Aircraft Speed Research Articles

Airborne Mid-Infrared Cavity enhanced Absorption spectrometer (AMICA)

Abstract. We describe the Airborne Mid-Infrared Cavity enhanced Absorption spectrometer (AMICA) designed to measure trace gases in situ on research aircraft using Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS). AMICA contains two largely independent and exchangeable OA-ICOS arrangements, allowing for the simultaneous measurement of multiple substances in different infrared wavelength windows tailored to scientific questions related to a particular flight mission. Three OA-ICOS setups have been implemented with the aim to measure OCS, CO2, CO, and H2O at 2050 cm−1; O3, NH3, and CO2 at 1034 cm−1; and HCN, C2H2, and N2O at 3331 cm−1. The 2050 cm−1 setup has been characterized in the laboratory and successfully used for atmospheric measurements during two campaigns with the research aircraft M55 Geophysica and one with the German HALO (High Altitude and Long Range Research Aircraft). For OCS and CO, data for scientific use have been produced with 5 % accuracy (15 % for CO below 60 ppb, due to additional uncertainties introduced by dilution of the standard) at typical atmospheric mixing ratios and laboratory-measured 1σ precision of 30 ppt for OCS and 3 ppb for CO at 0.5 Hz time resolution. For CO2, high absorption at atmospheric mixing ratios leads to saturation effects that limit sensitivity and complicate the spectral analysis, resulting in too large uncertainties for scientific use. For H2O, absorption is too weak to be measured at mixing ratios below 100 ppm. By further reducing electrical noise and improving the treatment of the baseline in the spectral retrieval, we hope to improve precision for OCS and CO, resolve the issues inhibiting useful CO2 measurements, and lower the detection limit for H2O. The 1035 and 3331 cm−1 arrangements have only partially been characterized and are still in development. Although both setups have been flown and recorded infrared spectra during field campaigns, no data for scientific use have yet been produced due to unresolved deviations of the retrieved mixing ratios to known standards (O3) or insufficient sensitivity (NH3, HCN, C2H2, N2O). The ∼100 kg instrument with a typical in-flight power consumption of about 500 VA is dimensioned to fit into one 19 in. rack typically used for deployment inside the aircraft cabin. Its rugged design and a pressurized and temperature-stabilized compartment containing the sensitive optical and electronic hardware also allow for deployment in payload bays outside the pressurized cabin even at high altitudes of 20 km. A sample flow system with two parallel proportional solenoid valves of different size orifices allows for precise regulation of cavity pressure over the wide range of inlet port pressures encountered between the ground and maximum flight altitudes. Sample flow of the order of 1 SLM (standard litre per minute) maintained by an exhaust-side pump limits the useful time resolution to about 2.5 s (corresponding to the average cavity flush time), equivalent to 500 m distance at a typical aircraft speed of 200 m s−1.

Aircraft Detection above Clouds by Sentinel-2 MSI Parallax

Detection of aircrafts in satellite images is a challenging problem when the background is strongly reflective clouds with varying transparency. We develop a fast and effective detection algorithm that can find almost all aircrafts above and between clouds in Sentinel-2 multispectral images. It exploits the time delay of a few seconds between the recorded multispectral images such that a moving aircraft is observed at different positions due to parallax effects. The aircraft speed, heading and altitude are also calculated accurately. Analysing images over the English Channel during fall 2020, we obtain a detection accuracy of 80%, where the most of the remaining were covered by clouds. We also analyse images in the 1.38 μm water absorption band, where only 61% of the aircrafts are detected.

The influence of molecular structure on the thermal properties and processability of nitrile-based resin molecules

With the increase in the speed of various aircraft and the demand for lightweight weapons and equipment, the demand for high-performance, high-temperature-resistant resin-based composite materials has become more urgent. The temperature resistance and molding process of composite materials are determined by the temperature resistance and manufacturability of the resin, so there is an urgent need to develop a resin that has both high temperature resistance and excellent process performance. The temperature resistance and processability of the resin are essentially determined by the molecular structure of the resin system. Therefore, in order to design a resin system with excellent heat resistance and processability, the relationship between molecular structure and performance must first be recognized. This paper collects a large amount of experimental data and preliminarily summarizes the influence of different molecular structures on the thermal performance and resin processability of resin polymers from the perspective of structure and performance. This provides a good experience and theoretical basis for the design of high-performance resin systems, providing references and ideas for related research.

