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).
Procedure to find the centre of gravity of an engine unit in end elevation using a knife-edge balance test.
| Identifier | ExFiles\Box 74\4\ scan0082 | |
| Date | 1st September 1923 | |
| X4604 Sept. 1923 107 TO FIND THE CENTRE OF GRAVITY OF UNIT IN END ELEVATION. Engine rested on knife edges by extensions from the crankshaft line. The line of the centre of the cylinders and crankshaft assumed an angle of 12º 25'. Therefore the centre of gravity in end elevation must lie on the line XA. A wt. M was then added at the point P - 12" from crankshaft centre, which just brought the line A B vertical. This mass was 51 lbs. Now the moment of this mass about the line of suspension equals the moment of the engine mass about the same line, or in other words, the distance horizontally of the C. of G.{Mr Griffiths - Chief Accountant / Mr Gnapp} of the engine from the crankshaft bearing centre. CRANKSHAFT CENTRE 51 x 12 = 641 x x ∴ x = (51 x 12) / 641 = .945 ZQ = x/.22 = .954/.22 = 4.43 ZR = .954 / Tan 12º25' = 4.33 [Text from diagrams] 12º25' 12" 51 LBS. 641 | ||