Browse Topic: Propellers and rotors
In the electrical machines, detrimental effects resulted often due to the overheating, such as insulation material degradation, demagnetization of the magnet and increased Joule losses which result in decreased lifetime, and reduced efficiency of the motor. Hence, by effective cooling methods, it is vital to optimize the reliability and performance of the electric motors and to reduce the maintenance and operating costs. This study brings the analysis capability of CFD for the air-cooling of an Electric-Motor (E-Motor) powering on Deere Equipment's. With the aggressive focus on electrification in agriculture domain and based on industry needs of tackling rising global warming, there is an increasing need of CFD modeling to perform virtual simulations of the E-Motors to determine the viability of the designs and their performance capabilities. The thermal predictions are extremely vital as they have tremendous impact on the design, spacing and sizes of these motors.
This paper presents the development of an alternative to the traditional multichannel Fiber Optic Rotary Joint (FORJ) using spatial division multiplexing. The proposed solution utilizes phase plates assembly in a compact housing made by a French optical communications company called Cailabs. It is distinguished from conventional multichannel technologies that rely on Dove prisms or wavelength multiplexing by using the housing of a single channel Fiber Optic Rotary Joint (FORJ) without needing strong constraint on the choice of optical transceivers. Our research focused on characterizing the specific mechanical parameters required to transfer optical modes from the rotor to the stator without deformation or misalignment of those. Three test campaigns were conducted, each with iterative improvements. The latest results demonstrate commercially viable performance for transmission of 3G-SDI video stream on up to 6 channels.
Swimming robots play a crucial role in mapping pollution, studying aquatic ecosystems, and monitoring water quality in sensitive areas such as coral reefs or lake shores. However, many devices rely on noisy propellers, which can disturb or harm wildlife. The natural clutter in these environments — including plants, animals, and debris — also poses a challenge to robotic swimmers.
A propeller driven rotor uses small electric motors and propellers attached to the rotor blade to spin the main rotor. Recent propeller driven rotor hover test campaigns suffered propeller failures at relatively low main rotor rotational speeds. The dynamics of spinning a fast propeller at the end of a spinning main rotor blade were the suspected cause of the propeller blade failure. An experiment using the 10 ft diameter vacuum chamber was designed to isolate and measure the propeller flapping motion of an articulated propeller blade from inertial loads. A Coriolis coupling exists between the propeller and the main rotor, resulting in large 20° sinusoidal propeller flapping motions. The vacuum chamber experiment also demonstrated that for the propeller/rotor speed ranges tested, increasing the propeller or the main rotor speed resulted in larger propeller flapping motion. An analytical model was developed to study the coupled propeller flapping motion due to the main rotor rotation
Current paper summarizes a correlation study of two flow solvers (CREATETE-AV Helios and Simcenter STAR-CCM+), routinely used at Sikorsky, with multiple model-scale wind-tunnel tests. The Helios modeling approach was aiming for a high-fidelity accurate simulation, whereas the STAR-CCM+ modeling approach was aiming for a fast turn-around time with reasonable solution accuracy with a relatively coarse mesh and simplifications. The two solvers generally agreed well with the test data within reasonable accuracy and captured the airloads and flowfield trends. The calculations presented herein show the impact of the turbulence model on component loads, the aerodynamic interactions among components, and the effect of transition modeling on rotor performance. The Reynolds-Averaged Navier-Stokes CFD model generally delayed separation and resulted in lower drag. By modeling the airframe supporting structure in CFD simulations, an improvement on correlation for inflow on the propeller plane was
In this study, we employ the Polynomial Chaos Expansion (PCE) and Monte Carlo (MC) methods to quantify the uncertainty of unsteady loading noise generated by a hovering rotor under the presence of vertical gust. The unsteady loading noise is predicted using a frequency-domain approach combined with a quasi-steady Blade Element Momentum Theory, accounting for time-varying aerodynamic forces. A sinusoidal gust is modeled using two parameters: gust length and gust amplitude. Then, the uncertainty quantification (UQ) of the unsteady loading noise is performed using the PCE and MC with these two gust parameters. The UQ analyses show that the largest uncertainty in unsteady loading noise occurs at the rotor axis, and PCE and MC simulations show good agreement. The individual and combined effects of the gust parameters on the acoustic uncertainty are analyzed, and parallel coordinate plots are utilized to visualize combinations of the gust parameters that produce noise outliers. It is found
