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).
Letter from the Admiralty Offices concerning the specifications and manufacture of 2 pr. gun barrels.
| Identifier | ExFiles\Box 176\3\ img111 | |
| Date | 7th August 1940 | |
| A.S.10808/40/P.23. 2a Admiralty Offices, Empire Hotel, Bath. 7th August, 1940. VE has this specification Dear Mr. Robotham, As arranged at the Meeting at Director of Naval Ordnance Office on the 4th August, I am enclosing a copy of N.O.D.2191/25 giving details of the 2 pr.{Percy H. Rose} Mark VIII barrel, and also specification E.38, covering the "NN" steel, from which these barrels are made. I shall be glad if you will acknowledge receipt, and arrange to have this information treated as Secret. Captain Slayter has forwarded me your letter of the 5th August, together with Drawing Q.1712, and it appears from this that you are already in possession of details of the chambering and rifling of the 2 pr.{Percy H. Rose} Mark VIII barrel. Your drawing does not indicate whether the 2 pr.{Percy H. Rose} Mark XIV barrel is being made of Vibrac V.30 or V.45; neither of these have specified yield points and "N.N." has not a specified brake, so that direct comparison is not possible. It seems, however, that there is not a great deal of difference in the tensile properties of the two steels, and consequently the factor of safety for the Mark XIV is probably well below that of the Mark VIII. You will note that the 2 pr.{Percy H. Rose} Mark VIII is a 40 calibre job as compared with 50 calibres for the Mark XIV. I am unable to confirm without further reference that existing Admiralty barrel plants will be able to undertake the manufacture of the longer barrels, and I will write you further on this point. It is possible that we shall have to look to the Ministry of Supply to produce the Mark XIV barrels, unless the U.S.A. plant arrives in time. /Contd. W.A. Robotham, Esq., Messrs. Rolls-Royce Ltd., Derby. | ||