Search

External factors such as geography and weather strongly affect bird migration influencing daily travel schedules and flight speeds. For strictly thermal-soaring migrants, weather explains most seasonal and regional differences in speed. Flight generalists, which alternate between soaring and flapping flight, are expected to be less dependent on weather, and daily travel schedules are likely to be strongly influenced by geography and internal factors such as sex. We GPS-tracked the migration of 70 lesser kestrels (Falco naumanni) to estimate the relative importance of external factors (wind, geography), internal factors (sex) and season, and the extent to which they explain variation in travel speed, distance, and duration. Our results show that geography and tailwind are important factors in explaining variation in daily travel schedules and speeds. We found that wind explained most of the seasonal differences in travel speed. In both seasons, lesser kestrels sprinted across ecological barriers and frequently migrated during the day and night. Conversely, they travelled at a slower pace and mainly during the day over non-barriers. Our results highlighted that external factors far outweighed internal factors and season in explaining variation in migratory behaviour of a flight generalist, despite its ability to switch between flight modes. [ABSTRACT FROM AUTHOR]

Currently aviation focuses mainlly on increasing the economy and ecology of engines. Production of NOx, CO2 and SO2 adversaly impacts the environment. Parallel goal to minimize SFC to achieve both lower: emission and mission costs. The optimization of components is thus very important. One of the ways of optimizing cycle is doing that based on compressor maps. However it is very expensive to plot one since experimental work needs to be done. The aim of this article is to present a methodology of creating compressor map based on ENGINE ANALOGY. There was used the virtual bench WESTT CS/BV for tests to receive pressure ratio and mass flow of DGEN 380 for three different values of flight speed and altitude, while the rotational speed was changed. The construction similarity of CFM 56-5B and APS 3200 gives the opportunity to plotted compressor maps using the engine analogy without the need for an experiment or using the virtual bench. [ABSTRACT FROM AUTHOR]

The results of hover and wind tunnel tests of a reduced-scale, model rotor operating with lift offset are presented. The two-bladed rotor had a diameter of 2.03 m and constant cross section untwisted blades. Measurements include steady and vibratory hub loads, as well as control angles and pushrod loads. The rotor system was tested in hover and at advance ratios between 0.21 and 0.53, at collective pitches ranging from 3° to 10°, achieving blade loadings in excess of 0.10. At each forward flight operating condition, sweeps of lift offset up to 15% were performed. In forward flight, the rotor effective lift-to-drag ratio was found to increase with increasing advance ratio and lift offset, with a maximum increase of 40% compared to the zero lift offset case. Vibratory loads increased with advance ratio, with the largest loads in the two- and four-per-revolution harmonics. Lift offset is shown to modify vibratory hub forces and moments transmitted to the fixed frame, increasing vibratory rolling and pitching moments while decreasing vibratory thrust and torque. [ABSTRACT FROM AUTHOR]

I often open my lectures with a question: Do you agree that as speed goes down in any landing, the vertical tail fails to orient the nose back to the runway under strong side winds while ONLY side deflecting jet-engine-steering (JES) can safely re-orient it to safe landing?Just facts, less opinions; And if you do, you accept the 1ST-element of jetonautics defined by 12 figures below, text and references 1 to 48. [ABSTRACT FROM AUTHOR]

The article discusses the supersonic transport airplane (SST) planned and financed by the U.S. government to increase the cruising speed of jet transports. The Federal Aviation Agency (FFA) has been authorized to spend $311 million for the preliminary development of the SST while the industry will contribute $100 million. Boeing Corp. and Lockheed Corp. are the prime contractors, however, only one will be selected to complete the program. Development costs of SST have been estimated at $2 billion to meet the FAA standards and total financing requirements for ten years have been estimated at $5 billion.