Operational noise optimization of aircraft approaches - Initial findings

As the pilots slow the aircraft down and extend flaps and landing gear in preparation for landing the characteristics of the aircraft as a noise source changes. In the OPNOP project, the possibility to use this variation in noise generation to minimize noise at a specified location is examined. Such analysis requires an increased understanding about aircraft noise generation as the aircraft changes configuration and speed during the approach, where theoretical models available can be overly simplistic and of little use for this purpose. Using flight data from 113 actual Airbus A321 flights, and corresponding noise measurements on the ground, this study reports on the initial findings forming the foundation on which further analysis will be conducted. Intermediary findings relate to: a comparison between models and actual measurements, the distance variability to the runway for various flap selections and extension of the landing gear as well as a comparison between flight data and on-ground noise measurements. Captured data suggest that it should be possible to use speed and configuration recommendations to reduce noise over selected approach areas. Future research will include scenario generation and incorporate flight data from an earlier study to increase validity.

Atmospheric dynamics and early warning system low level windshear for airport runway hazard mitigations

Natural disaster nowadays often occur in Indonesia due to climate change, especially those related to atmospheric dynamics anomalies. The statutory event of atmospheric turbulence statistically is quite significant in its improvement. This is an important issue to conduct research both in the analysis of atmospheric dynamics and early detection solutions for these events. The Windshear phenomenon is an atmospheric turbulence disaster that occurs below an altitude of 3000 feet, often known as low level windshear (LLWS), which is very dangerous for planes taking take-off or landing. Its effect on the aircraft will result in increased airflow on the wings, so this increased airflow will result in a sudden increase in aircraft speed. If the pilot is not aware of the indication of the windshear, he will instinctively throttle back to reduce/compensate for the aircraft’s speed. However, once the plane passes through the wind shear zone, the wind suddenly turns into a downdraft. The design of windshear early detection devices have been developed to complement research on the dynamics of the atmosphere. The results obtained are anomalous changes in temperature and atmospheric pressure at this time, and the windshear sensor can detect it well.

The method of increasing the accuracy of coordinates of the contaminated area and water surfaces during environmental monitoring

One of the methods for increasing the accuracy of compiling pollution maps based on the results of air and ground monitoring of environmental monitoring of territories is considered. It has been substantiated that for the study of large areas it is advisable to install equipment for monitoring the state of the environment on aircraft. To improve the accuracy of determining coordinates in difficult conditions, it is proposed to use a quasi-differential mode of operation of navigation equipment placed on an aircraft in the developed method. The aircraft is equipped with various equipment and moves at high speed, conducting research on large areas of the territory. At an aircraft speed of more than 250 km / h, the accuracy of determining the coordinates of 30 m for drawing up an ecological map on a large scale suits the services responsible for environmental safety. Based on these data, additional environmental monitoring is carried out only in areas where pollution is detected. This reduces the time for complete environmental monitoring and saves material resources.

A Deep Ensemble Method for Multi-Agent Reinforcement Learning: A Case Study on Air Traffic Control

Reinforcement learning (RL), a promising framework for data-driven decision making in an uncertain environment, has successfully been applied in many real-world operation and control problems. However, the application of RL in a large-scale decentralized multi-agent environment remains a challenging problem due to the partial observability and limited communications between agents. In this paper, we develop a model-based kernel RL approach and a model-free deep RL approach for learning a decentralized, shared policy among homogeneous agents. By leveraging the strengths of both these methods, we further propose a novel deep ensemble multi-agent reinforcement learning (MARL) method that efficiently learns to arbitrate between the decisions of the local kernel-based RL model and the wider-reaching deep RL model. We validate the proposed deep ensemble method on a highly challenging real-world air traffic control problem, where the goal is to provide effective guidance to aircraft to avoid air traffic congestion, conflicting situations, and to improve arrival timeliness, by dynamically recommending adjustments of aircraft speeds in real-time. Extensive empirical results from an open-source air traffic management simulation model, developed by Eurocontrol and built on a real-world data set including thousands of aircrafts, demonstrate that our proposed deep ensemble MARL method significantly outperforms three state-of-the-art benchmark approaches.

