Large Aircraft Research Articles

Formulating Strategy and Technology Path for Next Generation Airworthiness Regulations of Aero-Engines

Airworthiness regulations are key for guaranteeing the safety of civil aviation products and a significant indication of a nation’s aviation power. A well-developed airworthiness regulation system is an effective technical and management means by which a country with an advanced aviation industry ensures the safety of its civil aviation products and occupies the broadest market share while using International Civil Aviation Organization (ICAO) rules. As major national science and technology projects for large aircraft, aero-engines, and gas turbines are implemented, it is imperative for China to further improve its airworthiness regulation system. In this study, we clarify the implications of aero-engine airworthiness regulations and summarize the problems regarding aero-engine airworthiness regulations both in China and abroad. Based on this, the formation strategy and technical path for the next-generation airworthiness regulations of aero-engines are explored from the perspectives of ICAO and China’s civil aviation industry. The formulation strategy emphasizes the requirement for system safety, and specific principles include an equivalent level of safety, clear logic, international compatibility, and local applicability. Moreover, a new top-level framework for the aero-engine airworthiness regulations is proposed; it inherits the international lessons learned, ensures a high safety standard, and adapts to the progress of system safety technologies of aero-engines. Furthermore, we suggest that China should continuously deepen the research, simultaneously expand application, and coordinate industry development, thus to promote the construction of the aero-engine airworthiness regulation system in China.

Flow Simulation of the Flight Manoeuvres of a Large Transport Aircraft with Load Alleviation – ERRATUM

Flow Simulation of the Flight Manoeuvres of a Large Transport Aircraft with Load Alleviation – ERRATUM

Enhanced Pose Adjustment System for Wing-Box Assembly in Large Aircraft Manufacturing

Abstract Strict quality requirements in aircraft manufacturing demand high-accuracy pose adjustment systems. However, the pose alignment process of a large complex structure is also affected by thermal and gravity deformations to a great extent. Even though the pose adjustment system passes accuracy verification, the pose of the large complex structure remains challenging to smoothly and efficiently converge to the desired pose. To solve this problem, we developed a pose adjustment system enhanced by integrating physical simulation for the wing-box assembly of a large aircraft. First, the development of the pose adjustment system, which is the base of the digital pose alignment of a large aircraft’s outer wing panel, is demonstrated. Then, pose alignment principles of duplex and multiple assembly objects based on the best-fit strategy are successively explored. After that, contribution analysis is conducted for nonideal pose alignment. Immediately following, influences of thermal and gravity deformations simultaneously coexisting for the pose alignment are discussed. Finally, a physical simulation-assisted pose alignment method is developed considering multisource errors, which uses the finite element analysis to integrate temperature fluctuation and gravity field effects. Compared with a conventional digital pose adjustment system driven by the classical best-fit, deviations of the key characteristic points significantly decreased despite the impacts of thermal and gravity deformations. The enhanced pose adjustment system has been applied to large aircraft wing-box assembly. It provides an improved understanding of the pose alignment of large-scale complex structures.

Solving the dilemma in supplier selection by the group of weight vector with kernel

PurposeThe purpose of this paper is to solve the dilemma in the process of major selection decision-making.Design/methodology/approachFirstly, the group of weight vector with kernel has been defined. Then, the weighted comprehensive clustering coefficient vector was calculated based on the group of weight vector with kernel. Under the action of weighted comprehensive clustering coefficient vector, the information including in other components around component k and supporting object i to be classified into the k-th category has been gathered to component k. At last, a novel two-stage decision model based on the group of weight vector with kernel and the weighted comprehensive clustering coefficient vector is put forward to solve the dilemma in grey clustering evaluation. Then the overall evaluation conclusion can be consistent with the clustering result according to the rule of maximum value.FindingsA new way to solve the dilemma in the process of major selection decision-making has been found. People can obtain a consistent result with two-stage decision model at the case of dilemma. That is, the conclusion of the overall evaluation is consistent with the clustering result according to the rule of maximum value.Practical implicationsSeveral functional groups of weight vector with kernel have been put forward. The proposed model can solve the clustering dilemma effectively and produce consistent results. A practical application of decision problem to solve the dilemma in supplier evaluation and selection of a key component of large commercial aircraft C919 have been completed by the novel two-stage decision model.Originality/valueThe two-stage decision model, the group of weight vector with kernel and the weighted comprehensive clustering coefficient vector were presented in this paper firstly. People can solve the dilemma in grey clustering evaluation effectively by the novel two-stage decision model based on the group of weight vector with kernel and the weighted comprehensive clustering coefficient vector.

