Flight Angle Research Articles

NACA 4412 Kanadı Üzerinde Bir Emme Kanalı Tasarlanmasının Aerodinamik Etkileri

In this study, a wing is designed by using NACA 4412 profile and computational numerical analysis is discussed with suction method. First of all, the 3D wing is designed with the SolidWorks and the numerical study of this designed wing is carried out using ANSYS Fluent, a famous CFD (i.e. Computational Fluid Dynamics) software. It is based upon finite volume method approach. Two different configurations are used for numerical study. The first of these configurations is the S1, which represents the initial state of the wing; S2 refers to the wing design with suction channel. The straight flight angle of attack of the wing is 6 degree and the flow separations over the wing, which occurred in 25% of the wing chord length, are calculated at this angle of attack by the numerical study. At this point of chord length, a venturi channel is formed which initial point is the upper surface of the wing and throughout the inner part and finally meets with air from the trailing edge. The main purpose of this channel is to decrease the force at the place where the flow begins to deteriorate during the flight and to increase the aerodynamic performance. In order to be able to examine the change in aerodynamic performance, the lift and drag coefficient values on the wing are obtained in 10 angles of attack (i.e. -6, -4, -2, 0, 2, 4, 6, 8, 10, 12) separately for both configurations. These coefficients obtained for S1 and S2 configurations are compared with each other. In this numerical study based on the comparison results, it is found that there is a significant increase in the performance of S2 configuration compared to the S1 configuration.

Computational optimal launching control for balloon-borne solar-powered unmanned aerial vehicles in near-space.

The near-space solar-powered unmanned aerial vehicle has broad prospects in application owing to its high altitude long-endurance performance. Launching solar-powered unmanned aerial vehicle into the near-space with balloon-borne approach has advantages over the traditional sliding take-off methods, in that it is able to quickly and safely cross the turbulent zone. In this article, we investigate the control technology of balloon-borne launching for the solar-powered unmanned aerial vehicles. First, the motion of the launching process is divided into longitudinal and lateral-directional motion, with the longitudinal process and its equation addressed in detail. We then analyze the flight state and restriction conditions that the unmanned aerial vehicle should meet during the process. Second, the target variables and constraints are selected to formulate the optimization problem. The control variable parameterization method is applied to find the optimal pitch angle in the releasing-and-pulling process. More explicitly, a three-channel attitude stabilization controller is designed, in which the longitudinal channel takes the optimal pitch angle as the pitch instruction, the transverse channel carries out the zero control of the inclination angle, and the course channel takes the stabilization control, respectively. Numerical simulation results show that our proposed control design is capable of accelerating the solar-powered unmanned aerial vehicles from the vertical state and pulling them up to the horizontal cruising flight state, with the flight angle of attack, the maximum speed, and the maximum axial acceleration in the pulling process all within the designed range.

The effect of angle of attack on the aeroacoustic environment within the weapons bay of a generic UCAV

Cavity flow studies are generally concerned with observing the effect of geometry changes whilst maintaining a fixed zero angle of attack. Cavities employed as weapons bays will, however, experience a range of angles of attack. This paper presents the first known results showing the effect of flight angle of attack on the aeroacoustic characteristics of an internal weapons bay installed in an uninhabited combat air vehicle (UCAV). The UCAV geometry consisted of a Boeing M219-type cavity in a Boeing UCAV1303 airframe. Numerical simulation was conducted using a full-scale detached eddy simulation model and representative transonic flight conditions. As well as the reference case of zero degrees, data for angles of attack of 3.0, 4.5 and 6.0 degrees were analysed. Experimental data was used to validate the reference computational model, which agreed with the overall fluctuating sound pressure level (OAFPL) to within the experimental uncertainty of 4 dB. Data from the computational model was post-processed with frequency-domain and time-frequency-domain techniques showing that the flow structure within the weapons bay was altered significantly by the angle of attack changes, affecting the mean pressure distribution, frequency spectra and resonant modes. Overall, increasing the angle of attack from 0.0 to 3.0 degrees produced an increment in the acoustic load whilst a further increase tended to affect the resonance mechanism and thereby reduce the coherence and the temporal footprints of the resonant modes.

