The Investigators propose to design the outer-mold-line (OML) geometry and evaluate the aerodynamics, flight stability and control characteristics of a novel blended wing-body aircraft configuration with electric propulsion, the Kitty Hawk 2 (KH2). The OML design will be based on flight performance analysis of two or more candidate configurations (one of which may be supplied by the sponsor, if desired). The aerodynamic and stability and control evaluations will be conducted via a sequence of increasing-fidelity modeling tools as well as steady wind tunnel force and moment measurements of a scaled vehicle model. The objectives of this Phase I effort are to quantify the aircraft lift and drag performance in steady flight, static stability, control surface effectiveness, trimability, and perform preliminary assessment of dynamic stability of the selected OML design. In the process of characterizing the baseline vehicle geometry in Phase I, an important aim is to develop the necessary analytical/numerical toolsets, experimental setups, and workflows for improving the overall aerodynamic design and performing parametric and tradeoff studies of various geometry parameters (body-wing geometry, control surface placement, etc) in potential future development.

In this work, we will use a combination of theoretical and computational studies to develop improved insight into the flow physics of the unsteady aerodynamics of leading- and trailing-edge flows, which often involves vortex shedding. A key objective is to develop low-order predictive methods for such flows on unsteady airfoils, wings, and rotor blades. The improved understanding and low-order modeling capability will be useful in advancing the predictive capability for unsteady flows for rotorcraft applications.

The primary innovations of the proposed project will be: (1) a novel method of exercising control over the response of aeroelastic structures through prescribing upstream vortical flow disturbances; (2) an understanding of the mechanisms and governing parameters of unsteady wing force generation in response to impinging vortices; and (3) knowledge of the relationships between desired aeroelastic wing behavior and the appropriate spatial and temporal features of impinging flow disturbances. The current knowledge and understanding of the motion of elastic structures in response to impinging flow disturbances like vortices remains rudimentary and ad-hoc. Both natural and engineered systems offer numerous examples of vortical wakes and flow disturbances interacting with elastic structures. These examples range from fish adopting specialized swimming gaits to improve efficiency when in vortical wakes, to marine mammals sensing and following wake vortices of upstream prey via flexible whisker sensors, to oscillating fluid-elastic energy harvesters passively synchronizing and enhancing power extraction via constructive wake-coupled interactions. While these examples serve as motivating proofs of concept, engineering systems to exploit such interactions and use them as control mechanisms requires understanding of the nonlinear governing relationships between the flow disturbances and the structural dynamics. Our proposed aims will expand knowledge of the fundamental physics that facilitates these fluid-structure interactions such that we can tailor and control vortical disturbances to affect desired dynamic response from fluid-elastic structures. Our proposed work will create the required analytical framework, reveal the fundamental relationships between vortical flow feature parameters and wing forces, formulate control algorithms that produce desired aeroelastic wing responses on demand, and generate reproducible experimental validations that will enable engineers and scientists to understand, exploit, and control the interactions of elastic structures and vortical wake flows.

In this project we will perform additional enhancements to the research on aerodynamic modeling of close formation flight of aircraft and their interactions.

In this project we will continue further research on aerodynamic modeling of close formation flight of aircraft and their interactions.

In this research, we propose to study the effects of upstream vortical and viscous flow disturbances on the unsteady aerodynamics of airfoils undergoing prescribed motions and on the aeroelastic characteristics of flexible airfoils.

The research proposed in this effort aims to combine the prediction techniques and knowledge gained from the past efforts into developing a fast low-order aerodynamic prediction method for full-aircraft configurations (wing+tails+fuselage) and assess the suitability of this method for use in real-time simulation of flight dynamics.

We propose the development of low-order aerodynamic prediction methods for aircraft configurations at post-stall conditions, using computational fluid dynamics to help guide the development.

In this research effort, we will develop a vortex lattice method for determining the incremental loads on one aircraft flying in the vicinity of another, for the purposes of developing aerodynamic models for simulation.

In this project, we will computational fluid dynamics studies of two-dimensional and three-dimensional simulations of dynamic stall to guide the development of low-order prediction methods and to gain insight into the flow physics.