This paper demonstrates extraction of linear models from a state-space free wake model by applying analytical linearization, extending the research presented in (Ref. 1). Two distinct Linear Time Invariant (LTI) models are developed: the first is a high-order LTI model derived from the direct conversion of the analytical Linear Time Periodic (LTP) model, and the second is a reduced-order LTI model generated by first applying the Proper Orthogonal Decomposition (POD) model order reduction technique to the LTP model, followed by conversion. In both cases, the LTP-to-LTI conversion is achieved using harmonic decomposition. A substantial reduction in the number of wake states, from 15552 to 4050, is accomplished while maintaining a similar degree of accuracy. The time domain responses of step and doublet inputs for rotor collective and cyclic pitch are analyzed by comparing the GENHEL rotor model coupled with the LTI wake against the non-linear free wake model. Good agreement is observed
Future military missions for Agile Combat Employment (ACE) and next generation Special Operations Forces need an aircraft with effective hover and the ability to operate in transonic cruise. Hover requires significant power that can only be mitigated by larger diameter rotors, but large diameter rotors become a detriment to achieving transonic flight. The stop-fold rotor configuration can “make the rotor disappear” in cruise and stands out as the most viable option for meeting these next-generation air vehicle requirements. This paper discusses the progress Bell has made in developing enabling technologies for a practical and scalable high-speed VTOL (HSVTOL) based on the stop-fold configuration. To this end, a unique Track-Guided Test Vehicle (TGTV) was developed at Bell and tested at the 10-mile High Speed Test Track at Holloman Air Force Base. The test vehicle integrates all subsystems required to demonstrate the key technologies in a representative environment, including multi-mode
A joint acoustic flight test was conducted by NASA Langley Research Center and the U.S. Army Combat Capabilities Development Command Aviation & Missile Center, with the goal of investigating new methods for acoustic data collection. The impetus for the effort is the anticipated growth of Urban Air Mobility and Future Vertical Lift vehicles. Many of these vehicles are expected to have distributed propulsion systems that may result in unsteady vehicle state conditions even during steady flight. This work examines the acoustic measurements collected during purposefully unsteady maneuvers performed by an MD530F helicopter. A snapshot microphone array design was deployed for this test to capture the acoustic signature on the ground from the helicopter under maneuver conditions. An analysis of the acoustic emissions indicated the presence of blade-vortex interactions, not only during the rolls towards the advancing side of the main rotor, but also rolls towards the retreating side and during
Dragonfly is a rotary-wing lander, and its mission is to explore Titan. It will make multiple flights over several years to explore different sites on Titan. There is limited information on the chemical processes that led to life on earth. Among the other places in the solar system, Titan is the most like the early earth and therefore exploring its organic surface chemistry will help to better understand our own prebiotic history. During Titan flight the rotor induced unsteady aerodynamic loads, as well as the interactional aerodynamic loads due to the rotor to rotor and rotor to lander interferences drive the structural vibrations. Therefore, robust and accurate predictions of Dragonfly structural loads and vibrations are essential for designing a vehicle that can successfully perform its mission. This paper presents the structural loads and vibration predictions of the Dragonfly lander using Rotorcraft Comprehensive Analysis System (RCAS) coupled with the Viscous Vortex Particle
The influence of ground, wall, and corner boundaries on multirotor vehicle performance was investigated through a series of controlled flight tests. Changes in rotor inflow profiles were represented by near-field rotor pressure measurements captured by a custom Kiel probe wake rake. Ground effect was characterized by reduced thrust and power requirements, primarily driven by the vehicle fuselage, which induced regions of reduced pressure and increased flow unsteadiness around the airframe. Operating near a wall boundary was found to restrict airflow into the portion of the rotor disk closest to the wall, leading to increased power requirements to maintain hover and a consequent reduction in performance. While vehicle orientation had minimal impact on overall rotor performance, it did influence local rotor inflow behavior near the wall, depending on the relative position of the interaction region formed with adjacent rotors. As the vehicle descends from the isolated wall effect into
