Aircraft Performance Research Articles

飛行データの空力係数の推定と不確かさの要因分析

The aerodynamic coefficients are essential parameters to determine the flight performance of aircraft. They are estimated by wind tunnel tests and CFD analyses, and it is important to assess the validation by comparing those estimated from actual flight test data. In this comparison, uncertainties of estimated parameters are of strong interest, therefore the analysis of these uncertainties is a very important issue. In this paper, aerodynamic coefficients with their uncertainties are estimated from flight data, and their validation is implemented by the inverse simulation method. Then the causes of uncertainties are investigated and dominant causes are quantitatively identified. The aircraft weight has a dominant effect on CL, while the angle of attack and the thrust have a large effect on CD.

Time Stacking Decision Tree for Oscillatory Failure Case Detection in a Flight Control System

Flight control systems are an essential part of aircraft, consisting of all elements between the pilot and the movable parts, such as actuators, controllers, and sensors, to control the aircraft's attitude, trajectory and speed. In this context, oscillatory failure cases are problems that can occur in any part of the flight control system, causing undesired oscillatory behavior that affects the aircraft's structural load. On the one hand, correctly detecting such failures enables weight saving to improve aircraft performance in different aspects; on the other hand, such detection enables reconfiguring the control law to keep the aircraft in its path. This work describes a data-driven oscillatory fault detection model and the control law reconfiguration for a fight control system for the Aerospace Industrial Benchmark. Preliminary results indicate that the developed system can accurately detect faults in several scenarios and properly reconfigure the control loop.

Analiza performansi i kinematike kretanja bespilotnih vazduhoplova

The use of drones today has become an integral part of modern life to the extent that the level of drone utilization determines the quality of life. The expansion of drone applications has grown exponentially. This growth is primarily due to their low acquisition and maintenance costs, as well as their versatility. First of all, their expansion is contributed by the low costs of both acquisition and maintenance, as well as the possibility of various applications. The paper aims to present drones and their advantages compared to traditional aircraft as a means of transportation. The paper includes an analysis of unmanned aircraft performance, an examination of the kinematics of unmanned aircraft movement, a discussion of the most common structure used in unmanned aircraft (the quadcopter), and a comprehensive assessment of the risks associated with unmanned aircraft and their potential integration into civil air traffic. The quadcopter structure, as the dominant solution for the production of unmanned aircraft, is discussed in detail. At the very end, an overall analysis of the risks posed by unmanned aircraft and, as such, whether they can be integrated into civil air traffic is given.

Conceptual Design and Control Schedule Optimization for Parallel Hybrid Propulsion System of Regional Turboprop Aircraft

Current environmental policies for the aviation industry motivate the use of cleaner propulsion systems to reduce its CO2 and noise footprint in the coming years. In this context, hybrid propulsion systems have emerged as a potential solution as they have demonstrated a good trade-off between performance and low pollutant emissions. In the present work, the conceptual design and control schedule optimisation of a parallel hybrid propulsion system for the De Havilland Dash 8 regional turboprop aircraft is carried out. A parametric study of the turboprop engine with different degrees of hybridisation at design point and off-design performance analysis of the parallel hybrid propulsion system with different control schedules for an aircraft typical mission has been carried out. Overall aircraft performance parameters are used to evaluate hybrid propulsion systems with different degrees of hybridisation and control schedules. From the results, it was found that a control schedule with 10-15% hybridisation during the cruise phase is the most promising when considering the aircraft mission blocked fuel and fuel efficiency.

Risk Evaluation of Single-engine Turboprop Commercial Operations in IMC

The main topic is aimed at risk assessment and possible risk mitigation of single-engine turboprop (SET) aeroplanes as part of commercial air transport (CAT) and operated in instrument meteorological conditions (IMC) or at night. The paper in the introductory part describes the theoretical issues of the SET-IMC flights and reveals the reasons why the approval of this type of operation was needed. The used analysis verifies later compared results of risk segments along the two compared flight paths, depending on various determinants affecting aircraft performance. The outputs alternatively present new possibilities for enhancing safety in case of engine flameout and following emergency landing procedures. The aim of the paper is also to provide an overview of legislation and regulations related to the CAT operations with SET aeroplanes, which also reflects risk evaluation, especially in IMC.

