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).
Three potential causes for a collapsed propeller shaft within a torque tube on the Goshawk I.
| Identifier | ExFiles\Box 77\1\ scan0127 | |
| Date | 14th January 1921 | |
| X3539 To Da.{Bernard Day - Chassis Design} from R, c. to C.J. c. to Hs.{Lord Ernest Hives - Chair} c. to EFC. R10/G14.1.21. X,3539. RE "GOSHAWK I". I understand from your memo that the propeller shaft has collapsed inside the torque tube. I do not remember the thickness of this part particularly, or the diameter of the tube, but one may conclude that the failure has been caused through one of three things:- (1) The torsional vibration of the bevel gear system in the back axle caused by the irregular driving of the improved gears setting up a period, and so causing an enormous torque variation in this tube, which is relatively so much stiffer than the shafts going to the road wheels. I say that it is torsionally stiffer because of the ratio of the gearing in the the back axle. (2) The second cause would be possibly due to the tube being very thin, and not very stable as a torsional shaft, and so possibly being over-stressed when the powerful little engine is on the lowest gear. (3) The third possibility is that the running on the dynamometer has reached the whirling speed of this shaft. You will remember that it is a shaft with free ends, and not like a continuous piece of shaft running through bearings. I am not sure how far away from the whirling speed it is, but we think the modification you suggest of thickening the walls of the tube would probably clear the matter up. If it is anywhere near the whirling speed, the diameter of the tube should be increased. Great efforts Contd. | ||