The effect of hypoxia and hydrocarbons on the anti-predator performance of European sea bass (Dicentrarchus labrax)

Hydrocarbons contamination and hypoxia are two stressors that can coexist in coastal ecosystems. At present, few studies evaluated the combined impact of these stressors on fish physiology and behavior. Here, we tested the effect of the combination of hypoxia and petrogenic hydrocarbons on the anti-predator locomotor performance of fish. Specifically, two groups of European sea bass (Dicentrarchus labrax) were exposed to clean water (Ctrl) or oil-contaminated water (Oil). Subsequently, fish of both groups were placed in normoxic (norx) or hypoxic (hyp) experimental tanks (i.e. four groups of fish were formed: Ctrl norx, Ctrl hyp, Oil norx, Oil hyp). In these tanks, escape response was elicited by a mechano-acoustic stimulus and recorded with a high speed camera. Several variables were analyzed: escape response duration, responsiveness (percentage of fish responding to the stimulation), latency (time taken by the fish to initiate a response), directionality (defined as away or toward the stimulus), distance-time variables (such as speed and acceleration), maneuverability variables (such as turning rate), escape trajectory (angle of flight) and distancing of the fish from the stimulus. Results revealed (i) effects of stressors (Ctrl hyp, Oil norx and Oil hyp) on the directionality; (ii) effects of Oil norx and Oil hyp on maneuverability and (iii) effects of Oil hyp on distancing. These results suggest that individual stressors could alter the escape response of fish and that their combination could strengthen these effects. Such an impact could decrease the probability of prey escape success. By investigating the effects of hydrocarbons (and the interaction with hypoxia) on the anti-predator behavior of fish, this work increases our understanding of the biological impact of oil spill. Additionally, the results of this study are of interest for oil spill impact evaluation and also for developing new ecotoxicological tools of ecological significance.

Factors That Influence Flight Propensity in Anoplophora glabripennis (Coleoptera: Cerambycidae).

The effects of mating status, sex, beetle age, host quality, temperature, and wind speed on the propensity of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) to take flight were evaluated using a free flight test in the laboratory. Time to initiate flight, the angle of flight, and flight capability (when beetles were enticed to take flight) were also evaluated. Host quality, mating status, beetle age, sex, temperature, and the interactions between one or more of these were all found to be significant predictors of flight in A. glabripennis in one or more of the experiments. Female flight propensity peaked at sexual maturity and declined thereafter. Both sexes had a higher propensity to take flight from a stem section of dry host material than from a fresh one. Most (78%) males flew at least once during the four mating status/ages tested from a fresh host stem section, while only 43% of the females flew at least once after chewing an oviposition pit. Flight propensity and distance flown increased with temperature and there was no voluntary flight at 15°C. Flight propensity did not increase with wind speeds 0.0-1.0 m/s, but no ascending flight was observed at 0.5 or 1.0 m/s. Time to flight initiation did not vary with the factors evaluated. Implications these results could have on the success of eradication programs are discussed. Specifically, what factors increase the propensity of mated females to disperse, effectively expanding the infestation zone.

External Ballistics Simplified Model of the “RT – 400” Rocket Aerial Target

“RT-400” rocket aerial target system is described in the paper; research method of its simplified external ballistics characteristics is presented and the obtained results are discussed. This system was designed, tested, and produced by a research team of the Institute of Defence Technologies at Kaunas University of Technology and successfully implemented in practice. One of main aims of this paper was to develop external ballistics’ model of a rocket propelled aerial target which would enable obtaining various ballistic parameters of the investigated vehicle such as its acceleration, velocity, flight angle, flight range and trajectory using as input the internal ballistics data obtained at earlier experimental research of the “RV-12K” rocket motor in a static horizontal test stand for thrust measurements and determination of other internal ballistics’ characteristics such as combustion chamber temperature and pressure. During the experimental research process of the vehicle, under test site conditions, the main aim was to compare accuracy of the obtained external ballistics simulation data with the data obtained during experimental approaches using additional measurement techniques such as radar tracking and crash site and launch site GPS coordinates marking.

