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This paper describes the implementation and linearization of a coupled panel and vortex particle method in a state-variable form. More specifically, the coupled panel and vortex particle dynamics are formulated as a nonlinear system of ordinary differential equations in first-order form to be self-contained and inherently linearizable. Linearization of this coupled panel and vortex particle method is demonstrated via finite differencing and a novel analytical linearization technique to yield a linear time-invariant representation. The code is implemented in MATLAB® and validated against an open-source aerodynamic solver for a fixed wing in both stationary and unsteady conditions. The linearized models are verified against the nonlinear dynamics both in the time and frequency domains. Linearized models accurately represent the wake dynamics about the equilibrium condition for moderate amplitude inputs and for input frequencies covering the typical frequency range of flight dynamics and flight controls, i.e., 0.3-30 rad/s. Analytical linearization is shown to abate the cost of linearization over perturbation methods by O(n2), where n is the total number of states of the system. Linearized models of the coupled panel and vortex particle dynamics have applications in the flight dynamics of both fixed- and rotary-wing vehicles, where these dynamics can be used to augment the rigid-body dynamics. The coupled rigid-body and wake dynamics can be leveraged to assess the stability, response characteristics, and handling qualities of vehicles experiencing aerodynamic interactions between rotors, wings, and/or obstacles. [ABSTRACT FROM AUTHOR]

Laminar flow aircraft may potentially save fuel and reduce the emission of pollutants and greenhouse gases. However, laminar flow aircraft face challenges caused by contaminations on the wings, such as insect impact residue. To study insect residue on an aircraft airfoil, a new setup was developed that used rotary wings and shot an insect toward the leading edge. This setup kept insects intact before impact while airflow was maintained throughout the experiment. Additionally, the setup enabled the long-term observation of the impact residue while the test speed was adjusted. Two experiments were carried out to investigate inconsistencies from past studies about insect rupture velocity and the effect of airflow on residue. Drosophila Hydei was the insect used, and aluminum was used as the baseline substrate, which was also coated with polyurethane, acrylic, and two superhydrophobic coatings. Instead of a threshold velocity for the minimum rupture velocity of the insect, a range from initial insect rupture to the velocity at which insects ruptured in all instances was determined (i.e., 17–30 m/s). Furthermore, the presence of a coating (polyurethane) on the airfoil did not affect the minimum rupture velocity. It was observed that airflow, which has been previously mentioned as a mitigation method, did not change the residue amount after coagulation for all coatings. [ABSTRACT FROM AUTHOR]

The sparse atmosphere on the surface of Mars provides the necessary flight conditions for Mars unmanned aerial vehicles (UAVs) to perform low-altitude flights. This work presents a comprehensive overview of key technologies in the development of Mars UAVs, with a specific focus on rotary-wing Mars UAVs. It summarizes prototypes of rotary-wing Mars UAVs developed by various global research institutions. It reviews essential technologies in rotary-wing Mars UAV research, including the Mars near-surface atmospheric environment, aerodynamic characteristics, and principles of low-pressure flight control. This work also summarizes various experimental setups and ground test results for rotary-wing Mars UAVs. Furthermore, it discusses the future development trends of rotary-wing Mars UAVs. [ABSTRACT FROM AUTHOR]

The inherent stability of two-dimensional motion when hovering using beating wings that have a passive feathering motion is compared with that of rotary wings that have a passive flapping motion. The passive flapping motion of the rotary wings is determined by the bending elasticity, which is expressed by a spring at the wing root. The feathering motion of the beating wings is determined by the torsional elasticity, which is expressed by a damper and a spring at the wing root. The values of the damper and spring were determined by minimizing the necessary power in the present analysis. Unlike rotary wings with passive flapping motion, beating wings with passive feathering motion do not have pitch/roll damping. A flying robot with beating wings requires quicker flight control than one with rotary wings. The results indicate that a flying robot mimicking a living creature is more difficult to control than one with rotary wings. [ABSTRACT FROM AUTHOR]

