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Gains in school spending helped to lift achievement over the past half century. But California’s ambitious effort—progressively distributing $23 billion in yearly funding to poorer districts—has yet to reduce disparities in learning. We theorize how administrators in districts and schools, given organizational habits and labor constraints, may fail to move quality resources to disadvantaged students. We identify the exogenous portion of California’s post-2013 reform, finding that schools receiving progressively targeted funding tended to hire inexperienced teachers and disproportionately assign novices to courses serving English learners. New funding expanded the array of courses in high schools, as access to college-preparatory classes by English learners declined. These unfair mechanisms operated most strongly in high-needs schools serving larger concentrations of poor students.

Underprepared students at community colleges are often assigned to a sequence of developmental education (DE) courses that can substantially delay, or even halt, their progress to degree completion...

In 1990s America, the question of what made a ‘real’ man was at the forefront of debates about sex and gender. During this pivotal moment in American history, hegemonic masculinity in particular was experiencing numerous threats to its ontological security. For instance, masculinity was infamously pronounced in crisis, the advent of the ‘new man’ betrayed anxieties about an image-conscious and feminine performance of masculinity, and there was mounting social pressure from civil rights, feminist, and queer groups for straight, white, masculinity to be challenged as the centre of the patriarchal stage. In short, the issue for masculinity in the 90s was that of legitimacy. The response from Hollywood was an influx of films which featured leading men in costume, disguise, or masquerade. John Woo's Face/Off is one such film that betrays anxieties about the constructedness of hegemonic masculinity. Face/Off does so through the motif of plastic surgery. In this article, I will explore how Face/Off uses the image of plastic surgery to represent the masculinities of its male protagonists as masquerades. I will demonstrate how plastic surgery in Face/Off is a device which transforms hegemonic masculinity so that it may adapt to the climate of crisis and secure its continuation. Face/Off demonstrates that masculinity is a construct which masquerades as an ontology.

Some of the existing challenges of fixed-wing micro aerial vehicle designs at low Reynolds number are low lift and reduced aerodynamic efficiency. Delta wings, despite their characteristic maneuver...

The theoretical prerequisites for construction of road overbridges of car lift type for crossing railways by automotive vehicles are suggested. A technical solution has been proposed that makes it possible to ensure the crossing by cars of «problem» railway crossings during periods of their long-term closure for road traffic. The same solution can be used to organise a road overbridge in other locations where there is no railway crossing. The technical solution itself is based on the use of overhead road overpasses and is a «simplified» version of the solution implemented by Elon Musk and his company in Los Angeles based on a tunnel, moving platforms and freight elevators. For development of car lift type road overbridges, computational methods of theoretical mechanics, technical diagnostics and monitoring, as well as the theory of queuing should be used to estimate the number of cars passed through it when crossings are closed. It is proposed that the structures of the overbridge should be «built-in» into the landscape, equipped with alternative sources of energy supply and technical means of control, diagnostics and monitoring of rolling stock and of location of direct intersection of automobile and railway roads (an intelligent monitoring zone). The proposed promising technical solution in the form of a road overbridge makes it possible to increase comfort of road transportation and improve traffic safety at level crossings.

“Arne Duncan has said that if the country could turn around 1,000 schools annually for five years, ‘We could really move the needle, lift the bottom and change the lives of tens of millions of unde...

