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).
Graph comparing torsional vibration amplitudes for the Goshawk and Phantom models at critical speed without external damping.
| Identifier | ExFiles\Box 65\4\ scan0182 | |
| Date | 10th November 1926 | |
| TORSIONAL VIBRATIONS COMPARISON OF VIBRATION AMPLITUDES AT THE CRITICAL SPEED ON PHANTOM & 20 H.P. WITHOUT ANY EXTERNAL DAMPING PLAIN LINE GOSHAWK DOTTED LINE PHANTOM AMPLITUDE OF VIBRATION DEGREES CRANK ANGLE DEGREES ROLLS-ROYCE, LIMITED PRINT ROOM, 10 NOV 26 | ||