IMPROVING THE AERODYNAMICS OF A TRANSPORT AIRCRAFT WING USING A DELTA PLANFORM WINGTIP LEADING EDGE EXTENSION

The article explores the possibility of improving the aerodynamic properties of a supercritical-airfoil wing, typical for a modern passenger aircraft, using delta planform passive devices of large relative areas, installed along the leading edge at the wing tip. Delta extensions of various configurations were considered to be used as wingtip devices, potentially improving or completely replacing classical R. Whitcomb winglets. As a result of two- and three-dimensional CFD simulations performed on DLR-F4 wing-body prototype, the potential advantage of these devices was confirmed, particularly when they are installed in a combination with an elliptical planform, largely swept, raked winglet in terms of reducing the induced drag and increasing the aerodynamic lift-to-drag ratio at flight angles of attack. The growth in lift-to-drag ratio applying these devices owes it solely to the drop in drag, without increasing the lift force acting on the wing. In comparison to the classical winglets that lead to a general increase in lifting and lateral forces acting on the wing structure, resulting in a weight penalty, the Wingtip Ledge Edge Triangular Extension (WLETE) yields the same L/D ratio increase, but with a much smaller increase in the wing loading. A study has been made of the characteristics of the local (modified) airfoil in the WLETE zone in a two-dimensional flow context, and a quantitative analysis has been conducted of the influence of WLETE on both the profile and induced drag components, as well as its influence on the overall lift coefficient of the wing. The resulted synthesis of the WLETE influence on the wing L/D ratio will consist of its influence on each of these components. A comparison of the efficiency of using delta extensions against classical winglets was carried out in a multidisciplinary way, where in addition to the changes in aerodynamic coefficients of lift and drag, the increments of magnitude and distribution of the loads acting on the wing console were studied along with the maximum resulted structural stress. The study of the growth of structural stress on the wing structure after installing WLETE, confirmed the results obtained from CFD simulations that these delta extensions do not increase and do not change the distribution of total forces and moments acting on the wing console.

Spike Effects on Drag Reduction for Hypersonic Lifting Body

A high lift-to-drag ratio is considered crucial for high-altitude and long-endurance hypersonic vehicles. One of the simplest and most useful methods is to install an aerospike in front of the vehicle’s nose. In this paper, the flight aerodynamic characteristics are investigated by simulating and comparing the lifting body with or without the aerospikes at . The flowfields around aerospikes using different spike lengths and a hemispherical disk along with the lifting body are analyzed. The results of aerodynamic characteristics indicate that is the best ratio of the spike length to the nose diameter. By comparing with the baseline model, the maximum drag reduction of the nose’s part is 49.3% at using a hemispherical disk. In addition, three shapes of aerospike disks are compared to search for the best disk for hypersonic drag reduction. The best drag reduction is found for the double flat-faced disk aerospike, which gives a pressure drag reduction of 60.5% of the nose’s part at . Furthermore, when the flight angle of attack increases, the drag increases significantly. Employing a certain installation angle is shown to effectively improve the drag reduction around the angle of attack and results in improving the lift-to-drag ratio. At the end, the lift-to-drag ratio of the final optimized design is 9.1% better than that of the baseline model. The pressure center is moved forward by 1.6%, barely influencing the vertical static stability of the vehicle.

The acquisition radar’s detect annulus model of anti-submarine patrol aircraft

Aiming at solving the problem of anti-submarine patrol aircraft(ASPA) detecting different sea-surface and aerial objects, based on the operation performance of acquisition radar, the paper puts forward the concept of detect annulus and establishes the corresponding model, and it gives the manner and method of ASPA detected objects. Through simulation and calculation, it discusses the different pattern of optical axis angle of depression and flight altitude from the width of detect annulus. The paper also provides the basis for the best optical axis angle of depression and flight altitude to meet the operational requirements. At last, the searching method of anti-submarine patrol aircraft using acquisition radar is put forward.