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BACKGROUND: Spatial disorientation (SD) remains a stubborn and formidable challenge among rotary wing (RW) aircrews, particularly during times of high workload and deceptive visual cues. With tri-service agreement, British RW Forces employ a layered training approach that now includes simulator-based immersive scenarios. METHODS: Ten bespoke RW sD training scenarios were developed for the AW159 Wildcat helicopter simulator by a multidisciplinary team. scenarios were embedded within advanced training packages that were not solely focused on sD. a voluntary, anonymous survey instrument was distributed post-sD sortie to assess hazard awareness, training effectiveness, role and mission relevance, and perceived ability to respond to future sD threat. A corresponding assessment from the simulator instructor was used for independent determination if the crew became disoriented during the training. RESULTS: Over a 6-mo training cycle, 69 surveys were completed. seven-point Ukert-scale assessments yielded elevated median scores (6.0, respectively) across all four categories, suggesting favorable aircrew perceptions of training objective success. elevated scoring of previous sD training received suggests good penetrance among the RW community surveyed. Of all sorties flown, the majority of aircrew (68%) became disoriented at some point during the sortie. DISCUSSION: This report provides limited evidence in support of bespoke sD training scenarios within a synthetic training environment. the merits include flexible ability to address root causes, provision of an interactive and immersive environment, and compatibility with extant tactics and mission configurations. sD simulator-based training can serve as an important component of a layered, multimodal approach. [ABSTRACT FROM AUTHOR]

A rotor blade radial loading profile is presented that aims to passively mitigate the formation of coherent tip vortex structures in the near-field of the rotor wake. The method leverages principles of Helmholtz's theorems, where the strength of the vortex wake is proportional to radial gradients in the blade loading distribution. By avoiding such radial gradients, the near-field roll-up of the wake vortex can be mitigated. A pair of two-bladed rotor designs configured with the same thrust coefficient was produced using a finite-vortex rotary lifting line framework coupled to a constrained power optimization problem. A baseline rotor was designed based on a power-optimized approach, and a wake-optimized rotor was designed based on a power-optimized approach with an additional blade-root bending moment constraint. Phase-averaged stereoscopic particle image velocimetry data were acquired for each rotor operating in hover. The wake-optimized rotor blade produced a wake characterized by conical vortex sheets of significantly lower peak vorticity than the compact, helical tip vortices produced by the baseline design. The wake-optimized design exhibited increased axial velocities near the root that caused radial distortions of the wake flow structures, which were also found to decay at a faster rate than that for the baseline design. [ABSTRACT FROM AUTHOR]

Laminar flow aircraft may potentially save fuel and reduce the emission of pollutants and greenhouse gases. However, laminar flow aircraft face challenges caused by contaminations on the wings, such as insect impact residue. To study insect residue on an aircraft airfoil, a new setup was developed that used rotary wings and shot an insect toward the leading edge. This setup kept insects intact before impact while airflow was maintained throughout the experiment. Additionally, the setup enabled the long-term observation of the impact residue while the test speed was adjusted. Two experiments were carried out to investigate inconsistencies from past studies about insect rupture velocity and the effect of airflow on residue. Drosophila Hydei was the insect used, and aluminum was used as the baseline substrate, which was also coated with polyurethane, acrylic, and two superhydrophobic coatings. Instead of a threshold velocity for the minimum rupture velocity of the insect, a range from initial insect rupture to the velocity at which insects ruptured in all instances was determined (i.e., 17–30 m/s). Furthermore, the presence of a coating (polyurethane) on the airfoil did not affect the minimum rupture velocity. It was observed that airflow, which has been previously mentioned as a mitigation method, did not change the residue amount after coagulation for all coatings.

The sparse atmosphere on the surface of Mars provides the necessary flight conditions for Mars unmanned aerial vehicles (UAVs) to perform low-altitude flights. This work presents a comprehensive overview of key technologies in the development of Mars UAVs, with a specific focus on rotary-wing Mars UAVs. It summarizes prototypes of rotary-wing Mars UAVs developed by various global research institutions. It reviews essential technologies in rotary-wing Mars UAV research, including the Mars near-surface atmospheric environment, aerodynamic characteristics, and principles of low-pressure flight control. This work also summarizes various experimental setups and ground test results for rotary-wing Mars UAVs. Furthermore, it discusses the future development trends of rotary-wing Mars UAVs.

