Rotary Wing Research Articles

Mechanism Dynamic Model and Power Optimization of Flapping Wing Rotor

Mechanism Dynamic Model and Power Optimization of Flapping Wing Rotor

Improvement of UAV: design and implementation on launchability

PurposeThis study aims to a launchable design has been made to prevent wasted time in time-critical areas, and increase the efficiency of the unmanned aerial vehicle (UAV). In this way, a UAV can reach the mission height quickly.Design/methodology/approachA unique launchable UAV and launcher mechanism have been designed. The launchable UAV will be folded into the launcher mechanism and will automatically start flight after launch. The study includes mathematical calculations, 3D designs steps and produced UAV tests for the designed UAV. The launcher mechanism was designed in accordance with the tests for the UAV, and appropriate choices were made for the altitude and launch acceleration required by the UAV. According to the calculations, material selection and production were made.FindingsIn the tests, the climbing time was reduced by 1 s compared with the existing UAVs. With the launch, it enabled it to reach the altitude quickly and silently. In addition, because the launch energy was provided externally, it provided an advantage for the flight time.Practical implicationsA rotary-wing UAV with a launch mechanism and a fast launch was designed and prototyped. The maximum climb speed of the designed drone is 6.52 m/s. Frame arm length is 9.2 cm, propeller diameter is 15.24 cm and hover flight time is 7.2 m.Originality/valueThe UAV design can be launched. Design, calculation and experimental studies have been carried out for rapid take-off of the rotary wing UAV. The parts used in the UAV are originally produced. It is not a commercial product.

An Efficient Multimodal Nature‐Inspired Unmanned Aerial Vehicle Capable of Agile Maneuvers

Herein, the development of a multimodal, nature‐inspired unmanned aerial vehicle (UAV) that operates in three different flight regimes (rotor wing, tailsitter, cruise), unlike typical UAVs which only consist of two, is discussed. The platform uses a nature‐inspired method to achieve efficient hover, yet possesses the flexibility to enter a more agile state via additional tailsitter and cruise modes. Both the mechanical configuration and software/control architecture used to achieve three‐mode capability are documented in detail. A sigmoid blending control is implemented as the transition control strategy, consisting of transition coordinators that adjust the weight of each individual controller on the actuator outputs. To improve the transition sequence based on performance goals such as reduced altitude variation and throttle usage, an optimization routine is performed to obtain the optimized blending parameters. The optimized parameters are then experimentally verified on a physical prototype in lab conditions and shown to exhibit at least a 20% improvement for altitude variation and at least 5% less throttle usage across 4 consecutive transitions compared with baseline. Three‐mode capability outdoors in real‐world conditions are also demonstrated in multiple flights. Power draw in rotor‐wing mode is found to be 30% less than in tailsitter mode.

Effects of Shape Changing of Morphing Rotary Wing Aircraft on Longitudinal and Lateral Flight

Unmanned aerial vehicles are aerial robots controlled by commands sent from the ground control station. While fixed-wing aircraft have the advantages of long range and high altitude, they need a runway to create sufficient lift on the wings. The advantage of Rotary Wing Aircraft is that it does not need a runway, it can perform vertical take-off and landing. It can hover. Thanks to these features, it is used in tasks such as surveillance, search and rescue, and reconnaissance. In areas with chemical wastes or in closed environments without risking the human element; Desired tasks can be performed in places such as sewers, caves, and collapsed houses. For this, there is a flight control computer and software on the aircraft. Rotary-wing aircraft are more unstable than fixed-wing aircraft. Thanks to the flight controller, its stability and controllability are increased. In this study, a quadcopter, multicopter aircraft structure is used. The variation of the angle between the arms of a quadcopter aircraft and its effects on forward and sideways flight are examined. It is required that the aircraft be symmetrical in the longitudinal and lateral axis in order to cope with the disturbances to which it is exposed in external environments. In closed environments, atmospheric events are replaced by obstacles. One of the desirable features of the aircraft is that it can pass through narrow places. For this, the aircraft must perform a shape change. The change in structure will cause it to change in the dynamic’s equations, causing the rotors to react differently during linear and rotational movements of the aircraft. This study focuses on the system design and control of the aircraft. The geometric features obtained from the aircraft designed in the CATIA program were used in the creation of the mathematical model. The obtained values were created using the MATLAB Simulink program to create a digital twin of the aircraft. When the intersection angle between the arms is 90 degrees, the settling time of the 2-degree pitch angle is 7.48 seconds, and when it is 45 degrees, it is 10.3 seconds.

