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 use of cannon guns in Beaufighter aircraft, including details on 20 mm guns.
| Identifier | ExFiles\Box 176\1\ img084 | |
| Date | 20th September 1940 | |
| Cont'd.{John DeLooze - Company Secretary} - 2 - 2. They understand that one model of the Beaufighter with four cannon guns is definitely going to be used for ground strafing tanks. The gun installation will be normal, i.e. the axis of the barrel parallel with the horizon in level flight. Mr. Hives agreed that the 40 mm. should do this job a great deal better than the 20 mm. They are already catering for 2,000 lbs. trunnion load on the Hispano gun without the muzzle break and therefore the potential trunnion load of the 40 mm. does not alarm them. Other information obtained was :- 20 mm. GUN. 1. They are calling for belt feed in all 20 mm. guns, for long range fighters. The reason for this is that a large quantity of ammunition is required and they will not risk the magazine being unsteady under aerobatics when they are being changed. Considerable production of Chateau Leraux feeds has been put in hand. 2. They have had to make the belt link so that the ammunition can be twisted more easily and we attach a sketch of how this has been done. 3. They are not very happy about the behaviour of the Hispano gun under aerobatic conditions and seem to be having plenty of trouble. They say that they expect this trouble with any gun where the round is not very fully controlled from the time it leaves the magazine to the time it enters the breech. They are having to fit a special remotely controlled disc over the muzzle of the gun, which is automatically moved when the firing button is depressed. This is to prevent freezing up. - Continued - | ||