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 to Major Carter at the Royal Aircraft Establishment discussing discrepancies in crankshaft torsion test results.
| Identifier | ExFiles\Box 63\4\ scan0073 | |
| Date | 3rd September 1929 | |
| X4499. X4499. Hs{Lord Ernest Hives - Chair}/Tsn.1/MJ. September 3rd,1929. Major Carter, Royal Aircraft Establishment, Sth. Farnborough, Hants. Dear Major Carter, CRANKSHAFTS. This letter is by way of reply, now long overdue, to your last letter to me, and contains some more torsion test results. I have recalculated practically all my crankshaft figures and results, which to some extent explains the delay, in order to avoid further discrepancies between our figures. Dealing with the examples in you last letter, in turn; 16 C (1-G-L) This shaft was twisted before my time, and I have no records of the positions on the shaft at which the loads were applied and the twists measured. This accounts for the difference in our test stiffness figures for the single crank. With regard to the calculated value, it appears that the dimensions in my possession differ slightly from yours, but I believe mine are right; the differences are - h.730; w=2.20; r=2.250 I get - L=1.050 + .584 + 3.30 + 5.89 = 10.82". and stiffness - 1.45*10^6 lbs.ins/radian. 15 C (Expl. stiffer 20 HP.) I find that for this shaft I was working from the wrong pin diameter and the wrong stiffness figure. I get the calculated stiffness now to be 1.899, and taking your stiffness figure of 19,400 I get the stiffness figure per crank as 1.646. The three latest torsion test results which I give you in the attached tables (dimensions shown by sketches) show rather large departures from your formula. We are gradually arriving at a rather different kind of shaft from the type with which we started torsion experiments ( e.g. E.75216 and E.54064. | ||