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Accurate modeling of aircraft fuel consumption, emissions, and noise is crucial in evaluating new air transportation operational procedures and policies to abate negative environmental impacts. The...

This paper presents a practical method to compute the four-dimensional flight trajectories of aircraft in the presence of winds. The proposed method consisted of numerically integrating the aircraf...

This paper presents a method developed at the Laboratory of Applied Research in Actives Controls, Avionics, and AeroServoElasticity for calculating takeoff and departure trajectories of a Cessna Ci...

Recent research on flight-deck interval management technology, including the findings of a flight-test demonstration conducted by NASA, led to the development of an alternative control logic for fl...

This paper describes a novel finite-state conditional switching structure that enables autonomous recovery for a large envelope of loss-of-control conditions. The switching control architecture mim...

Purpose This paper aims to propose a novel approach, in which the reference data for the flow angles calibration are obtained by using measurements coming from an inertial navigation system and an air data sensor. Design/methodology/approach This is obtained by using the Kalman filter theory for the evaluation of the reference angle-of-attack and angle-of-sideslip. Findings The designed Kalman filter has been implemented in Matlab/Simulink and validated using flight data coming from two very different aircraft, the Piaggio Aerospace P1HH medium altitude long endurance unmanned aerial system and the Alenia-Aermacchi M346 Master™ transonic trainer. This paper illustrates some results where the filter satisfactory behaviour is verified by comparing the filter outputs with the data coming from high-accuracy nose-boom vanes. Practical implications The methodology aims to lower the calibration costs of the air data systems of an advanced aircraft. Originality/value The calibration of air-data systems for the evaluation of the flow angles is based on the availability of high-accuracy reference measurements of angle-of-attack and angle-of-sideslip. Typically, these are obtained by auxiliary sensors directly providing the reference angles (e.g. nose-boom vanes). The proposed methodology evaluates the reference angle-of-attack and angle-of-sideslip by analytically reconstructing them using calibrated airspeed measurements and inertial data.

Continuous descent operations (CDOs) with required times of arrival (RTA) have been identified as a potential solution for reducing the environmental footprint of aviation in the terminal maneuvering area without compromising capacity. This paper assesses the feasibility of replacing current air traffic control sequencing and merging techniques, mainly based on path stretching and air holding, by a control based on RTA over metering fixes on known and fixed arrival routes. Because the remaining distance to the runway threshold is always known by the aircraft crew, this would allow engine-idle CDOs that do not require speed-brake usage and where only elevator control is used to meet the RTA. The assessment has been performed for Barcelona-El Prat Airport (Spain) using historical traffic demand data. The earliest and latest trajectories at a metering fix for each inbound aircraft were computed assuming engine-idle CDOs. Given the attainable RTA window for each aircraft, the aircraft sequencing problem was solved. The results show that assigning RTA allows optimizing the landing sequence when air traffic is low. For scenarios with high-traffic loads and late RTA assignments, path stretching still was found to be necessary. The minimum distance from the runway where inbound aircraft should receive the RTA to fully remove any radar vectoring was also analyzed. It was demonstrated that the assignment of RTA well before starting the descent would favor to enable full CDOs.

Fixed and rotary-wing unmanned aircraft systems (UASs), originally developed for military purposes, have widely spread in scientific, civilian, commercial, and recreational applications. Among the most interesting and challenging aspects of small UAS technology are endurance enhancement and autonomous flight, i.e., mission management and control. This paper proposes a practical method for estimation of true and calibrated airspeed, Angle of Attack (AOA), and Angle of Sideslip (AOS) for small unmanned aerial vehicles (UAVs, up to 20 kg mass, 1200 ft altitude above ground level, and airspeed of up to 100 knots) or light aircraft, for which weight, size, cost, and power-consumption requirements do not allow solutions used in large airplanes (typically, arrays of multi-hole Pitot probes). The sensors used in this research were a static and dynamic pressure sensor (“micro-Pitot tube” MPX2010DP differential pressure sensor) and a 10 degrees of freedom (DoF) inertial measurement unit (IMU) for attitude determination. Kalman and complementary filtering were applied for measurement noise removal and data fusion, respectively, achieving global exponential stability of the estimation error. The methodology was tested using experimental data from a prototype of the devised sensor suite, in various indoor-acquisition campaigns and laboratory tests under controlled conditions. AOA and AOS estimates were validated via correlation between the AOA measured by the micro-Pitot and vertical accelerometer measurements, since lift force can be modeled as a linear function of AOA in normal flight. The results confirmed the validity of the proposed approach, which could have interesting applications in energy-harvesting techniques.

