Aircraft Maneuvers Research Articles

Exploring the impact of vector thrust on aircraft maneuverability utilizing bypass dual throat nozzle technology

With the progressive maturation of fluidic Thrust Vectoring technology, future advanced fighter aircraft are poised to adopt the new nozzle with higher vector efficiency. This research paper introduces an innovative analytical framework that seamlessly integrates nonlinear aircraft dynamics with thrust vectoring nozzles. An F-16 aircraft model and a bypass dual throat nozzle (BDTN) are introduced to analyze the impact of thrust vectoring on flight performance. Key findings indicate that thrust vectoring nozzles significantly enhance aircraft climb performance, resulting in a notable 28.1% increase in climb rate. Furthermore, the flow losses associated with these nozzles have minimal influence on the aircraft's kinematic state, with a mere 4.2% impact on mechanical energy within 10 s under a 20% thrust loss scenario. For thrust-vectored models performing maneuvers at a given pitch rate, a critical velocity threshold emerges. Above or equal to this threshold, thrust vectoring augments aircraft maneuverability; however, velocities below this threshold may lead to airspeed loss and increased risk of stall, emphasizing the delicate balance necessary for optimal performance. Lastly, the study reveals that during complex maneuvers, thrust vectoring enhances the aircraft's sideslip capability, further underlining its significance in enhancing overall flight performance.

Effect of hypergravity on CHF for water flow boiling in a rectangular channel

Abstract Hypergravity during the maneuver of aircraft can obviously increase the intensity of disturbance in flow boiling. The critical heat flux (CHF) is a critical parameter to prevent the aircraft thermal management system from drying out. On a rotating platform with distilled water as the working fluid, an experimental investigation into the water flow boiling CHF characteristics in a rectangular channel under hypergravity was carried out. In this study, the influence of hypergravity, entry temperature, mass velocity with heating direction on flow boiling CHF have been investigated and discussed. The results show that hypergravity has a clear effect on the CHF by improving two-phase mixing and bubble separation. CHF increases as the hypergravity and mass velocity increase but decreases as the inlet temperature rises. The orientation of the heating has a clear impact on CHF. A new fitting correlation was discovered as a result of the current study.

Comparative Study on the Application Efficacy of Small Disturbance Equation versus One-Dimensional Euler Equation in Nozzle Flow Analysis

This paper presents a numerical simulation study of subsonic and supersonic nozzle flow regimes utilizing the Small Disturbance Equation (SDE), implemented through Python to analyze flow stability under various boundary conditions. The SDE, extensively applied in aerospace, meteorology, and fluid mechanics, offers a critical framework for examining aircraft stability and maneuverability, essential for ensuring flight safety. Additionally, its application extends to spacecraft stability and control in aerospace science. The findings from this study reveal that subsonic flows, characterized by their stability and smoothness, respond more predictably under varying boundary conditions compared to their supersonic counterparts. Conversely, supersonic flows demonstrate increased sensitivity to changes in boundary conditions, resulting in more complex flow patterns. This sensitivity underscores the need for precise control mechanisms in supersonic applications to maintain flow stability and ensure the safety and efficiency of aerospace operations. The simulations underscore the practical importance of the SDE in advancing the understanding of dynamic flow problems across different scientific and engineering disciplines.

Selection of aerodynamic characteristics and engine parameters of a maneuverable aircraft under epistemic uncertainty

