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).
Calculation of the periodicity and frequency for a Lorraine Dietrich crankshaft.
| Identifier | ExFiles\Box 6\1\ 01-page058 | |
| Date | 21th April 1927 guessed | |
| PERIODICITY OF LORRAINE DIETRICH CRANKSHAFT [DIAGRAM] THE POSITION OF THE NODE IS GIVEN By l₂ = L [ (I₁ + 1/3 I₃) / (I₁ + I₂ + 1/3 I₃) ] OVERALL STIFFNESS OF SHAFT = C = 28350 lbs ft / RAD. WHERE - I₁ = .3767 = FLYWHEEL I₂ = .001437 = FAN PULLEY I₃ = .04322 = INERTIA OF CRANKSHAFT .01058 = BIG ENDS .00587 = DUE TO PISTONS. Ie = .05967 TOTAL OF CRANKSHAFT ASSEMBLY l₂/L = [ .3767 + (.05967 / 3) ] / [ .001437 + .3767 + 2 x (.05967 / 3) ] = .39659 / .417917 THE INERTIA OF THE PART OF CRANKSHAFT OF LENGTH l₂ WILL BE - .05967 x .3966 / .4179 = .0566 THIS INERTIA IS REPLACED BY ONE THIRD ASSUMED ACTING AT THE FRONT END = 1/3 x .0566 ≈ .01887 TO THIS IS ADDED THE INERTIA OF THE FAN PULLEY. ∴ INERTIA OF FRONT END EQVT = .01887 + .001437 = .020307 lbs ft² THE STIFFNESS OF A LENGTH OF SHAFT l₂ WILL BE APPROX. = 28350 x .4179 / .3966 = 29900. lbs ft / RAD. ∴ FREQUENCY = 1/(2π) * √(29950 / .02031) = 193 OSCILL / SEC. WITH THREE OSCILLNS OF THE DISTURBING FORCE PER REV, THE SYNCHRONOUS SPEED WOULD BE 193 x 60 / 3 = 3860 R.P.M. THIS IS IN CLOSE AGREEMENT WITH 3800 R.P.M OBtd BY EXPT. (Y) | ||