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1

Methods of physical and mathematical modeling method. instructions for completing individual tasks

Assignments for practical classes in the discipline “Methods of Physical and Mathematical Modeling” are given, which contribute to the acquisition of skills in developing algorithms, drawing up flowcharts, programming and working on a computer (entering a program, its debugging).

the specified format on the display "LPRINT USING" output of numerical variables in the specified format to print "TAB" location<...>performing an operation or group of operations that changes a value, form of presentation, or location<...>paper Interpage connector indicating the connection between disconnected parts of program algorithm diagrams located

2

RESEARCH OF THE OPERATION OF A THREE-TIER PLOW ABSTRACT DIS. ... CANDIDATE OF TECHNICAL SCIENCES

SARATOV INSTITUTE OF AGRICULTURAL MECHANIZATION NAMED AFTER M. I. KALININ

Experimental studies confirmed the theoretical conclusions drawn from the assumption that the traction force always passes through the centers of resistance of the plow in the horizontal and vertical planes.

year wrote: “Location of resistance N (formation resistance) and side |N (reaction on the field board)<...>Rxz"" located at a height equal to half the plowing depth from the toes of the corresponding plowshares.<...>The points of the dynamo ribs located above the bars were projected onto the transverse slats using plumb lines.

3

No. 9 [System administrator, 2016]

System Administrator magazine is the leading Russian industry publication for IT specialists. Its goal is to provide complete and objective information about the solutions, products and technologies of the modern IT industry. 90% of the articles in the magazine are of an applied nature, provided with examples, tables, and graphic material. That is why the System Administrator magazine is a reference guide for IT professionals and those who have decided to make a career in IT. Published since October 2002.

----------# Variables #------------# location where the wiki directory will be created base=/home/user/site1 # location<...>directory with MediaWiki engine files, ↵ optional parameter, default = "$mw"" echo "" echo "Location<...>In such cases, the antivirus, located at the second level of static analysis, checks the incoming letter<...>which includes five components: Dial Plan, Voice Policy, Route, PSTN Usage, Trunk Configuration, located<...>The second step is to create a “replacement query” identical in text to the original one (with the same location

4

Multi-agent technology for managing mobile resources in real time. allowance

IUNL PGUTI

Tutorial includes sections that describe in detail current state and adaptive planning methods, a multi-agent approach to solving problems of dynamic resource planning in real time, architecture and implementation of a multi-agent transport resource management system. The theoretical material is illustrated by a large number of examples of dynamic planning. The study guide contains test questions and exercises for all sections.

In order to enter a new entry, you must click on the “Create” button located at the top<...>tractors The "Location of tractors" option is intended to display all tractors for a specified date (Figure<...>Figure 73 – Location of tractors 3.4.4.3 View route “View route” (“Monitoring”  “View<...>The planned location of resources at the time of the preferred start of order execution AT000018 is given<...>Figure 113 – Setting the preferred resource Location of resources at the start of scheduling requests

5

No. 8 [Transport construction, 2010]

Information about organizations and enterprises of transport construction, their capabilities, complexity and quality of work performed and services provided.

For a rotor with radial blades (β = 0), inequalities (16), (17) take the form: N � 0 V0<...>When using rotors with a similar arrangement of blades in actual technological machines<...>It is advisable to use rotors with a similar arrangement of blades in cases where intensive<...>With a radial arrangement of the rotor blades, equation (13) of the relative motion of particles along them remains<...>The theoretical studies carried out allow us to draw the following conclusions: location of the blades

6

Veterinary and sanitary examination laboratory. workshop

The textbook examines modern organoleptic and laboratory methods for veterinary and sanitary examination of meat and meat products, as well as products of plant origin. The laboratory workshop contains requirements for the quality and safety of products based on current regulatory documents. The manual contains brief theoretical information on veterinary and sanitary examination of products, which contributes to better mastery of the discipline.

the esophagus in a single joint is suspended by the trachea on a hook or placed on the table so that their location<...>All bronchial and deep cervical lymph nodes located along the trachea are cut.<...>The topography of the location of the main internal organs and large lymph nodes is close to that of<...>Trichinella larvae are visible as roundworms up to 1 mm long with pointed edges, twisted into a spiral, located<...>using color standards sealed in test tubes and a comparator with six sockets (Figure 1.17) located

7

I live in Siberia and have been interested in hunting and fishing for a long time. Our places are wonderful. There are many rivers and lakes rich in fish and game. Most of all I like to hunt waterfowl. But sometimes it is impossible to take it: impassable swamps, swamps, quicksands, impassable reeds.