The advanced air mobility (AAM) sector is using novel aircraft configurations and distributed electric propulsion to revolutionize aviation. These concepts require rotors that are efficient in vertical and forward flight. A concept that shows potential for this application is the slotted, natural-laminar-flow (SNLF) airfoil due to its high lift and low drag characteristics. This work explores the impacts of using an SNLF airfoil on an AAM rotor. Comparisons are made with blade element momentum theory (BEMT) method and computational fluid dynamics (CFD) to study the impact on the performance of an isolated rotor in hover. It is found that the rotational speed of the SNLF rotor can be reduced by 8% while still maintaining the necessary thrust for trim. A rotor broadband noise prediction shows that the slower SNLF rotor is 1-2dB quieter in terms of overall sound pressure level. Comparison of both rotors in forward flight indicates that the SNLF rotor consistently has a 1-2% higher
A regulated hybrid-electric power sharing architecture was developed and tested for VTOL applications. In this architecture, there are two power supply branches and one load. The first branch draws power from an engine-generator, and it has additional components of an AC-DC rectifier, a DC-DC buck converter, and a power diode. The second branch draws power from a battery, and it has additional components of a solid-state relay, a DC-DC boost converter, and a power diode. Any specified ratio of battery-to-engine power can be achieved with this architecture. Testing on the full range of power share ratios was conducted at a low load power of 300W. The key conclusions are that: (1) regulated power sharing is feasible between an AC supply and a DC battery, including the extremes of all engine and no battery to all battery and no engine, (2) a specified power share ratio can be achieved both in steady-state and transient conditions, and (3) there is a delay in achieving a specified power
A study into the effects of a low ice adhesion strength coating and combined low power thermal heater system was conducted. Preliminary tests determined the mass of ice necessary to shed from the low ice adhesion strength coating at a specific ambient temperature (-4°C, -8°C, -12°C, and-16°C). The heater tests were conducted at an ambient temperature of -20°C, where the same mass of ice was accreted for each specific case temperature. With the accreted mass, the heaters were turned on until a shed event occurred. The surface temperature at the shed event was recorded. For colder temperatures such as -12°C and-16°C, the surface needed to reach a temperature within 1°C of -12°C and-16°C, respectively, to initiate a shed event. For the warmer cases the replication of ice at -20°C was not feasible, as the type of ice influences adhesion strength. Ice accreted at -20°C has different physical properties than ice formed at warm temperatures, therefore the surface temperature required for
Research into the feasibility of a scaled rim-drive propulsion product to enable ultra-heavy vertical lift (UHVL) is ongoing at the University of South Carolina in partnership with KRyanCreative, LLC, a start-up aerospace small business. The research team is advancing a superconductive design concept for a rotor system that delivers significant performance gains and flight envelope expansion disruptive to the vertical lift transportation sector. The team has conceived a novel electric tip-driven ducted propulsor to guide architectural and engineering investigations that improve hover and acoustic performance over current practice without penalty to weight and cost. This paper summarizes the data and assumptions that emerge from the systems engineering process of requirements decomposition for product realization. Requirements are categorized as to whether they are explicit (programs of record) or implied (comparable business case or as an alternative to a program of record). Risk
Electric aviation is advancing rapidly, with aircraft from manufacturers like Joby and Archer well on their way to certification, aircraft electrification will continue and begin to apply to larger aircraft. To support larger electrified rotorcraft, rotors will need to grow if disc-loading and hover efficiency are to be maintained. A consequence of this is the need to reduce rotor speed to maintain an acceptable acoustic signature, especially for operation in urban environments. Most current applications utilize radial flux motors, sometimes with a reduction gearbox. Gearboxes can improve overall propulsion system power density by enabling higher motor speeds but are generally not preferred as they introduce additional potential failure modes and maintenance schedules. In this paper a holistic approach is used to understand the trade-offs between rotor and motor and their consequences on propulsion system power density.
