Abstract: Rotor blade weighting apparatus comprising in combination at least one elongated rod carried within a rotor blade, and multiple weights received and retained on the rod, the number of weights adjustable for reducing vibration during rotor rotation.

Abstract: The invention concerns method and apparatus to obtain accurate tracking of rotor blades, as for example helicopter rotor blades, despite the existence of conditions transiently altering rotor angular velocity.

Abstract: Vibration of a bladed rotor is reduced by a method that includes:(a) rotating the rotor at a selected power level, at which vibration is produced,(b) detecting an out-of-track condition of a blade being rotated at that power level.

Abstract: The output of an aircraft propulsion or lift rotor blade out-of-track pick-up is processed in such a way as to enable quick determination of need for blade pitch adjustment, the approximate amount of such adjustment to optimize reduction of out-of-track vibration, and the need for blade substitution when such optimized reduction is insufficient.

Abstract: The method of balancing a rotor having multiple blades and defining an axis of rotation, and wherein structure proximate the rotor is subject to vibratory motion due to dynamic unbalance of the rotating rotor and an out-of-track condition of the rotor blades, the method employing two vibration pickups, the method including:A. operating the pickups to produce vibratory signals corresponding to up and down vibratory motion of the structure at port and starboard sides of said axis,B. combining said signals to produce a resultant oscillatory output signal characteristic of rotor vibratory motion due substantially to only one of said conditions,C. using said resultant output signal to alleviate said one condition.

Abstract: A starting device for a gas discharge lamp, to whose electrodes AC voltage is applied, comprises:A. first means electrically connected with at least one lamp electrode to apply to the lamp a transient voltage pulse which initially changes in amplitude in a polarity direction relatively in opposition to the polarity of the main voltage simultaneously supplied to the electrodes,B. said first means including circuitry to cause said pulse to thereafter change in amplitude in a polarity direction in aid of the polarity of the main voltage simultaneously supplied to the electrodes.

Abstract: A starting device for a gas discharge lamp, to whose electrodes AC voltage is applied, comprises:a. first means electrically connected with at least one lamp electrode to apply to the lamp a transient voltage pulse which initially changes in amplitude in a polarity direction relatively in opposition to the polarity of the main voltage simultaneously supplied to the electrodes,b. said first means including circuitry to cause said pulse to thereafter change in amplitude in a polarity direction in aid of the polarity of the main voltage simultaneously supplied to the electrodes.