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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).
Torsional vibrations and engine firing orders, comparing a Phantom II engine with a 60 Vee 6250 cc model.

Identifier  ExFiles\Box 138\1\  scan0015
Date  24th February 1932
  
x634.

R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}
c. to E.{Mr Elliott - Chief Engineer}
c. to Rs.{Sir Henry Royce's Secretary}

Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}S/MA.24. 2. 32.

TORSIONAL VIBRATIONS.

E.{Mr Elliott - Chief Engineer} has asked for a prediction of the relative severity of the 6th, order vibration on P.II and a 60 Vee 6250 cc. engine. That is of course a comparison of the Phantom half period and the 12 cylinder top period. Assuming the same indicator diagram in each case the period on the 12 cylinder should be 5/6 of the magnitude of that on P.II. This is true for any firing order of the Vee engine.

A 350 engine would be a negligible improvement. Lincoln employ an unusual firing order namely :-

1 → 5 → 3 → 6 → 2 → 4

For the 6th, order vibration this has no effect on the magnitude of the vibration. It is true to say that the magnitude of the nth order vibration of an n throw crankshaft engine is independent of the firing order. Other vibrations are however affected.

Hs{Lord Ernest Hives - Chair}/H.Grylls.
  
  


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