Study on performance and mechanisms of a novel integrated model with Power & Thermal Management system and turbofan engine

• A novel integrated model is developed by combining PTMS and engine system. • An off-design heat exchanger submodule without specifying detailed geometry is embedded. • The coupling influences of PTMS and engine are revealed over the entire flight envelope. • The weak cooling performance of PTMS arises in high Mach number and altitude regions. With the improvement of modern aircraft performance, thermal management has become increasingly challenging. The power and thermal management system (PTMS) proposed by Honeywell is an integrated approach to solve this problem. Although the PTMS has inevitable mass and energy interactions with the engine, the existing PTMSs are usually designed based on limited flight states without considering the full engine condition. Therefore, we first propose a novel integrated model combining PTMS and engine based on a semi-precise heat exchanger submodule. Parametric analysis is conducted to find out the impact of the engine and PTMS design variables on the propelling and cooling performance of the integrated system, and energy and exergy analyses are adopted to evaluate the degree of coupled effects between PTMS and engine over the whole flight envelope. Results show that the influence of FAN and HPC pressure ratio on refrigerating performance is more significant than the bypass ratio and inlet temperature of HPT at the design point. The cooling efficiency of PTMS is improved by 4.1% and 1.2%, respectively, as the pressure of HPC and FAN rises by 50%. Besides, the refrigerating performance of PTMS gradually weakens with the increasing flight Mach number, while the cooling efficiency reduces by 50% as the Mach number increases from 0 to 1.8. This trend indicates that the working condition and flight environment of the engine need to be considered in the design process of the PTMS system. As for the control variables of PTMS, the refrigerating efficiency of PTMS decreases by 60% when the pressure ratio of PTMS compressor (PTMS_COMP) changes from -33.3% to 33.3%. Inconsistently, the refrigerating efficiency shows a positive correlation with the heat transfer capacity of the kerosene heat exchanger (PTMS_KEHEX) and primary heat exchanger (PTMS_PRHEX). Meanwhile, the impact of the second heat exchanger (PTMS_SEHEX) on the cooling performance of PTMS can be neglected. Above all, in future PTMS designs, the influences of the pressure ratio of PTMS_COMP, the heat transfer capacity of PTMS_KEHEX and PTMS_PRHEX, as well as the engine control variables need to be considered simultaneously.

UAV Icing: A Survey of Recent Developments in Ice Detection Methods

In-flight icing remains a significant challenge for the aviation industry. While mature solutions for conventional aircraft exist, the options for small fixed-wing uncrewed aerial vehicles (UAVs) are limited, with the current solution being to postpone the flight until icing conditions have passed. Consequently, the challenges related to aircraft icing continue to be highly relevant, but now with a stronger emphasis on size, cost, and efficiency to better fit the smaller UAV platforms, which are currently experiencing high commercial interest. A crucial prerequisite for efficient ice protection solutions is the availability of real-time ice detection systems. This survey aims to provide an overview of recent developments in research on in-flight icing detection solutions suitable for UAVs. The survey covers atmospheric icing detection, direct ice detection, and indirect ice detection methods. Among these, the indirect methods, which are based on monitoring the aircraft performance degradation due to in-flight icing, are emphasized. The performance-based methods rely on flight data analysis, estimation, and detection algorithms, making them ideal for UAVs as they require only minimal aircraft modification and can be implemented retrospectively.

The Design of Advanced Very Light Jet Aircraft

The current state of the art in aircraft design has shown that in order to be economically viable and competitive it is necessary to investigate technology, which may give an improvement in performance and operational flexibility goal, but must be shown to be cost-effective. The current competitive environment forces the potential customers to buy advanced technology aircraft and requires manufacturers to provide more operational flexibility, without drastic performance penalties. This is a challenging task, which might be solved by the use of new technologies. It is believed that the application of an advanced high-lift capability, high cruise Mach number and lower moment turbulent airfoils derived from MS (1)-0317 and MS (1)-0313 to a wing would assist in achieving such a task. This paper describes an investigation aimed to examine the suitability of an aerodynamic wing design, allowing for the use of an advanced turbulent wing section concept for advanced medium-speed Very Light Jet (VLJ) aircraft. The paper describes the phenomenon of configuration design and outlines the wing design process. Description is then given of the aerodynamic design of a wing incorporated with an advanced turbulent wing section technology, tail design and aircraft performances. It concludes with a discussion of the results and recommendations for future work.