Design of Rotary Wings with Passive Mitigation of Coherent Tip Vortex Roll-Up

A rotor blade radial loading profile is presented that aims to passively mitigate the formation of coherent tip vortex structures in the near-field of the rotor wake. The method leverages principles of Helmholtz’s theorems, where the strength of the vortex wake is proportional to radial gradients in the blade loading distribution. By avoiding such radial gradients, the near-field roll-up of the wake vortex can be mitigated. A pair of two-bladed rotor designs configured with the same thrust coefficient was produced using a finite-vortex rotary lifting line framework coupled to a constrained power optimization problem. A baseline rotor was designed based on a power-optimized approach, and a wake-optimized rotor was designed based on a power-optimized approach with an additional blade-root bending moment constraint. Phase-averaged stereoscopic particle image velocimetry data were acquired for each rotor operating in hover. The wake-optimized rotor blade produced a wake characterized by conical vortex sheets of significantly lower peak vorticity than the compact, helical tip vortices produced by the baseline design. The wake-optimized design exhibited increased axial velocities near the root that caused radial distortions of the wake flow structures, which were also found to decay at a faster rate than that for the baseline design.

Developing a procedure to produce large-scale topographic maps of open-pit mines using rotary wing unmanned aerial vehicles

Recently, the rapid development of unmanned aerial vehicle (UAV) has led to increasingly popular applications of this technology in the field of surveying and mapping. This article presents the result of developing a procedure to produce large-scale topographic maps for open-pit mines in Vietnam in which unmanned aerial vehicles (UAV) are used to collect data. With the goal of creating a procedure that ensures accuracy, safety, and efficiency for the production of topographic maps, the theories and official regulations for measuring and editing topographic maps in general and in mines in particular, as well as using drones in Vietnam have been applied. The procedure is specifically developed for the vertical takeoff and landing (rotary) UAVs. Experiments consisting of the flight altitude calculation, determining the appropriate take-off position, and image acquisition were conducted at two open-pit mines, namely Dong Da Mai coal mine and Long Son quarry to verify the procedure. The digital surface models (DSM) and orthophotos are generated from the acquired photos, georeferenced to the VN-2000 coordinate system using ground control points (GCP), and evaluated with checkpoints. In addition, the experiment included the investigation of the various combination of GCP networks to determine the optimal GCP number for each case. Experimental results show that the procedure is logical, correct, straightforward, safe, and effective. UAV resulted products, such as orthophotos, DSM, and topographic maps were accurate and met the requirements of all the national standards.

Literature Review: Lower Back Pain in Military Rotary Wing Pilots

Lower back pain (LBP) is a major health care challenge affecting the military aircrew worldwide. Researchers conducted studies addressing this problem to provide insight into various aspects of the illness. A comprehensive literature review was carried out on peer-reviewed sources to identify evidence-based Research on lower back pain. The analysis has shown the causes of LBP, including long flight hours, full body vibrations, and personal risk factors such as genetic health status and psychological risks. Prevention measures include physical exercise, reducing flight hours, better mental health, and cockpit and equipment redesign. Treatment options for LBP are battlefield acupuncture and exercise therapy. Additionally, lower back pain negatively impacts the lives of military pilots.

