Blade Segments Research Articles

How to Design a 2D Active Grid for Dynamic Inflow Modulation

In free-field operation, many aerodynamic systems are confronted with changing turbulent inflow conditions. Wind turbines are a prominent example. Here, the rotation of the rotor blades causes incoming wind gusts to result in a local change in the angle of incidence for the blade segments, which changes the effective angle of attack and can lead to dynamic non-linear effects like dynamic stall. Dynamic stall is known to produce a significant overshoot in the acting forces and thus an increase in loads acting on the wind turbine, leading to long-term fatigue. To gain a better understanding, it is necessary to perform wind tunnel experiments under realistic and reproducible inflow with defined conditions. In this study, a so-called 2D active grid is presented, which allows the generation of defined two-dimensional inflow conditions for wind tunnel experiments. The focus is on generating sinusoidal transversal and longitudinal gusts with high amplitudes and frequencies. Different grid configurations and sizes are tested to investigate differences in the generated flow fields. Transversal gusts imposed in this way can be used to study dynamic phenomena without having to move the object under investigation itself. Inertial effects during force measurements and a changing shadow casting due to moving airfoils in particle image velocimetry measurements are thus avoided. The additional possibility to generate defined longitudinal gusts allows to generate a broad range of reproducible inflow situations like yaw or tower shadow effects during experimental investigations.

Design and analysis of a segmented blade for a 50 MW wind turbine rotor

Extreme-size wind turbines face logistical challenges due to their sheer size. A solution, segmentation, is examined for an extreme-scale 50 MW wind turbine with 250 m blades using a systematic approach. Segmentation poses challenges regarding minimizing joint mass, transferring loads between segments and logistics. We investigate the feasibility of segmenting a 250 m blade by developing design methods and analyzing the impact of segmentation on the blade mass and blade frequencies. This investigation considers various variables such as joint types (bolted and bonded), adhesive materials, joint locations, number of joints and taper ratios (ply dropping). Segmentation increases blade mass by 4.1%–62% with bolted joints and by 0.4%–3.6% with bonded joints for taper ratios up to 1:10. Cases with large mass growth significantly reduce blade frequencies potentially challenging the control design. We show that segmentation of an extreme-scale blade is possible but mass reduction is necessary to improve its feasibility.

Simulation and Experimental Study on the Ultrasonic Micro-Vibration De-Icing Method for Wind Turbine Blades

In cold and humid regions, ice accretion sometimes develops on the blades of wind turbines. Blade icing reduces the power generation of the wind turbine and affects the safe operation of the wind farm. For this paper, ultrasonic micro-vibration was researched as an effective de-icing method to remove ice from the wind turbine blade surface and improve the efficiency of wind turbine power generation. A blade segment with NACA0018 airfoil and the hollow structure at the leading edge was designed. The modal analysis of the blade was simulated by ANSYS, and the de-icing vibration mode was selected. Based on the simulation results, the blade segment sample with PZT patches was machined, and its natural frequencies were measured with an impedance analyzer. A return-flow icing wind tunnel system, and a device used to measure the adhesive strength of ice covering the airfoil blade, were designed and manufactured. The experiments on the adhesive strength of the ice were carried out under the excitation of the ultrasonic vibration. The experimental results show that the adhesive strength of the ice, which was generated under the dynamic flow field condition, was lower than the ice generated by water under the static flow field condition. Under the excitation of the ultrasonic vibration, the adhesive strength of the ice decreased. When the excitation frequency was 21.228 kHz, the adhesive strength was the lowest, which was 0.084 MPa. These research findings lay the theoretical and experimental foundations for researching in-depth the application of the ultrasonic de-icing technology to wind turbines.

Development of a passive‐adaptive slat for a wind turbine airfoil

AbstractA passive‐adaptive slat concept was designed to avoid separation in the root region of a horizontal‐axis wind turbine blade. This concept incorporates an autonomously moveable slat device only driven by the aerodynamic forces acting on it without the need for mechanical or electrical actuation. It opens at high local angles of attack to delay the stall angle and closes for small angles of attack to increase the lift to drag ratio of the blade segment. This article describes the development of a passive‐adaptive slat for a DU‐91‐W2‐250 airfoil, which is a segment of the reference rotor blade in the project SmartBlades 2.0. In the course of the passive‐adaptive slat design, the optimization of the slat and its extended position is presented. This is followed by the development of two passive‐adaptive slat kinematics, which are opening and closing the slat passively at different angles of attack. With the designed passive‐adaptive slat the stall of the airfoil is delayed by 20° in incidence and the maximum lift of the airfoil is increased by about 130% at the same time in comparison to the original airfoil. Furthermore, the DU‐91‐W2‐250 airfoil with moveable passive‐adaptive slat has in most conditions a higher climb index and therefore a better aerodynamic performance than the same airfoil with a fixed integrated slat.

