Low technology readiness level (TRL) technologies are attractive to the aerospace industry because their maturation cycles can happen simultaneously with the development lifecycle of the aircraft. However, due to the limited knowledge about a new technology in system evaluation, a low TRL technology’s high potential is counterbalanced by its inherent high risk and high uncertainty. As a result, the

In this paper, the validity of the thin-airfoil-theory-based source term modeling, Bender–Anderson–Yagle (BAY) model, for predicting the flows induced by a range of different vane-type vortex generators (VGs) is analyzed. By directly comparing the BAY model computations with the body-fitted VG computations using the same grids, the modeling errors involved in the BAY model are elucidated. The results

The unsteady flows produced over the stern of a Simple Frigate Shape 2 ship model are studied in a low-speed wind tunnel. Time-resolved particle image velocimetry (TR-PIV) measurements were performed in several streamwise and cross planes. Two grids of Cowdrey rods were used to simulate the basic characteristics of an atmospheric boundary layer in terms of upstream velocity profile and turbulence intensity

This paper details the successful takeoff and landing of a wing-tip-connected meta aircraft prototype. The aircraft consisted of two commercial off-the-shelf high wing trainers connected wing tip to wing tip with three neodymium magnets. The flight controller on board each aircraft was a Raspberry Pi 3B complete with Navio2 flight controller. The software running on the aircraft was built using Emlid

In this paper, a computationally efficient multifidelity local search algorithm for aerodynamic design optimization is presented. In this paper’s approach, direct optimization of a computationally expensive model is replaced by an iterative updating and reoptimization of a fast multifidelity model constructed using a low-fidelity model adapted locally using manifold mapping (MM) to become a reliable

Application of the aeroelastic analysis and design framework developed at Delft University of Technology to a design of two aeroelastically tailored composite wings for a flying demonstrator is presented. The objective of the design process is to minimize structural mass of the wing while maintaining a target cruise shape. For this purpose, the jig shape of the wing is parameterized and becomes an

A classical flow-vane approach for reconstructing translational gust velocities from air data and inertial sensor measurements was improved and implemented for real-time computation. The reconstructed turbulence measurements were then included in a system identification analysis to estimate nondimensional stability and control derivatives in a longitudinal short period model using the maximum likelihood

Waveriders have a high lift-to-drag ratio in hypersonic states, while the flexibility of design methods must still be improved because of some deficiencies such as unsatisfactory off-design performance and stability. In this paper, a geometric relationship in the osculating-cone method is derived and expressed by a differential equation set including five equations. Then the equation set is simplified

Journal of Aircraft, Ahead of Print.

Journal of Aircraft, Ahead of Print.

The Aircraft Noise Simulation Working Group (ANSWr) was established by DLR, ONERA, and NASA to compare simulation tools, establish guidelines for noise prediction, and assess uncertainties associated with the simulation. A benchmark test was initiated, and initial results for a reference and a low-noise vehicle are discussed. The reference aircraft is a conventional tube-and-wing configuration with

A computational study is conducted on thin flat plates to simulate flows of Reynolds numbers at 104 to provide understanding and guidance for micro air vehicles and other low-Reynolds-number airfoil designs. A synergistic effort between experiments and validated and computational fluid dynamics (CFD) tools were used as part of this study. The CFD tool used in this study is an established Reynolds-averaged

The second generation of supersonic civil transport has to match ambitious targets in terms of efficiency to be economically and environmentally viable. Computational fluid dynamics-based design optimization offers a powerful approach to address the complex tradeoffs intrinsic to this novel configuration. This approach is applied to the design of airfoils and wings at both supersonic cruise conditions

This research focused on furthering the current understanding of the flowfield inside a cavity under typical flight conditions. The flight envelope included altitudes of up to 40,000 ft and maximum Mach number of 1.28 and included several test points between Mach 0.9 and 1.1, which are challenging to isolate in wind tunnel testing due to tunnel wall interference. The pod was instrumented to collect

Air vehicle sizing requires the ability to estimate the propulsive power and energy requirements of a flight vehicle as well as its weight. Existing tools and methods for aircraft sizing typically focus on a specific air vehicle category, generally assume a conventional fuel-burning propulsion system architecture, and employ a point-mass performance model. These shortcomings limit or preclude their