The inevitability of technological progress is one of the most widely-held beliefs of our era but there is one very important field in which technological progress appears not only to have stagnated, but reversed. Examining the technical and commercial reality of modern aviation, there are three objective markers of slowdown. First, airplanes operational today can no longer reach the speed and altitude records set four decades ago. Second, commercial flight times have not only failed to get shorter, they actually take longer than they did in the past. Third, forty years after its introduction, supersonic flight is no longer available for civilians, neither in commercial nor private jets. While flight today is safer, cheaper, and more widespread than in the past, it has become slower, and jet-makers are strangely not even interested in exploring ways of making it faster. The paper concludes with a discussion of the cultural, political, economic, and institutional reasons behind this slowdown. The receding state of the art in aviation acts as both an object lesson and a warning for the state of economic dynamism overall. [ABSTRACT FROM AUTHOR]

The instability problems tend to be more severe when high speed compressors operate at partial speeds. This paper proposes an economic approach for casing treatment design that suitable to this situation. Aiming at reducing the expensive and time-consuming high-speed casing treatment experiments, the idea of low-speed similitude of high-speed compressors, which was originally practiced in mid-1980 with the purpose of loss reduction, is now extended to simulate the stability enhancement with casing treatment in this paper. The core idea of this approach is to replace a large portion of design processes for the high-speed compressors (the Prototype) with their equivalent large scale model compressors (the Model). Two different transonic rotors with skewed slots and circumferential grooves casing treatments are conducted as examples to demonstrate this approach. Following the selected similarity rules, the Model is firstly acquired by modeling the near stall point of the Prototype. A variety of casing treatments are designed and assessed on the Model. Then a few more promising configurations can thus be selected via low speed experiments. They are believed to have similar tendency on stall margin improvement on the Prototype. Finally, the selected configurations are converted back to the Prototype with based on the rule of similarity and validated by experimental data. In this paper, principles that guarantee the similitude of the flow field at near stall condition and the effectiveness of the casing treatment are discussed. [ABSTRACT FROM AUTHOR]

Efficient flight operations are crucial for the sustainable development of aviation. Continuous descent is a potential solution in a terminal airspace. At present, descent is evaluated based on the length or duration of level flight segments only. Typically, modern flight management systems calculate optimal descent profiles with level segments added only for necessary deceleration. If no wind disturbance is present, the aircraft can follow the path calculated and achieve the optimal descent. In practice, however, differences between the predicted and actual wind require changes to the descent profile such as adding thrust, drag, or flying additional level segments. This research analyses different descent control strategies and investigates their effects on fuel burn, flight time and path deviation. Monte Carlo simulations are conducted to account for various wind conditions. Results show that even strategies with level segments increased by an average of 22% can result in lower fuel burn. Therefore, it is concluded that level segments by themselves are not a sufficient metric for descent efficiency and a strategy for lower fuel burn descents is proposed. [ABSTRACT FROM AUTHOR]

A high fidelity aeroacoustic test was conducted in the NASA Langley 14- by 22-Foot Subsonic Tunnel to establish a detailed database of component noise for a 5.8% scale HWB aircraft configuration. The model has a modular design, which includes a drooped and a stowed wing leading edge, deflectable elevons, twin verticals, and a landing gear system with geometrically scaled wheel-wells. The model is mounted inverted in the test section and noise measurements are acquired at different streamwise stations from an overhead microphone phased array and from overhead and sideline microphones. Noise source distribution maps and component noise spectra are presented for airframe configurations representing two different approach flight conditions. Array measurements performed along the aircraft flyover line show the main landing gear to be the dominant contributor to the total airframe noise, followed by the nose gear, the inboard side-edges of the LE droop, the wing tip/LE droop outboard side-edges, and the side-edges of deployed elevons. Velocity dependence and flyover directivity are presented for the main noise components. Decorrelation effects from turbulence scattering on spectral levels measured with the microphone phased array are discussed. Finally, noise directivity maps obtained from the overhead and sideline microphone measurements for the landing gear system are provided for a broad range of observer locations. [ABSTRACT FROM AUTHOR]

In order to meet the high quality, reliability and high efficiency requirements of aircraft assembly, a new multifunction end-effector (MFEE) is developed, which integrates three functions: drilling, helical milling and oval countersinking. After an introduction to the design of the MFEE, the working principle of automatic oval countersinking is discussed in detail, which has rarely been studied before in literature. The architecture of the whole drilling system is elaborately presented, and particular emphasis is put on the key techniques to guarantee hole quality, which are hole position compensation, normal vector adjustment and countersinking depth control. Finally, results of drilling experiments conducted on aluminum 7050-T6 alloy and titanium Ti–6Al–4 V alloy are presented. It is shown that the system could improve the assembly quality and drilling speed of aircraft components effectively. The position accuracy could be controlled within ± 0.5 mm, the normal direction accuracy was better than 0.5°, and the countersinking depth variation could be controlled within 0.02 mm at the worst case, all the machined holes and oval countersinks satisfy both the geometric dimensions and surface roughness. [ABSTRACT FROM AUTHOR]

