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).
Mounting of a 40 mm gun in a Beaufighter aircraft, including design modifications.
| Identifier | ExFiles\Box 176\1\ img130 | |
| Date | 20th December 1940 | |
| S E C R E T. To Rm.{William Robotham - Chief Engineer} from Ev.{Ivan Evernden - coachwork} Copy to Ve. Rm{William Robotham - Chief Engineer}/HH. Ev{Ivan Evernden - coachwork}/ID. Ev.{Ivan Evernden - coachwork}10/ET.20.12.40. 40 mm. GUN IN BEAUFIGHTER. ------------------------- As requested, we are again making a powerful effort to get two 40 mm. guns in a Beaufighter. Recent information received from Bristol was a slight improvement on earlier efforts, but still left much to be desired. Our chance to see a Beaufighter at Hucknall and above all our accidental contact with Mr. Lusty, who has supplied us with complete drawings of the gun bay, now places us in a position to complete designs for mounting the guns. The one item outstanding is the magazine. On QPL.164 we shew the 40 mm. gun in position in the plane and fitted with the B.U.S.M. latest feed. In spite of our contact with B.U.S.M., on Nov. 1st, when we shewed them the difficulties we experience in trying to use their feed, we have received no improved design, consequently QPL.164 has all the bad features of QPL.154 and QPL.155, which we gave them. In QPL.165, we shew the gun in the plane and fitted with the "Ve" Vertical type Feed. This feed is very good, because it enables the gun to go into the plane without modifying the contour of the fuselage, and the gun can be positioned to leave adequate room for mounting. We shew the original experimental edition of the feed and this could be used for the first experiment, but we suggest that the following modifications are desirable in the final design:- a.{Mr Adams} The number of useful rounds in the magazine be increased from 6 to 8, or possible 12. b. The gun be so arranged that, on emptying the magazine, one round is left in the breech. This we are told, is necessary to avoid the rush of cold air up the barrel, which freezes the gun. c. The loading handle be positioned so that it is more easily operated. During a discussion with Ve., when he was shewn QPL.164 & QPL.165, it was decided that a position of this lever could be found which would be suitable both for gun in the Beaufighter and the gun on the Power Mounting. We are preparing two schemes for the mounting of the gun; one for use on the first trial, using the existing cradle, and the other, the final scheme, with a cradle modified to suit. Ev.{Ivan Evernden - coachwork} Original to Rm{William Robotham - Chief Engineer}/HH. Prints to Ev.{Ivan Evernden - coachwork} Ve. Rm{William Robotham - Chief Engineer}/HH. & Ashby. | ||