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).
The failure of a broken propeller shaft (E.27832) due to high stress range.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 21 | |
| Date | 1st April 1927 | |
| Hs{Lord Ernest Hives - Chair}/ST/LGS. 4. 27. RE. BROKEN PROPELLER SHAFT. This shaft (E.27832) failed at its smallest dia., close to the splines. The shear stress due to the steady engine torque corresponding to 480 HP. at 2100 r.p.m. speed is 15,600 lbs/sq.in. Reference to the torque diagram for the F.10. engine attached to our Hs{Lord Ernest Hives - Chair}1/LG4.3.27 will shew that the torque varies by amounts of + 2100 in.lbs. and - 2400 in.lbs. on the mean value of 14,400 in.lbs. These torque variations might possibly be doubled by crankshaft torsional vibrations which would produce a stress variation of approximately ± 5,400 lbs/sq.in. i.e. the stress range in this shaft might reach a figure of 11,000 lbs/sq.in. or even more under severe conditions of induced crankshaft vibration. It appears therefore that this shaft failed due to the stress range being too high at this point. This propeller shaft has run 68 hrs. on the hangar and 85 hrs. on the test bench. Hs{Lord Ernest Hives - Chair}/S.S.Tresilian. | ||