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This research presents a virtual reality flight simulator (VRFS) that combines the advantages of desktop simulations and hardware mock-ups, i.e., the flexibility of a desktop flight simulation with the level of immersion close to a full flight simulator. In contrast to similar existing virtual reality flight simulators, the presented system focuses on human factors (HF) engineering and is used for evaluating flight decks in an early phase of the design process. Hence, HF tools that are based on HF methods have been integrated; applying these methods requires collecting objective (e.g., eye tracking, physiological data, head and finger movements) as well as subjective data (e.g., questionnaires). In this paper, three user studies are presented that demonstrate the application of the integrated HF methods and the general usability of the system. These studies have been conducted as part of human–machine interface (HMI) development projects and range from basic cognitive research to HMI evaluations using realistic scenarios. The user studies indicate that HF engineering with the help of this system is possible and a feasible alternative to other means of evaluation. Yet, the abilities are limited due to technological and physiological constraints. This is why the scope of the VRFS lies between desktop simulations and a full hardware mock-up and cannot replace either of those. However, the presented studies show that the system can provide reliable information on the interaction with HMI. Thus, it is a reliable low-cost addition in the early development process of cockpit human machine interaction technologies when it comes to HF evaluations.

To accurately solve the helicopter optimal equilibrium solution, a novel hybrid genetic algorithm for trimming the helicopter flight simulation model is presented, which solves the problem that traditional trim algorithm is easy to fall into local optimum point. Taking the parts of the body as unit, the flight simulation dynamic model of the whole helicopter including rotor, tail rotor and empennage has been established, in which the Pitt–Peters dynamic inflow model and Leishman–Beddoes unsteady dynamic stall model were integrated into the rotor model. Based on the body dynamic equation, the trim controls and constraint conditions of level flight and steady pitching flight were derived. Using two cases, the effectiveness and accuracy of the hybrid genetic algorithm were verified by comparison with the flight test data from the trim results of UH-60A helicopter. It is shown that there is a good agreement between the trim results and the flight test data. The hybrid genetic algorithm can quickly converge to the optimal solution and is suitable for trimming the simulation model of different flight conditions.

Purpose This paper aims to present the novel methodology of computational simulation of a helicopter flight, developed especially to investigate the vortex ring state (VRS) – a dangerous phenomenon that may occur in helicopter vertical or steep descent. Therefore, the methodology has to enable modelling of fast manoeuvres of a helicopter such as the entrance in and safe escape from the VRS. The additional purpose of the paper is to discuss the results of conducted simulations of such manoeuvres. Design/methodology/approach The developed methodology joins several methods of computational fluid dynamics and flight dynamic. The approach consists of calculation of aerodynamic forces acting on rotorcraft, by solution of the unsteady Reynold-averaged Navier–Stokes (URANS) equations using the finite volume method. In parallel, the equations of motion of the helicopter and the fluid–structure-interaction equations are solved. To reduce computational costs, the flow effects caused by rotating blades are modelled using a simplified approach based on the virtual blade model. Findings The developed methodology of computational simulation of fast manoeuvres of a helicopter may be a valuable and reliable tool, useful when investigating the VRS. The presented results of conducted simulations of helicopter manoeuvres qualitatively comply with both the results of known experimental studies and flight tests. Research limitations/implications The continuation of the presented research will primarily include quantitative validation of the developed methodology, with respect to well-documented flight tests of real helicopters. Practical implications The VRS is a very dangerous phenomenon that usually causes a sudden decrease of rotor thrust, an increase of the descent rate, deterioration of manoeuvrability and deficit of power. Because of this, it is difficult and risky to test the VRS during the real flight tests. Therefore, the reliable computer simulations performed using the developed methodology can significantly contribute to increase helicopter flight safety. Originality/value The paper presents the innovative and original methodology for simulating fast helicopter manoeuvres, distinguished by the original approach to flight control as well as the fact that the aerodynamic forces acting on the rotorcraft are calculated during the simulation based on the solution of URANS equations.