International audience; With the aspiring development towards Trajectory-based Operations, novel tools for robust trajectory prediction are necessary. For this, the impact of uncertain input variables to the trajectory prediction must be understood to permit higher automation with increasing look-ahead times. In this study, a neural network provides input probability density functions for the aircraft mass and speed intent (multiple phases with constant calibrated air speed or Mach number). With our flight performance model, 10,000 climb phases are predicted in a Monte-Carlo simulation with a look-ahead time of 600 seconds for six different aircraft types. The resulting trajectory uncertainty is analyzed to prove that the stochastic characteristics of the input can be used to predict the arising uncertainties in future positions. Since the selected uncertainties are interdependent and time-lagged, the normality of the input vanishes in the trajectory uncertainty. However, a Beta distribution provides a good fit for up to 90% of the cases. The findings are applicable to decision support tools if the expected uncertainty shall be included.

Best paper award in the trajectory prediction track; International audience; Ground-based aircraft trajectory prediction is a major concern in air traffic control and management. A safe and efficient prediction is a prerequisite to the implementation of new automated tools. In current operations, trajectory prediction is computed using a physical model. It models the forces acting on the aircraft to predict the successive points of the future trajectory. Using such a model requires knowledge of the aircraft state (mass) and aircraft intent (thrust law, speed intent). Most of this information is not available to ground-based systems. Focusing on the climb phase, we train neural networks to predict some of the unknown point-mass model parameters. These unknown parameters are the mass and the speed intent. For each unknown parameter, our model predicts a Gaussian distribution. This predicted distribution is a predictive distribution: it is the distribution of possible unknown parameter values conditional to the observed past trajectory of the considered aircraft. Using this distribution, one can extract a predicted value and the uncertainty related to this specific prediction. Using a physical model like BADA, this distribution could be used to derive a probability distribution of possible future trajectory ([1]). This study relies on ADS-B data coming from The OpenSky Network. It contains the climbing segments of the year 2017 detected by this sensor network. The 11 most frequent aircraft types are studied. The obtained data set contains millions of climbing segments from all over the world. Using this data, we show that despite having an RMSE slightly larger than previously tested methods, the predicted uncertainty allows us to reduce the size of prediction intervals while keeping the same coverage probability. Furthermore, we show that the trajectories with a similar predicted uncertainty have an observed RMSE close to the predicted one. The data set and the machine learning code are publicly available.

Air transport planning takes new technologies, strategies, and procedures into consideration when optimizing both trajectory and air traffic management. Continuous Climb operations (CCO) are new op...

Over the past thirty years, the civil aeronautical community has actively pursued research to enable efficient and environmentally friendly arrival operations. One outcome of this research is a collection of new ground automation tools, developed to assist air traffic controllers (ATC) in managing traffic while maintaining safety. Another outcome is a set of Optimal Profile Descent (OPD) and Continuous Descent Arrival (CDA) procedures, designed to reduce emissions and noise. Recent years have seen significant efforts to integrate these new tools and procedures to manage arrival flights even more efficiently. In one such research activity, each arrival flight is scheduled to pass certain points along a specific route defined from the transition airspace all the way to the runway. This approach was initially called precision scheduling and, in later literature,renamed to precision operations. With this approach, air traffic controllers would use speed clearances as the primary means of guiding flights, reserving vectoring clearances for exceptions only. Precision operations, with its speed control, is in contrast to the conventional approach, in which aircraft follow a routine of vectoring clearances from ATC upon entering the terminal airspace.

A low-cost ($100) differential pressure-based commercial off-the-shelf angle-of-attack data acquisition system was designed, successfully reduced to practice, and wind-tunnel and flight tested. For...