A Sabreliner aircraft speed brake (SB) structure was redesigned, fabricated using the OoA (out-of-autoclave) composite curing processes, and this manufacturing data was subjected to cost evaluation. The OoA SB structures were fabricated using the VARTM (vacuum-assisted resin transfer molding) and VPH (VARTM and Prepreg Hybrid) processes developed by JAXA (Japan Aerospace Exploration Agency). The original SB material consists primarily of aluminum alloys 7178-T6, and the forming parts and metal fittings were assembled using bolts and rivets. Results show that the weight and part count of the fabricated OoA composite SBs were dramatically reduced, by 31% and to one tenth, respectively. Using the fabrication data, manufacturing cost estimations were performed for metal, conventional composite (Prepreg/Autoclave with Nomex core), and OoA composite (VPH) SBs. From these results, it was apparent that the manufacturing cost of SBs was reduced when using composite materials (both conventional and OoA) according to the reduction in parts. In small production lots, the OoA process gains an advantage from the low cost of tools; however, when the production lot size increases, the cost of manufacture using the conventional composite process becomes lower than that of the OoA process. Though the structural design of these SBs was the same, the cost of using the composite process was dependent on both the selected process and production number. It is suggested that the composite curing method for manufacturing batches should be selected on the basis of not only the parts count, but also the production number on the design phase. [ABSTRACT FROM AUTHOR]

This study explores wing morphing for load alleviation as a means to reduce the required wing structural weight without compromising aircraft performance. A comparative study between the lift-to-drag ratio ( L/ D) performance of a fixed wing glider (FWG) and a cambered morphing wing glider (CMWG) is presented. Both aircraft are aero-structurally optimized for the best L/ D for a given speed and payload mass. A combination of lifting-line theory and 2D viscous calculations is used for the aerodynamics and an equivalent beam model is employed for the structural analysis. Pull-up and -down maneuvers at 25 m/s and near stall angle of attack are assumed as critical load cases. Results of the FWG optimization are shown for several trimmed flight conditions with varying mass and velocity. Results are compared to the ones from the CMWG optimization and conclusions are drawn on the improvement in the L/ D ratio throughout the flight envelope and on potential reductions in the wing structural mass due to the load alleviation strategy. The wing camber adaptation provides significant performance gains in a large range of flight speeds with negligible penalties in the low speeds range. However, maneuverability is penalized. [ABSTRACT FROM AUTHOR]

'Phis paper presents an approach for velocity control of tilt-wing aircraft over their entire flight envelope, ranging from hovering flight to wing-borne flight. With their capability of vertical takeoff and landing operation in combination with efficient cruise flight, tilt-wing aircraft offer multiple benefits in unmanned aerial vehicle applications. Control of tilt-wing aircraft, in particular for fully automated flight, is challenging because along with their versatility comes significant variations in flight mechanics characteristics. Known approaches to this problem subdivide tilt-wing flight into discrete aircraft configurations. The presented control concept omits discrete configurations and instead allows for continuous flight state transitions over a unified flight configuration space. Actuation that is unique to tilt-wing aircraft, for example, tilt angle control, is not only used as an aircraft configuration parameter but also as a full-fledged motion control device. The concept includes a map-based feedforward controller to maintain trimmed straight-lined flight and uses virtual control devices for motion control independent of the flight state. Flight state transitions are conducted along state trajectories that are defined deterministically and safely with respect to flight envelope limitations. The controller is implemented for an unmanned tilt-wing demonstrator and evaluated in flight. Compared to prior results, velocity response is considerably improved. [ABSTRACT FROM AUTHOR]