A low-order method is presented for aerodynamic prediction of wings operating at near-stall and post-stall flight conditions. The method is intended for use in design, modeling, and simulation. In this method, the flow separation due to stall is modeled in a vortex lattice framework as an effective reduction in the camber, or “decambering.” For each section of the wing, a parabolic decambering flap

Hover performance and prediction for tiltrotor-like vehicles lack experimental data and computational models for rotor–wing interaction at low disk loading and low Reynolds number. An experimental investigation of rotor–wing interaction in hover near the small unmanned-air-vehicle scale (disk loading < 100 N/m2 and Re<100,000) is conducted to determine how changes in rotor–wing geometry influence rotor–wing

This paper presents an investigation of the effects of tip sweep on highly twisted composite rotor blades by acquiring strain data in vacuum. Three parametric test cases were designed for strain measurements, and predictions from a special three-dimensional (3-D) finite element method were used for assessment of data. A set of rotating aluminum beams was also tested as a rudimentary baseline. Three

Implementations of lifting-line theory predict the lift of a finite wing using a sheet of semi-infinite vortices extending from a vortex filament placed along the locus of aerodynamic centers of the wing. Prandtl’s classical implementation is restricted to straight wings in flows without side slip. In this Paper, it is shown that lifting-line theory can be extended to swept wings if, at the control

A self-adaptive dissipation method based on a fifth-order dissipative compact scheme is proposed to reduce the numerical dissipation in separated flow. The method involves a self-adaptive operating parameter to adjust the weight of upwind part, which is a major source of numerical dissipation. Cooperated with delayed detached eddy simulation, the method can perform with less numerical dissipation in

The paper presents an aerodynamic investigation of 70 different streamlined bodies with fineness ratios ranging from 2 to 10. The bodies are chosen to idealize both unmanned and small manned aircraft fuselages and feature cross-sectional shapes that vary from circular to quadratic. The study focuses on friction and pressure drag in dependency of the individual body’s fineness ratio and cross section

Formation flight has the potential to significantly reduce aircraft fuel consumption by allowing “follower” aircraft to fly in the aerodynamic wake of “leader” aircraft. However, this requirement for aircraft to be in close proximity for large parts of their journey raises questions about the suitability of flying in formation given the diverse range of existing flights and geographical regions. This

Hybrid wing body is a fuel-efficient aircraft configuration where the pressurized center section is confined by almost-flat panels jointed at right angles. The combination of internal pressure and in-plane loads imparts cyclic large out-of-plane deformations to the noncircular fuselage. These repeated pressure loads would lead to separation between the skin and flanges and delaminations in traditional

Airfoils tested at low speeds generally produce surface pressure distributions that differ substantially from those measured at transonic conditions, which in turn results in very different boundary-layer characteristics even for the same Reynolds number. A methodology is presented for mapping transonic pressure gradients to an equivalent low-speed airfoil. It is applied to the design of a low-speed

The aerodynamic data of winged and lifting space vehicles are considered. Recently, there was an investigation with respect to the longitudinal aerodynamics of these vehicles in the supersonic and hypersonic Mach number regimes with the astonishing result that for the lift and drag coefficients a similarity with regard to the geometrical configuration could be observed. It was shown that by introducing

Uncertainty based multidisciplinary analysis (UMDA) is a methodology to quantify uncertainty on the system-level quantity of interest by propagating uncertainty within and among multiple disciplines of a system. In an industrial setting, the design of complex systems involves the collaboration of multiple and diverse teams involving high-fidelity disciplinary tools and experts. Under such scenarios

An experimental study is conducted on a NACA 0012 airfoil with a control surface to investigate the influence of a propeller slipstream under a low-Reynolds-number condition. To investigate the influence of the propeller slipstream on a wing surface, the flowfield on the wing surface is visualized using a temperature-sensitive paint when the chord-based Reynolds number is equal to 3.0×104. The control

Flying animals exploit highly nonlinear dynamics to achieve efficient and robust flight control. It appears that the distributed flow and force sensor arrays found in flying animals are instrumental in enabling this performance. Using a wind-tunnel wing model instrumented with distributed arrays of strain and pressure sensors, we characterized the relationship between the distributed sensor signals