Low-Cost of Fix-Wing Prototype Using Zimmerman Design

This paper discussed the design and development of a fix-wing UAV that uses a Zimmerman parameter. To increase structural strength, a material made of expanded polypropylene and expanded polystyrene was used. Using a bagging vacuum technique for 24 hours, the structural strength procedure thoroughly combines the resin and fiber. The Zimmerman graph, generated at speeds between 50,000 and 200,000 using Reynolds Numbers (RE), was analyzed using three key variables: the coefficient of lift, drag, and the angle of attack (Alpha) of the airfoil. At 10o, the airfoil started to stall based on indicated coefficient used. The test flight is also comprised of pitch and roll flight with adequate force and little overshoot between the autopilot's requirement and the small aircraft's actual performance.

Deep generative modelling of aircraft trajectories in terminal maneuvering areas

Airspace design is subject to a multitude of constraints, which are mainly driven by the concern to keep the risk of mid-air collision below a target level of safety. For that purpose, Monte Carlo simulation methods can be applied to estimate aircraft conflict probability but require the accurate generation of artificial trajectories. Generative models allow to generate an infinite number of trajectories for air traffic procedures where only few observations are available. The generated trajectories must not only resemble observed trajectories in terms of statistical distributions but they should stay flyable and consider uncertainty due to weather, air traffic control, aircraft performances, or human factors. This paper focuses on the generation problem, and its main contribution lies in the adaptation of the Variational Autoencoder structure to the problem of 4-dimensional aircraft trajectories modelling using Temporal Convolutional Networks and a prior distribution composed of a Variational Mixture of Posteriors (VampPrior). The proposed model has been trained on trajectories in the Terminal Manoeuvre Area of Zurich airport, which have a particularly high degree of variability as air traffic controllers often take actions that deviate aircraft from the nominal approach procedure. The model has demonstrated great abilities to take into account such amount of uncertainty. Regarding metrics that evaluate the estimation of the statistical distribution of the observed trajectories, and the flyability of the generated ones, the proposed method outperforms traditional statistical methods by being able to generate more complex and realistic trajectories.

Numerical Studies on Fixed Wing Aircraft Aerodynamic Performance using Injection Suction Mechanism

In this current research work, a NACA 6321 flat bottom aerofoil has been altered to study its aerodynamic performance. A co-flow jet (CFJ) method was used with an injection slot located at 20% of chord length and the suction slot situated at 80% of chord length. Simulations have been carried out on the aerofoil models with various angles of attack (AOA) at a Mach number 0.05 to compute the variation in coefficient of lift (CL) and coefficient of drag (Cd) using a k-omega SST model. From the study, it was observed that CL and stalling AOA of an aircraft are increased by 27% and 33% respectively, with an introduction of the additional mass flow rate of 0.01 kg/sec in comparison with baseline aerofoil. It could be concluded that CFJ method enhanced the aerodynamic performance of fixed-wing aircraft due to boundary layer control over an aerofoil which reduces the overall aircraft weight and maintenance cost.

Addressing Thermal Distortion in Additive Manufacturing of Topology Optimized Structures Through Reverse Shape Morphing

Design of light weight structures is an important aspect in the aircraft industry, since minimizing the weightof components improves the overall aircraft performance. However, conventional manufacturing methods work on standard geometries and shapes, and often lead to overdesigning of parts. Additive Manufacturing (AM) overcomes these issues by allowing more design freedom. The present study focuses on two aspects of AM: (1) part consolidation through topology optimization, and (2) addressing thermal distortion through reverse shape morphing. An assembly of two load bearing brackets is first amalgamated into a single Topology Optimized (TO) part, which satisfies the displacement and stress requirements of the original design. After a series of optimization iterations, the final TO part (278 g) weighs 69 % lesser than the original assembled design (909 g), still meeting the design constraints. The TO part thus eliminates the need of fasteners to join both the brackets, thereby, making the design simpler yet effective. Moreover, a homogeneous stress distribution in the optimized part allows for efficient material utilization. In order to overcome thermal distortion that results during the AM process, the shape of the TO part is transformed in a sense opposite to the distortions produced. This is achieved through reverse shape morphing technique, that reduces thermal distortions in the printed part to sub-micron levels, and the morphed TO part conforms to the requirements meeting the design constraints. Therefore, the implementation of topology optimization along with reverse shape morphing makes the design simple and efficient having reduced distortion. This is achieved without any need of modifications in the manufacturing system or equipment, and such a strategy can be replicated and implemented at industrial scale as well.