<...>with outer corner; 12 – hinged blade; 13 – external duralumin corner.<...> <...> <...>And with the lateral arrangement of the blades, you can walk on both clean and overgrown reservoirs.

8

RESEARCH AND JUSTIFICATION OF OPTIMUM PARAMETERS AND OPERATING MODE OF ROTARY DUCT CLEANING MACHINES ABSTRACT DIS. ... CANDIDATE OF TECHNICAL SCIENCES

This work is devoted to the selection of the most rational type of working body, research and justification of its main parameters and mode of operation in relation to the cleaning of small and. middle channels

With a radial arrangement of the blades where "FiroSi3ifft>vf v" 5 ~ 5b4870ich "(22) Sx is the length of the blade,<...>^n ;" " . in ~ 2648700 h "(23) where e ". " " " " c0 - coefficient taking into account the location of the center,<...>blades.<...>blades<...>With this arrangement, the stream of soil thrown out by the working body is more compact, and near the working body

9

RESULTS OF THEORETICAL AND EXPERIMENTAL STUDIES OF MULTI-BLADE ROTOR-TYPE WORKING ENGINES FOR DISTRIBUTION OF SOLID MANURE [Electronic resource] / A.P. Dyachkov [etc.] // Bulletin of the Voronezh State Agrarian University. - 2014. - No. 1-2. - P. 80-86. - Access mode: https://site/efd/386825

The results of theoretical and experimental studies of the process of distributing solid manure using a spreader from rolls with multi-blade rotor-type working bodies are presented. Rational values ​​of the design and operating parameters of the proposed design have been determined, ensuring high-quality application of solid organic fertilizers that meets agrotechnical requirements.

last row of rotors, equal to R = 0.4 m, providing theoretical flight range, with a radial arrangement<...>Theoretical dependences of the “limit” loading zone on the angle of inclination of the blades for different blade lengths<...>Results of theoretical studies to justify the number of rows of blades and the radius of each blade<...>All blades on the rotor were installed radially. The width of the blades was bl = 0.13 m.<...>movement speed (Vр = 1.55…1.63 m/s), number of rows of blades (from 2 to 4 rows) and number of blades

10

Calculation of a centrifugal compressor method. instructions for course design in the discipline "Heat engines and superchargers"

Methodological instructions are presented for students studying in the field of "Thermal Power Engineering" in full-time and part-time forms of study.

impeller in two projections showing the location of the blades and the pump housing.<...>Based on the shape and relative position of the streamlines in the plan, one can judge the smoothness of the blade shape (Figure<...>The construction of a spiral outlet located behind the vane diffuser is carried out in the same way<...>ratios bsp/bd = 1.0÷1.5, the opening angle of the spiral sections  = 50÷60°, while for a spiral located<...>Vane diffuser Structurally, the vane diffuser consists of a grid of profiled blades located

11

M.: PROMEDIA

The number and location of blades within the raw material inlet device. 6.<...>and number of blades).<...>Rice. 9–11 show the CFD layout for three heights along with steam trajectory lines colored using<...>In the case of radial opposed fittings, a maximum peak speed of 143.5 was achieved<...>minimum entrainment within the criteria for optimal steam distribution and has a section of space for placement

12

SURVEY AND RESEARCH OF A ROTARY WORKING BODY FOR ACTIVE LOOSENING AND SOIL SEPARATION IN POTATO HARVESTING MACHINES ABSTRACT DIS. ... CANDIDATE OF TECHNICAL SCIENCES

BELARUSIAN RESEARCH INSTITUTE OF AGRICULTURE

Therefore, improving existing and finding new methods for separating soil and working bodies for these purposes is an important task.

located behind the rotor.<...>- angle of friction between tubers and blades.<...>There are three possible ways to position the blade on the rotor drum: along a radius of 7 - 0" with an inclination forward 7<...>with the blade tilted back, which ensures maximum driving force along the blade.<...>D - - 1000 mm; b) rotor drum diameter d = 300 mm; c) number of blades z = 8; d) pitch of the helical blade

13

The article presents the results of experimental studies on the study of the process of clinker grinding in a press-roll grinder and in a ball mill equipped with energy exchange devices. Designs of energy exchange devices have been determined that make it possible to create an effective force effect of grinding media on the crushed material.