Multi-objective aerodynamic optimization design of variable camber leading and trailing edge of airfoil

Variable camber is an effective method for improving the flight efficiency of large aircraft, and has attracted the attention of researchers. This work focused on the optimization of a variable camber airfoil. First, the influences of the variable camber of the leading and trailing edges on the airfoil aerodynamic performance were investigated using a computational fluid dynamics numerical simulation. An initial database was established for a deep neural network. Second, an iterative algorithm was constructed to optimize the variable camber airfoil in terms of the rotation angle of the leading edge, deflection position of the leading edge, rotation angle of the trailing edge, and deflection position of the trailing edge. A genetic algorithm was used in each iteration to maximize the lift coefficient and lift-to-drag ratio, as predicted using a deep neural network (DNN). The optimal results were validated using Fluent. If the DNN result approximated the Fluent results, the iterative process was stopped. Otherwise, the Fluent results were inserted into the database to update the DNN prediction model. The optimization results showed that the lift-to-drag ratio of the 2D airfoil could be increased by more than 14 when the angle of attack was less than 8° relative to the original airfoil. Furthermore, to validate the 2D optimal results, the optimized 2D airfoil was stretched into 3D, and it was discovered that the aerodynamic performance trend of the 3D airfoil with respect to the angle of attack was basically the same as that of the 2D airfoil. In addition, the corresponding 3D airfoil improved the aerodynamic performance and reduced the noise at a high frequency (by approximately 16 dB). In contrast, the noise in the low and medium frequencies remained unchanged. Therefore, the optimization method and results can provide a reference for the aerodynamic design and acoustic design of large civil aircraft wings.

On Creating Digital Technologies for the Production of Large Aircraft Frame and Skin Parts

On Creating Digital Technologies for the Production of Large Aircraft Frame and Skin Parts

Calculation of accuracy with the coordinate-positional method of basing

The article is devoted to the assessment of assembly accuracy when positioning with the use of industrial manipulators (robots). Classic assembly technologies are outdated and have many disadvantages that can be solved by the automation of industrial processes, which became possible due to the rapid development of robotization. In the material there are investigation the possibility of using industrial robots for positioning structural elements of aircraft from the point of view of achieving the required assembly accuracy. For the analysis, foreign literature sources and the current experience of introducing similar technologies by large aircraft manufacturers were used. To assess the assembly accuracy, the formulas for the functional size error were used. An enlarged technological assembly process is presented, graphic materials with basing schemes are presented. Based on the data obtained, the advantages and disadvantages of basing with the help of industrial robots at this stage of technology development are formulated, taking into account the existing production experience.

Experimental study of the resistance of RC walls with different transverse reinforcements subjected to large-scale rigid projectile impacts

After the 9/11 terrorist attacks, the nuclear power plants (NPPs) containment resisted a commercial aircraft or wind-borne missile impact has become one of the focus issues in the nuclear security field. Transverse reinforcement is typically used in reinforced concrete (RC) walls for nuclear engineering. However, there is little research related to the damage characteristics of RC walls with transverse reinforcement under the impact of a large-scale rigid projectile, and the effect of transverse reinforcement on penetration or perforation under projectile impact is still unclear. In this paper, according to different forms of transverse reinforcement, three types of RC walls were designed, and a total of eight large-scale rigid projectile impact tests for RC walls were performed. The failure mode of the walls, the concrete scabbed area, the penetration depth and the total failure number of longitudinal reinforcement were measured for comparison. The conclusion is that the form of transverse reinforcement influences the failure mode of an RC wall subjected to a rigid projectile impact. Transverse reinforcement plays a significant role in reducing the rear scabbing of the concrete. The tested walls with U-shaped transverse reinforcement show better performance than the walls in the form of classic stirrups with hooks with regard to perforation capacity under rigid projectile impact. In addition, the dynamic response characteristics of RC walls subjected to large-scale rigid projectile impacts are analyzed preliminarily, and the impact test results are consistent with the predictions of the Chang’s empirical formula on damage modes. The related works and conclusions can provide a basis for NPP structural optimization and the safety assessment of large commercial aircraft collision problems and can also provide experimental data to verify finite element methodology.