A concept of a new energy management system synthesizing meteorological and orographic influences on airplane safety envelope was developed and implemented at the ZHAW Centre for Aviation. A corresponding flight simulation environment was built in a Research and Didactics Simulator (ReDSim) to test the first implementation of the cockpit display system. A series of pilot-in-the-loop flight simulations were carried out with a group of pilots. A general aviation airplane model Piper PA-28 was modified for the study. The environment model in the ReDSim was modified to include a new ad hoc subsystem simulating atmospheric disturbance. In order to generate highly resolved wind fields in the ReDsim, a well-established large-eddy simulation model, the Parallelized Large-Eddy Simulation (PALM) framework, was used in the concept study, focusing on a small mountainous region in Switzerland, not far from Samedan. For a more realistic representation of specific meteorological situations, PALM was driven with boundary conditions extracted from the COSMO-1 reanalysis of MeteoSwiss. The essential variables (wind components, temperature, and pressure) were extracted from the PALM output and fed into the subsystem after interpolation to obtain the values at any instant and any aircraft position. Within this subsystem, it is also possible to generate statistical atmospheric turbulence based on the widely used Dryden turbulence model. The paper compares two ways of generating atmospheric turbulence, by combining the numerical method with the statistical model and introduces the flight test procedure with an emphasis on turbulence realism; it then presents the experiment results including a statistical assessment achieved by collecting pilot feedback on turbulence characteristics and turbulence/task combination.

In this paper, a high-fidelity computational fluid dynamics (CFD) and rigid body dynamics (RBD) coupled platform for virtual flight simulation is developed to investigate the flight stability of fixed canard dual-spin projectile. The platform's reliability is validated by reproducing the characteristic resonance instability of such projectiles. By coupling the solution of the Unsteady Reynolds-Averaged Navier-Stokes equations and the seven-degree-of-freedom RBD equations, the virtual flight simulations of fixed canard dual-spin projectiles at various curvature trajectories are achieved, and the dynamic mechanism of the trajectory following process is analyzed. The instability mechanism of the dynamic instability during trajectory following process of the fixed canard dual-spin projectile is elucidated by simulating the rolling/coning coupled forced motion, and subsequently validated through virtual flight simulations. The findings suggest that an appropriate yaw moment can drive the projectile axis to precession in the tangential direction of the trajectory, thereby enhancing the trajectory following stability. However, the damping of the projectile attains its minimum value when the forward body equilibrium rotational speed (−128 rad/s) is equal to the negative of the fast mode frequency of the projectile. Insufficient damping leads to the fixed canard dual-spin projectile exiting the dynamic stability domain during the trajectory following, resulting in weakly damped instability. Keeping the forward body not rotating or increasing the spin rates to −192 rad/s can enhance the projectile's damping, thereby improving its dynamic stability.

Radiotelemetry has advanced the field of wildlife biology, especially with the miniaturization of radio-tags. However, the major limitation when radio-tagging birds is the size of the animal to which a radio-tag can be attached. We tested how miniature radio-tags affected flight performance and behavior of Ruby-throated Hummingbirds (Archilochus colubris), possibly the smallest bird species that has been fitted with radio-tags. Using eyelash adhesive, we fitted hatch-year individuals (n = 20 males, n = 15 females) with faux radio-tags of 3 sizes that varied in mass and antenna length (220 mg, 12.7 cm; 240 mg, 12.7 cm; and 220 mg, 6.35 cm), then filmed the birds in a field aviary to quantify activity budgets. We also estimated flight range using flight simulation models. When the 3 radio-tag packages were pooled for analysis, the presence of a radio-tag significantly decreased both flight time (∼8%) and modeled flight range (∼23%) in comparison to control birds. However, a multiple-comparison analysis between the different packages revealed that there was a significant difference in flight time when the larger radio-tag package (240 mg) was attached, and no significant difference in flight time when the lighter radio-tag packages (220 mg) were attached. Our results are similar to those of other studies that analyzed the flight time or flight range of birds wearing radio-tags. Therefore, currently available lightweight radio-tags (≤220 mg) may be a new option to aid in the study of hummingbird biology. Future study should focus on the additional drag created by the radio-tag and the effects of the lightest radio-tag packages on free-ranging birds. These studies would provide additional information to determine the feasibility of the use of radio-tags to study hummingbird biology.

