Proposed alterations for a 3.250' bore engine, focusing on the design and material of cylinder studs.
| Identifier | WestWitteringFiles\T\March1929-December1929\ Scan084 | |
| Date | 18th April 1929 | |
| R. {Sir Henry Royce} FROM E. {Mr Elliott - Chief Engineer} SECRET ORIGINAL EI/M18.4.29. C. to SG. {Arthur F. Sidgreaves - MD} WCR. (SG. {Arthur F. Sidgreaves - MD} WCR. struck through) ✓ HS. {Lord Ernest Hives - Chair} BY. {R.W. Bailey - Chief Engineer} G. {Mr Griffiths - Chief Accountant / Mr Gnapp} 4. LARGER BORE. 45050 (struck through) 45040 We attach herewith blueprint LeC. 2695. shewing proposed alterations for 3.250" bore. The extra condition that the 3.25 bore demands is that the cylinder studs between cylinders 1 & 2., 2 & 3., 4 & 5., and 5 & 6., shall not be carried down to the crankchamber, but be studded into the cylinder block. On the existing 20HP. the central stud of all between 3 & 4. has always stopped short at the cylinder block on account of the induction passage passing through. These shortened studs would still retain a fair proportion of their elasticity, being about 4.5" long, and they could be reduced to the dia. of the thread bottom to augment this, in which case their torsional rigidity would be more like that of the long studs which are intermediate in stem dia. The reduction of the number of studs to the crank-chamber we think does not matter a bit. It does in fact represent a certain saving in weight. The head studs would be called upon to carry 17.5% more load, plus the increase due to higher compression ratio. The present studs are .312 dia. 22 T.P.I. in nickel steel, and an assumed pre-ignition load of 1000 lbs. per sq. in. creates a stud stress of 27,000 lbs. per sq. in. which is just under 90% of the SS. {S. Smith} stud stress under the same conditions, and is no doubt well within the tightening up stress. We should say the head studs would be quite satisfactory although they can be improved if desired. A blueprint of LeC. 2695. is also attached to BY's copy of this memo. E. {Mr Elliott - Chief Engineer} | ||
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).