| 摘要 |
A detector for checking the symmetry of a helicopter rotor while it is rotating has a scanner (11) which scans vertically a field of view (15) and the view is interrupted by a vertical strip on the blade tip (16). A slot (18) in the strip gives a characteristic signal as at (L2). The position of the signal (L2) in a scanning cycle gives an indication of the height of the blade tip and also the circumferential spacing between blades. |