This paper presents a hybrid robust control design method for a third-order lower-triangular model of nonlinear dynamic systems in the presence of disturbance. In this paper, a novel control design is presented systematically to synthesize a robust nonlinear feedback controller, called backstepping sliding mode control (BSMC), for the proposed system by a combined approach of backstepping design and sliding mode control. In this approach, a family of the “sliding surface” is introduced in state transformations. Then, a smooth switching function of the sliding surface is introduced and enforced to include in virtual feedbacks and a real control law from the control selection phrases of the backstepping design loop. The achieved control method proves a well-tracking command with asymptotic stability, provides a robustness in the presence of uncertainties, and eliminates completely a chattering phenomenon. The application of flight-path angle control corresponding to the longitudinal dynamics of a high-performance F-16 aircraft simulation model is implemented. Under some assumptions, full nonlinear longitudinal dynamics is reformed into a lower-triangular system for a direct application to formulate a control law. A closed-loop system is achieved for in-flight simulation with different flight profiles for a comparison of the existing methods. Also, an external disturbance on different loading/unloading conditions in flight is applied to verify and validate robustness of the proposed control method.

Changes in the flight attitude of plant protection unmanned aerial vehicles (UAVs) can lead to oscillations in the liquid level of their medicine tanks, which may affect operational accuracy and stability, and could even pose a threat to flight safety. To address this issue, this article presents the design of a flight attitude simulator for crop protection UAVs, constructed on a six-degree-of-freedom motion platform. This simulator can replicate the various flight attitudes, such as emergency stops, turns, and point rotations, of plant protection UAVs. This article initially outlines the determination and design process for the structural parameters and 3D model of the flight attitude simulator specific to plant protection UAVs. Subsequently, simulations were performed to analyze liquid sloshing in the pesticide tank under various liquid flushing ratios during flight conditions, including emergency stops, climbs, and circling maneuvers. Finally, the influence of liquid sloshing on the flight stability of the plant protection UAVs in different attitudes and with varying liquid flushing ratios is presented. These results serve as a cornerstone for optimizing the flight parameters of plant protection UAVs, analyzing the characteristics of pesticide application, and designing effective pesticide containers.

This paper introduces a novel gimballed rotor mathematical model for real-time flight simulation of tilt-rotor aircraft and other vertical take-off and landing (VTOL) concepts, which improves the previous version of a multi-purpose rotor mathematical model developed by ZHAW and Politecnico di Torino as part of a comprehensive flight simulation model of a tilt-rotor aircraft currently implemented in the Research and Didactics Simulator of ZHAW and used for research activities such as handling qualities studies and flight control systems development. In the novel model, a new formulation of the flapping dynamics is indroduced to account for the gimballed rotor and better suit current tilt-rotor designs (XV-15, V-22, AW-609). This paper describes the mathematical model and provides a generic formulation as well as a specific one for 3-blades proprotors. The method expresses the gimbal attitude but also considers the variation of each blade’s flapping due to the elasticity of the blades, so that the rotor coning angle can be represented. A validation of the mathematical model is performed against the available literature on the XV-15 Tilt-rotor aircraft and a comparison between the previous model is provided to show the improvements achieved. The results show a good correlation between the model and the reference data and the registered performance allow real-time flight simulation with pilot and hardware in the loop.

Large-scale Unmanned Aerial Vehicle (UAV) groups flight simulation in two-dimensional planes is commonly applied to UAV cluster mission planning algorithm design. In this paper, an UAV control algorithm optimized for two-dimensional planes is designed. The tandem structure of closed loops, as well as the control laws of L1 and Total Energy Control System (TECS), are transplanted to an UAV model that is simplified to a moving particle of a two-dimensional space, and UAV flight simulation is performed based on the flight control algorithm. Compared with the traditional 3D space flight simulation, it can save hardware resources and improve the simulation efficiency. Compare with the flight simulation based on the geometric method, on the premise of maintaining the dynamics basis, the trajectory and dynamics curves are closer to the actual flight results in 3D space, and the dynamics data onto the entire flight can be recorded. It has been verified that 50 UAVs need only 0.8s to perform 100 square-area snake-like search simulation experiments, and the fitting degree of the UAV's flight curve to the three-dimensional space is greater than 80%. The two-dimensional plane flight control algorithm and flight simulation proposed in this paper provide a new simulation method for the design of UAV cluster mission planning algorithms, therefore can help promote the development of the subject.