Loss Characterization of Advanced VIGV Configurations With Adjustable Blade Geometry

Abstract Variable inlet guide vanes (VIGV) are the main control element to adjust the flow rate of industrial centrifugal compressors by customized pre-swirl in the inlet plane of the impeller. The efficient working range of VIGVs is however restricted due to open flow separation occurring at critical stagger angles. In order to overcome the narrow limitations of current blade geometries and to enhance the operating range of the compressor, split blades consisting of a separate front and tail blade segment proved to be particularly promising in previous linear-cascade measurements. Each blade segment is thereby individually staggered. This enables a gradual flow deflection along the chord length. Secondary flow losses, however, were not considered in the previous investigations with linear cascades. To highlight the potential of the split blade concept under more application-oriented conditions including all relevant flow effects, highly resolved field measurements were conducted in the wake of annular VIGVs. Four different blade configurations, a customary reference case and three variations of the split blade with full, partial and missing sealing in the gap between the segments were assessed using five-hole probe measurements. By investigating a wide range of stagger angles, the coverage of the full low-loss working range of the VIGV could be ensured. Especially, the fully sealed split blade configuration proved its capacity to extend the efficient operational range significantly.

The Organization of Obsidian Exchange at Middle Postclassic Sauce and Its Hinterland in Veracruz, Mexico

To describe the structure of production and the organization of exchange of obsidian chipped stone during the Middle Postclassic period (AD 1200–1350) in south-central Veracruz, Mexico, I analyzed 65 residential inventories from the center of Sauce and its hinterland. Previous research on obsidian production found a spatial association with Sauce, which could support the political administration of exchange, or alternatively, identify market exchange nearby. I argue that reliance on spatially based models alone for identifying exchange mechanisms is not advisable because of potential equifinality, in which different forms of exchange appear alike. Local obsidian artifacts have additional interpretive complications: they come from a single geological source, there was universal access to them, and they were employed in potentially specialized activities. I used the articulation of production combined with spatial distribution and residential contextual information to distinguish between redistribution and market exchange. Results indicate that market exchange is the main mechanism. The largest concentrations of primary production indicators and the highest quantities of blade segments were found near the Sauce center, which suggest that political elites at Sauce encouraged market exchange, although they did not direct it to the extent that they were controlling significant amounts of obsidian.

Towards viable flow simulations of small-scale rotors and blade segments

The paper focuses on the possibilities of adequately simulating complex flow fields that appear around small-scale propellers of multicopter aircraft. Such unmanned air vehicles (UAVs) are steadily gaining popularity for their diverse applications (surveillance, communication, deliveries, etc.) and the need for a viable (i.e. usable, satisfactory, practical) computational tool is also surging. From an engineering standpoint, it is important to obtain sufficiently accurate predictions of flow field variables in a reasonable amount of time so that the design process can be fast and efficient, in particular the subsequent structural and flight mechanics analyses. That is why more or less standard fluid flow models, e.g. Reynolds-averaged Navier?Stokes (RANS) equations solved by the finite volume method (FVM), are constantly being employed and validated. On the other hand, special attention must be given to various flow peculiarities occurring around the blade segments shaped like airfoils since these flows are characterized by small chords (length-scales), low speeds and, therefore, low Reynolds numbers (Re) and pronounced viscous effects. The investigated low-Re flows include both transitional and turbulent zones, laminar separation bubbles (LSBs), flow separation, as well as rotating wakes, which require somewhat specific approaches to flow modeling (advanced turbulence models, fine spatial and temporal scales, etc). Here, the conducted computations (around stationary blade segments as well as rotating rotors), closed by different turbulence models, are presented and explained. Various qualitative and quantitative results are provided, compared and discussed. The main possibilities and obstacles of each computational approach are mentioned. Where possible, numerical results are validated against experimental data. The correspondence between the two sets of results can be considered satisfactory (relative differences for the thrust coefficient amount to 15%, while they are even lower for the torque coefficient). It can be concluded that the choice of turbulence modeling (and/or resolving) greatly affects the final output, even in design operating conditions (at medium angles-of-attack where laminar, attached flow dominates). Distinctive flow phenomena still exist, and in order to be adequately simulated, a comprehensive modeling approach should be adopted.