Development of Mathematical Model to Study the Variation Temperature due to the Collision of

To study the variation of temperature with the collision of the air molecules, with aircraft the authors consider the random velocities of the air molecules or aerosol and aircraft. After this, the authors start to develop and extend the old relation of gases, collision, velocities, and temperature. On combining, the authors derived a new equation and relation among these parameters. The derivation for this work assumes some suitable and considerable, assumptions based on collision theory. The relation shows, on collision between the aircraft and air molecules the velocity of the aircraft does not change while the velocity of the air molecules goes on change, which is our goal. 
 The change in velocity of gases is used to develop and study the variation of temperature of the atmosphere, the variation of temperature takes place because the speed of aircraft and air molecules are exchangeable in some cases. Therefore, two relations are developed (24) and (25), finally, which depend upon the initial velocities of aircraft and air molecules. On considering the case for initial velocities of aircraft is greater than initial velocities of air molecules, after the collision, the velocities of gases go on the increase, and hence the temperature increase and vice-versa in case of initial velocities of aircraft is less than the initial velocity of air molecules.

On One Solution of the Numerical Problem Differentiation in Calculation Vertical Speed of Aircraft

To ensure safety and improve the efficiency of flight missions, reliable information about the altitude and speed parameters of the aircraft (AC) is required. Therefore, improving the algorithm for calculating the vertical speed used as part of the algorithmic support for air signal systems (ASS) is a very urgent task. Purpose of the study. The problem of calculating the vertical speed of an aircraft in the ASS is considered. Materials and methods. The analysis of literature data on the use of numerical differentiation procedures to solve this problem is carried out, it is noted that the methods used are based on different ideas and approaches. It is indicated that two-point algorithms are significantly worse than multi-point algorithms in terms of the achieved accuracy, howe¬ver, they are characterized by significant simplicity and speed. Various versions of multipoint algorithms are used, differing in complexity, the amount of information used, and the accuracy achieved. The features of the regularizing algorithms, which are essentially filters of a low-frequency useful signal, suppressing the high-frequency component of the error in measuring the altitude signal or, what is the same, atmospheric pressure, are noted. The data on systems with hardware differentiation of the height signal are given. Results. A fairly simple four-point algorithm for numerical differen¬tiation is proposed and substantiated. Due to the averaging of both the measurement results themselves and the estimates of the derivatives, significant filtering of noise is realized, which is an important advantage of the algorithm. For greater accuracy in estimating the vertical speed, it is envisa¬ged to include a preliminary filtering algorithm in the experimental data processing scheme. The filtering algorithm is found from the solution of the optimization problem; it is shown that this algorithm is structurally similar to the filtering algorithms constructed according to the well-known approaches of R. Kalman. The results of computational experiments on the study of the features and characteristics of the proposed algorithms are presented, illustrating their advantages, performance and the possibility of further use in ASS. It is shown that preliminary filtering significantly increases the accuracy of the vertical velocity estimation. Conclusion. The developed algorithms can be used to improve the algorithmic support of the ASS.

Laser beam propagation simulations of long-path scintillation and fade with comparison to ground-to-aircraft optical link measurements

An analysis of optical scintillation and fade on long slant-path atmospheric channels is presented via a direct comparison between wave-optics-based numerical simulations and experimental flight data from a ground-to-aircraft optical communication link. In addition to physically modeling the propagation through slant-path atmospheric turbulence, the numerical simulations include simultaneously the effects of mechanical pointing jitter, aperture-averaging, and first-order scattering/absorption models. The power spectral density, fade probability, and mean fade time of the simulated power fluctuations are studied and validated against measurements taken at slant-path distances ranging from 60 to 113 km and aircraft speeds up to 70 m / s.

