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).
Page detailing the calculation and measurement of moments of inertia for crankshafts and the calculation of periodic speeds.
| Identifier | ExFiles\Box 25\3\ Scan315 | |
| Date | 7th February 1928 guessed | |
| contd :- -5- getting rather closer agreement, between calculated and test figures, than Major Carter did on the same crankshafts. This is probably due to the method of correction outlined above. The Sports Phantom crankshaft shewn in this table has been subse-quently abandoned and is not fitted to the Continental Phantoms. (3) Moments of interia - calculation and measurement. The required moments of inertia are :- (a) Crankshaft. (b) Any fittings rigidly attached to nose of crankshaft. (c) Flywheel; or in case of aero-engine, propeller. (a) Crankshaft. The inertia of this can be calculated from a drg. within about 5% for automobile crankshafts. The procedure adopted is to simplify the dimensions first. The crank pins can then all be taken together as one long rod; similarly the main bearings, and their weights and k² calculated. The webs are treated also as one revolving block. The method of measuring the actual inertia of the above three items is by means of "Bifilar suspension". This is explained on fig.3 attached. (4) Calculation of periodic speeds. The crankshaft and flywheel etc. may now be reduced to a simple system, consisting of two flywheels, connect-ed{J. L. Edwards} by a light flexible rod. One wheel is the existing FLYWHEEL of inertia If. The other is a flywheel of effective inertia Ic. contd :- | ||