2D optimization of a Small Horizontal Axis Wind Turbine blade using flow control techniques

In this work, the optimization of the efficiency of a small horizontal axis wind turbine (SHWT) blade segment is presented. Typically, SHWTs have a radius of 1.5 to 3.5 m and a hub height of around 15 m from the ground. SHWTs operate in a relatively small Reynolds numbers range (up to 1.5x106) and are installed inside the atmospheric boundary layer. This operational environment is characterised by volatile air flow, making the flow over the blade prone to separation. In order to counter this flow behavior, a set of flow control techniques is introduced and studied. These techniques control the flow, either passively, solely by the inclusion of blade add-ons, or actively, by adding energy to the boundary layer. More specifically, two passive flow control techniques and one active flow control technique are modelled and tested on a wind turbine blade segment. The passive techniques implemented in this study are based on the use of vortex generators and tubercles. Vortex generators are small vanes attached vertically to the lifting surface and are widely used in aerospace applications with varying degrees of success. Tubercles, which is a novel flow control technique, are sinusoidal modifications of the blade’s leading edge. The original concept has been inspired from the characteristic flipper of the humpback whale (Megaptera Novaeangliae). Regarding the active flow control technique, a dielectric barrier discharge (DBD) plasma actuator (PA) is used, a technique that adds momentum on the local flow, close to the blade’s surface, by ionizing the air. The impact on the blade aerodynamic efficiency for each technique are evaluated and presented. The results from this evaluation show that flow control techniques can offer a considerable benefit to SHWT by improving the blade’s aerodynamic characteristics, i.e. by increasing the blade lift-to-drag ratio and thus, improving their critical performance efficiency factor.

Micropropagation of Tarenaya rosea (Cleomaceae) from leaf explants

Abstract In vitro culture techniques are recognized as efficient strategies for large-scale plant production, as well as providing alternatives for plant conservation. In this study the micropropagation of Tarenaya rosea was established using petiole and foliar blade segments cultivated on MS medium with 6-benzyladenine (BA) and/or 6-furfurylaminopurine (KIN). The regeneration rate from explants was evaluated after 30-days in culture, as well as the proliferation rate from explant-derived shoots, reached after four subcultures performed at 30-days in culture. In vitro propagation occurred by both direct (DO) and indirect (IO) organogenesis. The highest regeneration rates by DO (50% to 100%) were reached on media containing only BA, while morphogenic calluses (IO) were mainly formed with BA+KIN. Explants on media with BA showed the presence of small black nodules on their surface, and histological analysis revealed the presence of trichomes with anthocyanin content. Elongation and rooting were reached on growth regulator-free MS. Acclimatization rates around 80% were achieved and the in vitro-regenerated plants were successfully maintained under field conditions. Results show significant morphogenetic potential of T. rosea from leaf explants, mainly when cultivated in the presence of 4.4 µM BA, providing a new alternative source of plant material for biotechnological and in vitro conservation studies.