Wing flexibility is critical to flapping rotary wings (FRWs), and in that the deformation is bilaterally coupled with aerodynamic forces and thus determines the performance. Conventional solutions to this fluid-structure interaction (FSI) topic require considerable computational resources. In this paper, an efficient FSI model is proposed to calculate the aerodynamic force and passive twisting of FRWs. The passive pitching is regulated by a torsional spring, and the twisting is simplified as a quadratic distribution. A well-verified quasi-steady model is employed to estimate the aerodynamic forces. Our results show that the performance of rigid FRWs is superior to twistable FRWs within an upper limit of the wing-root stiffness k1, which is around 3×10-3 N·m·rad-¹. At higher k1 values, the twistable FRWs generate comparable lift to rigid FRWs at a higher efficiency. An increase in flapping frequency can remarkably reduce the efficiency of twistable FRWs despite the lift enhancement, while a concomitant reduction of flapping amplitude can moderate the loss of efficiency at higher flapping frequencies. Our model provides an efficient tool for the quick estimation of the aeroelastic performance of twistable FRWs and can thus contribute to the wing stiffness design. [ABSTRACT FROM AUTHOR]

This paper presents high-fidelity and simplified computational fluid dynamics modeling approaches within an optimization framework for compound rotorcraft configurations with rotor/propeller aerodynamic interactions. Simulations of an axial-flight ducted propeller and a rotor/wing test case are first presented to validate the in-house Helicopter Multi-Block 3 solver and to assess the actuator disk/line models for the simplified main rotor modeling. The actuator disk/line models are then used to represent the main rotor for simulations of a generalized rotor/propeller combination. The propeller performance is analyzed in detail, and large variations are observed in the single blade loading due to the main rotor wake. A simplified model for the rotor/propeller interaction simulation is also put forward, and an inflow distortion metric is proposed to quantify the aerodynamic interactions. With the help of a kriging surrogate model and the inflow distortion metric, aerodynamic interferences through the propeller disk are quantitatively visualized with variations in the propeller position, propeller thrust, and main rotor advance ratio. Optimization of the propeller position under the main rotor for minimized interference with rolling/pitching moment constraints is also attempted using both gradient-based (adjoint) and gradient-free (efficient global optimization) approaches. The optimization results are verified using blade resolved simulations, and fluctuations of the propeller single blade loading were effectively reduced due to the optimization. The work is a first step toward high-fidelity methods for vehicle and configuration optimization. [ABSTRACT FROM AUTHOR]

The flutter analysis of rotary laminated structures has been performed using Carrera Unified Formulation (CUF). CUF is a one-dimensional higher-order structural model, in which the displacement at the cross-section is the only unknown parameter. The cross-sectional displacement fields of the model are defined using the Lagrange- and Taylor expansion. The quasi-steady and unsteady theories (Theodorsen and Loewy) have been used to apply the aerodynamic force. Subsequently, the equation of motion is defined in ‘fundamental nucleus’ form using Hamilton’s principle. The engineering solution of the flutter condition has been obtained by using p-k method. The computational studies of flutter analysis have been done for various rotor hub, lamination sequence, and structural models. The regular, irregular plies and arbitrary fiber orientation of the orthotropic structures have also been considered. The present study suggests that the proposed CUF model can obtain an aeroelastic solution of rotary structure in a computationally and economically efficient manner.