Instrumental resolution as a function of scattering angle and wavelength as exemplified for the POWGEN instrument.

The method of angular- and wavelength-dispersive (e.g. two-dimensional) Rietveld refinement is a new and emerging tool for the analysis of neutron diffraction data measured at time-of-flight instruments with large area detectors. Following the approach for one-dimensional refinements (using either scattering angle or time of flight), the first step at each beam time cycle is the calibration of the instrument including the determination of instrumental contributions to the peak shape variation to be expected for diffraction patterns measured by the users. The aim of this work is to provide the users with calibration files and - for the later Rietveld refinement of the measured data - with an instrumental resolution file (IRF). This article will elaborate on the necessary steps to generate such an IRF for the angular- and wavelength-dispersive case, exemplified for the POWGEN instrument. A dataset measured on a standard diamond sample is used to extract the profile function in the two-dimensional case. It is found that the variation of reflection width with 2θ and λ can be expressed by the standard equation used for evaluating the instrumental resolution, which yields a substantially more fundamental approach to the parameterization of the instrumental contribution to the peak shape. Geometrical considerations of the POWGEN instrument and sample effects lead to values for Δθ, Δt and ΔL that yield a very good match to the extracted FWHM values. In a final step the refinement results are compared with the one-dimensional, i.e. diffraction-focused, case.

Behavioral evidence for a magnetic sense in the oriental armyworm, Mythimna separata.

ABSTRACTProgress has been made in understanding the mechanisms underlying directional navigation in migratory insects, yet the magnetic compass involved has not been fully elucidated. Here we developed a flight simulation system to study the flight directionality of the migratory armyworm Mythimna separata in response to magnetic fields. Armyworm moths were exposed to either a 500 nT extreme weak magnetic field, 1.8 T strong magnetic field, or a deflecting magnetic field and subjected to tethered flight trials indoors in the dark. The moths were disoriented in the extreme weak magnetic field, with flight vectors that were more dispersed (variance=0.60) than in the geomagnetic field (variance=0.32). After exposure to a 1.8 T strong magnetic field, the mean flight vectors were shifted by about 105° in comparison with those in the geomagnetic field. In the deflecting magnetic field, the flight directions varied with the direction of the magnetic field, and also pointed to the same direction of the magnetic field. In the south-north magnetic field and the east-west field, the flight angles were determined to be 98.9° and 166.3°, respectively, and formed the included angles of 12.66° or 6.19° to the corresponding magnetic direction. The armyworm moths responded to the change of the intensity and direction of magnetic fields. Such results provide initial indications of the moth reliance on a magnetic compass. The findings support the hypothesis of a magnetic sense used for flight orientation in the armyworm Mythimna separata.

CHARACTERISTICS OF AIRBORNE INTERFEROMETRIC SYNTHETIC APERTURE RADAR WITH SECTOR SCAN

One of the drawbacks of airborne interferometric synthetic aperture radar is a relatively narrow swath compared to analogous space based systems. Increasing the swath with side view of the interferometer can be possible by increasing the flight altitude and angle of sight. At the same time the height measurement accuracy decreases due to slant range distance increase. Another possible way of swath increasing is using sector scan. The efficiency of sector scan using in interferometric synthetic aperture radar is analyzed in this paper. The mathematical model and geometry of height measurement at a sector scan have been discussed. There was made an analysis of the effect of terrain height and observation angle on received signal phase changing. Observation angle changing is shown to contribute to the phase changing. Potential height accuracy measurement was calculated. The calculation results show that increasing the observation angle reduces height accuracy measurement. The maximum accuracy decrease is obtained at the observation angle of 90°. Despite height accuracy measurement decrease applying the sector scan allow to expand the swath. The accuracy decrease can be limited by selecting optimal parameters of scanning.

