Air Force Academy Contributions to Development of the A-10 Drooped Leading Edge Modification

Abstract

To enhance overall performance of the A-10 Close Air Support Aircraft and enhance reliability and maintainability, the United States Air Force Academy (USAFA) Aeronautics Department proposed a fixed drooped leading edge configuration in the summer of 2011 to replace the current slat system located on the inboard leading edge of the wing. In the spring of 2012, the A-10 Systems Program Office at Hill AFB tasked the USAFA Department of Aeronautics to conduct an effort to evaluate the existing slats extended and slats retracted configurations as well as three drooped leading edge configurations so comparisons could be made [1–5]. This effort was a follow-on investigation of five drooped leading edge configurations plus two additional ones with geometric twist, and an additional one with fences. This wind tunnel evaluation was performed using a 1/20 scale model. Of the eight configurations evaluated, the 11% drooped leading edge with fences performed the best in minimizing total pressure distortion across various angles of attack and sideslip. However, the 10% droop had better drag characteristics (determined in a parallel investigation) and was projected to have significant drag reduction benefits at the higher angles of attack which could improve sustained turning performance. Based on these combined results, the 10% droop was the USAFA recommended configuration in the Fall of 2012 for further evaluations by USAFA and Arnold Engineering and Development Complex (AEDC).