Gliding Performance Research Articles

Gliding Performance of an Insect-Inspired Flapping-Wing Robot

Flying animals such as insects and birds use wing flapping for flight, occasionally pausing wing motion and transitioning into gliding to conserve energy for propulsion and achieve high flying efficiency. In this study, we have investigated the gliding performance of a gliding model based on a flapping-wing robot developed in a previous study, with the aim of developing a highly efficient flying robot that utilizes bio-inspired intermittent flight. Wind tunnel experiments with a gliding model have shown that the attitude of the wings has a strong influence on gliding performance and that a tail is effective in improving gliding performance. The results of this study provide important insights into the development of flying robots that can travel long distances with high efficiency.

Critical Parameter Analysis for Optimized Gliding Performance of Autonomous Underwater Vehicles

Critical Parameter Analysis for Optimized Gliding Performance of Autonomous Underwater Vehicles

Design of Glider Wing Shape and Research on its Aerodynamic Characteristics

The glider is a type of aircraft without a power device, which relies on airflow to obtain forward power and has important application value in environmental detection, rescue, and other scenarios. The wing shape of a glider is one of the biggest factors affecting its gliding performance. However, the quantitative mechanism by which specific airfoil parameters affect gliding performance is still unclear. This paper dives into the field of aerodynamics and analyzes which airfoil performs the best in realistic situations. Unlike traditional methods in which the only way to analyze such a foil is through rigorous testing in a wind tube, this paper uses two ways, both through simulation and idealized calculation to determine the best airfoil. The results demonstrate that the lift-to-drag ratio characteristics of NACA 4424 and NACA 4415 are better than those of NACA 64A210 and NACA 2412, but there is a certain difference between the simulation results and theoretical results, which may be related to the accumulated errors in the simulation and data processing processes. This study helps to enhance the understanding of the impact of different airfoil parameters on their aerodynamic performance, providing a reference for the optimization design of airfoils.

Interaction Between Ski and Snow for Excellent Gliding Performance

Interaction Between Ski and Snow for Excellent Gliding Performance

Palaeoatmosphere facilitates a gliding transition to powered flight in the Eocene bat, Onychonycteris finneyi

The evolutionary transition to powered flight remains controversial in bats, the only flying mammals. We applied aerodynamic modeling to reconstruct flight in the oldest complete fossil bat, the archaic Onychonycteris finneyi from the early Eocene of North America. Results indicate that Onychonycteris was capable of both gliding and powered flight either in a standard normodense aerial medium or in the hyperdense atmosphere that we estimate for the Eocene from two independent palaeogeochemical proxies. Aerodynamic continuity across a morphological gradient is further demonstrated by modeled intermediate forms with increasing aspect ratio (AR) produced by digital elongation based on chiropteran developmental data. Here a gliding performance gradient emerged of decreasing sink rate with increasing AR that eventually allowed applying available muscle power to achieve level flight using flapping, which is greatly facilitated in hyperdense air. This gradient strongly supports a gliding (trees-down) transition to powered flight in bats.

Influence of posture during gliding flight in the flying lizard Draco volans

The agamid lizards of the genus Draco are undoubtedly the most renown reptilian gliders, using their rib-supported patagial wings as lifting surfaces while airborne. Recent investigations into these reptiles highlighted the role of body posture during gliding, however, the aerodynamics of postural changes in Draco remain unclear. Here, we examine the aerodynamics and gliding performances of Draco volans using a numerical approach focusing on three postural changes: wing expansion, body camber, and limb positioning. To this aim, we conducted 70 three-dimensional steady-state computational fluid dynamics simulations of gliding flight and 240 two-dimensional glide trajectory calculations. Our results demonstrate that while airborne, D. volans generates a separated turbulent boundary layer over its wings characterized by a large recirculation cell that is kept attached to the wing surface by interaction with wing–tip vortices, increasing lift generation. This lift generating mechanism may be controlled by changing wing expansion and shape to modulate the generation of aerodynamic force. Furthermore, our trajectory simulations highlight the influence of body camber and orientation on glide range. This sheds light on how D. volans controls its gliding performance, and conforms to the observation that these animals plan their glide paths prior to take off. Lastly, D. volans is mostly neutral in pitch and highly maneuverable, similar to other vertebrate gliders. The numerical study presented here thus provides a better understanding of the lift generating mechanism and the influence of postural changes in flight in this emblematic animal and will facilitate the study of gliding flight in analogous gliding reptiles for which direct observations are unavailable.

