Aircraft Speed Research Articles

Aircraft Cruise Altitude and Speed Profile Optimization in a Real Atmosphere

Aircraft Cruise Altitude and Speed Profile Optimization in a Real Atmosphere

Effects of Reynolds number and solidity ratio on advection dominated mixing in a high-altitude instrument

Due to the role of ClO and BrO in the rate-limiting step of the catalytic cycles enabling ozone loss, measurement of concentrations of these halogen molecules is of critical importance to understanding the loss rate of ozone in the stratosphere. A key advantage of in situ measurements is that these rate-limiting molecules can be observed simultaneously with ozone in the same volume element of the stratosphere, with high spatial and temporal resolution. Historically, these in situ measurements were made using instruments on the NASA ER-2 flight platform for a few hours at a time. However, the development and advancement of a high-altitude long-endurance (HALE) solar aircraft has made it possible to monitor these radicals continuously in the stratosphere. The slower flight speeds of the HALE aircraft will greatly improve molecule detection sensitivity and spatial resolution. To ensure proper mixing and accurate measurements, a quantitative dissection of the flow dynamics within the instrument architecture is required. Of particular importance are the turbulent behavior and the boundary layer growth, both of which affect measurement quality. The geometry of the NO injector used for titration is studied as a function of its solidity and the flight airspeed, to understand its effect on turbulence and boundary layer growth. A 3D Computational Fluid Dynamics simulation of an Eulerian mixture model is used to analyze the advection-dominated mixing inside the instrument. The injector inside the instrument is found to act as a flow-conditioning device, with a lower solidity causing the downstream flow to be increasingly turbulent. Additionally, a quantitative relationship between the Reynolds number of the inlet air and the volume fraction of the flow is demonstrated. Analysis of the boundary layer dependencies demonstrates that the boundary layer does not encroach on the optical sensing area in any of the cases.

Modeling of an Environmentally Independent and Contactless Speed Sensor for Measuring the Speed of Ships, Submarines, and Aircraft in Relation to the Ground Development of Image

Modeling of an Environmentally Independent and Contactless Speed Sensor for Measuring the Speed of Ships, Submarines, and Aircraft in Relation to the Ground Development of Image

Aircraft Approach Noise Trials

This article presents the results from a series of aircraft approach trials that were conducted with the aim to investigate noise reduction procedures within the boundaries of a normal ILS approach. The significant decline in air traffic at Stockholm Arlanda, that occurred during the pandemic meant that the empty airspace and the availability of grounded aircrafts could be utilized to perform controlled flights - something that would have been difficult to achieve during normal traffic conditions. The approach trials were performed by two Airbus A321, which alternately carried out interrupted landing procedures starting 17 nautical miles (nm) from the runway threshold. During the trials, the aircraft speed and configuration (high lift devises and landing gear) were varied according to a predetermined schedule. To capture these variations, flight data (FDR) were recorded while the noise on ground was measured at positions approximately once every nautical mile along the flight track. Results suggest that speed and configuration recommendations can be effective to reduce noise, especially for the final 7 nautical miles of the flight track. However, whether a low speed is to be advocated during the entire approach is currently unclear.

Dynamic stress in the ground of rigid pavement subjected to moving aircraft loads at various speeds

ABSTRACT Dynamic soil stress in the ground induced by aircraft loads can lead to excessive and differential settlements. The effect of aircraft speeds on the dynamic stress is complicated due to runway roughness, lift force and wave propagation. In this paper, a virtual prototype model of B777-300 was initially developed to investigate the aircraft loads impacted by runway roughness and lift force. Subsequently, a finite element model of the runway was established for the dynamic stress in the ground subjected to moving aircraft loads. Results show that as aircraft speed increases, the aircraft-load-induced dynamic stress in the ground first increases and then decreases. The critical speed of dynamic stress accompanied with a peak stress varies with soil depth. In the shallow soil layers, dynamic stress in the ground is mainly affected by runway roughness and lift force. The critical speed of dynamic stress is close to the sensitive speed corresponding to peak aircraft loads. With the increase of soil depth and aircraft speed, the effect of dynamic amplification due to wave propagation becomes more pronounced. In the deep soil layers, the critical speed of dynamic stress approaches the Rayleigh wave velocity of soils, especially when soft soil layers exist.

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.