The flow angles calibration of air-data systems is based on the availability of high-accuracy reference measurements of angle-of-attack and sideslip angles. Typically, these are obtained by auxilia...

This paper presents an interface system display that is conceived to improve pilot situation awareness with respect to a flight envelope protection system, developed for a midsized transport aircra...

This paper discusses the development and testing of an upset recovery architecture that is applicable for both piloted and autonomous recoveries. The architecture was first developed for unmanned vehicles and intended for fully automated implementation. The architecture was extended for use in manned aircraft and, in particular, for situations in which recoveries are being manually flown by a pilot. This extension required development of display technology for presenting recommended recovery guidance to the pilot as well as modification of recovery strategies to make them suitable for execution by a human pilot. Most recently, the architecture has been extended to accommodate off-nominal vehicle dynamics (e.g., due to actuator failures) and has been structured specifically to facilitate implementation without modification and recertification of existing flight control software. The approaches have been tested in multiple pilot-in-the-loop simulation experiments, which have shown both favorable pilot opini...

This paper presents a mixed-integer programming approach to compute aircraft arrival routes in a terminal maneuvering area (TMA) with guaranteed temporal separation of all aircraft arriving within a given time period. Furthermore, the aircraft are assumed to be flying according to their optimal continous descent operation speed profile with idle thrust and no speed brakes usage. The arrival routes form a merge tree that satisfies several operational constraints; for example, all merge points are spatially separated. How the continuous descent operation speed profiles for different route lengths are computed is detailed. Experimental results are presented for calculation of fully automated continuous descent operation-enabled arrival routes during 1 h of operation on a busy day at a Stockholm terminal maneuvering area. The current framework successfully generates an arrival tree, merging the traffic from all TMA entry points to the runway for 30 min intervals. For a complete 1 h period, two trees (per 30 min) are computed that differ as little as possible.

International audience; The increased number of daily flights in the last decades has led to the densification of major airports and the proliferation of air traffic delays. The approach phase is inherently complex and labor extensive for flight crews, whose mission is to follow a stabilized approach. Current flight management systems do not provide much help in situations of high energy, where crews apply challenging energy management techniques to land in the destination runway. Go-around procedures shall be initiated as soon as the aircraft is not at the correct energy condition at the stabilization gate, despite the increase of workload this type of operation induces for crews and air traffic controllers. The continuation of a nonstabilized approach may put at peril the safety of flight. This paper presents an algorithm that computes the trajectory that stabilizes the aircraft in the minimum distance, which is also known as the high-energy-limit trajectory. The provision of this trajectory contributes to raising flight crew awareness of the aircraft energy state, and it informs that stabilization is not possible by giving the minimum distance to follow a stabilized approach. Flight simulator results helped to assess the operational concept and improve the representativeness of real flight operations. The calculation of the trajectory on a real-time basis provides flight crews with useful information of the aircraft energy condition, which improves flight safety and may ultimately reduce the number of nonstabilized approaches and go-around procedures.

This paper compares fuel consumption of descent trajectories from cruise altitude to meter fix when the required time of arrival is later than the nominal time of arrival at the meter fix. The required delay, which is the difference between the nominal and the required times of arrival, is achieved by either slowing down the aircraft in the cruise and descent phases or flying a longer route at a constant altitude. Performance models of 10 different Boeing and Airbus aircraft, obtained from the Base of Aircraft Data, are employed for generating the results. It is demonstrated that the most fuel-efficient speed-control strategy for absorbing delay is first reducing descent speed as much as possible and then reducing cruise speed. This is a common finding for all 10 aircraft considered. For some aircraft, flying at a fixed flight-path angle and constant Mach number/calibrated airspeed results in lower fuel consumption compared to standard descent at idle thrust and constant Mach number/calibrated airspeed. F...

In the present paper, an aircraft control surface flight cycle is predicted considering corner flaws and through crack under transport wing standard load using the NASGRO model available in AFGROW software. The effect of corner flaws length, depth of countersunk, panel thickness, axial load to pin load, composite patch, and disbond factor on the normalized stress intensity factor, critical flight cycle, and repeat inspection interval are investigated. The typical numerical prediction of the critical flight cycle is validated with analytical estimation and published experimental results, and shows excellent agreement.