A Conceptual Design Methodology for e-VTOL Aircraft for Urban Air Mobility

Recent progress of electric systems has raised attention towards hybrid-electric and full-electric aircraft. Nevertheless, the current low battery energy density limits the application of these propulsive architectures to large transport aircraft. In the context of the general aviation category, full-electric aircraft for the so-called Urban Air Mobility scenario are gaining increasing interest. These air taxis, also called e-VTOL, are conceived to exploit vertical take-off and landing capabilities, to carry people from one point to another, typically within the same city. In this paper, a new conceptual design methodology for urban air vehicles is presented and applied to an innovative convertiplane, called TiltOne, based on a box-wing architecture coupled with tilt-wing mechanisms. Several TiltOne configurations have been designed according to the current regulations imposed by European Union Aviation Safety Agency, and sensitivity analyses have been carried out on the varying main design parameters, such as wing loading and propellers’ disk loading, as well as main top-level aircraft requirements. The results provide an overview for today’s operational capabilities of such aircraft and, in addition, depict possible scenarios for a near-future horizon, based on the assumption of increased performance levels for the electric powertrain components. In such scenario, two different concepts of operations are analysed and discussed: the first is based on a given design range, long enough to cover the urban distances; the second is conceived to exploit the capability of flying multiple shorter missions with a single battery charge. The designed TiltOne configurations derived from these different approaches are presented, highlighting their potential capabilities and possible drawbacks.

Development of the Low Toxic Cross Polar Air Transport using Innovative Hydrogen Projection for Large Aircraft and Airships

The new shortly and low cost Regular Airlines Cargo & PAX directions via Arctic Cross Polar Air Transportation Routes of the future High Ecology Efficiency and Safety ICAO Strategy will be base on the more perspective for Trans Continental Airlines Operations by IATA International Law Regulations and World Climate Protect Law. Using the more shortly directions of Trans Polar Flight for Long-Haul Aircrafts (LHA) Routes by leader Airlines Sky Teams with Aeroflot are request to find new Geometrical Layout of Aircraft Design Industrial Projections & Products Lines. The increase in the dimension of LHA came into conflict with modern Airport Infrastructure and led to the search for alternative Arctic Planes & Dirigibles Options for constructively layout circuit solutions with protection of minimum weight and drag issues in order to deal with this contradiction. Computer Digital Aircraft Structural-Parametric Analysis of the influence of Aviation Infrastructure Constraints in the basing of LHA on the choice of alternative Design Options for Lift Fuselage Body or Flying-V layout was carried out.

A Substructure Synthesis Method with Nonlinear ROM Including Geometric Nonlinearities

Large flexible aircraft are often accompanied by large deformations during flight leading to obvious geometric nonlinearities in response. Geometric nonlinear dynamic response simulations based on full-order models often carry unbearable computing burden. Meanwhile, geometric nonlinearities are caused by large flexible wings in most cases and the deformation of fuselages is small. Analyzing the whole aircraft as a nonlinear structure will greatly increase the analysis complexity and cost. The analysis of complicated aircraft structures can be more efficient and simplified if subcomponents can be divided and treated. This paper aims to develop a hybrid interface substructure synthesis method by expanding the nonlinear reduced-order model (ROM) with the implicit condensation and expansion (ICE) approach, to estimate the dynamic transient response for aircraft structures including geometric nonlinearities. A small number of linear modes are used to construct a nonlinear ROM for substructures with large deformation, and linear substructures with small deformation can also be assembled comprehensively. The method proposed is compatible with finite element method (FEM), allowing for realistic engineering model analysis. Numerical examples with large flexible aircraft models are calculated to validate the accuracy and efficiency of this method contrasted with nonlinear FEM.

Development of a Critical Care Air Transport Team "Go Bag": Slimming Down ICU Capability to Augment Pararescue or Civilian Contract Medical Evacuation Personnel.

