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).
Analysis of crankshaft stiffness and inertia, comparing calculated values with test results and Carter's formula.
| Identifier | ExFiles\Box 125\2\ scan0051 | |
| Date | 14th June 1929 guessed | |
| contd :- -6- Correcting this figure for the extra lengths of journal, not included in the simple crank of Carter's formula, we get a stiffness per crank of 3.50 x 10^6 lbs.ins/ radian. The calculated value using Carter's formula comes to 4.49 x 10^6 lbs.ins/radian, which is 28% larger. We have not yet found an explanation for this discrepancy which is of the same order as the one we had recently when twisting the S.S. shaft. The inertias have been measured and calculated as follows : Crankshaft + C/wts .07120 slugs ft^2 6 big ends .01566 " " 3 pistons (at big end radius) .00922 " " 3/ .09608 -------- .03203 Slipper wheel hub and fan pulley .00329 -------- .03532 which is the total equivalent inertia on the nose of the shaft. Taking the stiffness at 45,000 we get a calculated period of 3600 r.p.m. If we take the real period as being at 45 actual m.p.h. in 2nd. gear, it comes out at 3640 r.p.m. This agreement appears to confirm our torsion test on the crankshaft, and to indicate that the discrepancy may be a departure from Carter's formula. In our opinion the Chrysler crankshaft is not up to its job, since it enables the torsional period to be so easily reached in 2nd.gear, which spoils its performance in this gear. contd :- | ||