Development of a New Slip-Ringless Propeller Blade Measurement System

A new system for acquiring, transmitting, and recording the steady-state and vibratory stresses from multiple strain-gage locations on a propeller during flight and ground operation has been developed and tested. The system eliminates conventional slip rings and increases data capacity. The data system employs a 16-channel FM multiplex to transmit information across a single capacitive coupling and is self-powered through the rotary motion of the test propeller. In addition, an rpm/phase reference signal, digitally encoded time signals, and seven channels of aircraft operating parameters are accommodated.