Fuel flow rate of an aircraft varies significantly during a typical flight, mainly due to required engine thrust, speed, weather conditions, aircraft configuration and aircraft mass. Of these, the effect of aircraft mass, being the non-payload portion, on fuel flow is investigated in this study. The investigation is carried out for twin-engined wide-bodied aircraft, during its intercontinental flights. Based on actual flight data records, two approaches are developed, in which the fuel flow rate is estimated based on three independent variables; altitude, aircraft mass and flight speed. The regression models are found to be highly significant and average fuel consumption is found to be 2-3% of the non-payload mass per flight hour. It should be noted that this percentage is affected by flight altitude and aircraft initial mass, of which the latter has a greater effect. In addition, it is worth noting that when the aircraft initial mass increases, the fuel consumption percentage also tends to increase. [ABSTRACT FROM AUTHOR]

This paper deals with three dimensional leader–follower formation control of unmanned aircraft systems. The main contribution of the paper is kinematic formulation of the leader–follower formation based on seeker measurements which omit the need for communication networks. Considering uncertainties in measurement of followers speeds, a robust controller is employed. Then, by proposing an integrated controller–estimator consisting of the robust controller and a disturbance compensator, keeping the formation while the leader is maneuvering is guaranteed. Simulation results verify the accuracy of the integrated controller–estimator system. [ABSTRACT FROM AUTHOR]

A fault-detection algorithm for a redundant multisensor navigation system for hypersonic cruise vehicles (HCVs) is proposed. The algorithm comprehensively diagnoses failures according to the failure level monitored by the sequential probability ratio test (SPRT) and chi-square test as well as the failure trend monitored by the SPRT. A test statistics feedback-reset loop is also added to shorten the recovery time after failure ceases. Simulations indicate improvements in both failure detection and recovery speed, contributing to improved accuracy and stability in HCV fault-tolerant navigation. [ABSTRACT FROM AUTHOR]

Among the premises of the Next Generation Air Transportation System initiative is the necessity for precision procedures in air traffic operations. Conformance with such procedures can help safety and the ability to accommodate higher traffic demand. The contribution of this paper is an algorithm for automating the process of speed control, aimed at separation assurance and conducted in current air traffic operations by human air traffic controllers. If a separation-compliant collective speed profile for the given set of aircraft exists, the algorithm computes this profile. If no such speed profile exists, the computer reports the nonexistence. Uncertainties such as weather are not considered, but the algorithm can be modified to include them. The algorithm proceeds in two stages. First, it finds an arrival sequence for the aircraft. The computational complexity of this stage is factorial in the number of aircraft but allows substantial parallelization. The second stage finds a collective speed profile for a given arrival sequence and has computational complexity that is polynomial in the number of aircraft. The algorithm is proved to find a solution whenever one exists and to ascertain nonexistence correctly. [ABSTRACT FROM AUTHOR]

Sandwich panels are increasingly being used in many different applications such as aerospace, automotive or military, mainly due to their high strength-to-weight ratio and impact and damage resistance. Understanding the behavior of these sandwich structures to low speed impact damage is of major importance when referring to both damage resistance and damage tolerance. Energy absorption criteria represent a way to asses crashworthiness of sandwich panels that are subjected to low velocity impact either by studying the core material or the overall structure. The following paper analyzes a metal sheet sandwich panel with an irregular honeycomb shaped polyurethane foam core by using three different impact velocities and three different foam core densities. [ABSTRACT FROM AUTHOR]

A typical jet flight pattern of linear shaped charges (LSCs) is studied, and analytical expressions are built for two important parameters of the angle of liner collapse line φ and jet projection angle ω. In order to simplify the nonlinear nature of the liner collapse behavior of LSCs, important assumptions are made, including (1) a constant jet projection velocity at the given standoff distance and (2) the liner collapse occurs in a steady-state fashion, generating a single straight collapse line during the detonation. Based on the assumptions, analytical expressions are derived and the result is compared with side-view images of LSC jet flight to evaluate accuracy and applicability. The analytical approach delivers reasonable accuracy in a given range and is applicable to a short range of standoff distances. [ABSTRACT FROM PUBLISHER]

