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).
Difficulties of installing a type A.A. .500 machine gun into a Spitfire wing.
| Identifier | ExFiles\Box 176\1\ img065 | |
| Date | 14th September 1940 | |
| To Ve. from Ev.{Ivan Evernden - coachwork} c. to Rm.{William Robotham - Chief Engineer} c. to Ve/NM. SECRET. Ev.{Ivan Evernden - coachwork}3/JH.14.9.40. re .500 M.G. type A.A. We thank you for the original of the type A.A. gun in No.3 bay of a Spitfire wing which we lent to you. It has been suggested that we should send to you certain schemes which we have made and which will illustrate our difficulties in installing the type A.A. Gun in the Spitfire. On APL.1&2 we shew a general layout of the gun bays in the Spitfire wing. Bays 1 and 2 are difficult, but it might not be impossible to get a stirrup for the rear support of the gun, over the body, but in the case of No.3 that is not true, whilst bay No.4 calls for a bulge on the top of the wing. We understand that a Spitfire is flying with 3, Browning .500 guns per wing and provision has been made for a fourth gun. The .500 Browning scores for this particular installation, because of its shallow depth. Its increased length over that of the A.A. gun is of no disadvantage in this instance, but ours would be very acceptable to the turret designer. On APL.131 we shew the .500 Browning and the type A.A. gun superimposed in side elevation, the barrels and the vertical centre lines of the breech blocks being lined up. The type A.A. gun is 1.875 higher above the barrel centre line (overall measurements) The extra 1.000 in. of width of the type A.A. gun makes it difficult if not impossible to provide a chute for the spent clips in the Spitfire Gun Bay. In order to pave the way to getting a set of guns tested under service conditions at the earliest possible date we suggest that if at all possible, an attempt might be made to get our gun to go onto the same mountings as those for the .500 Browning. To achieve this three modifications would be required. P.T.O. | ||