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).
From the Air Ministry regarding new standard fuel specifications for aircraft engines.
| Identifier | ExFiles\Box 27a\4\ Scan190 | |
| Date | 8th August 1933 | |
| Air Ministry, Copy Kingsway, W.C.2. 268050/33/I.M. August 8th, 1933. Inspector-in-Charge, A.I.D Messrs Rolls Royce Ltd. Derby. Standard Fuel for Aircraft Engines. So that development in Engine design may be supported by a corresponding development in their fuels, it has been found necessary to revise the existing fuel specification DTD.134 This has been achieved by the introduction of two new specifications Nos. DTD.224 and DTD.230. An advance copy of each of these specifications is enclosed for your information and retention. It is anticipated that the change over from the existing specification (DTD.134) to the new specification (DTD.224) will take place generally on October 1st, next. It will be observed that a new method of knock rating has been introduced i.e. Octane Number rating on the C.F.R.Engine by the "Motor Method" with a specified mixture temperature. Test methods have also been revised so that the Institution of Petroleum Technologists' methods of testing Petroleum and its Products may be adopted wherever possible. New methods of test have been introduced i.e. Vapour Pressure and Gum Determination, the latter due to the admission of cracked and/or coal spirit. D.T.D. Type Tests. It is now the policy that (a) future Type Tests are to be carried out on fuel to the new specifications and (b) all Type Tests be run on fuels which comply only with the bottom limit of the specification and are thus comparable with the lowest permissible grade of fuel which may be supplied in bulk to the R.A.F for use in these engines. Accordingly, when sub-contract orders for these fuels are being placed they must quote:- (a) For fuels to be supplied to Specification DTD.224 "The Fuel shall comply with the requirements of Specification No.D.T.D.224 except that the Octane Number shall not exceed 78 when determined by the Standard C.F.R Motor Method modified so that the unit is run with a mixture temperature of 260°F.{Mr Friese}" (b) For Fuel Supplied to Specification DTD.230. "The fuel shall comply with the requirements of Specification D.T.D.230. It shall have an Octane Number not exceeding 88 when determined by the Standard C.F.R Motor Method modified so that the unit is run with a mixture of 260°F.{Mr Friese} It shall contain tetra ethyl lead in the form of IT ethyl fluid in a concentration of 4 mls of tetra ethyl lead per Imperial gallon. It has not yet been possible to install a C.F.R Engine in the A.I.D Test House at Kidbrooke but it is anticipated that early in October our Test House will be able to undertake any such tests as may be required of it. | ||