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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).
Preliminary tests of a modified air-silencer carburetter (LRC.2786) for F.II engines.

Identifier  ExFiles\Box 13\3\  03-page209
Date  7th May 1930
  
To H.{Arthur M. Hanbury - Head Complaints} (Held up) From Hs{Lord Ernest Hives - Chair}/CHP.
c. to Sg.{Arthur F. Sidgreaves - MD} Mor.
c. to Rg.{Mr Rowledge} Da.{Bernard Day - Chassis Design}
c. to E.{Mr Elliott - Chief Engineer} Hy.{Tom Haldenby - Plant Engineer}

MODIFIED AIR SILENCER CARBURETTER (LRC. 2786).

Preliminary tests have now been carried out on the modified air-silencer carburetter for F.II engines; the results of which show that we are still losing too much power by the use of this instrument.

This carburetter is, however, a big improvement on the original one (LRC. 2734), a report on which was circulated 9.12.24. The construction has been modified so that a standard high-speed choke and diaphragm are utilised, also the air-valve is of standard dimensions so far as the air ports etc., are concerned. The only variation from a standard carburetter, is therefore the air-silencer and the cowling around the air-valve ports.

The curve V.850 shows that this carburetter causes no loss of power up to 1500 R.P.M.; after which the loss increases to a maximum of 8 B.H.P. (8%) at 2750 R.P.M. (this figure being the excess of loss over that caused by the Std. air-intake). In order to ascertain the loss caused by each individual part of the air-silencer etc., it is necessary to know what loss is occasioned by the standard type air-intake: therefore the top curve on V.851 (Std. carb. with air-intake removed) is taken as the datum. The total loss caused by the air-silencer and air-port cowling is therefore, 10.5 BHP.
  
  


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