SEARCH FOR SMALL-SIZED OBJECTS ON THE UNDERLYING SURFACE IN FRONT OF THE AIRCRAFT

The method of searching of small-sized ground or surface objects with unknown coordinates is proposed. The search is carried out using the thermal imaging or other IR remote sensing system (RS) of underlying surface (US) in front of the aircraft. The small size of objects requires the use of narrow fields of view for detection and recognition at ranges that allow to carry out operational actions, which are provided for by the flight mission for rescue operations on land and at sea or for aircraft emergency landing on an unprepared site. Two tasks are solved: 1) the maximization of the guaranteed bandwidth of objects searching on US with given characteristics of RS and aircraft speed; 2) the determination of the optimal characteristics of remote sensing systems and aircraft speed for a given search bandwidth of the US.A periodic change in the azimuthal orientation of the narrow field of view (automatic scanning of the US by the field of view of the IR system) is used for solving given tasks. For a given operating range of the IR system the proposed algorithm ensures that the pilot or operator can view the runway on US without “dead” zones (unseen areas). The optimal value of the search effort corresponding to the detection and recognition of objects is determined. The proposed algorithm implements symmetrical scanning (scanned areas of the same shape are formed to the left and right of the flight path on US). The symmetric scanning equation is derived for prediction search efficiency. The solution of given equation makes it possible to find the dependence of the guaranteed search bandwidth on the operating range of ranges in which detection and recognition are possible for given weather conditions. The examples of using the derived equation when searching for objects in simple and difficult weather conditions are given.

Airborne flight time: A comparative analysis between the U.S. and China

Actual airborne time (AAT) is the time between actual wheels-off and actual wheels-on of a flight. Given the ever-growing demand for air travel and growing flight delays, understanding the behavior of AAT is increasingly important for on time performance and delay propagation. Of particular interest is the comparison on AAT in different countries with varying air route structures, air traffic management systems, weather, and geography. This paper performs the first comparative empirical analysis of AAT behavior, focusing on the U.S. and China. The focus is on how AAT is affected by origin-destination (OD) distance, the possible pressure to reduce AAT from other parts of flight operations, hub status of departure/arrival airports, enroute and terminal traffic conditions, and convective weather. Econometric models are developed to quantify the impacts of factors on AAT behavior in China and the U.S., separately. The estimation results show that in both countries AAT is highly correlated with OD distance. Flight time in China is longer than that in the U.S. given the same OD distance which indicates a low effective speed may be the result of a low aircraft speed, or due to the flight experiencing metering, rerouting, holding or vectoring in Chinese airspace. In addition, we find that a flight has limited capability to make up for pre-departure delay. Sensitivity analysis of AAT to flight length and aircraft utilization is further conducted. Given the more abundant civil airspace, flexible routing networks, and efficient air traffic flow management (ATFM) procedures, we performed a counterfactual analysis to investigate how Chinese AATs would change if they were governed by the U.S. model. We find that this would result in significant efficiency gains for the Chinese air traffic system. On average, 13 min of AAT per flight would be saved. Systemwide fuel saving would amount to 326 million gallons with CO2 emission reduction of 2.7 million tons and direct airline operating cost saving of over $1.3 billion in 2016.

Investigation of the influence of engine displacement along the aircraft wing on the propagation of a condensation trail

With the publication of this article, the authors continue their research into the interaction of vortex and condensation trails behind aircraft, which has begun in the previously published articles in the Civil Aviation High Technologies of the Moscow State Technical University of Civil Aviation. This paper presents the investigation results of the influence of engine displacement along the A320 aircraft wing on the development and propagation of a contrail. It should be clear that a contrail is a product of aviation fuel combustion in the engine and represents condensed moisture in the form of ice crystals, which is formed under certain conditions of the atmosphere. As numerous studies and observations have shown, contrails can affect the heat exchange processes in the atmosphere and deteriorate the environment contributing to the greenhouse effect. This is especially true for the areas where numerous airways pass. It was noted that inboard engine displacement or, vice versa, outboard affects the development and propagation of a contrail. Therefore, when forming the aerodynamic configuration of the future aircraft, designers should take this aspect into account. The fact is that a wake vortex, which is formed behind the aircraft, impacts the contrail in different ways, depending on the engine proximity to the vortices, trailing from the airframe. Let us point out that a wake vortex is the area of the disturbed airflow behind the aircraft, generated as a result of its movement. A contrail, interacting with a vortex one, dissipates in the atmosphere, and the substances, composing a contrail, lose their concentration. It is also significant that a contrail, interacting with a wake vortex, can reveal its structure and visualize the wake vortex propagation and decay processes. In this paper, a special computational software application, based on the discrete vortex method, was used to study the influence of engine displacement along the A320 aircraft wing on the development and propagation of a contrail. When calculating the characteristics of a wake vortex, it takes into consideration the aircraft weight, speed and altitude, flight configuration, ambient conditions, axial velocity in the vortex core and some other factors. This complex passed the required testing and the state registration. A variety of activities was undertaken to validate and verify the developed complex, confirming the operability of its programs and the reliability of the results obtained. The results obtained allow us to understand how engine displacement along the A320 aircraft wing influences the contrail development and propagation.