Critical Care Air Transport Team (CCATT) is a three-person United States Air Force (USAF) medical asset, typically providing intercontinental medical evacuation on large military aircraft. The CCATT equipment Allowance Standard (AS) weighs approximately 272 kg (600 lbs). In austere locations, CCATT teams may augment contract medical evacuation (CME) personnel or Pararescue (PJ) in small aircraft with limited space for medical equipment. It was unknown what deployed PJ and CME carry within their packouts. We sought to design a packout or "Go Bag," weighing less than 22.7 kg (50 lbs) and sourced from the CCATT AS, that a CCATT member could use to complement CME or PJ equipment to provide a higher level of care while limiting redundancy. Equipment lists were obtained from a CME and PJs from two separate USAF squadrons. The equipment lists were combined to provide a reference for development of a CCATT Go Bag. Three members of a deployed CCATT team independently generated a list of necessary equipment from the CCATT AS. The list was peer reviewed by a separate, deployed CCATT team. A Go Bag was developed with the supplies and equipment necessary for video laryngoscopy, ventilation, invasive pressure monitoring, basic laboratory capability, chest tube placement, ultrasound, and advanced pharmacologic interventions. The Go Bag weighed 18.3 kg (40.4 lbs). A separate respiratory bag weighing 1.1 kg (2.4 lbs) was attached directly to a ventilator. Intravenous pumps and cardiac monitoring equipment were notable ICU equipment excluded from the Go Bag. Major components of the CCATT AS can be reduced into a Go Bag and accompanying Ventilator Accessory Bag. This may benefit CCATT teams required to augment PJs or CME in small aircraft during prolonged field care scenarios.

Which aircraft has a better fuel efficiency? – a case study in china

Different aircraft have different load capacity and fuel consumption. Understanding which aircraft has better fuel efficiency is meaningful for energy conservation and reducing operation costs. This paper derives the relationship between fuel consumption and aircraft payload through the flight dynamics model for flights in which the flight distance is smaller than 3000 Km. The fuel consumption of the aircraft during different phases can be considered linearly positively correlated with the payload of the aircraft when other parameters are fixed. A case study is carried out on which aircraft has better fuel efficiency in China and verifies the relationship between fuel consumption and aircraft payload. It can be found that with the increase of the payload, the average fuel consumption decrease and smaller aircraft always have a smaller average fuel consumption at the same payload than the larger aircraft. The work can help with energy conservation and fleet planning for airlines.

Исследование информационной полноты радиолокационных данных в задачах классификации точечных воздушных объектов.

In the article considers the estimation of completeness of radar data that obtained by the reflected signal from air spot targets as result of remote sensing. The feature space analyses based on information theory therefore evaluates maximum deviation data, which can be used for automatic target classification. The article demonstrates the study of trajectory (velocity, climb and height of flight) and signal (radar cross section and radar existing) features in respect of potential detected accuracy. As a priori data, reference information is used on various types and classes of air objects - aircraft (large transport aircraft, medium-haul aircraft, business jets, light motor aircraft, etc.). Modeling shows the most efficiency and completeness features are height of flight (Hh ≈ 5.17) and velocity (Hv ≈ 4.17) of air object systems.

Flow simulation of the flight manoeuvres of a large transport aircraft with load alleviation

AbstractA new method for predicting manoeuvre loads on a large transport aircraft with a swept-back wing and a load alleviation system based on control surface deflections is developed. For this purpose, three-dimensional Reynolds-averaged Navier–Stokes (RANS) simulations of the rigid wing–fuselage configuration are performed while the aerodynamics of the tailplane are estimated by means of handbook methods. For a closer analysis, different quasi-steady pitching manoeuvres are chosen based on the CS-25 regulations. One of these manoeuvres is also simulated with active load alleviation, leading to a reduction in the wing-root bending moment by more than 40%. Besides demonstrating the potential of the considered load alleviation system, it is shown which manoeuvres are especially critical in this context and which secondary effects come along with load alleviation.

Development and structural analysis on longeron cross sectional area in a flat stiffened panel with a broken central longeron

A substantial amount of parametric analysis and testing is carried out in the design and construction process for a large transport aircraft to achieve an optimal structure. One of the damage tolerance design objectives of any large transport aircraft is a two bay crack arrest in a circumferential direction. In this crack arrest ability, the longeron static strength plays a dominant role. Thus, a parametric analysis of the efficiency of the longeron on the residual strength of a two-bay circumferential crack have been carried out in this study. One of the critical load cases that the fuselage has to effectively tolerate is internal pressurization. In the fatigue life estimation for the fuselage, the compression and decompression cycles are generally used as an input. Pressurization load cases are considered for the study in the present work. Analytical method is used to calculate the circumferential crack arrest capability in the stiffened panel by considering longitudinal stresses. The stress intensity factor (SIF) values obtained using finite element analysis (FEA) agree with the SIF values obtained by theoretical method.

