Correlation of the Continuous Beta Sweep Test and Analysis Technique to Transonic Free-to-Roll and Flight Test Results

Abstract

Abrupt wing stall at transonic flight conditions can result in uncommanded rolling motions that have degraded flying qualities, compromised mission performance, and reduced safety of flight for a variety of legacy military aircraft, including the pre-production F/A-18E/F Super Hornet. In order to investigate how abrupt wing stall might be detected in static wind tunnel tests, an investigation of the transonic lateral characteristics of the pre-production F/A-18E Super Hornet was performed at the NASA Ames Research Center 11-foot wind tunnel. Rolling moment data from the test were analyzed using the continuous beta sweep test and analysis technique developed under the Joint Strike Fighter program. This paper compares the analysis of the wind tunnel data to results from the transonic free-to-roll wind tunnel test and flight tests at Mach 0.8 and Mach 0.9 at three leading edge flap deflections. Over 50 flight events were analyzed that correspond to the leading edge flap settings and Mach numbers evaluated. The continuous beta sweep test and analysis technique shows good correlation with flight data at Mach 0.9 for all leading edge flap configurations. Poorer correlation with flight data is observed at Mach 0.8 for two leading edge flap settings. Varying degrees of correlation with the free-to-roll figure of merit is observed for both Mach numbers and all flap deflections. Recommendations for use of the technique in abrupt wing stall screening are presented.