Generation Aircraft Research Articles

Structural Analysis of a Large-scale Model for the Wind Tunnel Test of a Multiadaptive Flap

Innovative studies on morphing wing structures with the highest potential to improve aerodynamic performance on large aircraft are running under the CleanSky2 platform to validate the morphing architectures on true-scale demonstrator through ground and wind tunnel tests. Research activities have been conducted to develop a revolutionary multi-modal camber morphing flap to enhance the aerodynamic behaviour of a new generation of regional aircraft within this challenging framework. The design and validation of the intelligent architecture capable of different morphing modes required for low-speed (take-off/landing) and high-speed (cruise)conditions. To enhance the significance and applicability of the wind tunnel test campaign, a significant scale factor of 1:3 was selected for the test article. In this study, general layout of the mechanical model and FE analysis performed both inner and outer flap will be presented. A comprehensive structural analysis of the flap test article was conducted to ensure the safety and effectiveness of the conceived mechanical solutions. Linear static analyses were performed using the finite element (FE) method within the Ansys Workbench® environment. These analyses aimed to assess the adequacy of the mechanical solutions and validate the test article’s structural integrity.

Aerodatabase Development and Integration and Mission Analysis of a Mach 2 Supersonic Civil Aircraft

The request for faster and greener civil aviation is urging the worldwide scientific community and aerospace industry to develop a new generation of supersonic aircraft, which are expected to be environmentally sustainable and to guarantee a high-level protection of citizens. A key aspect to monitor the potential environmental impact of new configurations is the aerodynamic efficiency and its impact onto the real mission. To pursue this goal, this paper discloses increasing-fidelity aerodynamic modeling approaches to improve the conceptual design of high-speed vehicles. The disclosed methodology foresees the development of aerodynamic aerodatabases by means of incremental steps starting from simplified methods (panels methods and/or low-fidelity CFD simulations) up to very reliable data based on high-fidelity CFD simulations and experimental measurements with associated confidence levels. This multifidelity approach enables the possibility of supporting the aircraft design process at different stages of its design cycle, from the estimation of preliminary aerodynamic coefficients at the beginning of the conceptual design, up to the development of tailored aerodatabases at advanced design phases. For each design stage, a build-up approach is adopted, starting from the investigation of the clean external configuration up to the complete one, including control surfaces’ effects and, if any, the effects of the integration of the propulsive effects. In addition, the applicability of the approach is guaranteed for a wide range of supersonic and hypersonic aircraft, and the developed methodology is here applied to the characterization of Mach 2 aircraft configuration, a relevant case study of the H2020 MORE&LESS project.

Impact of reduced sonic boom exposure on psychophysical and cognitive performance for simulated booms presented in a realistic indoor environment

This study aimed to quantify, in situations representative of the daily life of European citizens, the effects of sonic boom exposure on human responses, in the case of a new generation of supersonic commercial aircraft that should emit a reduced (compared to the past generation like Concorde) but perceivable boom while flying overland. Two reduced boom simulators were affixed to the bedrooms’ windows of a house located on our university campus. The simulators were used to study indoor the participants’ responses to realistic “outdoor” booms. Testing took place in both the living room and kitchen because the booms caused different intensities of rattle noise in those two rooms. Participants performed various tasks (communication, working memory, drawing, valence evaluation), took three mandatory rests and filled in various questionnaires about the annoyance caused by the booms and their mood. This paper focuses on the psychophysical and cognitive performance results. The booms resulted in delayed responses in the working memory task and in the valence evaluation task, and in a momentary slowing down in the drawing task. There was no significant effect in the communication task, even though a trend for a worsening of communication efficiency was observed. Taken together, the results suggest that reduced booms can interfere with cognitive and motor tasks by capturing attention, which can momentarily divert cognitive resources away from the task at hand. These results suggest future research directions and may lead to recommendations for future sonic boom regulations.