The paper presents the results of the simulation of secondary air pollution scenario in Ukraine due to the wind lift of anthropogenic radionuclides during a dust storm in April 2020. A variant of the Bagnold formula was used to parameterize the intensity of radionuclide resuspension. To set the initial pollution of the territory of Ukraine, the reconstruction of meteorological conditions and fallout of Cs-137 after the disaster at the Chernobyl nuclear power plant was carried out through the use of the RODOS nuclear emergency response system and the WRF meteorological model. For the normalized root-mean-square error of the calculated total fallout in the 50-km zone around the Chernobyl NPP the value NMSE=4,5 was obtained. A decrease in the levels of pollution of the Earth's surface during the time after the accident due to radioactive decay and other environmental processes was estimated. The distribution of contamination of the Earth's surface obtained in this way was used to assess the intensity of wind rise and atmospheric transport of radionuclides during a dust storm on April 16–18, 2020. The calculations were carried out using the CALPUFF model. The input meteorological data were the results of the WRF-Ukraine weather forecasting system. In the calculation of secondary contamination, the effect of fires in the Chernobyl Exclusion Zone (ChEZ) was not taken into account. The calculated average daily concentrations of Cs-137 in the air were maximum for the first day of the dust storm (April 16), when the wind speed was maximum (13 m/s with gusts up to 19 m/s). Average daily concentrations on April 16 ranged from the background values (5,8·10-6 Bq/m3 in Kyiv) to 2,2·10-3 Bq/m3 (ChNPP). The obtained estimates are much less than the permissible concentrations (0.8 Bq/m3). At the same time consideravle exceedance of background values were predicted in a large part of Ukraine – from Rivne NPP (2,2·10-5 Bq/m3) to Kharkiv (1,3·10-5 Bq / m3). In the vicinity of the ChEZ in the cities of Chernihiv and Slavutich, the obtained estimates of daily average concentration were 1,6·10-4 Bq/m3 and 3,2·10-4 Bq/m3 respectively.

Rotorcraft flight speed is limited by compressibility effects on the advancing blade side and decreasing lift potential on the retreating blade side. It may thus be beneficial to employ a hingeless rotor to generate additional lift with the advancing blade and compensate the resulting rolling moment with a fixed wing on the retreating blade side. This concept is a form of "lift compounding" that appears to show enormous potential. The present paper presents results of a wind tunnel test with a slowed, hingeless rotor and single fixed wing on the retreating blade side. Based on rotor test stand data and flow field measurements, the impact of operational and rotor parameters on system performance and aerodynamics is examined, mutual interaction effects between rotor and fixed wing are analyzed, and dominant flow structures are characterized in the reverse flow region on the retreating blade side. Flow field analysis reveals a reverse flow entrance vortex that freely convects through the reverse flow region and rivals the blade tip vortices in strength. Contrary to previous beliefs, this vortex originates from upstream of the reverse flow region and only its detachment from the rotor blade is related to entering this region. The combination of finite rolling moment trim and aft shaft tilt significantly increases rotor lift coefficient and corresponding peak lift-to-drag ratio of the compound rotorcraft. Results are compared with predictions from a comprehensive rotor analysis that is expanded to cover the main effects of the added fixed wing and is able to reproduce general performance trends of the rotorcraft. The present study highlights that adding a single fixed wing and hingeless rotor to a high-speed rotorcraft could significantly improve its performance.

A hover-capable insect-inspired flying robot that can remain long in the air has shown its potential use for both confined indoor and outdoor applications to complete assigned tasks. In this letter, we report improvements in the flight endurance of our 15.8 g robot, named KUBeetle-S, using a low-voltage power source. The robot is equipped with a simple but effective control mechanism that can modulate the stroke plane for attitude stabilization and control. Due to the demand for extended flight, we performed a series of experiments on the lift generation and power requirement of the robot with different stroke amplitudes and wing areas. We show that a larger wing with less inboard wing area improves the lift-to-power ratio and produces a peak lift-to-weight ratio of 1.34 at 3.7 V application. Flight tests show that the robot employing the selected wing could hover for 8.8 minutes. Moreover, the robot could perform maneuvers in any direction, fly outdoors, and carry payload, demonstrating its ability to enter the next phase of autonomous flight., Comment: Accepted for publications in IEEE Robotics and Automation Letters (RA-L) and the Proceedings of the 2020 IEEE/RSJ International Conference on Intelligent Robots and Systems. 8 pages, 12 figures