This paper presents the investigation of the applicability of a counterpropagating laser airspeed sensor system to measure airflow velocity in the subsonic-to-transonic aircraft flight regimes. The system uses the Doppler shift of an absorption line in the A-band of molecular oxygen near 760 nm combined with an independent measurement of the static pressure and temperature to determine the true airspeed. The unique experimental arrangement using laser diodes allows the possibility for fully analog signal processing, while the size and weight of the system would be appropriate for most commercial aircraft or unmanned aerial vehicles flying today. Static pressure and velocity regimes were investigated in wind-tunnel tests from static pressures of 20 to 150 kPa (altitude equivalent 40,000 ft to subsea-level) and airspeeds of 5 to 380 m/s. It is concluded that counterpropagating laser airspeed sensor is a viable airspeed instrument for these aircraft flight regimes as well as a safety-enhancing possible alte...

To facilitate the increasing amount of air traffic, current and future decision support tools for air traffic management require an efficient and accurate trajectory prediction. With uncertainty inherent to almost all inputs of a trajectory predictor, the accurate prediction is not a simple task. In this study, Monte Carlo simulations of a ground-based trajectory predictor are performed to estimate the prediction uncertainty up to 20 min look-ahead time and to assess the correlation between inputs and prediction errors. Selected inputs are aircraft bank angle, constant calibrated airspeed and Mach number speed settings, vertical speed, temporary level-offs, air temperature, lapse rate, wind, and air traffic control intent. These inputs are provided in the form of their distribution functions obtained from observed data such as surveillance data, weather forecasts, and air traffic controllers’ inputs. Simulations are performed for heavy and medium wake turbulence category aircraft. Results indicate that with 20 min look-ahead time, when outliers are not considered, along-track errors can reach up to 18 nmi, whereas altitude errors can reach up to around 13,000 ft. Cross-track errors in cruise highly depend on the lateral deviations due to Air Traffic Control instructions, and, in this study, are within 10 nmi. Wind conditions, vertical speed, calibrated airspeed, Mach number speed setting, and temporary level-offs are determined to be the most influential inputs.

This paper presents robust fault diagnosis and estimation for the calibrated airspeed and angle-of-attack sensor faults in the RECONFIGURE benchmark. We adopt a low-order longitudinal model augmented with wind dynamics. In order to enhance sensitivity to faults in the presence of winds, we propose a constrained residual generator by formulating a constrained moving horizon estimation problem and exploiting the bounds of winds. The moving horizon estimation problem requires solving a nonlinear program in real time, which is challenging for flight control computers. This challenge is addressed by adopting an efficient structure-exploiting algorithm within a real-time iteration scheme. Specific approximations and simplifications are performed to enable the implementation of the algorithm using the Airbus graphical symbol library for industrial validation and verification. The simulation tests on the RECONFIGURE benchmark over different flight points and maneuvers show the efficacy of the proposed approach.

Continuous descent arrival (CDA) procedures provide time and fuel savings, and reduce the noise impact of aircraft operations near airports. To date, these procedures have been designed to limit the performance envelopes to achieve trajectory commonality. In this paper, the performance bounds of CDA procedure via multiphase optimal vertical trajectory generation problems with respect to two performance indices—flight time and fuel consumption—have been investigated. The optimal CDA vertical profile is first divided into two segments: the cruise segment before the top of descent (TOD) and the descent segment from the TOD. Then, the second segment is further subdivided based on flap setting and speed constraints. Finally, the resulting multiphase optimal control problem is solved using a pseudospectral method. Two different types of aircraft, B737-500 (light) and B767-400 (heavy), are used in a numerical study, and the optimal CDA trajectories of the two types are compared with a typical vertical navigation...