ПРИМЕНЕНИЕ МЕТОДОВ ТЕОРИИ ВАЖНОСТИ КРИТЕРИЕВ ДЛЯ ОПРЕДЕЛЕНИЯ ОПТИМАЛЬНЫХ ВИДОВ ДЕЯТЕЛЬНОСТИ ПРИ УПРАВЛЕНИИ ВОЗДУШНЫМ СУДНОМ

The formalization of the activities of pilots in the controlling of the latest generation aircraft (AC) is experiencing difficulties due to significant changes in the structure of human activity - the operator. For the most complete analysis of the procedure for controlling the activities of pilots when using various levels of automation, it turns out to be not enough to use only the mathematical apparatus of probability theory and decision-making methods in vague conditions. The article presents the result of applying the methods of the theory of the importance of criteria in order to determine the most rational choice of crew members' activity at various stages of flight and piloting modes of the latest generation aircraft.

A Review of the Current Regulatory Framework for Supersonic Civil Aircraft: Noise and Emissions Regulations

The request for faster and greener civil aviation is urging the worldwide scientific community and aerospace industry to develop a new generation of supersonic aircraft, which are expected to be environmentally sustainable, and to guarantee a high level of protection for citizens. The availability of novel propulsive technologies, together with the development of new civil supersonic passenger aircraft configurations and missions, is pushing international authorities to update the regulatory framework to limit nuisances on the ground and the contribution to climate change. Existing ICAO noise and emissions standards are outdated as they were developed in the 1970s and tailored to Concorde, the only SST that has ever operated in Western airspace. This article provides (i) a comprehensive review of current environmental regulations for SST, encompassing noise and pollutant emissions near airports (LTO cycle) as well as CO2 emissions and sonic booms, and (ii) updated information about the ongoing rulemaking activities by ICAO, FAA and EASA. This review clearly highlights the following findings: (i) the need to revise current rules to better fit future SST design, operations and technologies; (ii) the need to introduce new regulations to cover additional aspects, including stratospheric water vapour emissions and ozone depletion; and (iii) the need to support regulatory activities with solid technical bases, fostering cooperation with academia, research centres and industry in R&D projects. Eventually, a practical example of how SST rulemaking activities are supported by the collaborative research H2020 MORE&LESS is reported.

Non-Linear Analysis in Post-Buckling Regime of a Tilt Rotor Composite Wing Structure Using Detailed Model and Robust Loading Approach

The design and development of a wing for a completely brand-new aircraft represents, in aeronautics, one of the highest challenges from an engineering point of view. The present work describes a novel methodology devoted to execute numeric simulation in a non-linear post-buckling regime to verify the composite wing compliance under the design load conditions. The procedure was developed as part of a wing design and research activity and was motivated by the need to have more realistic results, without standard conservatisms like the no-buckling up to ultimate load, to be of use for achieving further weight savings. To carry this out, it was obviously necessary to ensure that the structural integrity was also guaranteed in the post-buckling regime, above the limit load, and therefore in a highly non-linear regime. The present work illustrates a numerical approach based on non-linear finite element analysis which uses the inertia relief option in order to have a more realistic representation of the structural response of the wing in its real context. All that represents a novelty since, at present, the commercial FE codes allow us to use the inertia relief option exclusively for linear analysis. Obviously, the approach can be applied to any other structural component with similar needs. The obtained results show that the differences between linear and non-linear regime are not negligible and, above all, that it is possible to design a wing (or other structural components) considering, at the same time, the large deformation due to the post-buckling regime, the material non-linearities due to the failures and any other non-linearities in order to achieve the challenging weight requirement of the new aircraft generation.

Pilot study on evaluation indices for aircraft noise considering sound quality

In Japan, Lden is currently used as an evaluation index for aircraft noise. It is based on the A-weighted sound pressure. It evaluates differences in noise loudness, but it does not necessarily take into account differences due to changes in sound quality. Over the past several decades, single event of aircraft noise has been significantly reduced. As a result, we have experienced a change from the "noisy" sound quality of the old generation jets to the "soft" sound quality of the recent aircrafts. Has the sound quality really improved, and has its improvement been evaluated? On the other hand, since the 2000's, we have sometimes experienced hearing the extraordinary tonal sounds from landing aircraft. It has the characteristics of pure tonal tone with 250-500 Hz and has a short duration and a prominent level fluctuation. Doessuch a sudden tonality change, which is also negatively perceived, not affect the evaluation? This paper describes the results of trial calculation in order to examine the possibility of evaluating aircraft noise considering its sound quality, based on several indices such as EPNL, loudness, sharpness, and Tonal Audibility (TA), in addition to the A-weighted noise (LAmax, LEA), and its comparative verification including differences in aircraft generations.