Wind tunnel tests and comprehensive rotorcraft analysis were carried out on a slowed main rotor full-wing lift and thrust-compounded helicopter with a trailing propeller to investigate the effects of rotor and wing configuration on performance, blade structural loads, and hub vibratory loads. Experiments were conducted at advance ratios up to 0.7, incorporating three full-wing configurations with symmetric and asymmetric incidence angles and three different rotor shaft tilt angles. Propulsive thrust was measured by a trailing pusher propeller with its own balance system. The wind tunnel test data was used to validate the University of Maryland Advanced Rotorcraft Code (UMARC). Results showed that the maximum lift-to-drag ratio is achieved using either of the symmetric or asymmetric full-wing lift-compound configurations with high lift offloading and aft shaft tilt. Both blade structural loads and hub vibratory loads are significantly reduced when rotor lift is offloaded to the wings
Rotor performance in a Martian environment was analyzed with an objective of increasing thrust with minimal impact on efficiency. The Sample Recovery Helicopter (SRH) and Rotorcraft Optimization for the Advancement of Mars Exploration (ROAMX) rotors were studied by varying solidity, blade count, and chord distribution to determine which configuration delivered the most desirable performance. For all configurations, the ROAMX rotor displayed better performance than the SRH rotor. It was observed that increasing solidity reduced the blade loading required to achieve the peak figure of merit, and beyond a solidity ratio of 0.3 the figure of merit was negatively impacted. For both rotors a 6-bladed configuration with a solidity ratio of 0.3 delivered the optimal figure of merit.
The unconventional configuration of a 2 × two-bladed stacked rotor with a diameter of 0.82 m is studied experimentally throughout this paper. With the rotational speed kept constant at 2453 RPM and the dimensionless axial spacing fixed at 0.06, the main objective is to assess the effect of azimuthal spacing across multiple configurations in forward flight, varying the shaft angle and freestream velocity. First, an analysis of the baseline rotor in forward flight is presented, featuring four blades evenly spaced in a single plane. This is followed by results for the stacked rotor in hover flight, revealing a consistent trend with the literature: a low-performance region offering lower blade loading values for smaller azimuthal spacings, when both rotors closely overlap, and a region of increased performance for larger azimuthal spacings in both positive and negative directions. Most azimuthal spacings exhibit higher performance relative to the baseline rotor, with a maximum positive
The Sikorsky Boeing SB>1 DEFIANT is a technology demonstrator aircraft that was built under the Joint Multi-Role Technology Demonstrator (JMR TD) program to address the next generation performance requirements of the US Army Future Vertical Lift (FVL) initiative. The Main Rotor Gearbox (MRGB) incorporated several low Technology Readiness Level (TRL) technologies to improve power density and meet challenging program requirements for gearbox empty weight fraction. After the conclusion of the flight test program the ground test Main Rotor Gearbox was disassembled and evaluated to raise the TRL level of these technologies. The technology insertions, teardown observations, and laboratory test results are discussed.
