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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).
Letter from a supplier discussing specifications and load figures for a 12 1/2 inch transmitter for a Bentley.

Identifier  ExFiles\Box 136\2\  scan0397
Date  2nd March 1944
  
3
Chassis 1153

TELEPHONE SOUTHPORT 8102

TURBO TRANSMITTERS LIMITED
REGISTERED ADDRESS: 25/26, ST.{Capt. P. R. Strong} GEORGE STREET, HANOVER SQUARE, LONDON, W.1
48a, CAMBRIDGE ROAD,
SOUTHPORT,
LANCASHIRE.

DIRECTORS:
MAJOR J.{Mr Johnson W.M.} E.{Mr Elliott - Chief Engineer} D.{John DeLooze - Company Secretary} SHAW (CHAIRMAN).
J.{Mr Johnson W.M.} S. H.{Arthur M. Hanbury - Head Complaints} MOORE (MANAGING).
COMMDR. H.{Arthur M. Hanbury - Head Complaints} D.{John DeLooze - Company Secretary} SIMONDS R.N. RETIRED
E.{Mr Elliott - Chief Engineer} H.{Arthur M. Hanbury - Head Complaints} RICHES.
J.{Mr Johnson W.M.} T. BROCKHOUSE.
J.{Mr Johnson W.M.} L. BROCKHOUSE.
K.{Mr Kilner} E.{Mr Elliott - Chief Engineer} SHELLEY. K.C.

March 2nd. 1944.

W. A.{Mr Adams} Robotham Esq.
Messrs Rolls-Royce Ltd.
Belper, Nr.Derby.

Dear Roy{Sir Henry Royce},

Thank you for your letter of February 28th.

The transmitter we are proposing to supply for fitting to your Bentley is the 12½ in. the same as that fitted to my Humber.

I am enclosing drawings of the same size shells which are being made for the David Brown Tractors; they are pressed steel shells with hubs and flanges furnace brazed; they are not suitable for speeds in excess of 4000 r.p.m. as they would be liable to flex and distort. For your transmitter we shall use steel forgings of which we had a quantity at the beginning of the war.

The following figures give the loads on the shells of the 12½ in. transmitter

Fluid pressure due to centrifugal force is approximately 340 lbs per sq.in. at 4000 r.p.m.
" 530 " " " " 5000 " "

Total pressure on end of face (tending to disrupt main joint) is 10.6 tons at 4000 r.p.m.
" 16.6 " " " 5000 " "

You will notice from the drawing the large number of bolts required on the main joint to prevent stretching of the bolts and consequent leakage at high speeds.

The hoop tension in an aluminium shell due to the fluid pressure plus the hoop tension due to the whirling of the metal itself would be
with shell 5/16 thick, 4.3 tons per sq.in. at 4000 r.p.m.
" " " " 6.72 " " " " " 5000 " "
" " ¼ " 5.1 tons " " " " 4000 " "
" " " " 8. " " " " " 5000 " "
" " 3/16 " 6.45 " " " " 4000 " "
" " " " 10.1 " " " " " 5000 " "
  
  


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