Control device effectiveness studies of a 53∘ swept flying wing configuration. Experimental, computational, and modeling considerations

Abstract

The present investigation covers studies of different control devices on several 53 • swept flying wing configurations without a vertical tail plane. The wings considered share the same planform but differ in their spanwise profile shapes. The planform, developed under the NATO AVT-251 Task Group, is referred to as the MULDICON (or MULtiDIsciplinary CONfiguration). The objectives of this article are twofold: (1) to design yaw control surfaces for the MULDICON wing using an experimental/computational approach and (2) to develop aerodynamic models that rapidly and accurately predict the effectiveness of control surfaces over a wide range of flight conditions. The yaw control surface design (position and size) should provide sufficient yaw moment with almost no contribution in roll and pitch moment. To identify such concepts, a number of preliminary experiments on a generic flying wing configuration have been conducted. Two promising concepts from wind tunnel tests were then numerically examined for being implemented in the MULDICON baseline wing. Concepts with spoilers and a split flap were specifically considered. For medium to high angles of attack, the flow topology of the baseline wing is dominated by a vortical flow field on the upper outer wing. This leads to interactions between vortex and the control device which influences the flow and the attitude of the control device on the upper wing side. Furthermore, this work considers developing aerodynamic models for predicting stability derivatives of several MULDICON designs over a wide range of flight conditions. Aerodynamic loads models are only developed for normal force and pitch moment coefficients, however, the developed approach can easily being extended to include lateral aerodynamic coefficients as well. Quasi-steady models of this work are power series expansions of traditional linear aerodynamic models to capture nonlinear effects. Additionally, the models can estimate static and dynamic stability derivatives and the control surface powers.

A Novel Control Allocation Method for Yaw Control of Tailless Aircraft

“…Huber et al [15] performed experimental tests on a split elevon located inboard of the wing-tip. These experiments showed a significant roll-yaw coupling with control surface deflection in contrast to results presented in [1]. It is, hence, evident that the secondary control effects of split elevons are sensitive to the spanwise location of the control surface.…”

“…Current performance and operational requirements for low observable aircraft drive the design towards finless low aspect ratio flying wing configurations with a leading edge sweep between 45-60 degrees [1][2][3]. Yaw control is typically provided through laterally asymmetric deployment of drag-based aerodynamic control effectors in the form of spoilers or split elevons [4].…”

“…However, the use of permanently deflected controls increases signature and reduces aerodynamic performance of the aircraft. Löchert et al [1] investigated several forms of wing-tip drag devices and tip aligned spoilers using CFD simulations and experimental testing. They showed that folding wing-tips and spoilers at the wing-tips both produce significant cross-coupling, particularly in the roll axis.…”

Design studies and multi-disciplinary assessment of agile and highly swept flying wing configurations

“…For MULDICON-like configurations with their vortex-dominated flow fields, this would require a fast, robust, and automatic high-fidelity aerodynamics process which is still not available yet. Thus, in Mephisto the control surface design was still done manually [13,41,42].…”

Wing rock mode and its mechanism of a flying-wing aircraft

“…Therefore, a near-elliptic span load should be considered (Liebeck, 2004). However, in recent years, due to the strong demand for high-performance aircraft, increasingly more researchers have begun to pay attention to and try to solve the various flight control problems faced by low-aspect-ratio flying wings (Harvey et al., 2022; Löchert, Huber, Ghoreyshi, & Allen, 2019).…”