Justifying the Parameters for an Unmanned Aircraft Flight Missions of Multispectral Aerial Photography

The paper shows the possibility of collecting multispectral and RGB data on the crop condition using an unmanned aircraft. The use of several programs for creating a flight mission is likely to lead to the inefficient use of the unmanned aircraft resources. (Research purpose) To calculate the parameters of aerial photography with multispectral and RGB cameras to enable the improved efficiency of unmanned aircraft resources. (Materials and methods) The paper studies the specifi cations of RGB and multispectral cameras installed on the drone. The research uses the results of scientifi c research on the calculation of aerial photography parameters such as longitudinal and transverse overlap, as well as the flight speed of an unmanned aircraft. (Results and discussion) It is established that the calculated values of the longitudinal and transverse overlap for the Zenmuse X4S RGB camera, as well as the unmanned aircraft fl ight speed during the joint aerial photography with a multispectral camera, make it possible to use standard mobile applications to create a flight mission. (Conclusions) It is determined that the obtained values guarantee the creation of high-quality digital maps. The parameters for the flight mission are calculated ensuring the effi cient exploitation of the unmanned aircraft resources, using simultaneously the Zenmuse X4S RGB camera and six multispectral cameras on board the unmanned aircraft.

Victim identification and body completeness based on last known location at the World Trade Center

This analysis focuses on the identification efforts conducted by the New York City Office of Chief Medical Examiner (NYC OCME) over a 20-year period from September 11, 2001 to September 11, 2021. Due to this unprecedented level of commitment to victim identification, a wealth of data has been collected over the two-decade period and is still being collected as identification efforts are ongoing. The results of this data analysis are not only informative for the World Trade Center (WTC) victims, but may also be instructional for other large-scale, protracted victim identification efforts. Based on available data, most victims are associated with the impact zones and higher in both towers. No correlation was observed in the overall identification rates based on last known location in the buildings, suggesting that location in the towers does not affect the likelihood of a successful identification. There was, however, a significant difference in the body completeness values observed for victims from the upper floors compared to those below the impact zones. The identification rates and body completeness values for victims onboard the two airplanes are significantly different from each other, possibly related to the varying aircraft speeds at the time of impact.

Analisis Dimensi Propeler Untuk Kebutuhan Desain Konseptual Pesawat Piston

This research conducted a comparative analysis of propeller dimensions for the conceptual design of a piston aircraft. The method used is statistical linear regression by comparing some variables related to propellers from 27 piston aircraft data. Based on comparison results obtained 6 strong relationships, namely aircraft speed and engine power, aircraft weight and engine power, aircraft weight and propeller weight, aircraft weight and the number of propellers blades, engine power and propeller weight, and propeller weight and the number of propellers blades so that it can be used for conceptual design reference. The propeller diameter and engine speed variables do not have a strong relationship in regression but form a cluster so that it can be used as a conceptual design reference. The conceptual design simulation with an aircraft weight of 3500 lb produces a propeller with a diameter of 80 inches, the engine power of 325.51 hp, propeller weight of 86.13 pounds, engine speed of 2500 rpm, and 3 blade propellers with a thrust of 1340.05 lbf.

Analysis of skid resistance and braking distance of aircraft tire landing on grooved runway pavement

ABSTRACT Aircraft landing operations on the wet grooved runway are one of the critical safety concerns for airport agencies. This study aims to predict the friction coefficient between aircraft tires and wet grooved pavement and evaluate the braking distance on the runway. An improved three-dimensional tire-pavement-water interaction model considering squared pavement grooves was developed to evaluate contact force and frictional force at different speeds. The aircraft tire model was validated by the contact footprint and load-deflection curve. The calculated friction coefficients were found to match well with field measurements. The results show that tire wear and water film thickness make significant differences in the friction force between aircraft tires and wet grooved runways. The loss of tread depth degrades drainage capacity between the tire tread and grooved pavement surface. With the increase in speed and water film thickness, the worn tire tends to lose more friction than the new tire. Through the developed approach, the evaluation of hydroplaning speed and braking distance of the landing aircraft during the ground rolling process can be performed. The analysis findings can help airport agencies, aircraft manufacturers, and pilots mitigate the overrun risk of aircraft landing from different aspects.