The calculation of curving intensity while drilling with operated rotor systems

One of the recent achievements in the field of the systems of operated rotary wing providing fast increase of curving angle is a hybrid system combining the characteristics of the systems of control and deflection of axe. There are several theoretic methods of calculation of curving intensity іα. The first of them is a method of using the depth by the vertical h and by horizontal s. In this method curving radius R is considered permanent (i.e. it changes along the circle arch). The second method of calculation of curving intensity is a three-pointed technique, which can be applied for the drilling with a curved casing and with the systems of “Point the bit” as they are operated with similar mechanisms.

Sleep, Workload, and Stress in Aerial Firefighting Crews.

BACKGROUND:The challenges of climate change and increasing frequency of severe weather conditions has demanded innovative approaches to wildfire suppression. Australia's wildfire management includes an expanding aviation program, providing both fixed and rotary wing aerial platforms for reconnaissance, incident management, and quick response aerial fire suppression. These operations have typically been limited to day visual flight rules operations, but recently trials have been undertaken extending the window of operations into the night, with the assistance of night vision systems. Already a demanding job, night aerial firefighting operations have the potential to place even greater physical and mental demands on crewmembers. This study was designed to investigate sleep, fatigue, and performance outcomes in Australian aerial firefighting crews.METHODS:A total of nine subjects undertook a 21-d protocol, completing a sleep and duty diary including ratings of fatigue and workload. Salivary cortisol was collected daily, with additional samples provided before and after each flight, and heart rate variability was monitored during flight. Actigraphy was also used to objectively measure sleep during the data collection period.RESULTS:Descriptive findings suggest that subjects generally obtained >7 h sleep prior to flights, but cortisol levels and self-reported fatigue increased postflight. Furthermore, the greatest reported workload was associated with the domains of 'performance' and 'mental demand' during flights.DISCUSSION:Future research is necessary to understand the impact of active wildfire response on sleep, stress, and workload on aerial firefighting crews.Sprajcer M, Roberts S, Aisbett B, Ferguson S, Demasi D, Shriane A, Thomas MJW. Sleep, workload, and stress in aerial firefighting crews. Aerosp Med Hum Perform. 2022; 93(10):749-754.

Efficient Fluid–Structure Interaction Model for Twistable Flapping Rotary Wings

Wing flexibility is critical to flapping rotary wings (FRWs), and in that the deformation is bilaterally coupled with aerodynamic forces and thus determines the performance. Conventional solutions to this fluid–structure interaction (FSI) topic require considerable computational resources. In this paper, an efficient FSI model is proposed to calculate the aerodynamic force and passive twisting of FRWs. The passive pitching is regulated by a torsional spring, and the twisting is simplified as a quadratic distribution. A well-verified quasi-steady model is employed to estimate the aerodynamic forces. Our results show that the performance of rigid FRWs is superior to twistable FRWs within an upper limit of the wing-root stiffness , which is around . At higher values, the twistable FRWs generate comparable lift to rigid FRWs at a higher efficiency. An increase in flapping frequency can remarkably reduce the efficiency of twistable FRWs despite the lift enhancement, while a concomitant reduction of flapping amplitude can moderate the loss of efficiency at higher flapping frequencies. Our model provides an efficient tool for the quick estimation of the aeroelastic performance of twistable FRWs and can thus contribute to the wing stiffness design.

Parametric Study on Aerodynamic Performance of a Flapping Wing Rotor MAV Capable of Sustained Flight

By combining the flapping and rotary motion, a flapping wing rotor (FWR) shows unique kinematics of motion. It can produce a significantly higher aerodynamic efficiency and lift coefficient than insect-like flapping wings. However, due to the lack of controllable FWR aerial vehicles, the effect of different flapping parameters of the FWR on aerodynamic characteristics and efficiency remains to be evaluated experimentally. In this work, we conduct experimental studies to investigate the FWR’s lift performance based on our previous vehicle design, which has demonstrated sustained stable hover and maneuver. In particular, by using such flyable FWR as the test platform, the changes in attack angle of the wing, the torsion of wings, different neutral positions, different up and down flapping angles, and different flapping amplitudes, were studied respectively. CFD simulation was used as an auxiliary and supplementary means for validation. As a result, design essentials to lift maximization of the FWR are proposed. The result proves that changing the attack angle and the torsion of the wing will have a certain impact on the lift. In addition, the ideal lift force can be generated when the neutral position tend to zero degrees and the up and down flapping angles tend to be equal. With the growth of the flapping amplitude, the lift force increases continuously. These experimental results provide important design cues for maximizing lift and payload capability of FWR-MAVs.