This paper presents a meshless large eddy simulation approach for rotorcraft wake prediction, using a vortex particle method accelerated on GPUs. The solver couples a rotor model with a vortex particle wake model, employing the Fast Multipole Method for computational efficiency and implementing viscous diffusion through Particle Strength Exchange and Core Spreading Methods. GPU acceleration achieves speed-ups of up to 10x compared to CPU execution. The solver’s predictions are validated against experimental data, showing excellent agreement. Effects of time step size, numerical integration schemes, viscous models, and particle overlap factors on simulation accuracy and computational cost are systematically analyzed. This GPU-based vortex particle framework provides a fast, accurate, and scalable tool for rotorcraft wake simulations.
Blade–wake interaction (BWI) is a significant source of broadband noise and is often dominant in rotors with high blade counts. Accurately capturing the resulting unsteady blade loading is computationally expensive and, therefore, drives the cost of BWI noise calculation. To address this challenge, a low-fidelity BWI noise prediction tool was developed using aerodynamic data from the blade element momentum theory (BEMT) and the lattice Boltzmann method (LBM) for a series of rotor configurations with medium to high solidity. Starting from a six-bladed baseline rotor, 13 additional configurations were generated by varying blade twist, taper, root collective, solidity, and blade count. The relationship between vortex miss distance and blade loading unsteadiness was quantified to construct a semi-empirical BWI noise model. The model predicted BWI noise with a root mean square error of 3.9 dBA and a mean absolute percentage error of 1%. It was subsequently integrated into a BEMT framework
This work presents an extension of previous studies on the analytical linearization of state-space vortex particle methods (VPM) by incorporating viscous effects. The developed framework couples a panel method to capture blade surface and near-wake aerodynamics with a viscous vortex particle method (VVPM) for modeling the far-wake. The resulting formulation yields a nonlinear time-periodic (NLTP) system described by ordinary differential equations (ODEs) in first-order form. To enable linear analysis, the NLTP system is linearized into a linear time-periodic (LTP) representation using two techniques: finite differencing and a novel analytical linearization approach. Harmonic decomposition is then applied to transform the LTP system into a higher-order linear time-invariant (LTI) model, enabling the use of time-invariant analysis tools. The methodology is implemented in MATLAB® and applied to a representative utility helicopter rotor blade. Validation is performed against experimental
This study examines the ability of a large (1200 lb gross weight) hexacopter with collective pitch controlled rotors to tolerate single motor failure. The hexacopter is considered in various orientations, and the vehicle is trimmed with one motor inoperative (OMI). Unlike RPM-controlled hexacopters, which were trimmable but uncontrollable in hover, and were untrimmable in cruise with an aft-rotor failure; with pitch-control the hexacopter is controllable in hover as well as trimmable for failure of any rotor in cruise (including an aft rotor failure). The study examines how pitch controls, and thrust are redistributed amongst the operational rotors, post-failure, for the different hexacopter orientations. For each case, the maximum thrust and torque increases on any individual rotor, and the total power increase, post-failure is examined. It is found that the hardest to trim cases are those where the hub torque and the hub drag induced yaw moment of the failed rotor add, and fault
Axial velocity measurements were performed in the wake of a hovering rotor with constant and sinusoidal cyclic pitch inputs ranging from 0.05/rev to 0.4/rev using a fixed, 2D-3C PIV system. Measurements were taken at 36 azimuths of the rotor with a constant cyclic input producing a pitching moment of CM = -0.00037. Using a Pitt-Peters definition, a longitudinal inflow state of λ1c = 0.0059 was extracted from the velocity measurements. A phase-resolved, undersampling approach was used to reconstruct the time history of the wake for the dynamic inputs. Simultaneous rotor hub loads measurements were used to obtain the frequency response of the longitudinal inflow state to pitching moment perturbations. The pitching moment perturbations ranged from ΔCM = 0.00027 at f=0.05/rev to 0.00046 at f=0.4/rev. The inflow perturbations ranged from Δλ1c = 0.0085 at f=0.1/rev to 0.0085 at f=0.4/rev. A first order transfer function was fit to the frequency response to compute Pitt-Peters dynamic inflow
