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).
Typed memo discussing engine design choices and issues, comparing Phantom I and P.2 models, focusing on flywheel and crankshaft dynamics.
| Identifier | WestWitteringFiles\V\October1930-February1931\ Scan363 | |
| Date | 20th February 1931 guessed | |
| (2) ORIGINAL It should be understood that P. 2. crankchamber, though lighter, is stiffer, and therefore, as far as I know, would have a higher period than P. 1. There should be no difference in the speed of flywheel whirl in P. 1. or 2. and it should be the same on the test bed as on the car because there is a universal joint inside the flywheel so that the clutch and tail shaft does not help the rigidity of the flywheel support. Mr. Grylls photo shews a curious 4 point figure (standard 25HP. maximum 2500.) Mr. Elliott's extra bearing is a good experiment and has done exactly what we would expect - suggests that No. 6. crankpin or web is the source of flexibility and the piston inertia puts the flywheel in motion. In spite of contradictory evidence one cannot help but think that the flywheel is the trouble and that its periodicity should be raised. If the body responds to many periodicities in the same parts then it would confirm that the engine had a definite period at this 2500. I started to write this because I was not entirely pleased with our small balance weight scheme. The axial width of the base is narrow and perhaps we ought to take advantage of another .050; the balance weight would come out when crank flat because 4 in one plane. Secondly I do not like the overhang towards the con. rod. I would rather put something on the dia. and be content with less - (i.e. because of its greater inertia) - altered on drawing just received. Otherwise I think all the drawings you have sent me seem as good as we know how. I do not like disc to block holes in head: I prefer cast iron plugs screwed in with enamel. We must have no failures but I will leave this to E.{Mr Elliott - Chief Engineer}, BY.{R.W. Bailey - Chief Engineer}, and RHC.{R. H. Coverley - Production Engineer} to choose. Mr. Grylls should work on P. 2. as 25HP. flywheel has responded to treatment and promises to give no further trouble, and I think we can probably do some good by concentrating on this item on P. 2. R.{Sir Henry Royce} | ||