The decisions to impose sanctions on Russia and to lift them on Iran, in opposition to the wishes of the United States, contributed to the elevation of the profile of the European Union among the main global actors in international politics. However, the EU imposes sanctions since the spring of 1994, shortly after the entry into force of the Treaty of Maastricht. Even though the EU consequently has 26 years of experience herewith, EU sanctions have been mostly studied only on a case-by-case basis. The aim of this article is to provide an up-to-date and comprehensive overview of the experience of the EU with sanctions. Specifically, it presents the results of a newly constructed database of EU autonomous sanctions constituted by 48 cases of these restrictive measures, which have been subdivided in 85 episodes. The analysis revolves around four questions that we asked in each case: when sanctions were in force, what type(s) were used, where the targets were located and why restrictive measures were imposed. The analysis of the empirical database leads to observations about the EU as an international actor and, more generally, on the trends vis-a-vis the utilisation of sanctions as a foreign policy instrument.

Adult spotted lanternflies, Lycorma delicatula, launch themselves into the wind from elevated locations such as trees, lamp posts, and buildings. Individuals fly in short, successive bouts along descending trajectories of between 10 and 50 m before landing, crawling upward on a new structure, and again launching upwind. The possible physiological limits to the durations of flight-bouts, if not constrained by their poor ability to generate lift, however, remain unknown. In this study, we observed the behavior of tethered spotted lanternflies known to be prone to flight-dispersing, and recorded the number and durations of their successive flight bouts. Additionally, we recorded the flight distances and durations of similar spotted lanternflies in the field that had spontaneously taken flight or had been manually launched. We found that tethered females can perform >20 successive bouts with only 1 min between bouts when flight durations were limited to 20 s/bout. Bouts averaged 97.9 ± 11.4 s when bout durations were unlimited, with some females flying bouts lasting >400 s. Females could quickly advance upwind a distance >3000 m if the bouts of ~100 s each were performed in quick succession in the field. However, adults spontaneously taking flight in the field flew for an average of only ~13 s and traveled an average of ~29 m before landing on the ground or on nearby objects. This information is important to determine how far a locally dispersing adult can fly before finding a suitable host to finish feeding and attain reproductive maturity.

Since the theoretical aeroelasticity for flapping-wing aerodynamics was introduced in the 1920s, the effects of flexibility on aeroelasticity have been paid more attention to aerodynamic design. In recent years, the trait of the wing flexibility is applied for small-scale wings of biomimetic flyers including micro air vehicles and mini unmanned aerial vehicles. Until now, the aerodynamic performance and great agility of these flyers, which are beneficially used for military missions and other civilian applications, have been improved through surrogate flapping wings with the favorable effects of the flexibility. As per the aeroelasticity principle for the forward flying, the chordwise flexibility of an elastic flapping wing can generate thrust and lift redistributions, whereas the spanwise flexibility can result in variations of the angle of attack and the shift of phase along the wingspan direction. Consequently, all vortices generated by the flapping wing i.e. (1) leading-edge vortices, (2) tip vortices, and (3) trailing-edge vortices are blended supportively, thereby improving the aerodynamic performance and agility. Hence, the growth of research and development of the aerodynamic performance and agility for these flyers under the influence of flexible wings increases through experimental and computational studies dynamically and rapidly. This review aims to highlight the important role of the flexibility in the recent progress in wing aerodynamics of these flyers through several wing models done by famous groups of experts in this field. In addition, this review includes the acoustics of the wings under the flexibility effects which is considered as a new key for better flyer design and improvement. A comprehensive understanding of the integrated aerodynamics and acoustics under the wing flexibility is, therefore, needed.

Small fixed-wing unmanned aerial vehicles (UAVs) are becoming increasingly popular in civil and military use. However, their ability to fly in adverse weather and turbulent flows is hindered by the...

One of the few appreciative lines Beckett ever wrote about art criticism is that ‘it can lift from the eyes, before rigor vitae sets in, some of the weight of congenital prejudice’.1 The phrase fea...

The feasibility of a solar-powered hybrid airship where lift is generated by both buoyancy and aerodynamics is investigated using aerodynamic shape optimization. The design objective is to minimize...