As one of the subsystems of advanced flight simulators, Control Loading System (CLS) enhances the realism of simulation by artificially producing the control forces that occur during the actual flight. In this study, an engineering flight simulator is realized for the purpose of CLS development. The simulator integrates the CLS with a flight dynamics model and a visual system to enable validation with piloted simulations. A linkage type CLS is designed with high torque electric motors, while paying special attention to reconfigurability. Data measured from the actual flight controls is transformed to be input to the CLS by using the proposed systematic procedure. Performance of the designed CLS is investigated, according to the requirements of the international certification standards, by comparing the measured flight control behavior of the simulator with that of the actual aircraft. [ABSTRACT FROM AUTHOR]

In recent times, technological advancement boosts the desire of utilizing the autonomous Unmanned Aerial Vehicle (UAV) in both civil and military sectors. Among various UAVs, the ability of rotary wing UAVs (RUAVs) in vertical take-off and landing, to hover and perform quick maneuvering attract researchers to develop models fully autonomous control framework. The majority of first principle techniques in modeling and controlling RUAV face challenges in incorporating and handling various uncertainties. Recently various fuzzy and neuro-fuzzy based intelligent systems are utilized to enhance the RUAV's modeling and control performance. However, the majority of these fuzzy systems are based on batch learning methods, have static structure, and cannot adapt to rapidly changing environments. The implication of Evolving Intelligent System based model-free data-driven techniques can be a smart option since they can adapt their structure and parameters to cope with sudden changes in the behavior of RUAVs real-time flight. They work in a single pass learning fashion which is suitable for online real-time deployment. In this paper, state of the art of various fuzzy systems from the basic fuzzy system to evolving fuzzy system, their application in a RUAV namely quadcopter with existing limitations, and possible opportunities are analyzed. Besides, a variety of first principle techniques to control the quadcopter, their impediments, and conceivable solution with recently employed evolving fuzzy controllers are reviewed. [ABSTRACT FROM AUTHOR]

For airborne gravity gradiometry in rugged terrain, helicopters offer a significant advantage over fixed‐wing aircraft: their ability to maintain much lower ground clearances. Crucially, this provides both better signal‐to‐noise and better spatial resolution than is possible with a fixed‐wing survey in the same terrain. Comparing surveys over gentle terrain at Margaret Lake, Canada, and over rugged terrain at Mount Aso, Japan, demonstrates that there is some loss of spatial resolution in the more rugged terrain. The slightly higher altitudes forced by rugged terrain make the requirements for terrain correction easier than for gentle terrain. Transforming the curvature gradients measured by the Falcon gravity gradiometer into gravity and the complete set of tensor components is done by a Fourier method over gentle terrain and an equivalent source method for rugged terrain. The Fourier method is perfectly stable and uses iterative padding to improve the accuracy of the longer wavelengths. The equivalent source method relies on a smooth model inversion, and the source distribution must be designed to suit the survey design. [ABSTRACT FROM AUTHOR]

Applications for remotely operated rotary wing aerial vehicles, hereafter referred to as drones, are rapidly expanding in scope and such aircraft may soon become an integral part of everyday life as well as a source of innovation. However, it is quite difficult to improve drone flight performance and reduce development costs because performance optimization depends strongly on the intended application. As a result, drones are currently developed by trial and error using various rotary wing shapes. In this study, a device for evaluating the aerodynamic performance of rotary wings is proposed. We consider it likely that our proposed device will be useful for various drone-related applications in addition to facilitating drone development because it is inexpensive to produce and can eliminate the need for large expensive laboratory equipment such as wind tunnels when performing flight characteristic evaluations. In this paper, we report on the fabrication of our 3D general fused deposition modeling (FDM) printed device along with some experimental results.

The interaction of trailing vortices with lifting surfaces is investigated using two levels of modeling fidelity. An overset mesh-based Reynolds-averaged Navier-Stokes solver is considered as the high-fidelity computational model. A lower-fidelity model is developed by combining a vortex panel method with a propeller aerodynamic model and slipstream theory. The high-fidelity model is first validated against available experimental data obtained from the interaction of a trailing vortex generated by an upstream wing with a downstream wing. The ability of both models to represent the development of the vortex wake and integrated loads is assessed for a number of parametric configurations, including a case in which the vortex core directly impinges on the wing surface. Following this, isolated propeller and wing-mounted propeller configurations are studied. In all of these cases, the high-fidelity model is effective in predicting the details of the flow and integrated airloads. The low-fidelity model, although less accurate, is shown to accurately predict interactional air loads and performance at orders of magnitude less cost than the high-fidelity model, justifying its role as a viable tool in design and trajectory-planning applications. [ABSTRACT FROM AUTHOR]