The Instantaneous Efficiency of Cantilever Geared Rotary Actuators in Flight Control Systems

The instantaneous efficiency of an epicyclic geared rotary actuator is an important factor in sizing flight control systems where compound epicyclic gear trains are typically used. The efficiency variation can be smooth or fluctuating depending on the combination and timing of the teeth of ring gears, planet gears and sun gears.

In a previous paper [1], the instantaneous efficiency characteristics of actuators with symmetric planets were investigated. The actuator's reacting forces on the planets are symmetric and the overall length of the planet gears will not affect the efficiency.

In this paper, a cantilever actuator with asymmetric planet gears is studied. The length and location of the reaction forces on the planet gears are key factors in the efficiency calculation. Theoretical derivation is presented and test results are compared.