A Secure, Configurable, Wireless System for Transfer of Sensor Data from Aircraft to Ground

Modern aircraft are complex systems, equipped with hundreds of embedded sensors that record a wide repertoire of data during flight, such as crucial engine and airframe parameters, status of flight control system, air conditioning system, landing gear, life-saving and emergency systems. The data from the sensors is stored in the Flight Data Recorder. Maintenance personnel routinely transfer this sensor data to a ground terminal device to analyze it for aircraft health and performance monitoring purposes. Manual methods of extracting sensor data can be tedious and error-prone when large fleets of aircraft are involved. This paper presents a novel system to extract sensor data from aircraft to a ground terminal, wirelessly. The wireless system is implemented using unique, configurable wireless transmitter receivers (WTRs) designed for this purpose. The hardware for the wireless transfer of data was designed, interfaced with a modern aircraft’s system, and tested with the aircraft on the ground and another flying object. The data from the aircraft’s Flight Data Recorder was successfully transmitted and received wirelessly by the ground terminal, over a distance of 50 meters (with aircraft on ground) and 10 Kilometers (with a flying object), in a secure mode with zero packet loss. The WTRs have also qualified the requisite tests for airborne certification.

Hydrodynamic Derivative Calculation and Turning Performance Simulation of Amphibious Aircraft

To improve the rotation efficiency of amphibious aircraft on the water surface, CFD technology is used to simulate maneuverable motion in this paper. The numerical calculations of direct navigation, oblique towing, no drift angle in rotating arm motion, drift angle in rotating arm motion, direct navigation with rudder, and planar motion are carried out, respectively. The hydrodynamic derivatives such as position derivative, rotation derivative, coupling derivative, rudder derivative, and added mass are obtained. On this basis, the rotational performance of amphibious aircraft is predicted. The results show that when the rudder is fully deflected, the rotation radius is 3159.1 m; when the engine differential and rudder run together, the rotation radius is 1216.8 m; the engine differential can effectively improve the rotation efficiency of amphibious aircraft on the water surface.

Influence of key-slot structure on interior ballistic performance of low-velocity aircraft

To investigate the interior ballistic performance of the cooperation of the guide slot and the guide key at a low velocity, a pressure-structure coupling method was put forward to obtain the effect of different structures. A lumped parameter model of an interior ballistic was utilized to govern the propellant combustion. The mechanical behaviors were predicted based on the engineering software ABAQUS. We coupled the interior ballistic parameters and the structures through moving boundaries by using a user subroutine interface VUAMP in ABAQUS. The results show that the coupling approach can accurately predict the movement process of the aircraft in the barrel, and different numbers of slots and different guide key structures were simulated. The fewer the slots, the smaller the resistance of the aircraft, but the corresponding guiding performance is poor. Inversely, more slots lead to the better guiding performance. Furthermore, different guide key structures have a greater impact on the exit velocity of the aircraft, but have little effect on the guiding performance. The guide key with edge rounding-off in side is a better structure case, which can obtain a stable rotational velocity and high launch speed on the premise of ensuring rigidity. The result can be applied to provide an important reference in determining reasonable numbers of slots and guide key structures for the application in engineering.

Aircraft Detection in SAR Images Based on Peak Feature Fusion and Adaptive Deformable Network

Due to the unique imaging mechanism of synthetic aperture radar (SAR), targets in SAR images often shows complex scattering characteristics, including unclear contours, incomplete scattering spots, attitude sensitivity, etc. Automatic aircraft detection is still a great challenge in SAR images. To cope with these problems, a novel approach called adaptive deformable network (ADN) combined with peak feature fusion (PFF) is proposed for aircraft detection. The PFF is designed for taking full advantage of the strong scattering features of aircraft, which consists of peak feature extraction and fusion. To fully exploit the strong scattering features of the aircraft in SAR images, peak features are extracted via the Harris detector and the eight-domain pixel detection of local maxima. Then, the saliency of aircraft under multiple imaging conditions is enhanced by multi-channel blending. All the PFF-preprocessed images are fed into the ADN for training and testing. The core components of ADN contain an adaptive spatial feature fusion (ASFF) module and a deformable convolution module (DCM). ASFF is utilized to reconcile the inconsistency across different feature scales, raising the characterization capabilities of the feature pyramid and improving the detection performance of multi-scale aircraft further. DCM is introduced to determine the 2-D offsets of feature maps adaptively, improving the geometric modeling abilities of aircraft in various shapes. The well-designed ADN is established by combining the two modules to alleviate the problems of the multi-scale targets and attitude sensitivity. Extensive experiments are conducted on the GaoFen-3 (GF3) dataset to demonstrate the effectiveness of the PFF-ADN with an average precision of 89.34%, as well as an F1-score of 91.11%. Compared with other mainstream algorithms, the proposed approach achieves state-of-the-art performance.