At the preliminary stage of aircraft design, it is usually required to solve the problem of insufficient initial data for applying traditional algoristic-type mathematical programming models. In many cases, numerous input parameters cannot be accurately specified at the time of making design decisions. If the inaccuracy of parameters is not taken into account, the actual values of target functions may differ significantly from the calculated ones when solving optimization problems. In this regard, the issue of current interest is the development of algorithms to improve the reliability of design decisions under conditions of epistemological uncertainty when experts engage in the formation of initial data. The paper considers the problem of selecting aerodynamic characteristics and engine parameters of maneuverable aircraft under conditions of uncertainty associated with inaccuracy of expert data. The applied problem under consideration is further complicated by the necessity to include “black box” models in the algorithms being developed. The paper proposes algorithms that apply the uncertainty theory together with “black box” models that implement optimization calculation techniques derived from previous engineering practice of aircraft design. Using these algorithms, experts are able to set uncertain parameters whereby the lack of data is factored in using uncertainty distribution functions. In cases of monotonicity of uncertain parameters in target functions, application of the uncertainty theory provides a significant reduction in computational costs compared to the method of statistical modeling in optimization calculations. The paper presents the results of computational studies of the developed algorithms. A genetic algorithm (mathematical optimization solver) is used to optimize the search for design solutions. Pareto frontiers are obtained for different confidence levels enabling to make design decisions including values of aerodynamic characteristics and engine parameters of maneuverable aircraft.

Gust Response and Alleviation of Avian-Inspired In-Plane Folding Wings.

The in-plane folding wing is one of the important research directions in the field of morphing or bionic aircraft, showing the unique application value of enhancing aircraft maneuverability and gust resistance. This article provides a structural realization of an in-plane folding wing and an aeroelasticity modeling method for the folding process of the wing. By approximating the change in structural properties in each time step, a method for calculating the structural transient response expressed in recursive form is obtained. On this basis, an aeroelasticity model of the wing is developed by coupling with the aerodynamic model using the unsteady panel/viscous vortex particle hybrid method. A wind-tunnel test is implemented to demonstrate the controllable morphing capability of the wing under aerodynamic loads and to validate the reliability of the wing loads predicted by the method in this paper. The results of the gust simulation show that the gust scale has a significant effect on the response of both the open- and closed-loop systems. When the gust alleviation controller is enabled, the peak bending moment at the wing root can be reduced by 5.5%∼47.3% according to different gust scales.

Aircraft deicing based on large vibration of wings

Since aircraft icing will decrease the ability of aircraft to generate lift, it is significant to consider the aircraft deicing problem. The paper presents an aircraft deicing method based on the cracking of the ice layer caused by the large deformations of wings. To describe the deformation of wings, the absolute coordinate-based formulation is used. The aircraft with high aspect ratio wings is simplified as a hub-beam system. Such a rigid-flexible system with the fast rotation speed of hub and the large deformation of the beam is modeled using absolute coordinate-based formulation accurately. The maneuver of the rigid body will lead to the large deformation of wings to do the de-icing. Numerical examples are presented to reveal that the maximum tensile strength on the wing surface with sinusoidal control torques with some amplitudes and frequencies is larger than the ice’s tensile strength. Hence, the proposed de-icing method based on the aircraft maneuvering is potential.

Robust decentralized controller design for highly Maneuverable Aircraft

Large-scale control systems often encounter challenges due to their intricate control structures, leading to delays and uncertainties when traditional centralized control methods are implemented in engineering applications. In response to these challenges and with the aim of enhancing control efficiency, the exploration of decentralized control approaches has become increasingly prominent. This paper presents two decentralized control strategies: fixed structure control theory, which is built upon the foundational principles of traditional robust controller design, and the weighted model approximation method, which integrates weighted model reduction with optimization strategies. The fixed structure control theory predetermines architecture of the controllers, significantly alleviating the computational burden associated with the development of robust controllers. Conversely, the weighted model approximation method proposes a more intuitive and succinct pathway for controller design and engineering application. The efficacy of these strategies is evaluated through their application to the Highly Maneuverable Aircraft (HIMAT) system. The results demonstrate that, the fixed structure control theory generally exhibits good performance. However, in certain engineering scenarios, the conclusions derived from the weighted model approximation method for decentralized controller design are easier to comprehend and facilitate rapid application.