Takeoff trajectory computations are made for a typical lift+cruise small transport aircraft suitable for an urban air taxi. The selected wing–body model consists of lifting and pushing propellers. ...

Urban studies are still troubled by Friedrich Engels’ argument from 1872: that the bourgeoisie’s only method to solving housing problems is to shift them elsewhere. Through analysing urban policies in Oslo, Norway, this paper demonstrates that the almost 150-year-old argument is still relevant. This cannot be confronted without a better understanding of class as a complex and constituting process in relation to urban policy. In this paper class will be analyzed through three clusters of causal relations: (i) a stratification approach, (ii) an opportunity hoarding approach (related to Weber), and (iii) domination and exploitation (a Marxian approach). Urban polices in Oslo is to a large extent consistent with a stratification approach – i.e. both individuals and places can become ‘richer’ and ‘improve’ without other individuals or places losing anything – and to some degree with a Weberian approach – the municipality wants to include local residents in education and labour markets. In order to confront the ‘bourgeoisie method’, we need to open the door to the third approach and discuss class in relation to the broader political economy. Rather than an area-programme with the aim of ‘lifting the place’, what is needed is class-programmes that aim at ‘lifting the class’.

In 1981 Rose Fenton and Lucy Neal established the London International Festival of Theatre (LIFT). While the Festival is generally recognized as having been highly influential in the field of British theatre over the past twenty-five years, it has received little academic attention. In this article Phoebe Patey-Ferguson examines the founding of the event, arguing that the specific socio-political circumstances of its early years gave shape to the innovative form of a city-based international theatre festival. The bureaucratic conflict between Margaret Thatcher’s Conservative government and Ken Livingstone’s Greater London Council (GLC) is identified as a central factor in the creation of LIFT, with reference to Pierre Bourdieu’s concept of the bureaucratic field and Loïc Wacquant’s development of this model in relation to neoliberal market capitalism. The article is derived from Phoebe Patey-Ferguson’s recently completed PhD on LIFT in its social, cultural, and political context at the Department of Theatre and Performance, Goldsmiths, University of London.1

Covert feathers, a group of feathers on the upper surface of bird wings, are one of birds’ features that aid them in flight at high angles of attack, making them more maneuverable. In a previous st...

This paper presents an innovative design for a biomimetic whale shark-like underwater glider aiming at the combination of high maneuverability and long duration. As a hybrid of the underwater glider and the robotic fish, its pectoral fins and tail can serve as not only the external control surfaces for attitude regulation during gliding but also the propellers for agile fish-like swimming mode. To verify the gliding capability of the whale shark-like glider and prepare for future dynamic analysis, the hydrodynamic coefficients, including drag, lift, sliding force, and corresponding moments are estimated through computational fluid dynamics method. In addition, the hydrodynamic analyses of the proposed glider and an equivalent conventional glider during steady gliding motion are executed for comparison. Extended experiments are performed to verify the downward gliding performance. The results reveal that the whale shark-like glider has less drag as well as higher lift-to-drag ratio and a markable gliding capability in practice. It may offer important inspiration for improving the gliding efficiency and performance of an underwater glider in biomimetic shape design.

Ice formation on a wing poses threats to aircraft safety because it changes the effective shape of the airfoil and deteriorates its lift and moment performances dramatically. The present study deve...

Summary Feathered dinosaurs discovered during the last decades have illuminated the transition from land to air in these animals, underscoring a significant degree of experimentation in wing-assisted locomotion around the origin of birds. Such evolutionary experimentation led to lineages achieving either wing-assisted running, four-winged gliding, or membrane-winged gliding. Birds are widely accepted as the only dinosaur lineage that achieved powered flight, a key innovation for their evolutionary success. However, in a recent paper in Current Biology, Pei and colleagues 1 disputed this view. They concluded that three other lineages of paravian dinosaurs (those more closely related to birds than to oviraptorosaurs) — Unenlagiinae, Microraptorinae and Anchiornithinae — could have evolved powered flight independently. While we praise the detailed phylogenetic framework of Pei and colleagues 1 and welcome a new attempt to understand the onset of flight in dinosaurs, we here expose a set of arguments that significantly weaken their evidence supporting a multiple origin of powered flight. Specifically, we maintain that the two proxies used by Pei and colleagues 1 to assess powered flight potential in non-avian paravians — wing loading and specific lift — fail to discriminate between powered flight (thrust generated by flapping) and passive flight (gliding).