A standard descent procedure with a fixed flight-path angle is proposed to improve trajectory predictability for arriving small jets in the transition airspace into congested terminal area. Three candidate strategies for selecting fuel-efficient and flyable descent flight-path angles are proposed. The three strategies vary in operational complexity and fuel-burn merits. To mitigate variation of wind among flights, the two simpler strategies are adapted to airport, directions of arrival, and time. Three major U.S. airports with different degrees of wind variation and disparate arrival traffic flows are analyzed. Results show that, when compared to the simple airport–static adaptation, the finest adaptation of the simpler strategies recover up to 50–75% of the extra fuel burn relative to the minimum-fuel strategy. Wind variation, descent altitude restrictions, arrival directions, and fleet composition all affect the fuel efficiency of the simple strategies. Tradeoffs between fuel burn and planned speed-brak...

A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s−1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents) that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

This is a postprint (author final draft) deposit on institutional repository UPCommons from UPC, thanks to AIAA. Original version can be found on: https://arc.aiaa.org/doi/10.2514/1.C034251 This paper proposes an optimization framework that computes conflict-free optimal trajectories in dense terminal airspace, while continuously monitoring trajectory conformance in an effort to improve predictability. The objective is to allow, as much as possible, continuous vertical trajectory profiles without impacting negatively on airspace capacity. Given automatic dependent surveillance–broadcast intent information, the future state of potential intruder aircraft are predicted, and this nominal trajectory is used as a constraint in the ownship trajectory optimization process. In it, a continuous multiphase optimal control problem is solved, taking into account spatial and temporal constraints. Additionally, a linearized Kalman filter keeps track of the target by estimating the deviations of its actual trajectory from its nominal trajectory, issuing a warning when an appropriate threshold is exceeded. This may be due to unexpected events, biases in the performance and weather models, wrong parameter assumptions, etc. An illustrative example is given, based on a computer simulation of two hypothetical trajectories in the Barcelona terminal maneuvering area. The results show how this framework resolves the problem of uncertainties in the trajectory predictions and results in a more efficient conflict resolution.

Accurate predictions of aircraft noise levels are desirable to enforce noise control regulations around airports and to evaluate noise abatement procedures. The current best practice noise contour prediction models assume certain default net thrust values depending on the engine type and aircraft altitude. This Paper proposes a method for calculating the engine fan settings N1% (and, hence, the net thrust) directly from audio recordings. This method was tested with a large number of Airbus A330–300 and Boeing 777–200 flyover audio recordings. A significant correlation was found between the recorded noise levels and N1%, explaining up to 45% of the variability in the noise levels. Using the calculated N1% values in the noise prediction models, instead of the default values, increases the agreement with the actual recorded noise levels and explains parts of the variability. The inclusion of accurate values of N1% and the update of the aircraft noise prediction calculations is therefore highly encouraged, for example, by increasing the dependency on N1% of the noise levels.Read More: https://arc.aiaa.org/doi/10.2514/1.C034849

This paper presents selected results authors have reached during research of airspeed control algorithm developed for Single Engine Piston Light (SEPL) aircraft powered by piston engine with constant-pitch propeller in tractor configuration. There are some theoretical discussions about control law’s structure and methods of adjusting them to control plant’s operational features in this paper. Moreover, practical implementation of developed algorithm is described. Finally, results achieved both during computer simulations and flight tests are presented and discussed.

While operating any aircraft it is vital to know its current flight state. Some of the most important variables to assess the flight state are the airspeed, the angle of attack and the sideslip angle. Larger aircraft are equipped with sensors specifically designed to measure these variables. However on small unmanned aerial vehicles (UAVs) much stricter restrictions on size, weight and cost prohibit the use of such sensors. Therefore we propose a method to estimate the airflow variables utilizing only sensors that are part of a standard UAV autopilot. This includes an inertial measurement unit (IMU), a global navigation satellite system (GNSS) receiver and a pitot-static tube. These measurement together with kinematic and aerodynamic models will be fused within an estimator to estimate steady and turbulent wind velocities as well as aerodynamic coefficients. With these estimates it is possible to calculate the angle of attack, the sideslip angle and the airspeed. A main challenge is to distinguish between changes in the aerodynamic coefficients and changes in wind velocity, since pitot-static tube measurements of the relative airspeed are only available in one direction at a time and hence the system is not always observable. Therefore attitude changes have to be undertaken to achieve persistence of excitation. In this paper a Moving Horizon Estimator (MHE) is used for estimation. Simulation results show overall good estimation results and significant improvements compared to a previous Extended Kalman Filter approach. Root mean square errors (RMSE) are 0.25° for the angle of attack, 0.08m/s for the airspeed and 1.06° for the side slip estimates. This article will not be available due to copyright restrictions ©2017 by IEEE

