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).
Required diameter for propeller shafts to prevent whirling at high RPMs.
| Identifier | ExFiles\Box 105\2\ scan0122 | |
| Date | 4th November 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c.c. to WCE. Wor.{Arthur Wormald - General Works Manager} c.c. to Eg. R.{Sir Henry Royce} c.c. to Da.{Bernard Day - Chassis Design} Hy.{Tom Haldenby - Plant Engineer} X5340 Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}7/RT.4.11.31. X5340 PROPELLER SHAFTS. Referring to Oal/M.7.9.31. we consider it essential to have a 3" diameter shaft for J.{Mr Johnson W.M.} 3. The present 2 1/4" shaft begins to whirl at 3000 r.p.m. (80 M.P.H.). By shortening the shaft 3" due to the synchromesh gearbox, this speed would be raised to 3300. We anticipate using speeds up to 4000 r.p.m. for which a 3" diameter shaft would be necessary. We have been corresponding with OY. on this subject of propeller shafts. He questioned the P.II. shaft being stiff enough as the Mechanics Machine Company in America were astonished that we could run a 2 1/4" shaft for a length of 59". They recommend a minimum of 2 1/2" diameter of .065 material. We therefore ran up a P.II. chassis and found that whirling commenced at 90 m.p.h. or 3500 r.p.m. It does appear necessary, therefore, to raise the diameter of the P.II propeller shaft. Attached herewith copies of letters from Mr.Olley & Mechanics Joint Co. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||