Experimental Evaluation of the ASWING Aeroelastic Framework: Aerodynamics and Propeller Models

This article presents the experimental evaluation and modification of the aerodynamic features of ASWING, a software developed at MIT and mostly used for preliminary design and flight dynamic analysis of highly flexible aircraft. It focuses on the aerodynamic and propeller models and their interactions, investigating a large part of the steady and unsteady features. The paper starts with a brief literature review that justifies the choice of ASWING over other solutions and explains its need for validation. The methodology and various code modifications to improve prediction performance are then presented. The paper follows with a series of test cases to illustrate the capabilities of the tool and the improvements made by the modifications. These include the prediction of linear lift, stall, and drag; aerodynamic control surface effects; close interactions between lifting surfaces (fuselage carryover, wake interference, and downstream circulation influence); unsteady aerodynamics; and propeller jets interacting with downstream lifting surfaces. The paper concludes that ASWING is an accurate and efficient tool for predicting various macroscopic aerodynamic phenomena, making it an interesting framework to be coupled with multidisciplinary analysis and optimization software for aircraft predesign adapted to modern unconventional layouts. However, ASWING shows weaknesses in specific features with poor prediction performance; among them are secondary loads produced by the deflected flap (e.g., yawing moments induced by deflected ailerons); wing–body interactions (fuselage lift carry-over is not captured); propeller thrust in highly off-axis conditions (VTOL configurations); and propeller jet azimuthal speed predictions (swirl).