The calibration of air-data systems for the evaluation of the flow angles is based on the availability of high-accuracy reference measurements of angle-of-attack and angle-of-sideslip. Typically, these are obtained by auxiliary sensors directly providing the reference angles (e.g. nose-boom vanes) or by analytically reconstructing them using calibrated airspeed measurements and inertial data. With reference to this second methodology, this paper proposes a novel approach, in which the reference data for the flow angles calibration are obtained by using measurements coming from an inertial navigation system and an air data sensor. This is obtained by using the Kalman filter theory for the evaluation of the reference angle-of-attack and angle-of-sideslip. The methodology aims to lower the development costs of advanced aircraft. The designed Kalman Filter has been implemented in Matlab/Simulink and validated using flight data coming from two very different aircraft, the Piaggio Aerospace P1HH Medium Altitude Long Endurance (MALE) Unmanned Aerial System (UAS) and the Alenia-Aermacchi M346 ‘Master’ transonic trainer. This paper illustrates some results where the performance is evaluated by comparing the filter results with the data coming from high-accuracy nose-boom vanes.

This paper presents the design features and algorithms of processing the data of a vortex sensor of aerodynamic angle and true air speed aboard a subsonic airplane. This sensor provides measurement of the other altitude-speed flight parameters.

Flight data collected by various P2V and P3A air tankers in actual operation over several seasons have been used to construct statistical information on aircraft usage and maneuver load spectra in this role. The data used for this report consist of 5316 flight files, collected during the 2008 and 2009 fire seasons. Flights have been divided into multiple phases, separating the segments when retardant is dropped from others. Basic flight parameters such as airspeed, altitude, flight duration and distance, bank, and pitch angles are shown in statistical form. Vertical accelerations are used to construct V−n diagrams for comparison with the manufacturers’ data. Airframe cycle times are shown to be approximately 45 min. Several coincident flight events are shown and compared with operational limits when available. The altitudes, the normal accelerations, and the airspeeds have not revealed any operation outside of the established boundaries. Relatively large dive and roll angles were prominently present durin...

A method for estimating the airspeed, angle of attack, and sideslip without using a conventional, pitot-static air data system is presented. The method relies on measurements from Global Positioning System, an inertial measurement unit, and a low-fidelity model of the aircraft’s dynamics, which are fused using two cascaded extended Kalman filters. In the cascaded architecture, the first filter uses information from the inertial measurement unit and Global Positioning System to estimate the aircraft’s absolute velocity and attitude. These estimates are used as the measurement updates for the second filter in which they are fused with the aircraft dynamics model to generate estimates of the airspeed, angle of attack and sideslip. Methods for dealing with the time and interstate correlation in the measurements coming from the first filter are discussed. Simulation and flight-test results of the method are presented. Simulation results show that the root mean square error of the airspeed estimate is less than...

The Green Flight Challenge occurred in September 2011 as a competition to spur extreme flight efficiency for general aviation aircraft. In order to compete, an aircraft had to demonstrate flight over a 200 mile course at an average groundspeed of 100 mph with a fuel efficiency greater than 200 passenger miles per equivalent gallon. This paper describes the design of Taurus G4, the world’s first four-seat electric-powered aircraft, and the flight-planning techniques used in winning the competition. The aircraft demonstrated flight over a 196 mile course at an average speed of 107 mph and an average equivalent fuel efficiency of 403.5 passenger miles per equivalent gallon of automotive gasoline. In this demonstration, it showed that battery-powered flight is practical for general aviation missions.