To ensure the aerodynamic performance of the slat in aircraft when retracted, it is necessary to set rubber seals in the seam between the leading-edge slat and the fixed leading edge. However, the extrusion and friction of the seal will induce the increment frictional loading on the slat driver. In the present Paper, a rigid–flexible body configuration model of the increment frictional loading was

For small short/vertical takeoff and landing (S/VTOL) unmanned aerial vehicles, the propeller design should reach a compromise between S/VTOL and cruise. But the complexity cost of a variable-pitch propeller is too high to be applied to small propellers. To achieve the propeller pitch variability with minimum mechanic complexity and weight cost, an aerostable concept was used in the design of the blades

Research interest is growing for theoretical models of highly deflected structures in aeroelastic settings. Presented here is a model of a cantilevered plate subjected to axial supersonic flow to determine the flutter boundary and postflutter characteristics of a system such as a trailing edge control surface. The structural model is a nonlinear inextensible beam model with inertia and stiffness geometric

A first principles physics-based simulation framework that accounts for wind-over-deck (WOD) and ground effects during approach and landing of a helicopter on a ship deck is developed. The WOD velocities are obtained from unsteady detached-eddy simulation of the flow over a simple frigate shape version 2 ship. The HeliUM2 flight dynamics code was modified to include WOD, static and dynamic ground effects

Urban air mobility refers to an envisaged air taxi service, using small, autonomous, vertical-takeoff-and-landing, battery-powered electric aircraft. A conceptual design and optimization tool for urban air mobility, including vehicle, mission, and cost models, is presented in this paper. The tool uses geometric programming, a class of optimization problems with extremely fast solve times and for which

Journal of Aircraft, Ahead of Print.

Journal of Aircraft, Ahead of Print.

The flows past morphing cavities with different ramps of the leading wall and the fixed ramp of the trailing wall were investigated with direct numerical simulation and dynamic mode decomposition to analyze the oscillation phenomena. Based on the analysis of pressure signal and sound pressure level spectra obtained by direct numerical simulation, an interesting fact is found that there is a transition

The paper presents computational prediction of aerodynamic hysteresis loops in static conditions for a two-dimensional aerofoil that was used as a cross-section profile for a rectangular wing with an aspect ratio of five, tested in the TsAGI T-106 wind tunnel at a Reynolds number of Re=6×106 and a Mach number of M=0.15. Tests in the wind tunnel showed that minor changes in the curvature of the leading

Technology forecasting is an essential starting point for conceptual design of any complex engineering system. In fact, many research projects are focused on developing a small set of promising technologies to a suitable readiness level. However, selecting a set of technologies from a larger pool is a nontrivial task, opposed by uncertainty and subjective tradeoffs. This paper proposes a probabilistic

In forward flight, slowing down a rotor alleviates compressibility effects on the advancing side blade tip, extending the cruise speed limit, and inducing high-advance-ratio flight regime. Previous wind tunnel tests have shown that an articulated rotor trimmed to zero hub moment generates limited thrust at high advance ratios, because the advancing side needs to be trimmed against the retreating side

Journal of Aircraft, Ahead of Print.

Spatially distributed load on aircraft structures is difficult to obtain due to the limitation of measurement technology, the complexity of load and the external environment of the aircraft during flight, etc. A load identification method based on a subregion interpolation technique is proposed to indirectly estimate the distributed dynamic load from measured strain data on planar structures. The load

Conceptual sizing and performance estimation of four vertical takeoff and landing (VTOL) configurations for a package delivery mission is presented in this Paper. The multifidelity VTOL design framework HYDRA is used to size a notional quadrotor, hexarotor, quadrotor biplane tailsitter (QBiT), and a lift-augmented tricopter for weight classes of 10, 15, 20, and 25 kg. Sizing is performed using a combination

Journal of Aircraft, Ahead of Print.

Journal of Aircraft, Ahead of Print.

The modeling of different problems in aeroelasticity requires a time-domain equation of motion, especially to design modern controllers and study nonlinear characteristics. Typically, unsteady aerodynamic forces are written in the (reduced) frequency domain and then rewritten using rational function approximations in the time domain. In this context, this Paper presents an investigation of this topic

Journal of Aircraft, Ahead of Print.

