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).
Proposed modifications to the Bensport Engine to reduce critical vibration.
Identifier | ExFiles\Box 3\4\ 04-page065 | |
Date | 30th June 1932 | |
X4553. To W: from E.{Mr Elliott - Chief Engineer} E.2/HP.30.6.32. ------------ c. Sg.{Arthur F. Sidgreaves - MD} TDR. Hs.{Lord Ernest Hives - Chair} Hy.{Tom Haldenby - Plant Engineer} re Bensport Engine. ------------------ With the Bensport stroke shortened from 4.125 to 3.875, and with 2" dia. crankpins, and 2.25 Journals, the major critical vibration occurs at 6,500 r.p.m. Allowing for damper hub this would be reduced to about 6000, which should be quite safe for an operational speed of 5000 r.p.m. We attach herewith a print showing section through engine, and illustrating the following proposed modifications:- (1) Height of cylinder block increased from 11.0 to 11.25. This helps extracting piston pin at top without having to have pin too high in piston. (2) Modified rod increased in length from 7.200 to 7.625, large end to suit 2" pin, small end to suit .687" piston pin instead of .625, and stem stiffened a little also. The general stiffening is with the object of meeting the supercharged conditions. (3) Piston of same length as Peregrine - 3 inches, but with pin larger as mentioned, and raised somewhat to assist in extraction at top. Piston runs out at bottom of bore .625. The integral cylinder block and crankcase are shown as C.I. casting with inserted liners of C.I. having a shrunk fit at lower end. This is similar to what is running on Peregrine. The points in favour of this on Bensport | ||