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).
Fan failure on car model 6.B.IV, detailing the cause and subsequent actions.
| Identifier | ExFiles\Box 83\2\ scan0143 | |
| Date | 24th November 1937 | |
| To By.{R.W. Bailey - Chief Engineer} c. to Hs.{Lord Ernest Hives - Chair} c. to RHC.{R. H. Coverley - Production Engineer} c. to Dn. 200a also 2.34 Rm{William Robotham - Chief Engineer}/Std.1/JH.24.11.37. FAN FAILURE ON 6.B.IV. The fan blade set which failed on 6.B.IV. car was a single pressing as drawn originally for the Wraith to drawing EW.947. It ran 2,000 miles on 6.B.IV. car before failure occurred. The failure consisted of a crack which started at the end of the pressed 'buttress' at the base of the blade and then extended across the width of the blade. This allowed the main portion of the blade to fly off and the resultant out of balance force broke the fan bracket and allowed the remaining three blades to cut into the radiator matrix, bending them and causing one to show a crack at a similar point to that of the first failure. The failure was definitely a fatigue one and attached is the laboratory report on the failed pieces. We have endeavoured to check up on the manufacture of these blades and have only been able to obtain indefinite information - we have discovered that whereas the material specified for the blades is S.239.A., the first two made (of which the failed fan is one) were made from commercial black iron sheet while no accurate information is available as to the subsequent material used. We have done a good deal of running on Wraith cars with this type of fan blade without trouble, but our opinion is that the design of blade is such that the material is too highly stressed at the point where the blade twist runs into the stiffening buttress. Poor material and filing marks (see attached report) have obviously been contributory causes of the failure. As we have now abandoned this type of fan in favour of the five blade fan with aluminium blades, no further work need be done in connection with this failure. ENCLOSURE No 530 Rm{William Robotham - Chief Engineer}/Std. | ||