Aircraft climb trajectories are difficult to predict, and large errors in these predictions reduce the potential operational benefits of some advanced concepts in the Next Generation Air Transportation System. An algorithm that dynamically adjusts modeled aircraft weights based on observed track data to improve the accuracy of trajectory predictions for climbing flights has been developed. In real-time evaluation with actual Fort Worth Center traffic, the algorithm decreased the altitude root-mean-square error by about 20%. It also reduced the root-mean-square error of predicted time at top of climb by the same amount.

In this paper the airspeed control in an open circuit wind tunnel for a velocity range from 5 m/s to 25 m/s is presented. The instrument used for the velocity measurement was a type L Pitot tube, differential pressure, absolute pressure and temperature transducers were used too. Open loop tests were developed in the wind tunnel to determine modeling it through the Toolbox for system identification of MATLAB® for the design of the reference speed control strategy. By the process of identification the PI controller that is capable of maintaining a variation of ±2% with respect to the set point was obtained.

This paper discusses the subject of unmeasurable parameter (or state) estimation. It presents a viable option for carrying out this task, as well as augmentations for mending its flaws. The selected basic method is Multiple Model Adaptive Estimation, using multiple Kalman Filters (KFs) in parallel to determine the current value of the parameter (or state) using other sensor measurements. However, this method is proven to give a staircase function as estimate in case of continuous variation of the unknown parameter. In some cases this leads to unacceptable estimation errors. One possible solution is to increase the number of KFs but this can also highly increase the computational load. Searching for alternative solutions resulted in the idea of using parabolic curve fitting on the discrete parameter values, so that the minimal value of the parabola could interpolate between the fixed values and so better locate the true parameter. Tests in an example showed that this method gives satisfactory results inside the covered parameter range but on the boundaries it can be inaccurate. With supplementation of the original parameter range (extension of the boundaries) and extrapolation of the parabolic curve one can finally achieve a highly accurate parameter estimate. This is demonstrated by an application example which offers calibrated airspeed estimation on a high-fidelity Airbus civil aircraft model.

In this paper, we describe some principles of construction, algorithms for data processing, and a functional scheme of the vortex sensor for aerodynamic angles and true airspeed measurements in subsonic flight vehicles. Also presented are some relations for determining the ranges of measurements and indicated errors of this sensor and its design peculiarities and advantages are considered.

Unpowered descents of commercial transport aircraft are optimized in the presence of altitude-dependent winds with the objective of maximizing range. The optimal problem and an optimized constant calibrated-airspeed procedure are analyzed. The optimal problem is studied using the theory of singular optimal control. The optimal control is of the bang–singular–bang type, and the optimal trajectories are formed by a singular arc and two minimum/maximum-path-angle arcs joining the singular arc with the given initial and final points. The constant calibrated-airspeed procedure isoptimizedusing parametricoptimization theory. Results are presented fora model of a Boeing 767-300ER and for linear wind profiles. The effects of both the average wind and the wind shear on the optimalresults,aswellastheeffectsoftheaircraftweight,areanalyzed.Thewindshearisshowntohaveacleareffect onthemaximumrange.Thecomparisonbetweenthetwosetsofresultsshowsthattheoptimizedconstantcalibratedairspeeddescentisveryclosetooptimal.Fromtheoperationalpointofview,theoptimumdescentcalibratedairspeed is defined in terms of the wind profile and the aircraft weight.

We consider the peculiarities of constructing and the algorithms of primary information processing for a starting system of measuring the value and direction of the wind velocity vector during parking, in moving and maneuvering on the ground surface. Also the components of the true airspeed vector at the takeoff/landing and hovering regimes are considered.

WOS: 000295754500020, More accurate analytical solutions of the maximum rate of climb and maximum climb angle are proposed for the climbing flight of the piston-propeller airplane. For the solutions, it is assumed that the propeller efficiency is a function of the airspeed and the airplane has cambered wing drag polar. The solutions are compared with the performance calculated through traditional assumptions of a constant propeller efficiency and a symmetrical wing drag polar. Moreover, the quartic equation to find the best climb angle speed is solved exactly. The comparison proved that the solutions with traditional assumptions result in a higher service ceiling, a shorter climb time, and a shorter climb distance.