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).
Cylinder vibration characteristics and boost pressure for the Vulture I No.3 engine.
| Identifier | ExFiles\Box 138\2\ scan0161 | |
| Date | 9th July 1938 | |
| - 6 - the fitting of the reduction gearing or in better alignment on the test stand. (See also Series V). A series of records made from the top bank water connections showed an appreciable improvement effected since Series II. TABLE III. CYLINDER VIBRATION CHARACTERISTICS. 5½ lb/sq.in.boost. 'A' BLOCK. VULTURE I NO.3. (MASTER ROD IN 'C' BANK.) Crankshaft RPM. C/S Frequency. Observed Frequency. Amplitude (Master in 'C'). Amplitude (Master in 'D'). 3000 50 50 0.005" 0.007" 2900 - - 0.005" 0.009" 2800 46.7 45 - 0.015" 2700 - - 0.004" 0.013" 2600 43.4 - - 0.010" 2500 - - 0.004" - 2400 40 38 - - 2200 36.7 - 0.002" - TABLE IV. CYLINDER VIBRATION AND BOOST PRESSURE. 2700 RPM. 'A' BLOCK. VULTURE I NO.3. (MASTER ROD IN 'C' BLOCK). Boost lb/sq.in. Amplitude. (Master in 'C'). Amplitude (Master in 'D'). 6 0.004" 0.013" 4 0.004" 0.010" 2 0.003" 0.007" -2 - - * Taken for the purposes of comparison from the results of Series II. Examination of spectra taken from each of the blocks in turn at 2800 r.p.m. and 4 lb/sq.in. boost showed approximately equal vibration amplitudes of the order of 0.004" and occurring at crankshaft frequency. In the case of the diagrams taken on 'A' bank at varying speeds although the fundamental was at crankshaft frequency the third harmonic or piston side thrust frequency was appreciable at 2800 and 3000 r.p.m. Additional trials which have been carried out on other engines to date are as follows :- In Series III 9.7.38, a number of records were taken on a 'Merlin II' engine at the time when airscrew shaft frequency vibration troubles were experienced on the Vulture engines. In the case of the Merlin the main block vibration occurred at crankshaft frequency with an apparent 3rd harmonic. The trials were carried out concurrently with carburetter tests and were consequently confined to 2200 r.p.m. and 2½ lb/sq.in. boost. The amplitude was approximately 0.005" with the vibrograph held horizontally in a similar position to that adopted | ||