Computational investigation of both geometric and fluidic compressible turbulent thrust vectoring, using a Coanda based nozzle

This study addresses the challenge of enhancing aircraft maneuverability, particularly for vertical landing and takeoff, focusing on the fluidic aerial Coanda high efficiency orienting jet nozzle that employs the Coanda effect to achieve thrust vectoring. This research advances understanding of the interplay between geometric and fluidic factors in thrust vectoring. Stationary, turbulent, and compressible flow conditions are assumed, employing Favre-averaged Reynolds-averaged Navier–Stokes approach with the standard k-ε model. Computational solutions were obtained using a pressure-based finite volume method and a structured computational grid. The key findings include thrust vectoring enhancement due to an increase in the total mass flow rate, septum position (at no shock wave-related issues), and Reynolds number. In addition, shock wave formation (at specific mass flow rates and septum positions) considerably affects thrust vectoring. These insights are crucial for optimizing Coanda-based nozzle design in advanced propulsion systems, including in unmanned aircraft vehicles.

High-α maneuver under lateral centre of gravity uncertainty: A robust adaptive backstepping control scheme

The present note addresses the novel problem of executing complex aircraft maneuvers under considerable center of gravity (c.g.) uncertainties arising from asymmetrical loading or release of payloads, uneven fuel consumption etc. First, the aircraft flight dynamics under predominantly lateral c.g. movement, is approximated and expressed in a block strict feedback form and thereafter an adaptive backstepping controller is proposed to adapt to the c.g. variations. To alleviate the model uncertainty caused by this model approximation and also to provide robustness to aerodynamic uncertainties in high-alpha regions, a sliding mode control is further integrated with the adaptive backstepping control law. Asymptotic stability conditions of the proposed controller are derived from the first principle using Lyapunov’s method and Barbalat’s lemma. To validate the proposed control scheme, the high-alpha Herbst maneuver is implemented in simulation for the F18-HARV aircraft and the results show that the maneuver performance remains nearly the same under both the nominal and the off-nominal c.g. positions.

Research on morphing aircraft maneuver control based on active disturbance rejection control

Aiming at the problems of model uncertainties caused by morphing aircraft during morphing process and disturbance encountered when maneuvering, a morphing aircraft maneuver control method based on active disturbance rejection control (ADRC) is proposed to eliminate the influences of model uncertainty and external disturbance and improve the rapidity and accuracy of maneuver control. Firstly, a nonlinear model for morphing aircraft is established and the impact mechanism of morphing process is analyzed. Then, the ADRC technique is used to design the angular rate robust control law and the control performance of ADRC law is analyzed under the influence of disturbance. Finally, the immelmann turn maneuver is selected to verify the performance of the designed control law with aerodynamic parameters perturbation combined with the morphing process. The simulation results show that the method possesses good decoupling effect and strong disturbance rejection ability. Moreover, the aircraft's maneuverability and the control margin of control surface can be effectively improved through morphing

Imitation learning for aerobatic maneuvering in fixed-wing aircraft

This study focuses on the task of developing automated models for complex aerobatic aircraft maneuvers. The approach employed here utilizes Behavioral Cloning, a technique in which human pilots supply a series of sample maneuvers. These maneuvers serve as training data for a Machine Learning algorithm, enabling the system to generate control models for each maneuver. The optimal instances for each maneuver were chosen based on a set of objective evaluation criteria. By utilizing these selected sets of examples, resilient models were developed, capable of reproducing the maneuvers performed by the human pilots who supplied the examples. In certain instances, these models even exhibited superior performance compared to the pilots themselves, a phenomenon referred to as the “clean-up effect”. We also explore the application of transfer learning to adapt the developed controllers to various airplane models, revealing compelling evidence that transfer learning is effective for refining them for targeted aircraft. A comprehensive set of intricate maneuvers was executed through a meta-controller capable of orchestrating the fundamental maneuvers acquired through imitation. This undertaking yielded promising outcomes, demonstrating the proficiency of several Machine Learning models in successfully executing highly intricate aircraft maneuvers. This paper is an extended version of the previously ICCS 2023 published conference paper [1] .