Air traffic in European airspace is coordinated centrally by the air traffic flow management services – Network Management Operation Centre (NMOC). Their main task is to compare resources (number and capacity of air traffic control sectors) and needs (size of the planned and actual traffic). If it is found that the planned traffic exceeds the capacity of available airspace, corrective actions should be carried out. They consist in changing the takeoff time, or changing aircraft routes so as to avoid congested sectors or even cancelling the flight. Unfortunately, determining only the traffic volume is not sufficient to identify the needs, because very important are also: aircraft trajectories, manoeuvres performed, types of aircraft, their speed and other restrictions. Indeed, these factors determine the possibility to control the traffic by air traffic controllers. This makes it necessary to seek another indicator characterizing the traffic that must be handled. The paper proposes to use the notion of air traffic smoothness as a new, universal measure for characterizing the quality of air traffic. It can also serve as a measure of the traffic volume in the control sector or even as a traffic safety measure. The concept of smoothness is easier to use than the notion of the traffic complexity, which is increasingly being used, e.g. in the assessment of the capacity of the sector. The paper presents a new method for determining the air traffic smoothness, which uses both flight plans, their current implementation and the so-called favourable flight plans. On the basis of the measured data it is shown how to calculate the traffic smoothness for selected sectors. Indicating directions of further planned research, calculations were made to determine the relationship between the air traffic smoothness and its volume, which in turn may allow the use of the concept of smoothness to determine the capacity of control sectors and supporting air traffic flow management services. [ABSTRACT FROM AUTHOR]

This paper deals with the study of vibration analysis of the rolling aircraft tyre in various frequency conditions on free and braking conditions. This paper develops mathematical model for tyre and generates dynamic equations for numerical simulations in Matlab Simulink. The experimental test facility has been developed to measure the vibration parameters while rolling the tyre with load or no load conditions. Finally, the analysis has been carried out and the levels of vibration were measured experimentally. [ABSTRACT FROM AUTHOR]

The compound helicopter is a high-speed design concept that is once again being explored due to emerging requirements for rotorcraft to obtain speeds that significantly surpass the conventional helicopter. This increase in speed, provided efficient hover capability is maintained, would make the compound helicopter suitable for various roles and missions in both military and civil markets. The aim of this paper is to investigate the compounding of the conventional helicopter and how the addition of thrust and wing compounding influences the performance of this aircraft class. The paper features two compound helicopters. The first configuration features a coaxial rotor with a pusher propeller providing additional axial thrust, and is referred to as the coaxial compound helicopter. The second configuration, known as the hybrid compound helicopter, features a wing and two propellers providing thrust compounding. In this study, the performance of these two compound helicopter configurations are assessed and compared with a conventional configuration. The paper presents the standard performance parameters of each configuration which include the power required in steady level flight, the maximum range, the maximum endurance and the hover ceiling of each of the aircraft configurations. Furthermore, a performance analysis of each configuration flying standard helicopter missions is conducted. The results of the hybrid configuration show that the addition of the wing to the design successfully offloads the main rotor at high speeds; however, significant propulsive power is required by the propellers to overcome the airframe drag. Concerning the coaxial configuration, the power required by the coaxial compound and baseline configurations are comparable at low speeds. However, in high-speed flight a significant amount of power is required by the propeller to divorce the coaxial rotor of its propulsive duties. The results also reinforce the importance of reducing airframe drag in a potential compound helicopter design. [ABSTRACT FROM AUTHOR]

BACKGROUND: During approach and departure in rotary wing aircraft, a sudden loss of external visual reference precipitates spatial disorientation. METHODS: There were 10 Royal Canadian Air Force (RCAF) Griffon pilots who participated in an in-flight investigation of a 3-dimensional conformal Helmet Display Tracking System (HDTS) and the BrownOut Symbology System (BOSS) aboard an Advanced System Research Aircraft. For each symbology system, pilots performed a two-stage departure followed by a single-stage approach. The presentation order of the two symbology systems was randomized across the pilots. Subjective measurements included situation awareness, mental effort, perceived performance, perceptual cue rating, NASA Task Load Index, and physiological response. Objective performance included aircraft speed, altitude, attitude, and distance from the landing point, control position, and control activity. Repeated measures analysis of variance and planned comparison tests for the subjective and objective responses were performed. RESULTS: For both maneuvers, the HDTS system afforded better situation awareness, lower workload, better perceptual cueing in attitude, horizontal and vertical translation, and lower overall workload index. During the two-stage departure, HDTS achieved less lateral drift from initial takeoff and hover, lower root mean square error (RMSE) in altitude during hover, and lower track error during the acceleration to forward flight. During the single-stage approach, HDTS achieved less error in lateral and longitudinal position offset from the landing point and lower RMSE in heading. DISCUSSION: In both maneuvers, pilots exhibited higher control activity when using HDTS, which suggested that more pertinent information was available to the pilots. Pilots preferred the HDTS system. [ABSTRACT FROM AUTHOR]

