WAT's Up with using the Small Angle Approximation to Estimate Climb Gradient Limited Departure Weights

摘要

This paper expands upon problems that arise when engineers use the classic work-energy-theorem equation, climb gradient equals thrust minus drag over weight, to predict climb performance. These equations are commonly used to schedule the WAT limit; the maximum allowable takeoff weight that guarantees a minimum climb capability in the event of an engine failure. The classic formulation relies upon a small-angle-approximation form of the work-energy-theorem. In this new work, we examine the continuing implications of using the full equations of motion to determine the schedule performance. An increase in predicted allowable payload is permissible if the engineer considers the implications of the general equations of motion.