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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).
Mathematical calculations for determining the conditions and extent of interference in pitch circles.

Identifier  ExFiles\Box 28\5\  Scan100
Date  28th April 1917
  
H.R. 235a (500 T) (S.D. 408. 28-4-17.) Bm. 2/156/13.

-2-

Contd.

Let O1C = r, and O2C = s; be the radii of the pitch circles and a the addendum, then to express the condition of interference mathematically we have:-

O2 P1^2 = P1 P2^2 + O2 P2^2

= (r + s)^2 sin^2 θ + s^2 cos^2 θ.

= (r^2+2r s) sin^2 θ + s^2

O2K1^2 = (s + a)^2 = a^2 + 2as + s^2

Interference occurs if

O2 K1^2 > O2 P1^2

i.e. if

(r^2 + 2rs{Sir Henry Royce's Secretary}) sin^2 θ < a^2 + 2as

i.e. if sin^2 θ < (a^2 + 2as) / (r^2 + 2rs{Sir Henry Royce's Secretary})

i.e. if sin θ < sqrt((a^2 + 2as) / (r^2 + 2rs{Sir Henry Royce's Secretary}))

==================================

To determine the extent of the interference we have:-

CK{Mr Clark}1 = P2K1 - P2 C

= sqrt(O2K1^2 - O2P2^2) - P2 C

= sqrt((s + a)^2 - s^2 cos^2 θ) - s sin θ

= sqrt(s^2 sin^2 θ + a(2s + a)) - s sin θ.
  
  


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