Flight Test Investigation of Propeller Effects on the Static Longitudinal Stability of the E-2C Airplane

A flight test investigation of the E-2C airplane fitted with two different propeller designs – the Hamilton-Sundstrand model 54460-1 and model NP2000 – was conducted to study propeller effects on airplane static longitudinal stability. Test measurements were recorded at predetermined, mission-representative flight conditions for each propeller model while maintaining the remaining component contributions to longitudinal stability constant. Results were compared at similar test conditions to isolate changes in static stability resulting from a change in propeller contribution. Static elevator position neutral points were determined for those test conditions that indicated a definitive change in airplane static stability as a result of changing propeller design. The results of this work indicated that replacing the model 54460-1 with the model NP2000 propeller reduced the stick-fixed static longitudinal stability of the E-2C in the landing approach configuration, causing an approximate 3x change in the slope of elevator deflection versus airspeed and a 2% forward shift of the static neutral point at landing approach airspeeds.