Observations suggest that the vertical distributions of air pollutants, such as black carbon (BC), present as various types depending on the emission sources and meteorological diffusion conditions. However, the formation process and source appointment of some special BC profiles are not fully understood. In this paper, by using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) with a BC-tagging technique, we investigate the formation mechanism and regional sources of a BC peak in the free troposphere observed by an aircraft flight in Beijing (BJ) on 5 May 2018. The results show that the contribution rate of the Beijing–Tianjin–Hebei (BTH) region to the surface BC of BJ exceeded 80 % in this case. Local sources dominated BC in BJ from the surface to approximately 700 m (78.5 %), while the BC peak in the free troposphere (∼4000 m) was almost entirely imported from external sources (99.8 %). Combining BC tracking and process analysis, we find that horizontal advection (HADV) and vertical advection (VADV) processes played an important role in the convergent and upward movement and the transport of BC. The BC originating from the surface in central provinces, including Shanxi (SX), Henan (HN), and Hebei (HB), had been uplifted through a cyclone system 16 h previously, was transported to a height of approximately 3000 m above BJ, and was then lifted by the VADV process to approximately 4000 m. At the surface, BJ and its surroundings were under the control of a weak pressure gradient, leading to the accumulation of BC within the boundary layer. Our results indicate that cyclone systems can quickly lift air pollutants, such as BC, up to the free troposphere, as well as extend their lifetimes and further affect the regional atmospheric environment and climate.

Cutting the weight of fuel tanks and continuing advances in fuel-cell technologies are key to making hydrogen competitive in aviation.

Researchers are alarmed at England's plan to lift COVID restrictions on 'freedom day' amidst soaring infections Researchers are alarmed at England's plan to lift COVID restrictions on 'freedom day' amidst soaring infections

China’s first Mars exploration mission (Tianwen-1) landed on the southern part of Mars’ Utopia Planitia on 15 May 2021. The Zhurong rover will focus on high-resolution and in situ observations of key areas on the surface of Mars. Dust devils (DDs) are heat-driven vortices that lift material from the surface and inject it into the atmosphere. The dark or bright surface lineaments left by DDs are called dust devil tracks (DDTs). Dust devils can clear dust from solar panels deposited by gusts and dust storms. Therefore, it is of importance to study the encounter rates of dust devils at the Tianwen-1 landing site for achieving the rover’s long-term scientific goals. Based on High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) images, 248 newly formed DDTs in 12 image pairs were firstly identified, and their lengths, widths, and direction in the study area were measured. The distribution of their width frequency follows a −2 differential power law. Secondly, DDT formation rates were computed and analyzed with the range of 0.00006 to 0.1275 ddt km−2 sol−1, mainly affected by factors such as seasons and dust storm occurrence. Thirdly, the solar panel clearing recurrence interval derived from the orbital data in our study area was calculated from ~980 to 166,700 sols. The dust storm occurrence probability at the Tianwen-1 landing area is less than 3%, and there is a special anti-dust coating on board the Zhurong rover. Thus, the Zhurong rover can be considered competent for scientific exploration.

