Pressure Port Placement for Lift Distribution Measurement on a Model Aircraft with Optimized Trailing-Edge Flaps

This paper describes a case study in the selection of the chord-wise location of a set of pressure ports that can be used in a simple sensing scheme to approximate the lift coefficient for in-flight application on a testbed model aircraft. Jepson and Gopalarathnam describe a sensing scheme by which the lift coefficient can be approximated using only 4 pressure ports per span-wise section of an aircraft wing that provide a measure of the change in the pressure differential between the front and the aft portions of an airfoil. In this study, an analysis of the aerodynamic performance of the Clark Y airfoil used on the Rascal testbed aircraft is performed to determine suitable locations for the 4 pressure ports. XFOIL is used to analyze the 2-D aerodynamic performance of the baseline airfoil at a range of Reynolds numbers of the testbed aircraft with and without a trailing-edge flap deflection. The selection of the front pressure ports that provide a differential pressure measurement near the leading edge of the airfoil is arrived at following an analysis of the location of the suction peak and the linearity of the pressure metric calculated. The rear pressure ports are selected based on the linearity of the pressure metric to lift coefficient calibration curves. The resulting pressure port locations are at 2% and at 60% of the chord for the case considered here.

Pressure Port Placement for Lift Distribution Measurement on a Model Aircraft with Optimized Trailing-Edge Flaps Conference Paper