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).
Design history, different versions, and concerns over rivet sizes for the Bentley fan.
| Identifier | ExFiles\Box 86\5\ scan0016 | |
| Date | 13th January 1934 | |
| X224. To BY.{R.W. Bailey - Chief Engineer} from E.{Mr Elliott - Chief Engineer} E.3/HP.13.1.34. c. Wer. Hs.{Lord Ernest Hives - Chair} Sft.{Mr Swift} Mx.{John H Maddocks - Chief Proving Officer} re Bentley Fan. We disagree with Hs.{Lord Ernest Hives - Chair}2/MJ.12.1.34 somewhat with regard to the history of the above. The Chrysler assymetrical fan was tried on the Bentley and recommended for adoption. The Design department however objected to agree to this before trying a symmetrical fan of similar blade form and angle designed to pump less air, and issued a drawing LeC.3650 for making up a Bentley fan on these lines. The symmetrical fan was produced and when tested was passed as equally good for the purpose and it avoided any question of paying royalty. It was subsequently found that this fan had not been made from LeC.3650 but was based on the original model. There is, however, no apparent difference between the features of LeC.3650 and the Chrysler model but unfortunately the latter is assembled with .187" diameter rivets having small heads corresponding approximately to .156 rivets as used by RR. and the design shows these heads and nothing else. The 10,000 mile tested fan at present on the Bentley in U.S.A. so far as we are aware, has .187" rivets. The detail production drawings show .125 diameter rivets and a somewhat different shape of blade where the blade is rivetted to the arm of the hub. This latter point we consider of no account, the essential difference being in the size of the rivets. The stresses on the .125 rivets, we think, are too high, especially having regard to the fact that in practice they are bound not to be equally loaded. The failure of the fan used by Mx.{John H Maddocks - Chief Proving Officer} for repeated engine bed tests rather leads to the conclusion that these fans are unsafe and it will be necessary to come to some decision as to what is to be done with regard to all similar fans on Bentleys. In the meantime we have asked for the rivets to be immediately altered to .187" diameter like the 10,000 mile tested model. E.{Mr Elliott - Chief Engineer} | ||