Investigation of Magnetic Flux Pulsations in the Aircraft Generator Having a Solid Rotor with Laminated Shroud

Investigation of Magnetic Flux Pulsations in the Aircraft Generator Having a Solid Rotor with Laminated Shroud

Application of magnus effect on wings

As an important part of the aircraft, the wing provides enough lift for the aircraft, but also creates additional drag. An effective wing design guarantees sufficient lift while minimizing the impact of drag on the aircraft. Aerodynamic analysis is an interdisciplinary research in the course of wing design. In this paper, the design of Magnus type is discussed by means of computational fluid dynamics. First, the airfoil with Magnus rollers was designed. Then, the key parameters such as rotational speed and Angle of attack are studied. Through the analysis of the line chart and calculation domain image of the calculation results, the results show that the installation of Magnus roller on the wing can effectively increase the lift and reduce the drag. With the increase of the rotational speed of Magnus Roller, the lift generated is larger. In the process of increasing the rotational speed, the reflux area behind the airfoil keeps decreasing until it disappears. It is proved that the Magnus airfoil can effectively avoid the phenomenon of airflow separation and avoid the stall of the aircraft. The conclusion can provide theoretical basis for the optimization design of the new generation aircraft airfoil.

A new method to perform Lithium-ion battery pack fault diagnostics – Part 1: Algorithm development and its performance analysis

The successful integration of Li-ion batteries in the automotive industry paved the way for their integration into a new generation of aircraft with zero emission. However, potential hazards associated with Li-on batteries are a major concern for the safety-critical aerospace sector. Removing or reducing the hazards from Li-ion batteries while preferable, requires fundamental changes to the battery chemistry. Another way to address this is the implementation of fault diagnostics and prognostics for forecasting or detecting the presence of faults before an aircraft is airborne. This article, part of a three-part series, presents a novel algorithm exploiting the data collected while charging a battery pack for diagnosing faults. The algorithm works off-board, thus not adding any computational burden or weight to the aircraft while minimising aircraft turn-around time, which is crucial for commercial flight operation. This paper presents the underlying method of the algorithm involving the computation of resistance, charge energy and incremental capacity curve using the charging data followed by a combined horizontal and vertical comparative scheme for diagnosis of faults. The performance of the proposed algorithm was validated via module-level experiments considering three cell inactivation faults. Results indicated that the algorithm successfully segregated faulty and unfaulty cells in multiple test scenarios with different number of faults in a laboratory-assembled module. Upon testing the algorithm in experiments conducted using a real-life aerospace battery module, there was a slight reduction in the performance, attributed to greater thermal variation. Nevertheless, the results indicated promising prospects for practical implementation in eVTOL batteries.

Hydrogen-Powered Aircraft at Airports: A Review of the Infrastructure Requirements and Planning Challenges

Hydrogen-fueled aircraft are a promising innovation for a sustainable future in aviation. While hydrogen aircraft design has been widely studied, research on airport requirements for new infrastructure associated with hydrogen-fueled aircraft and its integration with existing facilities is scarce. This study analyzes the current body of knowledge and identifies the planning challenges which need to be overcome to enable the operation of hydrogen flights at airports. An investigation of the preparation of seven major international airports for hydrogen-powered flights finds that, although there is commitment, airports are not currently prepared for hydrogen-based flights. Major adjustments are required across airport sites, covering land use plans, airside development, utility infrastructure development, and safety, security, and training. Developments are also required across the wider aviation industry, including equipment updates, such as for refueling and ground support, and supportive policy and regulations for hydrogen-powered aircraft. The next 5–10 years is identified from the review as a critical time period for airports, given that the first commercial hydrogen-powered flight is likely to depart in 2026 and that the next generation of short-range hydrogen-powered aircraft is predicted to enter service between 2030 and 2035.

