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).
Modifications for installing a 40mm gun in a Beaufighter aircraft.
| Identifier | ExFiles\Box 176\1\ img168 | |
| Date | 28th April 1941 | |
| SECRET Ims. from Ev{Ivan Evernden - coachwork}/JD.{J. Draper - Frames} c.c. Ev.{Ivan Evernden - coachwork} O.{Mr Oldham} Ve. Ev{Ivan Evernden - coachwork}/JD.{J. Draper - Frames}5/M.28.4.41. INSTALLATION OF 40 mm. GUN IN BEAUFIGHTER. We confirm that during the visit of Mr. Green (Bristol Aeroplane Co.,) the following points were discussed and agreed upon :- 1. The position of the gun as designed to fit in the Beaufighter as FL.173, FL.175 and FL.176, was first investigated and the following modifications will be required to suit the 'plane :- (a) The front housing channel supporting the spherical bearing will require modifying to match up with the existing dead eyes in the centre plane, that were used to support the 20 mm. Hispano gun housings. (b) The flying and trimming cables require moving considerably to allow for an ejection shot in the keel plate, FL.184 shows this but does not allow for horizontal and vertical adjustment. (c) The Bristol stress people will have to be satisfied that the holes in the floor crossmembers do not upset the stresses in the members that we have used to support the rear mounting adjusters. (d) The gun trigger mechanism may make it necessary to modify the keel plate to provide clearance. (e) The type of rear gun mounting we have done will have to be modified when the gun is finally accepted. Items (a), (b), (c), and (e) would certainly have been avoided had the Bristol Aeroplane Co., co-operated with us earlier. We then considered moving the position of the gun by rocking it inwards 10° from the vertical and found that by moving the gun forwards .500 and outwards .250 several advantages would be obtained as enumerated below :- - Continued - | ||