The UH-60A slowed rotor test campaign carried out at the 40- by 80-Foot Wind Tunnel at the U.S. Air Force's National Full-Scale Aerodynamics Complex (NFAC) provided valuable information of a classical helicopter rotor blades operating at very high advance ratios. This paper aims to show the correlation of the RCAS and HOST comprehensive analysis (CA) tools with respect to several experimental campaign cases. Particularly the influence of the rotor aerodynamic performance as a function of the advance ratio and the collective angle is studied. The influence of the shank drag modeling is observed and its importance to obtain accurate results is highlighted. The RCAS and HOST simulations are capable of reproducing the rotor performance trends observed in the test campaign. Furthermore, the correlation of RCAS and HOST with respect to the measured rotor loads data is studied for the advance rations of 0.4, 0.5 and 0.7 at iso-thrust coefficient conditions. The aerodynamic loads and the
During helicopter air-to-air refueling the rotor of the helicopter might enter the slipstream of the tanker aircraft's propeller. Based on blade element momentum theory, the impact of the accelerated air within the propeller slipstream on rotor blade aerodynamics (thrust, rolling and pitching moments) can be solved analytically. Also, DLR's comprehensive rotorcraft code has been used with the Pitt-Peters induced inflow plus rotor-rotor interference model. Additionally, DLR's free-wake code was used for both the propeller and the helicopter main rotor, including mutual wake-wake-interactions. The helicopter rotor's collective and cyclic controls needed for disturbance rejection are computed with all these models for a typical air-to-air refueling scenario without and with blade flapping motion. A propeller wake affecting the retreating side of the rotor requires much larger control inputs to retrim than an impingement on the advancing side. The results of all modelling approaches are
The Sikorsky BLACK HAWK® is the primary medium lift helicopter for the U.S. Army performing a wide range of missions that encompass Air Assault, MEDEVAC, CSAR, Command and Control, and VIP transport. The Multimission UH-60M is one of the latest in the BLACK HAWK helicopter product family, more capable, more survivable, more maintainable, more powerful, and more effective than its predecessors. In previous efforts, a high-fidelity CFDCSD based full-aircraft trim and maneuvering simulation methodology was developed and applied to model both coaxial aircraft and single main/tail rotor configurations (Refs. 1-4). The CFD solver is based on the CREATE™-AV HELIOS toolset (Ref. 5) and the CSD solver is based on Rotorcraft Comprehensive Analysis System (RCAS) (Ref. 6). The current paper further enhances the previously developed 6-DOF CFD-CSD full-aircraft trim methodology to robustly handle the trim solution for the single main/tail rotor configurations. The enhanced methodology was applied to
In this work, comparisons between simulations & measurements in flight are proposed for different low-speed flight conditions out of ground effect on an Airbus Helicopters H175 PT1 rotorcraft equipped with a 5-bladed Spheriflex® rotor. Numerical results have been obtained by full-helicopter unsteady simulations relying on a single-rotor loose coupling approach between the Computational Structure Dynamics& Computational Fluid Dynamics parts, assuming blade elasticity and six degrees-of-freedom trim. One flight condition is tackled with both rigid-blade and elastic-blade modelling so as to highlight the influence of the blade softness on the results. The paper showcases good agreement between the simulation results & flight-test measurements regarding variations of main-rotor collective pitch, airframe attitude angles, rotor power & rotor loads with true airspeed. Airframe download is also numerically analysed.