THE LITHIC INDUSTRY FROM THE SITE OF KOBULETI

The Kobuleti site is located on the territory of the Kobuleti village in Adjara (Georgia). The site was discovered on the cape of the left bank of the Kintrishi River. The cape formed by two ravines occupied the area ca. 50 Ч 50 m, towering 16—25 m above the river level. The site height above the sea level is 60 m. The cape is composed of basalt rocks, only its upper part is associated with sediments of a pack of paleosoils.
 Geographically the site is connected with the Colchis Plain which occupies the part of coastal territory. The Kintrishi River flows along the southern part of the plain at the very border with the foothills. Currently the Colchis Plain is associated with a subtropical climate zone but this does not mean that the climate was the same at the beginning of the Holocene when the site was abandoned. At the beginning of the Holocene the territory of Western Georgia had a rather temperate climate where coniferous species of trees including fir, spruce, and pine were widespread.
 The inhabitants of the site, therefore, chose a strategically important place for settlement, only 20 km from the sea coast, on the banks of the river flowing into the Black Sea, on the border of two landscape zones of the plain and foothills.
 In total, 1529 artifacts have been found, including 911 made of flint and 618 made of obsidian.
 The technique of blanks removal is focused on obtaining blades and microblades by manual pressing method. Findings of round tablets are also associated with the same cores, with the negatives of removing flakes to correct the working platform.
 In general, we can say that flint knapping occurred mainly outside the site. This is evidenced by the ratio of blades and flakes. There are almost three times more blades than flakes. This circumstance suggests that the site was visited sporadically, that the base camp of visitors was situated in a different place.
 The complex has 257 tools. The most numerous are retouching blades, bladelets, and microblades and their segments. Mostly, such products have a small semiflat retouch along the edges, but there are also products with alternative retouching. There are blades with notches. Marked products with single wide notches and products with 2—3 edge notches.
 Burins also are represented in a large series. Burins show a great typological diversity. There are burins on truncated facetted blades, including bilateral burins. There are many angle burins on broken blades. Often, such blades are double. There is a symmetrical dihedral burin. All of the listed burins are made on blades. All transverse and dihedral angle burins are made on flakes. There is one combined tool: burin on truncated facetted blade — the endscraper.
 Scrapers are very few in comparison with burins. All of them are made on flakes, they are the endscrapers. There is a series of chisels on massive segments of blades and on flakes. Probably, some retouched flakes were used as scrapers and chisels.
 Truncated facetted blades are found, including oblique truncated facetted blades and oblique truncated facetted blade with a negative of microburins spall. A fairly representative complex associated with hunting weapons. This is a series of bladelets and microblades with abrupt retouch.
 In general, the typology of the assemblage indicates that the site was used as temporary hunting camp where a minimal number of production activities were carried out.

Blade Segment with a 3D Lattice of Diamond Grits Fabricated via an Additive Manufacturing Process

Diamond tools with orderly arrangements of diamond grits have drawn considerable attention in the machining field owing to their outstanding advantages of high sharpness and long service life. This diamond super tool, as well as the manufacturing equipment, has been unavailable to Chinese enterprises for a long time due to patents. In this paper, a diamond blade segment with a 3D lattice of diamond grits was additively manufactured using a new type of cold pressing equipment (AME100). The equipment, designed with a rotary working platform and 16 molding stations, can be used to additively manufacture segments with diamond grits arranged in an orderly fashion, layer by layer; under this additive manufacturing process, at least 216000 pcs of diamond green segments with five orderly arranged grit layers can be produced per month. The microstructure of the segment was observed via SEM and the diamond blade fabricated using these segments was compared to other commercial cutting tools. The experimental results showed that the 3D lattice of diamond grits was formed in the green segment. The filling rate of diamond grits in the lattice could be guaranteed to be above 95%; this is much higher than the 90% filling rate of the automatic array system (ARIX). When used to cut stone, the cutting amount of the blade with segments made by AME100 is two times that of ordinary tools, with the same diamond concentration. When used to dry cut reinforced concrete, its cutting speed is 10% faster than that of ARIX. Under wet cutting conditions, its service life is twice that of ARIX. By applying the machine vision online inspection system and a special needle jig with a negative pressure system, this study developed a piece of additive manufacturing equipment for efficiently fabricating blade segments with a 3D lattice of diamond grits.

DTU’s blade research and demonstration platform

At DTU Wind Energy, a 12.6 m wind turbine rotor blade and the corresponding blade moulds were designed and manufactured to establish a blade research and demonstration platform. The blade research and demonstration platform shall allow manufacturing of a blade or blade segments under controlled conditions, allowing realizing theoretical concepts and testing these in full-scale for materials, manufacturing and design concepts of next generation wind turbines. For this purpose, the entire blade design with detailed airfoil and structural design as well as the manufacturing and test data of the blade will be published. Static tests, fatigue tests, post-fatigue static tests as well as a modal testing of the manufactured rotor blade are planned to characterize the blade response. In this way, the DTU 12.6m wind turbine rotor blade and the blade moulds can serve as a reference rotor blade to benchmark numerical simulations and to test new materials, designs, manufacturing concepts or embedded sensors for future prognostics health management systems. In this article, results of a 3D scan of the blade moulds are presented as well as description of the water-based heating and cooling system and a resistance temperature detectors (RTD) measuring system.