Traffic congestion mechanism in mega-airport surface

In this paper, guided by macroscopic cell transmission models, a cell transmission model of aircraft traffic flow on runways, taxiways and aprons was established to deduce and analyze the evolution rules of an airport surface traffic. The model was simulated by adopting data from a large domestic airport in China. The relationship between three parameters of traffic flow on taxiways was evaluated, and the airport surface traffic flow characteristics were analyzed. Moreover, this paper macroscopically analyzed the characteristics of spatial–temporal distribution of airport surface recurrent and non-recurrent traffic congestion. Simulation results showed that arrival rates and pushback rates had significant influence on the formation and dissipation of recurrent traffic congestion in different phases of the surface aircraft traffic flow. When the arrival rate was 0.3 aircraft/minute and the pushback rate was 0.23 aircraft/minute, the speed of aircraft on taxiways was high, the density and flow were large, and the aircraft had a high degree of obstacle-free taxiing. At this time, the airport ran smoothly and the surface network operation efficiency was high. Compared with the arrival rate, the outward expansion trend of each parameter was more obvious when the pushback rate changed. Parallel taxiways are less robust than apron taxiways and connect taxiways.

Disturbance Observer Enhanced Neural Network LPV Control for a Blended-Wing-Body Large Aircraft

The problem of trajectory tracking control for a blended-wing-body (BWB) large aircraft with model parameter uncertainties and unknown disturbances is considered. A linear parameter-varying (LPV) model is derived from the nonlinear dynamics of the BWB aircraft from which a robust linear parameter-varying controller is designed to track a desired trajectory. Using a single quadratic Lyapunov function (SQLF) and an infinite number of linear matrix inequalities to be evaluated at all vertices, a pair of positive definite symmetric matrix solutions are determined via Lyapunov stability theory and linear matrix inequality technique. Furthermore, a disturbance-observer is designed to process the unknown disturbances. Considering the plant exists some model errors except for disturbances, a radial basis function neural network approximation is embedded into the SQLF LPV controller to improve tracking performances, and a composite disturbance-observer based neural network single quadratic Lyapunov function (NNSQLF) controller can realize desired trajectory tracking of the linear parameter-varying system through regulating performance weighting functions. The closed-loop system of trajectory tracking control is proved to be asymptotically stable by using Lyapunov theory. Simulation results of forward flight speed and altitude tracking control of the BWB aircraft show that the proposed disturbance-observer based NNSQLF control can robustly stabilize the LPV system and precisely track the desired trajectory by comparing with conventional SQLF control and parameter-dependent Lyapunov function control, even in unknown exterior disturbances and model uncertainties.

New flight trajectory optimisation method using genetic algorithms

AbstractThis paper presents a new flight trajectory optimisation method, based on genetic algorithms, where the selected optimisation criterion is the minimisation of the total cost. The candidate flight trajectories evaluated in the optimisation process are defined as flight plans with two components: a lateral flight plan (the set of geographic points that define the flight trajectory track segments) and a vertical flight plan (the set of data that define the altitude and speed profiles, as well as the points where the altitude and/or speed changes occur). The lateral components of the candidate flight plans are constructed by selecting a set of adjacent nodes from a routing grid. The routing grid nodes are generated based on the orthodromic route between the flight trajectory’s initial and final points, a selected maximum lateral deviation from the orthodromic route and a selected grid node step size along and across the orthodromic route. Two strategies are investigated to handle invalid flight plans (relative to the aircraft’s flight envelope) and to compute their flight performance parameters. A first strategy is to assign a large penalty total cost to invalid flight profiles. The second strategy is to adjust the invalid flight plan parameters (altitude and/or speed) to the nearest limit of the flight envelope, with priority being given to maintaining the planned altitude. The tests performed in this study show that the second strategy is computationally expensive (requiring more than twice the execution time relative to the first strategy) and yields less optimal solutions. The performance of the optimal profiles identified by the proposed optimisation method, using the two strategies regarding invalid flight profile performance evaluation, were compared with the performance data of a reference flight profile, using identical input data: initial aircraft weight, initial and final aircraft geographic positions, altitudes and speed, cost index, and atmospheric data. The initial and final aircraft geographic positions, and the reference flight profile data, were retrieved from the FlightAware web site. This data corresponds to a real flight performed with the aircraft model used in this study. Tests were performed for six Cost Index values. Given the randomness of the genetic algorithms, the convergence to a global optimal solution is not guaranteed (the solution may be non-optimal or a local optima). For a better evaluation of the performance of the proposed method, ten test runs were performed for each Cost Index value. The total cost reduction for the optimal flight plans obtained using the proposed method, relative to the reference flight plan, was between 0.822% and 3.042% for the cases when the invalid flight profiles were corrected, and between 1.598% and 3.97% for the cases where the invalid profiles were assigned a penalty total cost.