In this regard, studies were carried out to study the influence of the relative position of the power plant, operating modes<...>The working surfaces of the ellipse segment and the double-action blades are parallel to each other,<...>grinder and ball mill equipped with energy exchange devices: 1 – PVI; 2 – drum; 3 – blade<...>Romanovich From the graphical dependence Q, N, q = f(ξ, ϕ 2) (Fig. 4) it is established that the relative position<...>double action blades and elliptical segment in the mill drum has a significant impact on

14

General ichthyology workshop

The workshop outlines laboratory works to study the external characteristics, body shape, fins, scales, and muscles of fish; their measurement and anatomical dissection. In this case, special attention is paid to provisions that promote in-depth study external signs, which are of systematic importance and reflect the exceptional adaptability of various fish species to living conditions.

The length of the upper and lower lobes of the caudal fin (C) is the length of the largest rays of the upper and lower lobes<...>Drawings: " Various shapes mouth", "Dimensions of the fish's mouth", "Location of the eyes", "Location of the nostrils in fish"<...>This arrangement is called jugular, and it is typical for large-headed fish with a compact arrangement<...>) the upper lobe is shorter (flying fish, sabrefish), with isobathic (isocercal) both lobes have the same<...>Figure 23 – Layout of the caudal fin blades relative to the vortex zone and friction layer at

15

technical characteristics and examples of the use of some types of connections of wooden structures that have been developed over the last century are given. An analysis of the advantages and disadvantages of connectors such as ring, T and disk keys, claw and glued-in washers, and cleestal wavy toothed keys is given. The ranges and load-bearing capacities of some connectors are given.

Increased requirements for manufacturing precision, quality and moisture content of wood. ring key with blades<...>blades.<...>These blades are pieces of strip steel with a length equal to approximately three times the diameter of the ring<...>The key consists of a metal strip with teeth stamped into it, arranged asymmetrically.<...>The key is equipped with teeth and tenons located respectively on the depressions and ridges on the Copyright side

16

Wind power plants and prospects for their use in the Arctic zone of the Russian Federation: textbook. allowance

The relevance of the development of wind energy in Russia, including in its Arctic zone, is substantiated. Data on wind power plants (WPPs) and wind energy are summarized, the classification of WPPs and information on the aerodynamic profiles used are provided. A methodology for assessing wind energy potential and an example of its practical implementation for the Solovetsky Archipelago are presented. The issues of designing wind farms using Windsim, as well as the influence of wind turbines on environment. The state and prospects for the development of wind energy in the Arkhangelsk region and the Nenets Autonomous Okrug are presented. The initial data for completing individual tasks are provided.

historically established energy supply systems, increasing the energy security of areas and consumers located<...>The torque is also created by the lifting force of two vertically located blades with an aerodynamic<...>the blade rotates in a turbulent flow disturbed by previous blades.<...>the most basic aesthetic needs; – carrying out computer modeling with various layout options<...>However, when the wind turbine is located at a distance of 300 m from the permanent residence of people, the level

17

RESEARCH OF THE MIXING PROCESS IN A DOUBLE-SHAFT HORIZONTAL FEED MIXER WHEN PREPARING A MIXTURE OF WET FEED ABSTRACT DIS. ... CANDIDATE OF TECHNICAL SCIENCES

AZERBAIJAN AGRICULTURAL INSTITUTE NAMES

Objectives: a) to study the physical and mechanical properties of wet crust mixtures; b) identify the main patterns of distribution of various components in wet feed mixtures; c) identify factors in the mixing process that affect energy consumption; d) establish the optimal parameters of a two-hall continuous-action paddle feed mixer, ensuring effective mixing.

Mm; R outer radius of the blade, w; Z is the distance from the lower edge of the blade to the axis of the blade shaft,<...>when the blades are located at an angle ot "10, 20, 35, 45" and 60° relative to the shaft axis" 3) From type<...>and the shape of the blades, power consumption was studied on 3 design shapes and blade sizes. " ".*) From „<...>from the width of the blade and according to the experimental data obtained, the optimal width of the blade was determined<...>blade width.

18

THE ROLE OF LEXICAL AND GRAMMATICAL TRANSFORMATIONS IN THE TRANSLATION OF TECHNICAL TEXT

FSBEI HPE "IGLU"

The purpose of the work is to determine what difficulties a translator faces when working with technical texts in Spanish, and to identify methods for solving translation problems.