Effect of Three-Dimensional Aerodynamics and Dynamic Stall on Lead–Lag Damping of an Isolated Rotor

This paper investigates three-dimensional aerodynamic effects due to radial flow on lead–lag damping of a rotor in forward flight conditions. Three-dimensional effects in this study are restricted to yawed flow aerodynamics and radial flow coupling between blade segments. These effects are included in the ONERA dynamic stall model, and lead–lag damping for an isolated torsionally stiff rotor is calculated for different forward flight conditions. This augmented aerodynamic model with three-dimensional effects and Peters–He dynamic wake model improves the correlation of lead–lag damping with experimental data at high advance ratios. The effect of modeling static lift characteristics on damping correlation is also presented. Finally, a modification to the trailing edge separation point–based static lift model for improved yawed flow modeling amenable to aeromechanical stability analysis is proposed.

Contactless Localization of Premature Laminar–Turbulent Flow Transitions on Wind Turbine Rotor Blades in Operation

Thermographic flow visualization enables a noninvasive detection of the laminar–turbulent flow transition and allows a measurement of the impact of surface erosion and contamination due to insects, rain, dust, or hail by quantifying the amount of laminar flow reduction. The state-of-the-art image processing is designed to localize the natural flow transition as occurring on an undisturbed blade surface by use of a one-dimensional gradient evaluation. However, the occurrence of premature flow transitions leads to a high measurement uncertainty of the localized transition line or to a completely missed flow transition detection. For this reason, regions with turbulent flow are incorrectly assigned to the laminar flow region, which leads to a systematic deviation in the subsequent quantification of the spatial distribution of the boundary layer flow regimes. Therefore, a novel image processing method for the localization of the laminar–turbulent flow transition is introduced, which provides a reduced measurement uncertainty for sections with premature flow transitions. By the use of a two-dimensional image evaluation, local maximal temperature gradients are identified in order to locate the flow transition with a reduced uncertainty compared to the state-of-the-art method. The transition position can be used to quantify the reduction of the laminar flow regime surface area due to occurrences of premature flow transitions in order to measure the influence of surface contamination on the boundary layer flow. The image processing is applied to the thermographic measurement on a wind turbine of the type GE 1.5 sl in operation. In 11 blade segments with occurring premature flow transitions and a high enough contrast of the developed turbulence wedge, the introduced evaluation was able to locate the flow transition line correctly. The laminar flow reduction based on the evaluated flow transition position located with a significantly reduced systematic deviation amounts to 22% for the given measurement and can be used to estimate the reduction of the aerodynamic lift. Therefore, the image processing method introduced allows a more accurate estimation of the effects of real environmental conditions on the efficiency of wind turbines in operation.

Computational aeroacoustic prediction of trailing edge noise for small wind turbines

The study of aeroacoustic noise generated by small wind turbines is important to increase acceptance and implementation of the technology. Small wind turbines have unique challenges due to the low Reynolds number (Re) flow the blades experience, which introduces a potential for tonal noise. Computational aeroacoustics can be applied during the design stage of the turbine blades to improve acoustic performance. This work aims to validate a fully analytical aeroacoustic model by analyzing a SD 7037 blade segment at static angles of attack, with comparison to experimental flow and acoustic data. The Ffowcs-Williams and Hawkings (FW-H) acoustic model is used in combination with Large Eddy Simulation (LES). The following simulation parameters were examined: mesh quality, mesh density, inlet turbulence and spanwise boundary condition. These parameters change the boundary layer (BL) transition process and the formation of the laminar separation bubble on the suction side of the blade segment, both of which impact the aeroacoustic noise prediction. It was found that improvement in mesh quality and density on the surface of the blade segment resulted in improved BL simulation and tonal noise prediction. Alteration of the inlet turbulence and spanwise boundary condition did not have as large of an effect.

Experimental updating of a segmented wind turbine blade numerical model using the substructure method

During the development of the wind turbine system, blades are considered as the most critical components. The blades’ dynamic characteristics must be investigated during the design process to improve their mechanical performance. This work presents an experimental updating of a segmented wind turbine blade numerical model. For this purpose, the blade segments were manufactured using the fused deposition 3D printing technology and assembled using a threaded spar and nut. For different values of the segments assembly load, the natural frequencies and damping ratios were identified using the eigensystem realization algorithm method. The dynamic behavior of the segmented blade was examined numerically using the three-node shell element, taking into consideration the additional stiffness generated by the applied assembly load. In this study, numerical and experimental modal analysis were used to identify the first five eigenfrequencies of the blade. To update the numerical model parameters, through the identified experimental results, an iterative method was developed based on the Craig–Bampton substructure approach. Results show that the blade natural frequencies are proportional to the segments assembly load. The application of the proposed method on the segmented blade numerical model updating shows that the present method is computationally efficient.