Enhancing aero-engine thrust response: Accounting for combustion delays

In scenarios like aircraft landing, Rapid Thrust Modulation (RTM) is required to achieve high-precision attitude and trajectory manipulations. However, the traditional manipulated variable in aero-engines, specifically the fuel flow, experiences sluggishness in adjusting thrust (Fn) due to combustion delays. In contrast, geometric variable areas, like the nozzle throat area (A8), offer rapid responsiveness but have limited thrust-adjusting capacity. Hence, the proposal of an innovative parallel Valve Position Control (VPC) scheme, combining redundant control inputs, emerges as a groundbreaking solution to enable RTM. In the pursuit of achieving RTM, the non-minimum phase thrust responses are first addressed, which has not been recognized previously to the best of the author's knowledge. This includes the implementation of a new valve position control (VPC) structure, incorporating a dual input Single Output (DISO) system, which is vital for optimizing response time and minimizing the delayed effects in combustion processes. After proper selection of operating conditions, the synthesis process of VPC is outlined by three key requirements, including: 1) realizing the 10 rad/s thrust bandwidth despite the combustion delay; 2) ensuring continuous modulation capability by mid-ranging the A8; 3) decoupling the A8 and thrust during flights. The VPC controller is implemented and compared with the classical Edmond algorithm in a turbofan engine. Results emphasize VPC's robustness in handling combustion delays, meeting specified requirements, and showcasing its potential as an effective RTM solution. Practically, the VPC system's architecture allows for critical rapid thrust changes within a 10 rad/s bandwidth, essential for operations like VSTOL aircraft maneuvers.

Future flight deck design: Developing an innovative touchscreen inceptor combined with the primary flight display

The touchscreen has the potential to optimize the space usage and efficiency of the flight deck. Currently, touchscreens can combine the input and output functions of different systems. However, it does not yet serve as an inceptor to replace the sidestick or control column for aircraft manoeuvres. This study aims to examine the potential of a touchscreen as a flight inceptor compared with a traditional sidestick and gamepad. This research recruited 72 participants who interacted with three inceptors for both an instrument landing with disturbance and without disturbance using the Future System Simulator. The findings demonstrated that pilot performance, system usability and pilots’ situation awareness of touchscreen inceptors were significantly inferior to those of traditional sidesticks and gamepads. Compared to the sidestick and gamepad, the touchscreen provided a poorer situation awareness with the highest supply and demand. In addition, the performance of all inceptors was significantly influenced by disturbance. There is still a long way to go for certification of a touchscreen as an inceptor on the future flight deck. This research showed that even though the touchscreen inceptor scored the lowest on both SUS and SART, the majority of pilots agreed that the touchscreen inceptor provided a better attentional supply in challenging disturbance circumstances, providing proof of concept for its possible inclusion in flight deck design. There is a potential that the emerging touchscreen as an inceptor may develop further along with human-system integration flight deck design.

Analysis of Flight Loads during Symmetric Aircraft Maneuvers Based on the Gradient-Enhanced Kriging Model

The analysis of flight loads during symmetric aircraft maneuvers is an essential but computationally intensive task in aircraft design. The significant structural elastic deformation in modern aircraft further complicates this work, adding to the computational demands. Therefore, improving the analysis efficiency of flight loads during maneuvers is crucial for accelerating design interactions and shortening the development cycle. This study explores a method for analyzing flight loads in the time domain during maneuvers of elastic aircraft by introducing a database of high-precision rigid-body aerodynamic loads. Furthermore, it combines the gradient-enhanced Kriging model to efficiently predict elastic flight loads during longitudinal maneuvers. The results indicate that the proposed surrogate-based method has high fitting accuracy with significantly improved computational efficiency, providing a new approach for efficient analysis of flight loads during aircraft maneuvers.

Fluid–Structure Coupled Analysis of Maneuver Load Alleviation on a Large Transport Aircraft

Fluid–structure coupled simulations are performed for quasi-steady pitching maneuvers of a large transport aircraft with a load alleviation system consisting of trailing edge flaps and droop noses at the leading edge. For the fluid part of the simulation, a RANS approach is used, whereas the structural simulation is based on a linear modal model. The selected maneuvers are located on the lift boundary of the maneuver envelope at maximum load factor, as not only are the structural loads high here, but also redistributing lift for load alleviation is especially challenging as the wing is close to stall. For a target value of 33% reduction in wing bending loads, which is derived from the CS-25, the effects of applying load alleviation on wing loads, deformations, and aircraft maneuverability are investigated. It is found that the desired reduction of wing bending loads can be achieved for all maneuvers considered, while controlling the torsional moment turns out to be more difficult. A loss of maneuverability due to load alleviation is observed for only one of the maneuvers, while for the other maneuvers, maneuverability could even be increased. To assess the influence of the elasticity of the wing, additional simulations of the rigid wing are carried out and compared with the elastic results. Finally, other potential applications of the considered flap system are also explored. Here, for example, a cruise drag reduction of up to 1.8% is possible by adjusting the spanwise lift distribution.