<...>deflection of the blade when the propeller rotates.<...>Figure 2.6 shows various ways of arranging the rotor blades.<...>rotation of the blade in the main rotor hub.<...>However, as the blade flaps, the distance between the center of gravity of the blade and the center of gravity of the blade itself changes.

19

No. 10 [Invention, 2010]

Theory and practice of creating inventions and registration of rights to inventions, information about the most important inventions, regulations, court decisions.

Located along a helical line (Fig. 3).<...>Due to the arrangement of the blades along the helical line, the proton rotates during its interaction<...>Due to its curly shape in the form of a twisted blade, the electron occupies the proton at the ends of its blades<...>X. No. 10. 2010 38 to the crest of one of its blades.<...>X. No. 10. 2010 39 between themselves their blades.

20

No. 5 [Humanities and social sciences, 2016]

Science Magazine"Humanitarian and Social sciencies» is an online publication that publishes articles, messages, reviews and other materials of an educational, scientific, humanitarian, socio-economic and cultural-educational nature and provides an opportunity for teachers, doctoral students, graduate students, practitioners to present the results of their scientific research for consideration by the widest possible audience.

The location of the members of a sentence - determiners, subject, predicate - within the topic is relative<...>Sciences 2016. No. 5 105 Copyright JSC Central Design Bureau BIBKOM & LLC Book-Service Agency In the given example, the location<...>The location within the topic of the component of the verbal predicate and other members of the sentence (subject<...>winged or with a wing: the hair is pulled together by a sderichoy at the back of the head, the magpie is attached to the back with wings, blades<...>"friendly zone" - "location of friendly troops").

21

No. 3 [Helicopter industry, 2011]

The HELICOPTER INDUSTRY magazine is a competent analysis of the Russian helicopter industry. This is a publication that meets the interests of business executives Russian aviation. This is a respectable magazine designed for all representatives of business aviation. The magazine is published for organizations providing services in the helicopter and aircraft industries, business aviation, representative offices of foreign companies, aviation holdings throughout Russia and owners of private helicopters. The magazine is published by the HELICOPTER INDUSTRY ASSOCIATION (AVI), the first organization in Russia to unite all the main structures of the helicopter industry that exist today in Russia.

linings, through which a screw column is mounted in the center of the blade.<...>The only place that was not allowed to be visited was the control and testing station located<...>Fuel tanks on vehicles are connected to a 7-ton fuel tank located behind a protective concrete barrier.<...>Russia has vast territories and large volumes of natural resources located in areas where it is difficult to<...>with unevenly spaced blades make the EC135 the quietest helicopter in its class.