Moving Spatial Turbulence Model for High-Fidelity Rotorcraft Maneuvering Simulation

A moving spatial turbulence model is developed for rotorcraft maneuvering simulation under different flight conditions. The recursive algorithms are adopted to model its distributed longitudinal turbulence components, which are correlated with the lateral and vertical axes to form a local spatial turbulence field. The flow field is constrained around the rotorcraft by following its movement, and the corresponding turbulence components are updated at a constant spatial interval. The statistical properties along the longitudinal, lateral, and vertical directions have been validated against the von Kármán theory. A synthetic simulation environment consisting of a flight dynamics model and a pilot model is constructed to demonstrate the effectiveness of the turbulence model. Its performance is validated by comparing the power spectral densities of both rotorcraft responses and pilot controls in turbulence against flight test data. The piloted simulation results on an Approach-to-Hovering task show that the handling qualities ratings are susceptive to the level of turbulence and significantly increase when performing aggressive controls. The simulation also accurately predicts the expected effect of varied aircraft speed, wind speed, turbulence intensity, and stability augmentation system on piloted handling qualities rating for rotorcraft flight in turbulence.

GPS spoofing detection algorithm for quad-rotor helicopter based on speed/height comparison

In order to detect whether the GPS is abnormal in the flight state of small size quad-rotor, a GPS spoofing detection algorithm based on data fusion is proposed. Firstly, the velocity data from the monocular camera is calculated by using the self-velocity measurement algorithm based on the improved pyramid optical flow method. Secondly, the speed and altitude data of the IMU sensor unit of the small size quad-rotor were obtained, exactly the speed data were fused with the velocity data measured by using the optical flow method to obtain the optimal velocity estimation at that time. Finally, the small size quad-rotor GPS sensor data information is obtained, the aircraft speed and altitude data are calculated, and comparing with the data calculated in the previous step, to determine whether the GPS data at this time is abnormal. The experimental results on Anafi show that the present GPS spoofing detection algorithm can quickly detect data anomalies during flight. It can be seen that the present algorithm can provide strong technical support for GPS spoofing detection of quad-rotor.

IMAGE MOTION COMPENSATION – THE VEXCEL APPROACH

Abstract. Motion compensation in general and forward motion compensation in particular was an important milestone in aerial imaging when presented for film-based camera systems in the late 90ts of the last century. It focused on the forward motion compensation to enhance the image quality when flight speed and image scale produce such motion blur even at short exposure time. Another development and milestone in aerial photogrammetry, the active mount, contributed as well to reduce motion blur.When digital aerial cameras replaced the film-based camera systems in the first decade of the 21st century, forward motion compensation (FMC) could be implemented as an electronic feature of the CCD sensors, namely the time delayed integration (TDI) feature, which worked fine and did not require a mechanical component. Not all cameras could make use of that but large format frame cameras like DMC and UltraCam were able to compensate forward motion blur exploiting this feature of the electronic sensor component.Since CMOS sensors were replacing the CCD sensor component of digital aerial cameras there was a need to implement the FMC mechanism by another solution. One approach was based on a mechanical device able to move the sensor along the flight path of the aircraft like it was the approach for film cameras.At that time Vexcel Imaging decided to develop a more versatile solution based on software and without any additional mechanical part in the camera body. This solution was designed to not only compensate for a uniform compensation to the forward motion but also for angular motion blur and for different scales in one and the same image. This is especially important for the oblique viewing direction of a camera when foreground and background of an oblique scene show different scales in one and the same image.The need to compensate for motion blur is evident when large scale aerial imaging is required, and best image quality is expected. Motion blur is caused from the speed of the aircraft over ground, the image scale, and an angular component – the angular motion blur - caused from turbulences if they exist.The magnitude of the forward motion blur can be estimated when multiplying aircraft speed and image scale and exposure time (e.g. speed over ground 75 m/sec, scale 1/10000 and exposure time 0,001 seconds leads to 0,0075 mm or 7,5 µm in the image). Different image scales result in different magnitude of motion blur. This is evident for oblique camera systems.

Effects on Taxiing Conflicts at Intersections by Pilots’ Sensitive Speed Adjustment

The pilot is the main person in charge of taxiing safety while moving on the airport surface. The visual separation and speed adjustment are directly related to safety and efficiency of airport surface operation. According to the actual taxiing procedures and airport control rules in China, this paper proposes a novel microscopic simulation model based on the pilots’ visual separation. This model is also built by refining the aircraft taxiing procedures at intersections. The observation range, the separation judgment, pilots’ visual distance, rate of proximity and the intention for speed governing are discussed as parameters in the model. The rules for aircraft separation judgment, pilots’ autonomous speed governing, and position updates are also set up and discussed. The proposed simulation can accurately simulate the acceleration and deceleration intentions under different motion trends while reproducing the motion process including the following acceleration, following deceleration and delayed deceleration caused by separation changes. The results demonstrate that the number of conflicts can be reduced to 50% based on visual separation adjustment of 50 s when the convergence angle is 30°. The pilot’s visual distance is inversely proportional to the fluctuation range of the speed of the rear aircraft, the proximity rate of the front and rear aircraft and the probability of conflict. The simulation results of this model conform to the actual taxiing routes and control rules, which provides technical support for improving the safety level of airport surface operation and presents certain reference value and practicability.