This study presents computational analyses of coaxial rotor hub flows and validation against experimental data obtained from the fifth Rotor Hub Flow Prediction Workshop. Experiments were conducted in a 12-inch diameter water tunnel at Pennsylvania State Applied Research Laboratory, employing tomographic particle-image velocimetry (Tomo-PIV) and precise hub drag measurements. Three CFD codes (UMD Mercury, CREATETM-AV Helios, and OVERFLOW) utilizing hybrid Reynolds-Averaged Navier-Stokes (RANS) / Large Eddy Simulation (LES) modeling based on Spalart–Allmaras turbulence model, were applied to replicate and analyze hub flows. Counter-rotating coaxial rotor hubs under free-air condition was simulated as the simplest case and the hub drags are compared between the three CFD codes. The full water tunnel configuration, consisting of two hubs, a fairing, and shafts, was also simulated and compared to experimental results, with a focus on hub drag, wake velocity fields, and turbulence
Single microphone measurements lack the ability to separate nondeterministic noise sources on multipropulsor vehicles, limiting their usefulness to understand the dominant noise generation mechanisms. To advance the state-of-the-art for measuring multipropulsor aircraft in support of future Urban Air Mobility (UAM) and Future Vertical Lift (FVL) testing, a 117-channel phased array was deployed during an Army/NASA acoustic flight test of an MD530F helicopter. A time-domain beamforming algorithm, namely, the ROtating Source Identifier (ROSI), was utilized to track the aircraft's forward motion and main rotor rotation. This process isolates nondeterministic sources of the main rotor, effectively filtering out contributions of the tail rotor and other nonrotating components. Source maps are provided for low-speed forward flight and illustrate aeroacoustic sources near the main rotor blade tips over a broad frequency range. Particular emphasis is given on the benefits of flying at a lower
The development of a coupled computational structural dynamics (CSD) and electrodynamic suspension (EDS) system was critical in modeling and predicting the aeromechanics of MagLev Aero's (MLA) propulsion system, ensuring safe testing and proving viability of levitated rotors for vertical lift systems. This advancement validates the feasibility of this enabling technology in applications of uncrewed aerial systems (UAS) with high hover lift efficiencies. This paper explores the implementation of an electromagnetic motor hub on a large-root-cutout, slowed rotor system with a specific focus on the impacts on aeromechanics: loads, performance, vibrations, and aeroelastic stability. The performance benefits of a large-root-cutout system, with an external or internal rotor, are well known; however, the mechanisms to implement such a design have been impractical. The development of an EDS motor bearing enables previously unattainable configurations like large-root-cutout and tip-driven ducted
A wind tunnel investigation to characterise the aerodynamic performance and aeroelastic response of a tiltrotor blade set operating in propeller mode is presented. A custom blade set was instrumented with fully bridged axial strain gauges to monitor the flap bending and torsional strain at several radial locations. Propeller thrust and torque measurements were acquired using a custom six component Rotating Shaft Balance. Measurements of blade tip deflection were obtained via stereoscopic Digital Image Correlation. Testing was performed at a range of rotational frequencies, blade pitch angles and advance ratios to assess the blade aerodynamic performance and aeroelastic response in both attached and stalled operating conditions. Strain measurements were shown to identify stall and blade eigenmode frequencies, where flap bending bridges show a more reliable capture of stalled flow than torsional bridges. Furthermore, blade tip deflection measurements were shown to reduce with increased
Enhancing rotor efficiency has been a persistent challenge in the development of micro aerial vehicles (MAV) especially for surveillance and covert operations. This study introduces a new Hybrid Flapping Wing Rotor (Hybrid FWR) configuration inspired by insect's wing flapping mechanics to address the efficiency limitation of traditional rotor designs. Unlike traditional rotary systems that rely solely on rotational motion, the Hybrid FWR combines rotational and flapping motions to significantly enhance lift generation. A comprehensive mathematical model was developed to analyze and predict the optimal aerodynamic performance, demonstrating that the Hybrid FWR configuration achieves a substantial improvement, with a power efficiency increase of up to 2.148-fold compared to conventional micro rotorcraft. Experimental validation was conducted to confirm the theoretical predictions, identifying an optimal hybrid ratio of approximately 0.7, which effectively minimizes aerodynamic resistance
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