To reduce the load on the combining transmissions in two engine turboshaft helicopters, the torque must be leveled. It is proposed to undertake: to evaluate three concepts of a torque sensor for turboshaft engines, including their senitivity, linearity, and accuracy; selection of the best concept for detailed design, including a block diagram of its associated electronics. Two concepts make use of a self-contained collar that is attached to the shaft in situ. In one concept, a traditional strain gage bridge is mounted within the collar with an rf antenna and an electronics module. In the second concept, amorphous alloy ribbons are bonded to the outside of the collar: along the line of compression on one section of the sleeve; and along the line of tension on another section of the sleeve. A stationary drive/pickup coil is mounted around and away from the collar. The third concept utilizes a reflectance grating, laser diode, and ccd array to optically determine shaft torque. These concepts are expected to result in highly accurate sensors that will not require individual calibration at installation, and will be robust and easy to maintain.