Gliding performance in the inland sugar glider in low-canopy forest

Knowledge of the gliding performance of gliding mammals provides important insight into how these species have evolved to use their environment but it can also be used to guide tree retention and habitat restoration. We investigated the glide performance of the inland sugar glider (Petaurus notatus) in central Victoria. We measured 40 glides from untagged individuals during nest box monitoring. On average, gliders launched into a glide from a height of 14.7 m above the ground and landed at 6.2 m above the ground. The average horizontal glide distance was 18.1 m (range 8–41 m). The glide ratio (horizontal glide distance/height dropped) and glide angle averaged 2.2 and 26.4°, respectively. These values represent a better average glide performance than any previously measured for an Australian gliding mammal. These data are contrasted with those of other gliding mammals to explore the hypothesis that smaller species may be more capable gliders than larger related species.

A flexible and efficient optimization design framework for the shape of blend-wing-body underwater glider

Shape optimization design plays an important role in improving the gliding performance of blended-wing-body underwater glider (BWBUG), but it faces the challenges of how to handle the geometric constraints and improve the optimization efficiency when building the surrogate-based optimization (SBO) framework. To address these issues, a flexible and efficient optimization design framework for the shape of BWBUG is proposed to perform the shape optimization design of BWBUG. In the framework, an axis-driven geometric free-form deformation method is presented to reduce cost of the BWBUG shape deformation by reasonably controlling the scale of optimization variables, and the rapid calculation method of geometric constraints are derived for the proposed shape deformation method. Based on these, a constrained SBO optimization strategy is developed to directly employ the geometric constraints into the training dataset generation and infill criteria. Finally, the shape of one BWBUG example is optimized, and the results show the flexibility and efficiency of the proposed optimization framework.

Assessment of Functional and Physical Performances of Pre-filled Syringes in Deep Cold Storage Conditions.

The recent emergence of new drug technologies such as messenger ribonucleic acid-based vaccines developed to fight the outbreak of the COVID-19 global pandemic has driven increased demand for delivery solutions capable of withstanding deep cold storage conditions down to -50°C, and even down to -80°C. Although significant data exist for deep cold storage in vials, little evidence is available for pre-filled syringes. Because pre-filled syringes serve as both the storage container and the delivery mechanism, there are additional risks to performance that must be evaluated, such as plunger gliding performance, syringe lubrication, silicone layer stability, and container closure integrity (CCI). In the present study, a comprehensive assessment of functional and physical performances of pre-filled syringes (PFS filled with water) was performed after one or multiple freeze/thaw (F/T) cycles between ambient temperature and various temperature cycles including -40°C, -50°C or -80°C for both 'staked needle' and 'luer lock' configurations. The experiments were guided by historical normative methods such as ISO 11040-4 and USP <1207> and combined with headspace gas analysis for barrel-stopper tightness testing. In addition, they were complemented with a novel approach, namely in situ real-time optical imagery, to track plunger stopper movement during the F/T cycle. The findings indicated that there is no significant impact on the functional performances from F/T down to -80°C, whereas no CCI risk was found after F/T down to -50°C.

A Bio-Inspired Flapping-Wing Robot With Cambered Wings and Its Application in Autonomous Airdrop

Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some ingenious flapping-wing robots have been designed during the past two decades, development and application of autonomous flapping-wing robots are less successful and still require further research. Here, we report the development of a servo-driven bird-like flapping-wing robot named USTBird-I and its application in autonomous airdrop. Inspired by birds, a camber structure and a dihedral angle adjustment mechanism are introduced into the airfoil design and motion control of the wings, respectively. Computational fluid dynamics simulations and actual flight tests show that this bionic design can significantly improve the gliding performance of the robot, which is beneficial to the execution of the airdrop mission. Finally, a vision-based airdrop experiment has been successfully implemented on USTBird-I, which is the first demonstration of a bird-like flapping-wing robot conducting an outdoor airdrop mission.

An evaluation of film coating materials and their predicted oro-esophageal gliding performance for solid oral dosage forms