Dynamics of sideslip perching maneuver under dynamic stall influence

This paper presents the optimization framework and aerodynamic modeling of a sideslip perching trajectory under dynamic stall influence. Based on the optimal trajectory solutions, an impact study of dynamic stall on the spatial and state trajectories of the three-dimensional (3D) perching maneuver is also discussed. At high angles of attack, the behavioral effects of the dynamic separation point on the transient post-stall region are distinguishable with rapid changes of angles of attack and aircraft's turn rates. Introduction of three internal variables thus becomes mandatory for addressing variations in flow state influenced by the swift changes in longitudinal and lateral flight angles. These variables are then integrated into a static nonlinear aerodynamic model, developed using empirical and analytical methods, and into the simulative framework as state variables. In the absence of dynamic stall effects, there is a significant discrepancy in trajectories as opposed to counterpart trajectories inclusive of this phenomenon. The consideration of dynamic stall in longitudinal frame is found to have heightened impact on perching trajectory in response to optimized control inputs as compared to that in lateral frame. With the inclusion of dynamic stall deemed necessary, a comparative study between 2D and 3D perching models is also presented to discuss the distinct drag mechanisms involved. The 3D accommodated perch utilizes the additive combination of longitudinal and lateral drag to dispense its reliance on the gravitational force. Measured against performance parameters which include metrics of spatial cost such as perching distance, longitudinal/lateral deviations and time, the study reveals the 3D mode is an improvement over the 2D mode as the latter model's intransigent characteristic of the undershoot becomes obsolete in the 3D version.

Physical Mathematical Modelling of Difficult Elements of Acrobatic Rock-and-Roll

It is shown directions of biomechanics substantiation of implementation acrobatic rock-and-roll Fus-salto element taking into account concrete physical data of sportsmen. Mathematical model is developed for determination the influence on a quality of implementation of technical element of such parameters as: speed and angle of flight of centre-of-mass sportsman’s body, position of centre-of-mass body of sportsman in the initial phases of throw exercises, initial angular velocity of rotation of body of sportsman. It is developed mathematical model to determine the impact on the quality of the technical element parameters such as speed and angle of flight of centre-of-mass of the athlete's body, the position of center-of-mass of the athlete's body in the initial phases of throwing exercises in the initial angular velocity of the athlete's body. The parameters of exposure axial moments of inertia for different groupings of body angular velocity the athlete's body in flight and air resistance forces of environment to flight characteristics of the body. Directions of choice of necessary biomechanics descriptions which are able to realize sportsmen are shown. It is offered recommendations are on the increase of efficiency of implementation of element of acrobatic rock-and-roll of Fus-salto.

Study of co-rotational Maxwell fluid in helical screw rheometer

In this paper, the steady flow of an incompressible, co-rotational Maxwell fluid in a helical screw rheometer is studied by ‘unwrapping or flattening’ the channel, lands, and the outside rotating barrel. The geometry is approximated as a shallow infinite channel, by assuming the width of the channel large as compared to the depth. The developed second order nonlinear coupled differential equations are transformed to a single differential equation. Using perturbation methods, analytical expressions are obtained for the velocity components in the x- and z-directions and the resultant velocity in the direction of the screw axis. Volume flow rates, shear and normal stresses, shear at wall, and forces exerted on fluid and average velocity are also calculated. The behavior of the velocity profiles are discussed with the help of graphs. We observe that the velocity profiles are strongly dependent on the non-dimensional parameter $(Wi)^{2}$ , the flight angle ϕ and the pressure gradients.

Performance of a ducted propeller designed for UAV applications at zero angle of attack flight: An experimental study

Performance characteristics and velocity field of a 16 inch diameter ducted propeller are investigated experimentally using five different duct shapes. Experiments are conducted at zero angle of attack which simulates takeoff and forward flight modes of a vertical takeoff and landing (VTOL) tilt ducted propeller UAV. Effect of duct geometry is studied by means of force, torque, velocity field and surface pressure measurements under various flow conditions. Force and torque transducers are embedded into motor hub so that they do not disturb the flow. Thrust components acting on duct and propeller are measured individually. Velocity profiles at the inlet and exit sections are measured with hot-wire anemometer. Experimental results obtained for open and ducted propellers are compared. It is shown that power coefficients obtained for all ducted propeller arrangements are lower than that of open propeller which indicates that propeller operates more efficiently inside a duct. However, thrust obtained from the duct decreases and reaches negative values with increasing advance ratio which makes duct unfavorable at high freestream velocities. Pressure measurements show that, the origin of the duct thrust is suction effect induced by the propeller in converging part (forebody) of the duct, and magnitudes of pressure coefficients inside forebody diminish with increasing advance ratio. Optimization of inlet shape for all advance ratio range of the vehicle is essential for a better design.

