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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).
Theory of high-speed steering wobble and a proposed apparatus for demonstration.

Identifier  ExFiles\Box 28\4\  Scan361
Date  29th August 1925
  
To Hs.{Lord Ernest Hives - Chair} from DA.{Bernard Day - Chassis Design}

X457

DALQ/29. 8. 25.

HIGH SPEED STEERING WOBBLES.

X.457
X. 8430

Mr. Royce is anxious to prove if possible that the wobble set up is due to conical precession without torque, or with very little torque. As we have previously pointed out, the moment of inertia of the wheel about the king pin is (apparently) much less than that about the axis of rotation, whereas for conical precession at the same angular speed as rotation it should be the same -

I_R W = I_pΩ(cos θ) = approx. 1.000

On the other hand, the moment of inertia of the wheel etc. about the centre line of the car is much more than that about the axis of rotation.

The theory is that the wheel may be precessing about some point which is a mean of these two, and to demonstrate this Mr. Royce would like to have made some little apparatus such as indicated in the enclosed sketch. It is not intended to bind you down to any details of manufacture as you will know what you have available. The apparatus is to be suspended by a spring to simulate the suspension of the axle.

DA.{Bernard Day - Chassis Design}
  
  


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