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Calculation of the moment of inertia (k²) for car model 11-G-111 with a landaulet body by the swinging method.


Identifier  ExFiles\Box 5\2\  02-page128
Date  1st December 1927 guessed
  
X5830 4538
V5830
TO FIND k² FOR 11-G-111 BY SWINGING.
(LANDAULET BODY, SPARE WHEEL AT REAR).

Let k²_GT = k² of total car (including axles) about c.g. of total car.

= (T²pg / 4π²) - p² ft²

Where p = distance of c.g. from point of support when swinging = 10.167'

T = 3.9 secs.

Ther'f k²_GT = 22.6 ft².

Weight of total car = 4004 lbs.

∴ I_GT = 4004 X 22.6 = 90,500 lbs.ft².

From this must be subtracted the axle inertias about the same point.

Weights are ( Front 305 lbs. k² = 1² + 6.083²
( Rear 485 lbs. k² = 1² + 4.708²

Inertia for two = 305(1² + 6.083²) + 485(1² + 4.708²) = 22,840 lbs.ft².

∴ I_G = Inertia of sprung part about c.g. of sprung + unsprung parts = 67,660 lbs.ft².

Weight of sprung part = 3214 lbs.

∴ k_G² = 67,660 / 3214 = 21.06 ft².

To find position of c.g. of sprung part.

contd :-
  
  
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).


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