California sea lions (Zalophus californianus) are a highly maneuverable species of marine mammal. During uninterrupted, rectilinear swimming, sea lions oscillate their foreflippers to propel themselves forward without aid from the collapsed hindflippers, which are passively trailed. During maneuvers such as turning and leaping (porpoising), the hindflippers are spread into a delta-wing configuration. There is little information defining the role of otarrid hindflippers as aquatic control surfaces. To examine Z. californianus hindflippers during maneuvering, trained sea lions were video recorded underwater through viewing windows performing porpoising behaviors and banking turns. Porpoising by a trained sea lion was compared with sea lions executing the maneuver in the wild. Anatomical points of reference (ankle and hindflipper tip) were digitized from videos to analyze various performance metrics and define the use of the hindflippers. During a porpoising bout, the hindflippers were considered to generate lift when surfacing with a mean angle of attack of 14.6±6.3 deg. However, while performing banked 180 deg turns, the mean angle of attack of the hindflippers was 28.3±7.3 deg, and greater by another 8-12 deg for the maximum 20% of cases. The delta-wing morphology of the hindflippers may be advantageous at high angles of attack to prevent stalling during high-performance maneuvers. Lift generated by the delta-shaped hindflippers, in concert with their position far from the center of gravity, would make these appendages effective aquatic control surfaces for executing rapid turning maneuvers.

A comfortable wind environment favors the sustainable development of urban residential districts and public health. However, the rapid growth of high-rise urban residential districts leads to low wind velocity environments in summer. This study examines the influence of enclosure boundary patterns and lift-up design on the wind environment and proposes an optimization strategy to improve the low wind velocity environment in residential districts in summer. A typical residential district in Hangzhou was selected; the average wind velocity, calm wind zone ratio and comfortable wind zone ratio were selected as the evaluation indexes. The wind environment for different enclosure boundary patterns and lift-up designs were obtained via computational fluid dynamics (CFD) simulations. The results indicate that the pedestrian wind environment is greatly improved in residential districts by reducing the height/width of the enclosure boundary, increasing the permeability rate and adopting a lift-up design in all buildings within residential districts. A combination of permeable railings and lift-up design is recommended; this can increase the average wind velocity and the ratio of comfortable wind zones by 70% and 200%, respectively. This study provides practical guidelines for the optimization of a low wind velocity environment in Chinese high-density residential districts in summer.

Insects and birds have been in the sensory-motor control business for more than 100 million years. The manned aircraft developed over the last 100 years rely on a similar lift to that generated by birds’ wings. Aircraft designers have paid little attention, however, to the pilot’s visual sensor that finely controls these wings, although it is definitely the most sophisticated avionic sensors ever known to exist. For this reason, the thinking that prevails in the field of aeronautics does not help us much grasp the visuo-motor contol laws that animals and humans bring into play to control their flight. To control an aircraft, it has been deemed essential to measure state variables such as barometric altitude, groundheight, groundspeed, descent speed, etc. Yet the sensors developed for this purpose usually emissive sensors such as Doppler radars, radar-altimeters or forward-looking infrared sensors, in particular are far too cumbersome for insects or even birds to carry and to power. Natural flyers must therefore have developed other systems for controlling their flight. Flying insects are agile creatures that navigate swiftly through most unpredictable environments. Equipped with “only” about one million neurons and only 3000 pixels in each eye, the housefly, for example, achieves 3D navigation at an impressive 700 bodylengths per second. The lightness of the processing system at work onboard a fly makes us turn pale when we realize that this creature actually achieves just what is being sought for in the field of aerial robotics: dynamic stabilization, 3D autonomous navigation, ground avoidance, collision avoidance with stationary and nonstationary obstacles, tracking, docking, autonomous takeoff and landing, etc. Houseflies add insult to injury by being able to land gracefully on ceilings. The last seven decades have provided evidence that flying insects guide themselves through their environments by processing the optic flow (OF) that is generated on their eyes as a consequence of their locomotion. In the animal’s reference frame, the translational OF is the angular speed ω at which contrasting objects in the environment move past the animal (Kennedy, 1939; Gibson, 1950; Lee, 1980; Koenderink, 1986). In the present chapter, it is proposed to summarize our attempts to model the visuomotor control system that provides flying insects with a means of autonomous guidance at close range. The aim of these studies was not (yet) to produce a detailed neural circuit but rather to obtain a more functional overall picture, that is, a picture that abstracts some basic control

At the time of Caliph Abu Bakr As-Siddiq basically not muchdifferent with future educational Prophet. However, since the CaliphUmar bin Khattab more education increases, the teachers have beenappointed and in salaries to teach in areas newly conquered. At thetime of Uthman education handed over to the people andcompanions (to lift the teacher) and then spread to teach every aspectof the area. While at the time of Caliph Ali bin Abi Talib, theeducation received less attention due to polical conflicts that alwayshappens.