The plane is an aerodyne equipped with a flat bearing surface ensures sustentation due speed. Travel speed can be achieved either by the action of powertrains or action component weight (for flight or flight descent without engine) [ABSTRACT FROM AUTHOR]

A flush mounted ultrasound device is potentially of interest for the non-intrusive measurement of the velocity field around a moving body. Ultrasound sending and receiving transducers might combine in one technique that could determine certain parameters of flow direction as, for example, around the fuselage of an aircraft in flight. The study reported here focused on the measurement and the prediction of times of flight in the configuration of a flat wall surrounded by a turbulent boundary layer. The presence of sheared flow and a turbulent boundary layer affects the propagation of acoustic waves. Time of flight was first estimated by a simplified model involving the convection effect and ignoring the shear layer. A numerical model based on the ray theory was also developed to take into account the propagation effect of the boundary layer. Indeed, the approximation of geometric acoustics was valid for high frequencies. In the first part, a comparison is presented to show that both approaches demonstrated similar trends at low Mach numbers. However, experiments conducted in a wind tunnel up to Mach 0.15 showed that the measurements were in better agreement with the estimates provided by ray theory. [ABSTRACT FROM AUTHOR]

This paper presents a strategy for stochastic control of small aerial vehicles under uncertainty using graph-based methods. In planning with graph-based methods, such as the probabilistic roadmap method (PRM) in state space or the information roadmaps (IRM) in information-state (belief) space, the local planners (along the edges) are responsible to drive the state/belief to the final node of the edge. However, for aerial vehicles with minimum velocity constraints, driving the system belief to a sampled belief is a challenge. In this paper, we propose a novel method based on periodic controllers, in which instead of stabilizing the belief to a predefined probability distribution, the belief is stabilized to an orbit (periodic path) of probability distributions. Choosing nodes along these orbits, the node reachability in belief space is achieved and we can form a graph in belief space that can handle higher order dynamics or nonstoppable systems (whose velocity cannot be zero), such as fixed-wing aircraft. The proposed method takes obstacles into account and provides a query-independent graph, since its edge costs are independent of each other. Thus, it satisfies the principle of optimally. Therefore, dynamic programming (DP) can be utilized to compute the best feedback on the graph. We demonstrate the method's peiformance on a. uni cycle robot and a six degrees of freedom (DoF) small aerial vehicle. [ABSTRACT FROM AUTHOR]

This study demonstrates an autonomous formation flight of multiple flapping-wing flying vehicles for the first time. In order to extract the position and attitude information of each flying vehicle, an external motion capture system is applied. A path-following controller is designed so that each flapping-wing flying vehicle has a time-independent circular path with the predetermined radius, and the constant forward flight speed and altitude. Due to the variations in flight characteristics among four different flapping-wing flying vehicles, the gain of the directional control, which generates nonlinear rolling moment using the changes of the tension in flexible membrane wings, is individually tuned for each vehicle. The rotational speed of the circular path is kept constant by controlling the desired radius rather than the forward flight speed so that the formation angles between two closest flapping-wing flying vehicles are maintained at 90 degrees. The performances of the individual path-following controllers and the circular formation controller are statistically evaluated in terms of the mean and standard deviation of the flight state variables. [ABSTRACT FROM AUTHOR]