ASPECTS RELATED TO THE VERSATILITY OF THE F-16 MLU AIRCRAFT

The intelligent use of the armament capabilities of the modernized F16 aerial platform, combined with the gradual training of the pilots, gives Romania a plus in the fulfillment of the missions assigned to the Air Force. Increasing the number of F16 aircraft from 17 to 49, diversifying armament capacities, training aeronautical personnel and the sustained, pragmatic use of these resources for a few years is bound to enable the Romanian Air Force to gradually advance towards higher generation aircraft.

Review of Sonic Boom Prediction and Reduction Methods for Next Generation of Supersonic Aircraft

The reduction of sonic boom levels is the main challenge but also the key factor to start a new era of supersonic commercial flights. Since 1970, a FAA regulation has banned supersonic flights overland for unacceptable sonic booms at the ground, and many research studies have been carried out from that date to understand sonic boom generation, propagation and effects, both on the environment and communities. Minimization techniques have also been developed with the attempt to reduce sonic boom annoyance to acceptable levels. In the last 20 years, the advances in both knowledge and technologies, and companies and institutions’ significant investments have again raised the interest in the development of new methods and tools for the design of low boom supersonic aircraft. The exploration of unconventional configurations and exotic solutions and systems seems to be needed to effectively reduce sonic boom and allow supersonic flight everywhere. This review provides a description of all aspects of the sonic boom phenomenon related to the design of the next generation of supersonic aircraft. In particular, a critical review of the prediction and minimization methods found in the literature, aimed at identifying their strengths, limitations and gaps, is made, along with a complete overview of disruptive unconventional aircraft configurations and exotic active/passive solutions to boom level reduction. The aim of the work is to give a clear statement of state-of-the-art sonic boom prediction methods and possible reduction solutions to be explored for the design of next low-boom supersonic aircraft.

Analytical Formulations for Nitrogen Oxides Emissions Estimation of an Air Turbo-Rocket Engine Using Hydrogen

According to the latest report of the Intergovernmental Panel on climate change, aviation contributes to only about 2% to anthropogenic global greenhouse gas (GHG) emissions. However, in view of the growing market demand and the dramatic reductions in other transport sectors, including maritime and automotive, the aviation sector’s percentage impact on global GHG emissions is expected to reach 50% of the transport share by 2040. High-speed aviation exploiting liquid hydrogen as the propellant can represent a valuable solution toward the decarbonization of the sector. However, to avoid jeopardizing the dream of a new generation of high-speed aircraft, it will be necessary to introduce non-CO2 emissions estimations beginning with the design process. To unlock the possibility of anticipating the nitrogen oxides emissions estimation, the authors developed the hydrogen and high-speed P3-T3 methodology (H2-P3T3), an evolution of the widely used P3-T3 method, properly conceived to support (i) innovative air-breathing propulsive systems for supersonic and hypersonic flights and (ii) greener fuels, such as hydrogen. This paper presents a step-by-step approach to developing novel analytical formulations customized for an Air Turbo-Rocket engine and discusses the discovered correlation of nitrogen oxides production with the fuel-to-air ratio (FAR), the Mach number, and the Damköhler number (Da), the last being a nondimensional variable directly related to hydrogen/air combustion, considering the matching between the residence time and the ignition delay times. The most complete formulation allows for reduction in the prediction errors below 5%.

Amorphous/Nanocrystalline, Lightweight, Wave-Transparent Boron Nitride Nanobelt Aerogel for Thermal Insulation.