188 Comparison of Nutritive Value Parameters to Normalized Difference Vegetation Index by Means of Unmanned Aerial Vehicle

Abstract Remote sensing has opened doors for grazing management by allowing producers to monitor forage in a more efficient way. The objective of this study was to observe the relationship between the normalized vegetation index (NDVI) from images taken by an unmanned aerial vehicle (UAV) to nutritive value parameters. This project took place at the H. H. Leveck Animal Research Center located in Starkville, MS where 9, 2-hectare pastures planted in Marshall annual ryegrass (Lolium multiflorum) were utilized. Each 2-hectare pasture was subdivided into 0.20-hectare sections where forage samples were collected from 3, 1/4 of a meter quadrat every 14-days. Images were taken with UAV over a 76-day grazing period every 14-days. Images from the UAV were captured at 121.9 m above ground level using a DJI inspire 2 rotor wing fitted with a MicaSense RedEdge camera (MicaSense; Seattle, WA). Images were processed using Pix4D (Pix4D SA; Prilly, Switzerland) and analyzed in QGIS (QGIS; OSGeo; Finland). Raster calculator in QGIS was utilized to calculate NDVI values. Forage samples were analyzed using NIR for crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), relative forage quality (RFQ), and invitro dry matter digestibility (IVDMD) and correlated to NDVI values. Regression analysis was conducted in R (RStudio, PBC) using the package easynls (easynls-package) procedure within package ggplot2 (ggplot2-package). Regression models were obtained through a backward-elimination technique. Neutral detergent fiber (r2 = 0.27) had the best correlated relationship to NDVI compared with CP (r2 = 0.21), ADF (r2 = 0.25), RFQ (r2 = 0.18), and IVDMD (r2 = 0.22). As NDVI values increased, CP, RFQ, and IVDMD increased while ADF and NDF decreased. There was a weak correlation between all nutritive value parameters and NDVI values. In conclusion, weak relationships indicate that NDVI values may not be the best predictor of nutritive value.

The Study of Electrical Energy Power Supply System for UAVs Based on the Energy Storage Technology

Unmanned aerial vehicles (UAVs) are increasingly attracting investment and development attention from many countries all over the world due to their great advantages. However, one of the biggest challenges for researchers is the problem of supplying energy to UAVs to ensure they can operate for a longer time. Especially in the case of rotary wings, they consume more energy than other UAV types as the motors need to spend a lot of energy to operate in order to overcome the gravity of the earth. The article aims to research power supply, energy consumption on UAVs, and a method of taking advantage of external energy sources to provide power for the operation of UAVs and discuss UAVs’ structure, categories, and control. Two experiments were conducted separately to evaluate the energy consumption of UAVs and the energy conversion from external energy sources to electrical energy. A test bench was designed to evaluate and determine the maximum efficiency using regenerative braking mode. The measuring device was manufactured to measure the necessary parameters to calculate the energy consumption and performance of the system. Experimental numerical results show that energy conversion from external sources is one of methods that can help increase the flight time of the UAV.