Visitors to Manchester cannot fail to notice the city’s building boom. At present the view out from the city centre in every direction is punctuated by the lift shafts of new apartment blocks and t...

To understand the working principle of ornithopters, various surveys were made on the natural flyers with flapping wings and their ability to produce lift and thrust. The crank mechanism is...

At low Reynolds numbers, revolving wings become less efficient in generating lift for hovering flight due to the increasing adverse viscous effects. Flying insects use reciprocating revolving wings...

The US Department of Defense has established an initiative to develop a family of next-generation vertical lift aircraft that will fly farther, faster, and more efficiently than the current fleet of rotorcraft. To accomplish these goals, advanced rotorcraft configurations beyond the single main rotor/tail rotor design must be considered. Two advanced configurations currently being flight tested are a lift offset coaxial rotorcraft with a pusher propeller and a tiltrotor. The US Army Aviation Development Directorate has developed generic, high-fidelity flight-dynamics models of these two configurations to provide the government with independent control-system design, handling-qualities analysis, and simulation research capabilities for these types of aircraft. This paper describes the modeling approach used and provides model trim data, linearized stability and control derivatives, and eigenvalues as a function of airspeed. In addition, control allocation for both configurations is discussed.

The deflected slipstream is one kind of vertical takeoff and landing technology with lightweight lift machinery. Thus, the influence of different parameters on the aerodynamic characteristics of a ...

The new bird inspired wing sweep was introduced and compared with straight and conventional swept wings in gliding flight by an experimental test setup. Due to the similarity with the birds’ wing, all test models have S1223 airfoil. Swept models inspired from the bird consist of two parts: the straight part near the root and the swept part near the tip. Aerodynamic forces on each wing were measured from 0° to 24° angles of attack and Reynolds numbers of 4.3×104, 8.6×104, 1.3×105, and 1.7×105. Wind tunnel test results show that wings with an innovative sweep at α > 0 have more lift for Reynolds numbers between 4.3×104 and 8.6×104. Also, innovative sweep increases the stall angle, and the wing did not stall until α = 24° for Reynolds between 1.3×105 and 1.7×105. An increase in lift and having sufficient aerodynamic performance in low Reynolds numbers for birds’ inspired wing sweep in gliding flight may be the answer to why the wing sweep of birds is not like conventional sweeps.

Cooperative transportation of payloads by multiple unmanned air vehicles has received increasing interest due to unique operational advantages. These include the portability of the individual vehic...

Purpose The purpose of this paper is to mount Gurney flaps at the trailing edges of the canards and investigate their influence on aerodynamic characteristics of a simplified canard-configuration aircraft model. Design/methodology/approach A force measurement experiment was conducted in a low-speed wind tunnel. Hence, the height and shape effects of the Gurney flaps on the canards were investigated. Findings Gurney flaps can increase the lift and pitching-up moment for the aircraft model tested, thereby increasing the lift when trimming the aircraft. The dominant parameter to influence aerodynamic characteristics is the height of Gurney flaps. When the flap heights are the same, the aerodynamic efficiency of the triangular Gurney flaps is higher than that of the rectangular ones. Moreover, the canard deflection efficiency will be reduced with Gurney flaps equipped, but the total aerodynamic increment is considerable. Practical implications This paper helps to solve the key technical problem of increasing take-off and landing lift coefficients, thus improving the aerodynamic performance of the canard-configuration aircraft. Originality/value This paper recommends to adopt triangular Gurney flaps with the height of 3 per cent chord length of the canard root (c) for engineering application.