Autonomous and collaborative trajectory planning for traffic complexity management

AbstractTo accommodate growing air traffic demand, the traffic complexity management plays a crucial role in the capacity improvement of future automated air traffic management. In this paper, an autonomous and collaborative trajectory planning (ACTP) method is presented to facilitate collaborative decision‐making and enhance flexibility of the traffic complexity management in the en route airspace. A nonlinear integer model is formulated for the conflict‐free autonomous trajectory planning by reorganizing the trajectories with the combination of speed adjustment, lateral rerouting and flight level allocation maneuvers. Within the framework of the air‐ground situation awareness sharing, the spatio‐temporal reachable space is defined to describe the feasible solution space under the constraints of aircraft performance and required time of arrival. In addition, both the system‐level and the individual‐level objectives, traffic complexity and flight efficiency, are considered in the model, which are measured through the metric based on linear dynamical systems and the deviation from the user‐preferred trajectory. To balance the optimality and computational efficiency in the multi‐aircraft trajectory planning, a multi‐aircraft clustered and collaborative optimization algorithm is proposed based on the hybrid distributed‐centralized control strategy. The experimental results of the scenario in Western China airspace is presented, which verify the effectiveness of the proposed ACTP method through the comparison of other methods. Furthermore, a multi‐criteria decision‐making problem is discussed to strike a better trade‐off between different objectives in the trajectory planning.

Sizing of High-Aspect-Ratio Wings with Folding Wingtips

High-aspect-ratio wings are of particular interest to modern aircraft design due to the inherent reduction in induced drag that they provide. However, such wing configurations often come with problems such as increased structural weight and oversized wingspans for existing airport facilities. Unlike conventional folding wingtips, as used on the 777-X, this paper demonstrates the use of semi-aeroelastic hinge devices that enable aircraft incorporating high-aspect-ratio wings not only to fit into airport gates, but also to alleviate aerodynamic loads by allowing floating wingtips to be used in-flight. This study establishes a preliminary design process for such a wing configuration and undertakes a comprehensive sizing process to investigate the impact of the device on wing weight and aircraft performance. For the cases considered, a reduction in wing weight of approximately 25% can be achieved by utilizing the semi-aeroelastic hinge, which can lead to more than 5% improvement in aircraft range.

Comparison of Pollutants Emission for Hybrid Aircraft with Traditional and Multi-Propeller Distributed Propulsion

Due to the dynamic development of environmentally friendly aircraft propulsion, the paper describes the effect of distributed propulsion on the emission and fuel consumption changes of aircraft in comparison to aircraft with traditional propulsion. A distributed propulsion is a propulsion composed of a set of units located on the leading edges of the wings or on the fuselage, generating a thrust symmetrically distributed on both sides of the fuselage. The analysis was based on the technical data of AOS H2 motor glider. During the tests for the adopted geometry of distributed propulsion, the improvement of airframe aerodynamic parameters was determined by conducting a CFD flow analysis. Based on the energy method, the flight range and duration were determined for the aircraft with distributed propulsion. It occurred that they increased by 19% compared to the initial variant—traditional propulsion. For the adopted energy source—Wankel AG-407TGi engine, the emissions of CO, CO2, and NO in the exhausts were measured. After the application of distributed propulsion, the emissions and fuel consumption were reduced by 16%. The research conducted showed that the application of distributed propulsion instead of traditional propulsion can bring measurable environmental benefits. Conducting further research on multi-criteria optimization of aircraft structures may bring further benefits in terms of improving aircraft performance and environmentally friendly indicators.

A Simulation and Verification Platform for Avionics Systems Based on Future Airborne Capability Environment Architecture

Avionics systems, which determine the performance, stability, and safety of aircraft, are a crucial part of aircraft. With the rapid development of the aviation industry, there are many serious problems in the process of the traditional simulation and verification of avionics systems, especially in the aspects of poor reusability of the hardware and software, poor real-time data interaction, and the high cost of development. In order to solve these problems, a simulation and verification platform for avionics systems based on the Future Airborne Capability Environment (FACE) architecture has been designed by using component and memory database technology. First, a general architecture is designed by referencing the FACE architecture, which allows flexible access to software and hardware resources of avionics systems. Second, the key technologies involved in the platform are described in detail, including scheduling management, communication management, and configuration management, which provide technical support for the simulation and verification of avionics systems. Finally, the simulation and verification environment of avionics systems is established, which realizes data interaction and management of various models, and improves the efficiency of the development and implementation of avionics systems.