Problems of interception of high speed aircraft maneuvering according to complex laws. Part 2. Analysis of flight paths of foreign aircraft

Problems of interception of high speed aircraft maneuvering according to complex laws. Part 2. Analysis of flight paths of foreign aircraft

A real-time digital twin for active safety in an aircraft hangar

The aerospace industry prioritises safety protocols to prevent accidents that can result in injuries, fatalities, or aircraft damage. One of the potential hazards that can occur while manoeuvring aircraft in and out of a hangar is collisions with other aircraft or buildings, which can lead to operational disruption and costly repairs. To tackle this issue, we have developed the Smart Hangar project, which aims to alert personnel of increased risks and prevent incidents from happening. The Smart Hangar project uses computer vision, LiDAR, and ultra-wideband sensors to track all objects and individuals within the hangar space. These data inputs are combined to form a real-time 3D Digital Twin (DT) of the hangar environment. The Active Safety system then uses the DT to perform real-time path planning, collision prediction, and safety alerts for tow truck drivers and hangar personnel. This paper provides a detailed overview of the system architecture, including the technologies used, and highlights the system’s performance. By implementing this system, we aim to reduce the risk of accidents in the aerospace industry and increase safety for all personnel involved. Additionally, we identify future research directions for the Smart Hangar project.

Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

Thrust vectoring technology plays an important role in improving the maneuverability of aircraft. In order to overcome the disadvantages of mechanical thrust vectoring nozzles, such as complications of structure and significant increases in weight and cost, fluidic thrust vectoring nozzles are proposed. Dual Throat fluidic thrust vectoring Nozzle (DTN) has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss. In this study, three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response. Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated. It is found that the dynamic response will experience three stages: rapid-deflecting stage, oscillating stage, and steady stage. A complete recirculation zone forms at the end of the rapid-deflecting stage, which pushes the primary flow to attach to the wall opposite the secondary injection. Meanwhile, the exhaust flow is deflected. In terms of DTN’s application, the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers. In addition, continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios. The control moment is generated due to the asymmetrical pressure distribution of nozzle surface, which is mainly contributed by the pressure decrease on the secondary injection surface. Moreover, the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/% and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4. These results provide an important theoretical basis for the practical application of DTN.

Problems of interception of high speed aircraft maneuvering according to complex laws. Part 1. Features of the use of high speed aircraft, complicating their interception

Problems of interception of high speed aircraft maneuvering according to complex laws. Part 1. Features of the use of high speed aircraft, complicating their interception

Model-based manoeuvre analysis: a path to a new paradigm in aircraft flight dynamics

We propose a closed-form system of nonlinear equations for the pitch plane or longitudinal motions of a fixed-wing aircraft and use it to demonstrate a possible path to the unification of theoretical flight dynamics and practical analysis of aircraft manoeuvres. The derivation of an explicit model free of data tables and interpolated functions is enabled by our use of empirical formulae for lift and drag which agree with experiments. We validate the model by recovering the well-known short period and phugoid modes, and the regions of normal and reversed command. We then use the model to present detailed simulations of two acrobatic manoeuvres, an Immelmann turn and a vertical dive. Providing new quantitative insights into the dynamics of aviation, our model-based manoeuvre analysis has the potential to impact both the academic flight dynamics curriculum and the ground training program for pilots of manned and unmanned aircraft. Possible consequences of future model-centric pilot training may include improved safety standards in general and commercial aviation as well as expedited theoretical course completion in air transport.