There are few aircraft other than lighter-than-air vehicles that have the payload carrying capability, short field take-off, and slow speed ranges afforded by a powered parafoil. One very interesting aspect of the powered parafoils or paramotors, is their tendency to fly at a constant airspeed whether it is climbing, descending, or flying straight-and-level. Not only are the aircraft speed stable, but they have pendulum stability as well, due to the mass of the airframe suspended significantly below the canopy. This allows the aircraft to maintain a safe roll attitude and effectively turn in a coordinated manner when the steering pedals are deflected. One of the challenges of flying these aircraft is the necessity of controlling altitude with thrust, and direction with asymmetric drag. The paper presents a practical method to estimate the aerodynamic coefficients of a small-scale paramotor in order to obtain a suitable mathematical model for the aerial vehicle. Thus, a reduced state linear model based on a simplified nonlinear six degree-of-freedom model (6 DOF) is described. The autonomous control relies on the paramotor dynamics. And those equations depend on the aerodynamic coefficients. The task in this paper is to record the data of steady state flight regime, and to process it offline. Therefore, the system identification of the small-scale aerial vehicle can be done using the Two-Step Method, resulting an efficient six degree-of-freedom mini-paramotor model. The current work will permit the implementation of the control architecture in order to achieve the autonomous control of the small-scale paramotor through waypoints. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a high-order continuous nonlinear differentiator with lead compensation is presented based on finite-time stability. Not only the proposed high-order nonlinear differentiator can obtain the high-order derivatives of a signal, but also the chattering phenomenon can be reduced sufficiently. The parameters regulation is only required to be satisfied with Routh–Hurwitz Stability Criterion. The presented differentiator is a generalization of sliding mode differentiator and linear high-gain differentiator. The merits of the continuous differentiator include its simplicity, selecting parameters easily, restraining noises sufficiently, decreasing the phase shift and avoiding the chattering phenomenon. The theoretical results are confirmed by computer simulations and an experiment on a quadrotor aircraft: (i) the estimation of flying velocity and acceleration from the position measurement; (ii) a control law is designed based on the presented nonlinear differentiator to track a reference trajectory. [Copyright &y& Elsevier]

Detecting and solving aircraft conflicts, which occur when aircraft sharing the same airspace are too close to each other according to their predicted trajectories, is a crucial problem in Air Traffic Management. We focus on mixed-integer optimization models based on speed regulation. We first solve the problem to global optimality by means of an exact solver. Since the problem is very difficult to solve, we also propose a heuristic procedure where the problem is decomposed and it is locally exactly solved. Computational results show that the proposed approach provides satisfactory results. [ABSTRACT FROM AUTHOR]

In this paper empirical formulas relating the speed to principal dimensions of aircraft carriers have been obtained through regression analysis of the data of 105 aircraft carriers. To reduce uncertainty as much as possible, aircraft carriers are classified into several different categories. In each category, regression analysis is separately performed such that a variety of regression (empirical) formulas have thus been obtained for possible use at the initial design stage of a carrier. The goodness of fit of these formulas is finally analyzed through variance analysis. [ABSTRACT FROM AUTHOR]

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 during all but the drop phases. Nonetheless, they are shown to remain within the limits stated by the manufacturer or imposed by the Federal Aviation Administration type certificate data sheets. Cumulative occurrences of maneuver loads have been examined and compared with data from other sources when available. It is shown that the cumulative occurrences of maneuver load factor varies by flight phase, with the largest values associated with the drop and exit phases. For the overall flight, maneuver loads were shown to occur at lower frequencies than those stated in Military specification MIL-A-8866C(AS). [ABSTRACT FROM AUTHOR]

Abstract: In bird strike analyses, in order to validate the numerical model, usually the obtained pressure profile from a bird model impacting a rigid plate is compared with the corresponding values from the experimental and theoretical values. But Hugoniot and steady pressures obtained from the theoretical and experimental results are so far from each other, especially at velocities lower than . The numerical values calculated by different authors are in a wide range between the experimental and theoretical values. Therefore, it is an important problem to find out what the real values of Hugoniot and steady pressures are and which values are acceptable. In this work, it was attempted to find out where these differences between the experimental, theoretical and numerical values come from and that what the true values are. Two finite element bird models (hemispherical-ended cylinder and mallard) were used and two ways of pressure reading (averaging and sensor) were used. It was seen that the hemispherical-ended model gives pressure reading near the theoretical values when the pressure is read by sensor, and on the other hand gives pressure reading near the experimental values when the pressure is calculated by averaging. For the mallard model, the pressure reading is near the experimental values, even if the pressure is read from the sensors. Therefore it can be seen that the results of the new mallard model introduced in this paper correlate much better with the experimental results, although it is far from the theoretical values which are derived for a simple but unreal bird geometry. [Copyright &y& Elsevier]