Impact of Rotary-Wing UAV Wobbling on Millimeter-Wave Air-to-Ground Wireless Channel

Millimeter-wave rotary-wing (RW) unmanned aerial vehicle (UAV) air-to-ground (A2G) links face unpredictable Doppler effect arising from the inevitable wobbling of RW UAV. Moreover, the time-varying channel characteristics during transmission lead to inaccurate channel estimation, which in turn results in the deteriorated bit error probability performance of the UAV A2G link. This paper studies the impact of mechanical wobbling on the Doppler effect of the millimeter-wave wireless channel between a hovering RW UAV and a ground node. Our contributions of this paper lie in: i) modeling the wobbling process of a hovering RW UAV; ii) developing an analytical model to derive the temporal autocorrelation function (ACF) for the millimeter-wave RW UAV A2G link in a closed-form expression; and iii) investigating how RW UAV wobbling impacts the Doppler effect on the millimeter-wave RW UAV A2G link. Numerical results show that different RW UAV wobbling patterns impact the amplitude and the frequency of ACF oscillation in the millimeter-wave RW UAV A2G link. For UAV wobbling, the temporal ACF decreases quickly and the impact of the Doppler effect is significant on the millimeter-wave A2G link.

Aerodynamic Performance of a Flyable Flapping Wing Rotor With Passive Pitching Angle Variation

This article is based on an experimental study on the aerodynamic performance of a flapping wing rotor (FWR) and enhancement by passive pitching angle variation (PPAV) associated with powered flapping motion. The PPAV (in this article, 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> –50 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> ) is realized by a specially designed sleeve-pin unit as part of a U-shape flapping mechanism. Through experiment and analysis, it is found that the average lift produced by an FWR of PPAV is >100% higher than the baseline model, the same FWR of a constant pitching angle 30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> under the same input power. It is also noted that the lift–voltage relationship for the FWR of PPAV is almost linear and the aerodynamic efficiency is also over 100% higher than the baseline FWR when the input voltage is under 6 V. The aerodynamic lift or efficiency of the FWR of PPAV can be also increased significantly by reducing the weight of the wings. An FWR model is fabricated and achieved vertical take-off and free flight powered by 9 V input voltage. The mechanism of PPAV function provides a feasible solution for aerodynamic improvement of a bioinspired FWR and potential application to micro air vehicles.

Experimental Validation of an Effective Control Mechanism to Enable Flapping Wing Rotor Stable Flight

Design and implementation of an effective control mechanism is the key to enable the controlled flight of flapping wing rotor micro aerial vehicles (FWR-MAVs). In order to address this open challenge, in this paper, a triple-wing FWR-MAV with its particular control system is proposed. The corresponding experimental study of the vehicle is conducted. As a result, the triple-wing propulsion system demonstrates advantages in both lift generation and flight stability based on the force measurement. The control torques of the proposed FWR-MAV are generated by a particular slip flow rudder mechanism. The effectiveness of such a design combination has been validated experimentally. A series of flight tests are conducted, including sustained hovering and forward-backward maneuvering. To the best of our knowledge, such a design yields the world’s first FWR-MAV capable of sustained controlled flight.

High-Order CFD Solvers on Three-Dimensional Unstructured Meshes: Parallel Implementation of RKDG Method with WENO Limiter and Momentum Sources

In aerospace engineering, high-order computational fluid dynamics (CFD) solvers suitable for three-dimensional unstructured meshes are less developed than expected. The Runge–Kutta discontinuous Galerkin (RKDG) finite element method with compact weighted essentially non-oscillatory (WENO) limiters is one of the candidates, which might give high-order solutions on unstructured meshes. In this article, we provide an efficient parallel implementation of this method for simulating inviscid compressible flows. The implemented solvers are tested on lower-dimensional model problems and real three-dimensional engineering problems. Results of lower-dimensional problems validate the correctness and accuracy of these solvers. The capability of capturing complex flow structures even on coarse meshes is shown in the results of three-dimensional applications. For solving problems containing rotary wings, an unsteady momentum source model is incorporated into the solvers. Such a finite element/momentum source hybrid method eliminates the reliance on advanced mesh techniques, which might provide an efficient tool for studying rotorcraft aerodynamics.