At present, the new generation of aircraft is developing in the direction of high speed, long endurance, high mobility, and repeatability. Some studies have shown that the surface temperature of the radome can reach even 1800 °C as the flight speed of the aircraft increases. However, the antenna inside the radome cannot serve at this temperature. Consequently, a thermal insulation system with electromagnetic wave-transparent ability and high-temperature resistance is urgently needed to protect the antenna from working normally. An aerogel material is known as "solid smoke," with the lowest density currently. Because of its high porosity (>90%) and the characteristics of nanopore size, its application in the field of thermal insulation always draws the attention of researchers. In this work, a novel amorphous/nanocrystalline boron nitride (BN) nanobelt aerogel was synthesized successfully. The BN aerogel shows lightweight (18 mg/cm3), good thermal stability (1400 °C under an inert atmosphere and 750 °C under an air atmosphere), wideband wave-transparent performance (dielectric constant of 1.03 and dielectric loss of 0.016 at 4-18 GHz), and thermal insulation property (43 mW/(m·K) at room temperature and 73 mW/(m·K) at 600 °C). The BN aerogel is a suitable candidate as an electromagnetic wave-transparent thermal insulator and fire-resistant material. What is more, the structural stability of the BN aerogel is good (Young's modulus remains basically constant during the fatigue tests), and the energy loss coefficient (∼0.56) is high; it also has the potential to be a mechanical energy dissipative material. The study on the amorphous/nanocrystalline BN nanobelt aerogel provides a new idea for structure design and performance optimization of a high-temperature electromagnetic functional insulation material.

Application of exergetic analysis to inverted Brayton cycle engine at different flight conditions

The aviation sector has continued to be modernized by overcoming technological challenges involving strict constraints for mission requirements. In this context, the great attention to newly proposed methods which the requirements satisfied has been drawn in the related aviation field. As a novelty, performance and exergy analyses of inverted Brayton cycle engine (IBCE) are investigated at supersonic speed (2.5 M) by comparing it with a conventional afterburning turbojet engine (CATE) in this study. Moreover, exergy analysis is performed solely for the IBCE at 5 M where only the IBCE could generate thrust. According to performance findings, specific fuel consumption (SFC) of the CATE changes from 57.97 g/kNs and 71.72 g/kNs whereas it raises from 51.76 g/kNs and 56.57 g/kNs for the IBCE due to variation of turbine inlet temperature (TIT) and afterburner exit temperature (AET) at 2.5 M. Also, thermal efficiency of the CATE varies approximately between 32.97% and 46.73% while that of IBCE changes between 50.72% and 58.43% for IBCE at 2.5 M. At hypersonic speed, SFC of the IBCE is measured to vary between 71.34 g/kN and 85.49 g/kN at 5 of Mach. Lastly, the exergy efficiency of IBCE changes between 23.73% and 27.70% at same conditions. Where the higher TIT leads to lowering it whereas the higher AET provides increment of exergy efficiency. This study shows that thanks to cycle change, gas turbine engines could provide more advantages for new generation aircraft compared with conventional ones.

Concept and Demonstration of a Coaxial Magnetic Coupling With Electromagnetic Disconnection for Aircraft Permanent Magnet Generators

The application of more electrified systems in aircraft is required to achieve the target of a more sustainable aviation industry. This in turn relies on the development of new electro-mechanical devices to ensure reliability of critical aircraft functions during flight. The aim of this work is to develop and test a device capable of protecting permanent magnet generators from damage, thus enabling the practical use of such high power density generators in aircraft while eliminating their inherent vulnerability to sustained electrical faults. A novel electromechanical actuator concept for decoupling a permanent magnetic generator from an aircraft gas turbine engine is introduced and experimentally validated. The proposed concept combines a coaxial magnetic coupling with an electromagnetic actuator, allowing for rapid disconnection in case of electrical fault detection. The 2D finite element magnetic analysis methodology employed in the design of the magnetic coupling and electromagnetic actuator is validated with experiments that reveal the peak torque results of the magnetic coupling are accurate to within a 2.5% error and the actuator can produce the 450 N pull force required for disconnection. The device is capable of operating at a maximum speed of 12,000 RPM and transmitting a load of 32 Nm.