Design and implementation of an intelligent multi modular joint (MMJ)-brain controller: application to aircraft and brushless DC (BLDC) systems

This paper presents a new intelligent controller by inspiring the mammalian brain connections with various internal parts. Cerebrum, Cerebellum and brain stem are modeled to develop a new intelligent control scheme. There is a modular connection between Cerebellum and Cerebrum with deep nuclei and red nuclei that passes through brain stem to send an action signal. A computational model is developed by inspiring connections and named as Multi Modular Joint-Brain controller (MMJ-BC). The proposed MMJ-BC controller effectiveness is validated by applying on nonlinear dynamical systems such as position control of Aircraft system and speed control of Brushless DC motor. MMJ-BC performance has been analyzed under various operating conditions and obtained results are verified by comparing with the performance of existing Cerebrum (BELBIC) and with Cerebellum based controllers. The results demonstrates excellent performance and capable to withstand under different operating conditions.

Методология разработки датчика статического и полного давлений на базе упругих чувствительных элементов и оптических линеек

Information on the parameters of static atmospheric pressure and total pressure of the incoming air flow is the primary information in the air signal system, which is part of the integrated aircraft control system. This information makes it possible to calculate the altitude and speed of the aircraft for automated and automatic control. Static and total pressures are measured by aerometric parameter sensors, whose technical characteristics largely determine the range and values of the measurement accuracy of the air signal system. Relying on the requirements for aircraft flight safety and in accordance with the existing standards for horizontal and vertical separation, rather stringent requirements are imposed on the accuracy of air pressure measurement. Instrumental errors in measuring static and total air flow pressures with a probability of 0.95 should not exceed 0.02 and 0.05 % of the measurement range. The considered original aerometric pressure sensor based on an optical rule, whose high sensitivity requires minimal deformation of the elastic sensitive element, makes it possible to fulfill these requirements. The non-contact digital information retrieval and the operation of the information system under vacuum conditions significantly increased the efficiency of measurement processes. The paper focuses on an algorithm for calculating the main design parameters of elastic sensitive elements in almost the entire range of their standard sizes taking into account the technical capabilities of the secondary converter. The results of the experiments and experimental studies confirmed the sufficiency of theoretical methods for calculating the parameters of elastic elements for pressure sensors

RESEARCH OF THE A380 AIRCRAFT VORTEX WAKE IMPACT ON MS-21 CLASS AIRCRAFT

The paper is devoted to the problem of safe flight in vortex hazard conditions. A vortex wake is always produced behind flying aircraft. This vortex wake is invisible to other aircraft following it. Therefore, getting into a vortex wake from a preceding aircraft often becomes unexpected and quite often leads to flight incidents. This is confirmed by the statistics of flight accidents. With the introduction of aircraft weighing more than 500 tons, the problem of vortex safety has only sharpened. The fact is that the old standards that define safe intervals between flying aircraft are still active. These standards are given in this paper. It is also shown that even if these standards are observed, the flight of a medium-class aircraft at the same level as a heavy-class aircraft is unsafe. To study the effect of the vortex wake from the preceding aircraft, a special computational software complex based on the discrete vortex method was developed. This complex has passed the necessary testing and state registration. A number of measures were carried out to validate and verify the developed complex, confirming the operability of the programs included in it and the reliability of the results obtained. On the basis of this computational and software complex studies on the effect of the A380 aircraft vortex wake on MS-21 class aircraft were performed. The studies were undertaken for various altitudes and speeds of the A380 aircraft and for its various flight configurations. As a criterion for the MS-21 aircraft safe flight, the roll moment that occurs due to falling into the vortex wave, in particular, its coefficient was chosen. If the coefficient of the MS-21 aircraft roll moment when it hits the vortex wake exceeds that from the ailerons, such a flight is considered dangerous. The distances behind the A380 that are unsafe for the MS-21 aircraft flight are given.