Impact of the atmosphere state on interaction of aircraft vortex and condensation trails

Currently, much emphasis is given to the environmental problems. This article is not an exception. It is devoted to the issue of propagation and interaction of vortex and condensation trails that form behind aircraft when flying in the atmosphere, depending on its state. A vortex trail is an area of disturbed air flow behind an aircraft formed as a result of its motion. A condensation trail is a product of the aviation fuel combustion in the engine and represents condensed moisture in the form of ice crystals, which is generated under certain ambient conditions. As the numerous studies and observations have shown, condensation trails can affect the heat exchange processes in the atmosphere, contributing to the greenhouse effect, deteriorate the environment. It is especially relevant for the area where numerous transitional airways pass. Therefore, it is essential to understand behind what aircraft type the condensation trail, interacting with the vortex one, dissipates in the atmosphere, and the substances composing the condensation trail lose their concentration. And on the contrary, behind what aircraft type the condensation trail does not dissipate for a long term, and the substances, composing the contrail, retain concentration for a long time. It should also be noted that the contrail, while interacting with the vortex wake, can reveal its structure and visualize the processes of propagation and attenuation of the vortex wake. This paper uses a special computational software application, based on the discrete vortex method, to study the interaction of condensation and vortex trails. It considers the flight weight, aircraft speed and altitude, its in-flight configuration, atmospheric conditions, axial velocity in the vortex core and some other factors, when calculating the vortex wake performance. This complex passed the required testing and state registration. Several procedures were executed to validate and verify the developed complex, confirming its program efficiency and the reliability of the results obtained. The Airbus A320 and A380 were selected as the research object of this article. The flight mode and atmospheric conditions are similar for all aircraft. The results obtained allow us to understand how atmospheric conditions affect the propagation of contrails behind aircraft of different classes, provided their interaction with vortex trails.

Critical groove depth and width for maintenance management of runway pavements

ABSTRACT Groove deterioration and accumulation of surface contaminants have the negative effect of reducing groove depth and width. Reduced depths and/or widths of grooves in a runway pavement would adversely affect its safety functions. Currently, no mechanistic solutions are available to quantitatively evaluate the effect of groove depth and width on the safety effectiveness of a grooved pavement against skidding and hydroplaning. This study developed a finite-element procedure to provide a mechanistic solution to the dynamic tire-pavement skid resistance problem, and calculate the skid resistance and hydroplaning speed of grooved pavement. Based on the standard FAA square grooves, analyses were presented in this paper to analyze the impacts of groove deterioration on the skid resistance and hydroplaning speed for a B777 aircraft. The analyses offered insights into the variations of skid resistance and hydroplaning speed with groove dimensions, and provided supporting results to the minimum 3 mm groove depth and width recommendation by FAA for runway pavements. The solution offers a useful tool to quantify the reduced safety margins of deteriorated grooves with shallow depths and widths. It can be applied to analyze the safety impacts of changes in the dimensions of any runway pavement groove configuration.

Air Traffic Complexity Map Based on Linear Dynamical Systems

This paper presents a new air traffic complexity metric based on linear dynamical systems, of which the goal is to quantify the intrinsic complexity of a set of aircraft trajectories. Previous works have demonstrated that the structure and organization of air traffic are essential factors in the perception of the complexity of an air traffic situation. Usually, they were not able to explicitly address trajectory pattern organization. The new metric, by identifying the organization properties of trajectories in a traffic pattern, captures some of the key factors involved in ATC complexity. The key idea of this work is to find a linear dynamical system which fits a vector field as closely as possible to the observations given by the aircraft positions and speeds. This approach produces an aggregate complexity metric that enables one to identify high (low) complexity regions of the airspace and compare their relative complexity. The metric is very appropriate to compare different traffic situations for any scale (sector or country) by associating a complexity index to each trajectory sample in the airspace. For instance, to compute the complexity for a sector, one must just sum-up the complexity for trajectory samples intersecting such a sector. This computation can also be extended in the time dimension in order to estimate the average complexity in a given airspace for a period of time.