Examination of Sustainable Water Management at Norway’s Major Hub Airport: The Case of Oslo Airport Gardermoen

The present study used a detailed qualitative longitudinal research approach to examine the trends of water consumption, wastewater volumes, and drainage water volumes in Oslo Airport Gardermoen, which is Norway’s major hub airport, between the years 2005 and 2020. An overall upward trend was observed in the water consumption at Oslo Airport Gardermoen, which was consistent with the growth in air traffic and aircraft movements during the study period. The annual water consumption per enplaned passenger was observed to fluctuate during the study period. While the lowest water consumption per passenger (8 liters per passenger) was recorded in 2008, the highest levels (14.6 liters per passenger) were recorded in 2020. The annual water consumption (cubic meter per aircraft movement) increased during the study period, which was consistent with the growth in aircraft movements and the use of larger aircraft. The annual wastewater volume generally increased during the study period, while the annual drainage water volume fluctuated remarkably during the study period, with the latter reflecting varying drainage patterns at the airport. Oslo Airport Gardermoen has implemented a range of sustainable water management practices to supplement its existing water management practices and policies.

Structural Analysis and Improvement Design of Brake Pressure Valve Feedback Stage in Multivalve Parallel Brake System

The wheel brake device is one of the most widely used landing deceleration devices in modern aircraft. For large aircraft, a multivalve parallel brake system is usually used. When a brake pressure servo valve of a certain type of aircraft is debugged, the output brake pressure of the system shows obvious periodic oscillation with constant amplitude. This paper focuses on the brake pressure servo valve, which is the key component of the system. There are a large number of feedback and adjustment segments in the brake pressure servo valve, which can not only improve the control accuracy but also introduce nonlinear factors to cause system vibration. Therefore, in this paper, the feedback stage structure of the brake pressure servo valve is analyzed and improved, and a new two-stage pressure servo valve is designed to restrain the output brake pressure vibration of the system. Firstly, the structure principle of the original pressure servo valve is defined, and the function of the feedback stage is analyzed. Secondly, in view of the vibration problem caused by the original brake pressure servo valve, a new two-stage brake pressure servo valve is designed, which is the main contribution of this paper. Thirdly, the dynamics model of the proposed two-stage brake pressure servo valve is established, and the simulation model of the brake pressure servo valve-controlled cylinder system and the multivalve parallel brake servo control system is built. Finally, experiments are carried out on the experimental platform of a multivalve parallel brake system to verify that the proposed two-stage pressure servo valve can restrain the vibration of the system more effectively than the original brake pressure servo valve. And the two-stage pressure servo valve prototype is successfully applied to the actual aircraft brake control system; the system can better maintain a stable brake pressure output.

A Review of Modern Thermal Imaging Sensor Technology and Applications for Autonomous Aerial Navigation.

Limited navigation capabilities of many current robots and UAVs restricts their applications in GPS denied areas. Large aircraft with complex navigation systems rely on a variety of sensors including radio frequency aids and high performance inertial systems rendering them somewhat resistant to GPS denial. The rapid development of computer vision has seen cameras incorporated into small drones. Vision-based systems, consisting of one or more cameras, could arguably satisfy both size and weight constraints faced by UAVs. A new generation of thermal sensors is available that are lighter, smaller and widely available. Thermal sensors are a solution to enable navigation in difficult environments, including in low-light, dust or smoke. The purpose of this paper is to present a comprehensive literature review of thermal sensors integrated into navigation systems. Furthermore, the physics and characteristics of thermal sensors will also be presented to provide insight into challenges when integrating thermal sensors in place of conventional visual spectrum sensors.

Certification-Driven Platform for Multidisciplinary Design Space Exploration in Airframe Preliminary Design

Airworthiness certification is a mandatory but expensive process in aircraft development. To reduce certification cost, it is desired to incorporate certification considerations into aircraft early design stages. The tradeoff between performance and certification constraints and the interactions between the behind-the-scene disciplines require a multidisciplinary design optimization (MDO) method implemented to incorporate certification considerations. Several MDO frameworks currently exist with mixing levels of fidelity and multidisciplinary coupling. However, few of them capture the impacts of certification constraints on the overall aircraft performance. Moreover, preceding MDO studies have mostly focused on optimizing a single design point, whereas little attention is paid to design space exploration. To fill these gaps, this paper proposes a certification-driven platform for airframe early preliminary design. With statistical methods applied, this platform allows efficient design space exploration and multi-objective optimization. To demonstrate the capabilities of this platform, a test case of preliminary horizontal tail design of a large twin-aisle aircraft is performed. The feasibility test and multi-objective optimization conducted in the test case prove that certification constraints play a critical role in the design space exploration at the early preliminary stage.