Approaching birds with drones: first experiments and ethical guidelines.

Unmanned aerial vehicles, commonly called drones, are being increasingly used in ecological research, in particular to approach sensitive wildlife in inaccessible areas. Impact studies leading to recommendations for best practices are urgently needed. We tested the impact of drone colour, speed and flight angle on the behavioural responses of mallards Anas platyrhynchos in a semi-captive situation, and of wild flamingos (Phoenicopterus roseus) and common greenshanks (Tringa nebularia) in a wetland area. We performed 204 approach flights with a quadricopter drone, and during 80% of those we could approach unaffected birds to within 4 m. Approach speed, drone colour and repeated flights had no measurable impact on bird behaviour, yet they reacted more to drones approaching vertically. We recommend launching drones farther than 100 m from the birds and adjusting approach distance according to species. Our study is a first step towards a sound use of drones for wildlife research. Further studies should assess the impacts of different drones on other taxa, and monitor physiological indicators of stress in animals exposed to drones according to group sizes and reproductive status.

Design of Composite Control System for an Air-Breathing Hypersonic Vehicle with Wing-Rudder Deflection

The Scramjet performance of air-breathing hypersonic vehicle is highly correlated with flight height, Mach and angle of attack (AOA). The violent disturbance of the AOA can cause the engine power off. Consequently the maneuverability of hypersonic vehicle is strictly limited in the phase of cruise. A composite Control system for an air-breathing hypersonic vehicle is presented. The hypersonic vehicle has a configuration with tail control rudders and a set of deflectable wings installed nearby the center of gravity. During the phase of cruise, the precision of AOA is achieved by deflecting tail rudders, and the maneuverable acceleration command is tracked by deflecting wings. A linear quadratic (LQ) track control algorithm with integrator is used to design the composite control system. Simulation results demonstrate that the composite control system has good performance in tracking AOA and acceleration command by respective deflection in cruise.

Lorentz force time-optimal transfer trajectory design in Jovian magnetic field

In this paper, the Lorentz force in Jupiter’s magnetic field is used to design the transfer trajectory between Galileo moons’ Lagrange points. The equatorial orbits of charged spacecraft in three-body axis-aligned nontilted-dipole magnetic field model are analyzed and the results show that the libration point L1 and L2 become nearer or further away from Europa with the variable size and polarity of the charge. The bang–bang charge control with the variable size and polarity of the charge can be used to change orbit’s direction and shape. Analytical and numerical iteration methods give the fast and accurate bang–bang charge control to send the spacecraft to the L2 point of Europa, respectively. Finally, two numerical methods, the indirect and direct methods, give the time-optimal charge controls which are similar to but different from the semi-revolution variable polarity control maneuver. The optimal results achieve the final position and the flight angle at the same time, and need less time and less magnitude of charge compared with the numerical iteration method.

English

The combat features of the Ground Based Air Defence Systems represent the potential of search, discovery, indicate, combat and destruction of the enemy's air assets and the ability to manoeuvre of forces and combat means, for the purpose of capturing the enemy's airspace and avoid actions and attack to defend objectives (of troops) assigned in the area of responsibility tacking into account the conditions established by the mission. The paper is focused on a comparative study on the possibilities of target destruction of the Air Air Defence Systems (antiaircraft artillery and Surface-To-Air Missiles). Two situations were chosen: for the first case, related to S1, S2 and S3, we've assumed the presence of a flying target describing a uniform rectilinear trajectory both in the presence and in the absence of the enemy's electronic jamming. For the second case concerning S4 we've assumed that the target changed its angle of flight.