment to the hand operated revolving casting of the mounting by straps, but it will be seen that the section at the handwheel bearing will not permit of this. We suggest that the holes be drilled in position, the drill being allowed to penetrate part way into the main mounting casting. This would avoid having to dismantle all of the mountings, which will be a long task. We indicate a position for the tray relative to the handwheel which should be tried on the first two service guns. This ammunition tray dictates that the layer be on the gunners side of the barrel. The tray should be finished with a final coat of grey paint to match the mounting. [Illegible signature] Original to Rm{William Robotham - Chief Engineer}/HH. Print to Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} Ve. Rm{William Robotham - Chief Engineer}/HH. Ev.{Ivan Evernden - coachwork} & Blackstone. | ||