Research of the Materials and Reinforcement Schemes Effects on a Mechanical Behavior Smart Structure with Embedded Piezo Actuators

The present work is devoted to the research of a helicopter blade segment stress-strain state. The segment was made of polymer composite materials with embedded piezoelectric actuators. The computational model of the blade segment takes into account the technological order of laying and the anisotropy of the reinforcing layers properties. The reinforcement schemes under consideration were [0°/90°], [45°/-45°], [0°/45°/-45°/90°]. The static strength margin was estimated using the criterion of maximum stresses. A layered analysis of the structure stress-strain state was carried out. It was shown that the most dangerous, determining the structure margin of safety, are normal interlayer stresses. It was found that the GFRP material and the structural reinforcement scheme [0°/90°], selected during the design, provide the greatest torsion angles.

Uncertainty identification of blade-mounted lidar-based inflow wind speed measurements for robust feedback–feedforward control synthesis

Abstract. The current trend toward larger wind turbine rotors leads to high periodic loads across the components due to the non-uniformity of inflow across the rotor. To address this, we introduce a blade-mounted lidar on each blade to provide a preview of inflow wind speed that can be used as a feedforward control input for the mitigation of such periodic blade loads. We present a method to easily determine blade-mounted lidar parameters, such as focus distance, telescope position, and orientation on the blade. However, such a method is accompanied by uncertainties in the inflow wind speed measurement, which may also be due to the induction zone, wind evolution, “cyclops dilemma”, unidentified misalignment in the telescope orientation, and the blade segment orientation sensor. Identification of these uncertainties allows their inclusion in the feedback–feedforward controller development for load mitigation. We perform large-eddy simulations, in which we simulate the blade-mounted lidar including the dynamic behaviour and the induction zone of one reference wind turbine for one above-rated inflow wind speed. Our calculation approach provides a good trade-off between a fast and simple determination of the telescope parameters and an accurate inflow wind speed measurement. We identify and model the uncertainties, which can then be directly included in the feedback–feedforward controller design and analysis. The rotor induction effect increases the preview time, which needs to be considered in the controller development and implementation.

Acoustic Emissions from Wind Turbine Blades

Research on broadband aerodynamic noise from wind turbine blades is becoming important in several countries. In this work, computer simulation of acoustic emissions from wind turbine blades are predicted using quasi empirical model for a three-bladed horizontal axis 3 MW turbine with blade length ~47 m. Sound power levels are investigated for source and receiver height of 80 m and 2 m above ground and located at a distance equal to total turbine height. The results are validated using existing experimental data for Siemens SWT-2.3 MW turbine having blade length of 47 m, as well as with 2.5 MW turbine. Aerofoil self-noise mechanisms are discussed in present work and results are demonstrated for wind speed of 8 m/s. Overall sound power levels for 3 MW turbine showed good agreements with the existing experiment data obtained for SWT-2.3 MW turbine. Noise map of single source sound power level, dBA of an isolated blade segment located at 75 %R for single blade is illustrated for wind speed of 8 m/s. The results demonstrated that most of the noise production occurred from outboard section of blade and for blade azimuth positions between 80° and 170°.

A Simulation Model for Computing the Loads Generated at Landing Site During Helicopter Take-Off or Landing Operation

Summary The paper presents simulation method and results of calculations determining behavior of helicopter and landing site loads which are generated during phase of the helicopter take-off and landing. For helicopter with whirling rotor standing on ground or touching it, the loads of landing gear depend on the parameters of helicopter movement, occurrence of wind gusts and control of pitch angle of the rotor blades. The considered model of helicopter consists of the fuselage and main transmission treated as rigid bodies connected with elastic elements. The fuselage is supported by landing gear modeled by units of spring and damping elements. The rotor blades are modeled as elastic axes with sets of lumped masses of blade segments distributed along them. The Runge-Kutta method was used to solve the equations of motion of the helicopter model. According to the Galerkin method, it was assumed that the parameters of the elastic blade motion can be treated as a combination of its bending and torsion eigen modes. For calculations, data of a hypothetical light helicopter were applied. Simulation results were presented for the cases of landing helicopter touching ground with different vertical speed and for phase of take-off including influence of rotor speed changes, wind gust and control of blade pitch. The simulation method may help to define the limits of helicopter safe operation on the landing surfaces.