Journal of Aircraft

This paper presents a summary of the computational flutter results associated with the AIAA Third Aeroelastic Prediction Workshop, High Angle Working Group. The computational results are compared against the experimental data collected during the Pitch and Plunge Apparatus Benchmark Supercritical Wing test campaign conducted in the Transonic Dynamics Tunnel at NASA Langley Research Center in 1993…

Modern unmanned aerial vehicles (UAVs) demand improved aerodynamic performance and control authority. This study uses numerical simulations to compare the aerodynamic performance in longitudinal trim of two distinct control surface configurations that can be used in modern UAVs. The first configuration, the hinged system (HS), uses a traditional flap at 70% chord and a hinged elevator. The second…

With the widespread use of composite materials and the increasing demand for weight reduction in modern aircraft, the stiffness of the fuselage has gradually decreased, leading to more frequent occurrences of pendulum motions. Traditionally, pendulum test rigs often overlook the elasticity of the fuselage, which can affect the accuracy of the pendulum test results. This study, based on fuselage d…

Broadening interest by the aeronautics community in distributed electric propulsion systems has revealed a need for design and analysis methods capable of resolving the two-way coupling of aeropropulsive systems. A 2D, inviscid, and incompressible scheme to investigate the performance of these systems is described, which builds on prior, extensively used developments toward modeling airfoils in p…

The paper addresses the study and design of the autorotation maneuver for a remotely operated helicopter model, developing guidance and control algorithms to automatically track the designed maneuver in case of engine failure. The steady descent phase is investigated first, during which the rotor angular rate and helicopter velocity components are kept at constant values. During the final flare, …

This paper examines the impact of two potential solutions for increasing fuel efficiency and reducing emissions in commercial aviation: hybrid-electric propulsion and the use of drop-in synthetic aviation fuels (SAFs). The authors modeled three representative aircraft employed in the U.S. domestic market: a 70-seat regional turboprop, a 100-seat airliner, and a 180-seat airliner. These aircraft w…

This study presents a unified aeroelastic modeling framework that augments classical lifting-line theory (LLT) with a Goman–Khrabrov (GK) dynamic stall model to capture unsteady aerodynamic and structural interactions under gust and maneuvering conditions. The model formulates the coupled aeroelastic system in state-space form, integrating structural degrees of freedom (plunge and pitch), aerodyn…

A 4.75-ft-diameter, dynamically scaled, swept-tip proprotor was tested up to 200 kts. The stability roots (frequencies and damping) were collected for wing-pylon beam, chord, and torsion motions. The impacts of both gimbaled and gimbal-locked hubs were measured. Predictions from an in-house rotor aeromechanics solver were compared with data to understand the stability behavior and identify gaps i…

The phenomenon of stable lift oscillations occurring on an elliptic wing section utilizing circulation control at transonic speeds was evaluated using numerical simulations. As the momentum of the jet increases beyond a prescribed magnitude, periodic detachment occurs from the trailing edge. This behavior conforms to a bistable state, consistent with prior experimental observations. Analysis by b…

Unmanned aerial vehicles (UAV) frequently experience landing-induced impact forces that can compromise landing-gear integrity, thereby affecting mission reliability. Conventional solid structures have challenges in balancing weight reduction with effective energy absorption, underscoring the need for novel structural designs. This study presents a lightweight, impact-resilient unmanned aerial veh…

A hybrid framework for aerodynamic shape optimization is presented. The framework implements a sequential procedure, exploration-then-exploitation, coupling Bayesian global optimization with an adjoint-based gradient method. Gradient-based methods efficiently refine a design but are inherently sensitive to the initial point and often converge to a local minimum. To address this limitation, the Ba…

Thermoplastics provide several advantages over thermoset composites, including the potential for fastener-free assembly via induction welding. Key parameters in modeling this process include coil frequency, excitation current, and coil offset distance. However, optimizing heat generation through coil geometry remains underexplored. This study aims to derive relationships between coil geometry, he…

This paper aims to advance the understanding of greener technologies suitable for the aviation industry by introducing a dynamic modeling approach for the integration of hydrogen solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid systems as a power unit in electric aircraft propulsion. Despite the significant potential for emission reduction and improved fuel efficiency, the adoption of the…

Airfoil design optimization involves iterative processes, often using less accurate low-fidelity tools due to limitations on computational costs. Surrogate modeling bridges the gap between low computational costs and high-accuracy analysis tools (such as computational fluid dynamics). This study explores the benefits of a vectorized implementation of artificial neural networks (ANNs) as a surroga…

The Adaptable Distributed Electric Propulsion Testbed (ADEPT) Wing was tested in the NASA Langley 12-Foot Low-Speed Tunnel to investigate electric propulsion technologies for commercial transport aircraft. The purpose of the test was to study the aeropropulsive effects across angle of attack and fan speed variations for several propulsor placements and array sizes, and to investigate how distribu…

In-flight ice accretion poses a significant risk to aircraft safety and performance. Despite advancements in ice protection systems, aircraft must demonstrate the ability to operate safely under icing conditions, highlighting the importance of reliable ice accretion simulations. Traditional multistep simulations divide the accretion process into discrete stages, improving the accuracy of ice pred…

In this study, direct numerical simulations are conducted to exhibit the viscous drag reduction effect of equilateral triangle riblets at Mach 0.85 and investigate the optimal groove width for maximum drag reduction. Additionally, the Mach number effect on their drag reduction performance is elucidated by comparing the drag reduction effect of riblets at Mach 0.85 with that at Mach 0.2. The compu…