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).
Technical note detailing calculations for balance weights and their effect on shaft critical speed.
| Identifier | ExFiles\Box 14\2\ Scan121 | |
| Date | 20th May 1931 | |
| For Files. 87010 20.5.31. P.II. BALANCE WEIGHTS TO LEC.2616. These balance weights have not been made to the drawing being only 1.04" thick. They are fitted to a shaft with chamfered webs, the amount of chamfer being equivalent to 2.86 lb. ins. The weights were machined to balance exactly an unchamfered shaft of total out of balance per crank of 14.6 lb. ins. Out of balance of big end is 2.53 lbs at 5 1/2" = 6.95" These weights balance 41% of the big end. Total out of balance per standard Phantom crank including big end = 21.55 lb ins. Critical speed of standard shaft = 3900 rpm = 100 mph. Critical speed of chamfered shaft with 12 wts = 3200 rpm = 82 mph. Critical speed of chamfered shaft with 6 wts = 3500 rpm = 90 mph. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} | ||