Концепция построения стехиометрического турбореактивного двигателя

The paper proposes an alternative approach to design and development of the supersonic and hypersonic gas turbine engines. Currently, the leading aircraft engine companies, such as General Electric, United Technologies, Rolls-Royce and SNECMA Group, are pursuing the active technical policy in creating the new generation aircraft gas turbine engines (VAATE, IHPET, UEET, VITAL and other programs). At the same time, dynamics in such engines development demonstrates that timing of alteration in the aircraft engines generations is lengthening, and boundaries between generations are becoming more conditional indicating a systemic crisis. To maintain stable operation of the gas turbine engines, aircraft compressors are regulated. To this end, they are made double-circuit and multi-shaft, which makes it possible to maintain stable operation at subsonic and moderate supersonic flight speeds, but appears to be an obstacle in their further growth. It is proposed to refuse regulating a compressor as a method of ensuring the engine stable operation and to pass to regulating the turbine as an approach to maintain the compressor given operation mode. In order to exclude the compressor stages mismatch as a phenomenon, it is necessary that the compressor operating mode, regardless of the engine operating mode, remains calculated or close to it. In accordance with this principle, the gas-dynamic appearance of a gas turbine engine was formed as a stoichiometric single-circuit turbojet engine with the single-stage adjustable turbine. The engine control program was determined by dependence of the reduced rotation rate on the outside air stagnation temperature and was implemented by changing the gas temperature in front of the turbine and the pressure drop in it. Transition to a new concept of constructing a gas turbine engine opens new prospects, expands the flight speed range up to hypersonic, increases the gas-dynamic efficiency (overall efficiency of more than 40%) and reduces (by more than 2 times) the specific mass. The key condition in implementing the concept should include creation of new technologies making it possible to increase the gas temperature in front of the turbine up to 2300–2400 K.

A Self–Tuning Intelligent Controller for a Smart Actuation Mechanism of a Morphing Wing Based on Shape Memory Alloys

The paper exposes some of the results obtained in a major research project related to the design, development, and experimental testing of a morphing wing demonstrator, with the main focus on the development of the automatic control of the actuation system, on its integration into the experimental developed morphing wing system, and on the gain related to the extension of the laminar flow over the wing upper surface when it was morphed based on this control system. The project was a multidisciplinary one, being realized in collaboration between several Canadian research teams coming from universities, research institutes, and industrial entities. The project’s general aim was to reduce the operating costs for the new generation of aircraft via fuel economy in flight and also to improve aircraft performance, expand its flight envelope, replace conventional control surfaces, reduce drag to improve range, and reduce vibrations and flutter. In this regard, the research team realized theoretical studies, accompanied by the development and wind tunnel experimental testing of a rectangular wing model equipped with a morphing skin, electrical smart actuators, and pressure sensors. The wing model was designed to be actively controlled so as to change its shape and produce the expansion of laminar flow on its upper surface. The actuation mechanism used to change the wing shape by morphing its flexible upper surface (manufactured from composite materials) is based on Shape Memory Alloys (SMA) actuators. Shown here are the smart mechanism used to actuate the wing’s upper surface, the design of the intelligent actuation control concept, which uses a self–tuning fuzzy logic Proportional–Integral–Derivative plus conventional On–Off controller, and some of the results provided by the wind tunnel experimental testing of the model equipped with the intelligent controlled actuation system. The control mechanism uses two fuzzy logic controllers, one used as the main controller and the other one as the tuning controller, having the role of adjusting (to tune) the coefficients involved in the operation of the main controller. The control system also took into account the physical limitations of the SMA actuators, including a software protection section for the SMA wires, implemented by using a temperature limiter and by saturating the electrical current powering the actuators. The On–Off component of the integrated controller deactivates or activates the heating phase of the SMA wires, a situation when the actuator passes into the cooling phase or is controlled by the Self–Tuning Fuzzy Logic Controller.

Development of an Active Wingtip for Aeroelastic Control

This paper presents the design of an innovative wingtip device actively actuated to control the aeroelastic loads, with a focus on the gust load alleviation. It summarizes the work carried out in the Clean Sky 2 AIRGREEN2 project, where the device was developed from scratch and reached a relevant technology readiness level with the full-scale prototype manufacturing and testing, compulsory to obtain the permit to fly. This paper describes the overall design of the devices, covering the structure, the aero-servo-elasticity characteristics of the whole aircraft, the actuation system design, the scaled wind tunnel testing, and the full-scale structural qualification tests. The paper proves how the development of a new item involves several disciplines simultaneously, remarking on the importance of an integrated approach to the new generation aircraft design.