Oral drug therapy is generally provided in the form of solid oral dosage forms (SODF) that have to be swallowed intact and move throughout the oro-esophageal system until reaching the stomach. Previous studies have provided evidence that the surface characteristics of SODF play an important role during oro-esophageal transit, while their nature may govern the degree of interaction (adhesiveness) with the esophageal tissue. In order to better predict the synergy of SODF surface coatings to the esophageal mucosa during drug administration therapy, an in vitro system has been implemented to investigate their gliding performance across an artificial mucous layer. Coating formulations comprised of different film-forming and slippery-inducing agents were evaluated using the established in vitro artificial mucous system. Polyvinyl alcohol (PVA), polyethylene glycol (PEG), hydroxypropyl methylcellulose (HPMC) and Kollicoat IR (K-IR) were applied as film-forming agents, whereas sodium alginate (SA), carrageenan (CA) and gellan gum (GG) were evaluated both as film-forming and slippery-inducing agents. Carnauba wax (CW), lecithin (LE), xanthan gum (XG) and sodium lauryl sulfate (SLS) were applied as slippery-inducing agents. Two polar wax coating materials were also investigated for their gliding performance. GG displayed suitable gliding performance when applied as film-forming agent, being this effect enhanced when combined with CW/SLS and XG, as slippery-inducing agents. Optimal performance was also demonstrated by the polar waxes. The multivariate approach applied allowed a higher granularity in the analysis of the gliding results and supported a better identification of combinations of excipients and respective concentrations required for improved gliding performance, as such, the obtained gliding results support the identification of coating materials and their suitable combinations that are predicted to improve in vivo swallowing safety.

Using the combined flow control accessory to the aerodynamic performance enhancement of bio-inspired seagull airfoils

An airfoil with good stability and a high lift-drag ratio can effectively improve the stability and aerodynamic performance of the wind turbine blade. Inspired by the excellent gliding performance of the seagull wings, the unique profile and structure of the seagull wings are first extracted to restructure the bionic airfoil. Then, the flow control accessory combined the bionic flap and Gurney flap is introduced to further improve the static and dynamic aerodynamic performance of bionic seagull airfoil. Under different Reynolds numbers, the effects of the combined flow control accessory on the bionic seagull airfoil are investigated using the numerical simulation method. Based on the analysis of flow fields, the flow control mechanism of the combined flow control accessory on the stall characteristics of bionic seagull airfoil is revealed. The results show that for the static stall characteristics, when the flow control accessory is applied to the bionic airfoil, the static lift coefficient of the airfoil is increased by 15% at Reynolds numbers of Re 2.0 × 105. For the dynamic stall characteristics, the lift coefficient of the airfoil is improved during the whole dynamic stall process, the maximum is increased by 13.12%, and the area of the dynamic hysteresis loop is reduced.

Investigation of the gliding performance by the cross-sectional shape of the flying snake

Investigation of the gliding performance by the cross-sectional shape of the flying snake

HYDRODYNAMIC ANALYSIS OF BIONIC CHIMERICAL WING PLANFORMS INSPIRED BY MANTA RAY EIDONOMY

In this paper, inspired by the external morphology of a manta ray (Mobula alfredi), four chimerical wing planforms are designed to assess its gliding performance. The planforms possess an arbitrary combination of extra hydrodynamic features like tubercles at the leading edge (L.E.) and trailing edge (T.E.) inspired by humpback whale's flippers and flukes, respectively, as longitudinal ridges inspired by whale shark's economy. In addition, another planform is designed to investigate the possible effects of manta ray's injuries (geometric deficiency) generated by predator's attacks or boat strikes on its locomotion (gliding) performance. In this regard, turbulent flow physics involved in the problem is numerically simulated at different angles of attack (AoA). High Reynolds number, 106, corresponding to the swimming of a juvenile manta ray at an average speed equals one m/s. The results show that the manta ray-inspired planform with L.E. undulations exhibits a superior performance at high AoAs than its other counterpart variants. In addition, the results demonstrate that injuries on the manta ray's body can noticeably modify hydrodynamics and, as a result corresponding hydrodynamical forces and moments acting on the swimming animal in the gliding phase.

An Efficient Surrogate-Based Optimization Method for BWBUG Based on Multifidelity Model and Geometric Constraint Gradients

Performing shape optimization of blended-wing-body underwater glider (BWBUG) can significantly improve its gliding performance. However, high-fidelity CFD analysis and geometric constraint calculation in traditional surrogate-based optimization methods are expensive. An efficient surrogate-based optimization method based on the multifidelity model and geometric constraint gradient information is proposed. By establishing a shape parameterized model, deriving analytical expression of geometric constraint gradient, constructing multifidelity surrogate model, the calculation times of high-fidelity CFD model and geometric constraints are reduced during the shape optimization process of BWBUG, which greatly improve the optimization efficiency. Finally, the effectiveness and efficiency of the proposed method are verified by performing the shape optimization of a BWBUG and comparing with traditional surrogate-based optimization methods.

