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).
Need to increase propeller shaft diameter to prevent whirling at higher RPMs.
| Identifier | ExFiles\Box 15\4\ Scan077 | |
| Date | 4th November 1931 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} c. to Eg. Wor.{Arthur Wormald - General Works Manager} c. to RG.{Mr Rowledge} K.{Mr Kilner} c. to Da.{Bernard Day - Chassis Design} By.{R.W. Bailey - Chief Engineer} PROPELLER SHAFTS. Referring to Del/N.7.9.31. we consider it essential to have a 3" diameter shaft for J.{Mr Johnson W.M.} 3. The present 2 3/4" 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 1/2" shaft for a length of 59". They recommend a minimum of 2 3/4" 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} | ||