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Calculations for inertia and natural frequency of vibration for engine components using the Bifilar suspension method.


Identifier  WestWitteringFiles\P\2July1926-September1926\  Scan139
Date  4th September 1926 guessed
  
contd :-
-12-

The Bifilar suspension method was employed.
The following are the results :-

[Image of a Bifilar Suspension blueprint with labels d, l, and W]
BIFILAR SUSPENSION

SPRING DRIVE PARTS :-

l = 4'
d = .404'
W = 6.875 lbs.
Time for complete oscillation = 1.81 secs.
I = .005819 units.

CRANKSHAFT.
I = .016823 units.

FLYWHEEL.
I = .6911 units.

BIG END BEARINGS - LOOSE SHELL TYPE.

Rotory mass equivalent to 1.22 lbs.
I = .008 units for the six big ends.

This increases the total inertia of the crankshaft alone to .016823 + .008 = .024823 Units.

ESTIMATION OF NATURAL FREQUENCY OF VIBRATION OF CRANKSHAFT FROM INERTIA & TORSIONAL RIGIDITY.

For the purpose of simplicity we assume the crankshaft to consist of a shaft with a flywheel at each end. It differs from a simple torsional pendulum inasmuch as the fixed end is replaced by a nodal point and when oscillating the forward end will rotate in the opposite direction to the rear end relative to the modal point.

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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