Understanding the effects of training on underwater undulatory swimming performance and kinematics

ABSTRACT In swimming, the underwater phase after the start and turn comprises gliding and dolphin kicking, with the latter also known as underwater undulatory swimming (UUS). Swimming performance is highly dependent on the underwater phase; therefore, understanding the training effects in UUS and underwater gliding can be critical for swimmers and coaches. Further, the development of technique in young swimmers can lead to exponential benefits in an athlete’s career. This study aimed to evaluate the effects of a training protocol on UUS and underwater gliding performance and kinematics in young swimmers. Seventeen age group swimmers (boys = 10, girls = 7) performed maximal UUS and underwater gliding efforts before and after a seven-week training protocol. Time to reach 10 m; intra-cyclic mean, peak, and minimum velocities; and gliding performance improved significantly after the training protocol. The UUS performance improvement was mostly produced by an improvement of the upbeat execution, together with a likely reduction of swimmers’ hydrodynamic drag. Despite the changes in UUS and gliding, performance was also likely influenced by growth. The findings from this study highlight kinematic variables that can be used to understand and quantify changes in UUS and gliding performance.

Simulation Analysis of the Aerodynamic Performance of a Bionic Aircraft with Foldable Beetle Wings in Gliding Flight.

Beetles have excellent flight performance. Based on the four-plate mechanism theory, a novel bionic flapping aircraft with foldable beetle wings was designed. It can perform flapping, gliding, wing folding, and abduction/adduction movements with a self-locking function. In order to study the flight characteristics of beetles and improve their gliding performance, this paper used a two-way Fluid-Structure Interaction (FSI) numerical simulation method to focus on the gliding performance of the bionic flapping aircraft. The effects of elastic model, rigid and flexible wing, angle of attack, and velocity on the aerodynamic characteristics of the aircraft in gliding flight are analyzed. It was found that the elastic modulus of the flexible hinges has little effect on the aerodynamic performance of the aircraft. Both the rigid and the flexible wings have a maximum lift-to-drag ratio when the attack angle is 10°. The lift increased with the increase of the gliding speed, and it was found that the lift cannot support the gliding movement at low speeds. In order to achieve gliding, considering the weight and flight performance, the weight of the microair vehicle is controlled at about 3 g, and the gliding speed is guaranteed to be greater than 6.5 m/s. The results of this study are of great significance for the design of bionic flapping aircrafts.

An Investigation into the Relationship between Xanthan Gum Film Coating Materials and Predicted Oro-Esophageal Gliding Performance for Solid Oral Dosage Forms.

Oral drug therapy is generally provided in the form of solid oral dosage forms (SODF) that have to be swallowed and move throughout the oro-esophageal system. Previous studies have provided evidence that the oro-esophageal transit of SODF depends on their shape, size, density, and surface characteristics. To estimate the impact of SODF surface coatings during esophageal transit, an in vitro system was implemented to investigate the gliding performance across an artificial mucous layer. In this work, formulations comprised of different slippery-inducing agents combined with a common film forming agent were evaluated using the artificial mucous layer system. Xanthan gum (XG) and polyethylene glycol 1500 (PEG) were applied as film-forming agents, while carnauba wax (CW), lecithin (LE), carrageenan (CA), gellan gum (GG) and sodium alginate (SA), and their combination with sodium lauryl sulfate (SLS), were applied as slippery-inducing components. All tested formulations presented lower static friction (SF) as compared to the negative control (uncoated disc, C, F0), whereas only CW/SLS-based formulations showed similar performance to F0 regarding dynamic friction (DF). The applied multivariate analysis approach allowed a higher level of detail to the evaluation and supported a better identification of excipients and respective concentrations that are predicted to improve in vivo swallowing safety.

Gliding performance is affected by cranial movement of abdominal organs

Swimming is an extremely popular sport around the world. The streamlined body position is a crucial and foundational position for swimmers. Since the density of lungs is low, the center of buoyancy is always on the cranial side and the center of gravity is always on the caudal side. It has been reported that the greater the distance between the centers of buoyancy and gravity, the swimmer’s legs will sink more. This is disadvantageous to swimming performance. However, the way to reduce the distance between the centers of buoyancy and gravity is yet to be elucidated. Here we show that swimmers with high gliding performance exhibit different abdominal cavity shapes in the streamlined body position, which causes cranial movement of the abdominal organs. This movement can reduce the distance between the centers of buoyancy and gravity, prevent the legs from sinking, and have a positive effect on gliding performance.

A study on the hydrodynamic performance of manta ray biomimetic glider under unconstrained six-DOF motion.

A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated. The results show that the glider will show the optimal gliding performance when the center of mass is 20mm in front of the center of geometry and the initial attack angle range lies between A0 = -5° to A0 = -2.5° at the same time. The optimal gliding distance can reach six times its body length under these circumstances. Furthermore, the stability of the glider is explained from the perspective of Blended-Wing-Body (BWB) configuration.