Aerodynamic Investigation of Morphing Wing UAV with Adjustable Slotted Airfoil Configuration

Aviation has wide aspects to challenge and discover, the ability to land and take off at slow speed, sudden increase in drag for short runway landings. This paper puts forth the solution by the use of adjustable multi slots configuration of an airfoil. In this case, the slots extend from the wing leading edge to trailing edge. This causes change in the chord, thereby changing the camber of unsymmetrical airfoil. An investigation was made to determine and compare the aerodynamic characteristics of multi slotted adjustable airfoil with unmorphed unsymmetrical airfoil at varied speeds and Angle of Attack (AoA). There are three slots distanced equally along the airfoil. The extension of these slots increases the chord length by 10% of total chord. The slotted and unslotted airfoil profile are then studied using computational fluid dynamics of external flow over a body. The flow simulation is done at 10m/s, 20m/s, 30m/s, 40m/s and 50 m/s flow velocity and at 0, 3, 6, 9 ,12, 15 AoA. The results were obtained for each case and the values for base and slotted model were compared. It was found that lift of slotted model is slightly higher than base model at low flow velocity. It was also seen that the use of slots at high speed causes a large amount of drag. This increased drag factor can be used in UAV’s as spoilers during landing or for landing at shorter runways at lower speed, allowing a sudden decrease in aircraft speed and also to glide at a steeper angle over obstruction.

Reachability analysis on optimal trim state for aerial docking

Aerial refueling is an important capability to increase the endurance and flight range of aircraft, but it often suffers from a low success rate. The altitude and speed of the tanker aircraft in the docking phase play a great role in the docking success rate. According to this, the optimal trim state, namely the optimal speed and altitude of the tanker aircraft, is investigated through the reachability analysis method in this paper. The optimal problem is transformed to find the trim state corresponding to the maximum volume of the reachable set. First, a relative motion model of the receiver aircraft with respect to the drogue is proposed. Then, based on reachability analysis, an optimization problem is formulated and a solution procedure is given in detail. In the simulation, the volumes of reachable sets are plotted with respect to the given discrete speeds and altitudes, based on which the optimal trim state of the docking phase is determined. Finally, the determined optimal trim state is verified by using numerous docking control simulations and the degree of controllability from another aspect. The effectiveness of the proposed method is demonstrated.

Применение уравнения Больцмана для определения аэродинамических характеристик летательных аппаратов

In this paper we present the derivation of new one-dimensional non-stationary nonlinear system of moment equations and an approximation of the microscopic boundary condition when part of molecules reflect from the surface specularly and part diffusive with Maxwell’s distribution. Macroscopic boundary conditions for the system of moment equations depend on the evenness and oddness of the approximation , where is the partial sum of expansion of the distribution function of molecules  into eigenfunctions of the linearized collision operator. The formulation of the initial and boundary value problem for the system of moment equations in the third approximation under the Maxwell-Auzhan macroscopic boundary conditions is given. To analyze aerodynamic characteristics of aircraft in transient regime was used complete integro-differential Boltzmann equation, which contains a term depending on the moving speed of aircraft, and under Maxwell's microscopic boundary conditions, depending on the surface temperature.

Variational bias correction for Mode-S aircraft derived winds

A variational bias correction (VarBC) technique is proposed within the three-dimensional variational (3D-Var) assimilation system of the Météo-France convective scale model AROME to remove biases present in horizontal wind components derived from aircraft Mode-S data. A set of two predictors derived from the geometry between ground and air speeds has been chosen in order to correct the aircraft speed and heading. Data collected from a set of 8 ADS-B antennas located over France for two periods in 2018 (April and October) have been used to assess the VarBC. Thanks to the availability of anchoring data (radiosoundings, AMDAR aircraft reports), the adaptive bias correction scheme is very efficient for improving the quality of Mode-S derived winds to a level that is similar to those from AMDAR and Mode-S bias corrected by the KNMI. The heading bias correction is the most important one in order to reach background departure values around 2.5 m/s. The behaviour of the VarBC is assessed more precisely for specific aircraft where its capacity to adapt to rapid changes due for example to aircraft maintenance is demonstrated. Moreover, when examining separately predictors for both wind components they appear to converge most of the time towards similar speed and heading corrections. Additional quality controls have allowed to reach background departure values of 2.2 m/s while increasing by a factor of ten the number of aircraft observations to be assimilated in the AROME-France domain.