HOVER PERFORMANCE ANALYSIS OF COAXIAL MINI UNMANNED AERIAL VEHICLE FOR APPLICATIONS IN MOUNTAIN TERRAIN

Due to its compactness, agility, good hover performance, and ease of carriage, coaxial rotor Mini UAV is apt for various military and civilian applications in mountain terrain. This paper examines various factors to arrive at viable configurations of coaxial rotor Mini UAV for applications in mountain terrain. A consideration of the coaxial rotor Mini UAV to analyse the suitability for mountain terrain is presented. Coaxial rotor design is evaluated to assess the design requirements of mountain terrain. Various design parameters are analysed to arrive at viable design configurations for coaxial rotor Mini UAVs to operate in mountain terrain. Due to mechanical complexities, more than three blades per rotor for a small coaxial rotary wing aircraft is not recommended. The compact frame of the coaxial rotor Mini UAV is a key advantage, so rotor blades with a radius bigger than 1 m are not desirable. With a radius smaller than 1 m, a range of 0.9 m to 1.2 m, and an rotor speed between 900 RPM and 1200 RPM for 3-blade and 2-blade coaxial rotors, the Mini UAV offers a variety of options for applications in mountain terrain.

Prehospital Use of Whole Blood for Ill and Injured Patients During Critical Care Transport

ObjectiveHemodynamic instability and hemorrhagic shock are frequently encountered by emergency medical services providers managing ill and injured patients during critical care transport. Although many critical care transport services commonly transfuse crystalloids and/or packed red blood cells (PRBCs), the administration of whole blood (WB) in prehospital care is currently limited. WB contains PRBCs, plasma, and platelets in a physiologic ratio to aid in oxygen delivery to tissue as well as hemostasis. This study describes a single critical care transport program's experience using WB for critically ill and injured patients and reports important clinical and safety outcomes. MethodsThis study was a retrospective review of patients who were transported by a single rotor wing–based critical care transport service to 1 of 2 tertiary care receiving hospitals within a single health system. Patients who were transported between November 1, 2018, and November 30, 2019, and who received at least 1 unit of low-titer group O WB during critical care transport were included. The primary outcomes of interest included 24-hour mortality and the total 24-hour transfusion requirement. The safety outcomes included transfusion reactions, acute lung injury, acute kidney injury, and the incidence of venous thromboembolism. ResultsDuring the study period, there were 3,084 total patients transported by our critical care transport service. There were 71 patients who received prehospital WB, 64 of whom met the inclusion criteria. The top 3 indications for WB administration included blunt trauma (n = 27, 42.2%), gastrointestinal hemorrhage (n = 15, 23.4%), and penetrating trauma (n = 11, 17.2%). The median total number of blood components transfused within 24 hours was 4.0 (interquartile range, 2.0-9.5), and the overall 24-hour mortality rate was 21.9%. ConclusionsThe administration of WB by emergency medical services providers to critically ill and injured patients in the prehospital setting is feasible and is associated with low incidences of adverse events and transfusion reactions. Further research is needed to elucidate the benefits of WB relative to current prehospital standards of care.

Döner Kanatlı İHA’larda İçe Eğimli Yerleştirilmiş Pervanelerin Askıda Kalma Direngenliğine Etkisi

Rotary Wing UAVs (RWUAV) with control inputs (thrust, pitch torque, roll torque, yaw torque; 4 at total) less than the degree of freedom (3 angular motion, 3 linear motion; 6 at total) can move in the X-Y plane by rotating the thrust vectors, i.e their bodies. Deflections caused by external disturbances like winds are also eliminated by angular positioning which creates tractions against disruptive drag forces. However, the fact that the thrust vectors (propeller axis) placed perpendicular to the flight plane do not intersect in space carries the outer center of rotation of the platform to infinity, causing linear acting forces to deflect the system in the same direction in both translation and rotation. This coupling leads to an increase in the net deflection of the geometric center. It is observed that the deflection of the geometric center decreased and converged to the pure translation curve as the propeller placement angles decreased. With the study reported here, it has been analytically modeled and demonstrated how inward tilted propellers increase the hover stiffness of the platform against external disturbances. For future studies, the phenomenon suggesting inward tilted propellers may enhance the platform maneuverability by forming the outer rotation center (thrust vectors’ intersection point) is developed.