In recent years, multilayered hierarchical compositions of the well-known and widely used Gaussian process models called deep Gaussian processes are finding use in the approximation of black-box functions. In this paper, the performance of deep Gaussian process models is empirically evaluated and compared against the well-established Gaussian process models with a special emphasis on engineering problems

This paper uses gradient-based optimization to minimize the mass of a solar-regenerative high-altitude long-endurance flying-wing aircraft while accounting for nonlinear aeroelastic effects. The aircraft is designed to fly year round at 35° latitude at 18 km above sea level and subjected to energy capture, energy storage, material failure, local buckling, stall, longitudinal stability, and coupled

The present Paper investigates the ditching characteristics of a helicopter model by means of an in-house-developed smoothed-particle-hydrodynamics solver coupled with a six degree-of-freedom motion equation. Verification and validation have confirmed the feasibility and accuracy of the developed solver in predicting hydrodynamic problems. In view of the inherent importance, the effect of initial pitching

In this Paper, the wake dynamics of coaxial rotors are studied using the high-wake-resolution method. The high-wake-resolution method is a novel combination of the truncated vortex tube model for initial and boundary conditions and the wave-number-extended finite-volume interpolation scheme. The wake resolution of this method is verified by comparison with other general computational fluid dynamics

Air traffic controller workload is considered to be a limiting factor for further air traffic growth. To reduce workload, increased automation levels and novel decision-support tools are being investigated. This Paper describes the adaptation and evaluation of a previously developed interface, called the Solution Space Diagram, in a route merging task. It portrays both constrained and unconstrained

Some of the existing challenges of fixed-wing micro aerial vehicle designs at low Reynolds number are low lift and reduced aerodynamic efficiency. Delta wings, despite their characteristic maneuverability, are rarely used for micro aerial vehicles, perhaps due to the limited lifting capacity because of the reduced aspect ratio. Corrugations on insect wings are ubiquitous and augment the aerodynamic

Droplet deformation and breakup in the continuously accelerated flowfield generated by an incoming airfoil have been studied. The upper limit of droplet deformation and the minimum distance to the airfoil model at which the breakup onset takes place have been modeled. Three analytical equations have been developed based on the combination of two models: a droplet deformation and trajectory model for

A 10%-scale high-lift version of the Common Research Model and an active flow control (AFC) version of the model equipped with a simple-hinged flap were successfully tested. The main objective of the test was to develop an AFC system that can provide the necessary lift recovery on a simple-hinged flap high-lift system while minimizing its pneumatic power requirement. The tests were performed in the

A simple, accurate, reduced-order model is developed for predicting the maximum available thrust performance of subsonic ring-wing propulsors varying in shroud airfoil length, thickness, camber, and/or angle of attack relative to the centerline. The method, applicable to drones, aircraft, ships, and more, identifies the potential upper limit to the thrust augmentation available from hover to cruise

Recent aircraft noise calculation methods separate engine and airframe noise components to provide accurate single-flight noise predictions. General noise mapping, such as legal compliance calculations, usually relies on position data as the only available input. Therefore, more advanced input variables of engine and airframe noise models require estimation based on position data. This paper presents

Regime recognition (RR) is an important aspect of condition-based maintenance for modern helicopters. RR involves the postflight classification of flight data into regime categories. These classifications are then used to predict fatigue damage and vehicle usage spectra. Although several RR algorithms have been proposed to date, many suffer from an overreliance on training data or poor accuracy when

Because of the large domestic civil aircraft projects started in China a decade ago, there is a greater need to control the accuracy of the Mach number in aerodynamic tests, especially near the designed cruise point of large commercial aircraft. Nowadays the control accuracy of China Aerodynamics Research and Development Center 2.4-meter transonic wind tunnel Mach number is in the range of ±0.002 to

This paper presents a thorough evaluation of three flutter prediction techniques based on the well-understood autoregressive moving-average (ARMA) parametric model. Other than the original stability parameter Fz that is derived from the identified autoregressive coefficients, the flutter margin and the Houbolt–Rainey (H-R) method are also presented and adjusted to provide alternative flutter predictions

In this Paper, the integrated propeller–wing system design space is investigated to gain insight into the influence of propeller diameter, location, and rotation direction. To conduct this investigation, a methodology is developed that uses the propeller power required during steady-level flight as a metric for efficiency. Full mutual interaction between the propeller and wing are taken into account