22

Indigenous, ancient varieties growing in various regions of grape cultivation are an important part of the global gene pool of culture. Many native Don grape varieties (Vitis vinifera L.) are of significant value for cultivation and use in breeding work. Among the Don varieties, both groups that are similar in basic characteristics and those that are more distant are distinguished. The main characteristics of the leaves of grape varieties are the most important ampelographic character. DNA research is the most informative method for analyzing plant genotypes. Microsatellite markers are widely used for genotyping grape varieties and rootstocks, and are also successfully used in studying the origin of varieties and analyzing their pedigrees. We assessed the relatedness of a number of Don varieties based on the results of microsatellite genotyping. The purpose of this work was to study the genetic similarity of native Don varieties based on DNA analysis and compare the results obtained with the data from the analysis of the main characteristics of the formed leaf, as well as the conclusions of other authors. The research was carried out on 16 varieties growing in the collection of the All-Russian Research Institute of Viticulture and Winemaking named after. ME AND. Potapenko (Novocherkassk) and in the Russian ampelographic collection (Anapa). All studied varieties were described according to their main ampelographic characteristics. The work used a polymerase chain reaction with separation of its products by electrophoresis. DNA was isolated from young leaves of the apical part of the shoots of 4-5 typical bushes of the variety. Six SSR markers recommended as the main ones for V. vinifera fingerprinting were used. The control varieties were Chardonnay and Cabernet Sauvignon, the allelic composition of which is known based on the studied SSR loci. The matrix of genetic distances was built using similarity coefficients (indices) according to M. Nei and W. Li. Cluster analysis based on SSR genotyping data was performed using the unweighted pairwise clustering method with arithmetic averaging (UPGMA). A graphical construction of dendrograms was carried out. Data on morphological characteristics leaves and SSR genotyping results were analyzed by the principal coordinate method (PCA). Using an automatic genetic analyzer ABI Prism 3130 (Applied Biosystems, USA), DNA profiles of local Don grape varieties were obtained for microsatellite loci VVMD5, VVMD7, VVMD27, VVS2, VrZAG62 and VrZAG79. In the genotypes of the studied Don varieties, six (at loci VVS2, VVMD5, VVMD7, VrZAG62) and seven (at loci VVMD27, VrZAG79) alleles per locus were identified. Cluster analysis made it possible to divide the varieties into two main branches: one included Sibirkovy, Pukhlyakovsky Bely, Sivolistny, Pukhlyakovsky Cherny, Kosorotovsky and Kukanovsky (all of them belong to the group of natural seedlings of Pukhlyakovsky Bely), the other included Bezymyanny Donskoy, Plechistik bisexual, Stary Goryun, Tsimlyansky white, Tsimlyansky black, Tsimladar, Plechistik, Sypun black, Makhrovatchik and Bessergenevsky No. 7. It is interesting that in the second branch three subgroups emerged. One included the varieties Bezymyanny Donskoy, Plechistik bisexual, Tsimlyansky white, Tsimlyansky black, Tsimladar, Plechistik, Sypun black (a group of Tsimlyansky varieties), the other included Bessergenevsky No. 7 (presumably a seedling of Pukhlyakovsky white) and Stary Goryun (a group of Tsimlyansky varieties); The Makhrovatchik variety stood out separately (considered a seedling of the Kokur white variety). In the space of principal coordinates, we did not find a distribution of varieties according to the main characteristics of leaves in accordance with their presumed origin. According to the results of SSR analysis, most varieties were distributed in accordance with previously made conclusions about their origin. Thus, the most informative assessment of collections, landraces, breeding material and introduced samples based on a set of ampelographic characteristics and SSR markers can be considered. Keywords: indigenous gene pool, SSR markers, ampelographic characteristics of leaves, Vitis vinifera L., Don grape varieties, genetic similarity.

apical tooth to its width, 078-2 - ratio of the length of the lateral tooth to its width, 068 - number of lobes<...>, 067 - plate shape, 065 - plate size, 082 - location of the blades of the upper side notches,<...>079 - location of the petiole notch blades, 084 - cobwebby pubescence between the main veins on

23

No. 8 [Model designer, 2015]

Popular monthly scientific and technical magazine. Published since August 1962 in Moscow. Well-known aircraft designers A. Tupolev, S. Ilyushin, and cosmonaut Yu. Gagarin gave good parting words to the new edition. Since then, the magazine has been covering issues of scientific and technical creativity, amateur design, and talks about the history of domestic and foreign technology for over forty years. Among its authors, along with famous inventors and designers, champions of technical sports, there is a large army of versatile craftsmen, lovers of technology and its history. “Modelist-Constructor” is the only magazine in the country, in each issue of which drawings, diagrams and descriptions of a wide variety of home-made structures are printed. The editors see one of the main tasks as helping every reader, no matter what age, to become a jack of all trades, not only a connoisseur of technology, but also a versatile craftsman, capable of making with his own hands everything necessary for work and leisure. TRANSFER OF SUBSCRIBER NUMBERS IS CARRIED OUT WITH A DELAY OF 12 MONTHS!!!

Rods (11) with small “fins”-blades (12) are attached to them.<...>Blade pattern and fastening Fig. 5.<...>I made my first skis with bottom position blades<...>And with the lateral arrangement of the blades, you can walk on both clean and overgrown reservoirs.<...>The location of the fibers is along the largest size.

24

No. 6 [Aviation collection, 2014]

Supplement to the magazine “Modelist-Constructor”, published since July 2003. A specialized magazine for fans of aviation history and aircraft modellers. Each issue is a mini-monograph about domestic or foreign aircraft designs. Each issue contains information about the history of the creation of an airplane or helicopter, its mass production, modifications, operation, combat use and painting. A brief technical description and drawings of the machine are provided. And a large number of photographs, including photographs of components and assemblies. TRANSFER OF SUBSCRIBER NUMBERS IS CARRIED OUT WITH A DELAY OF 12 MONTHS!!!

The pilot sat in a seat located in the center plane, with seats on the sides and slightly behind<...>The relative position of the blades and the absence of general unbalance of the propeller were guaranteed by three cables<...>Trimmers for finishing the blade are glued to the stringer.<...>The tip of the blade is encased in a thin strip of stainless steel.<...>In the front part of the cabin there are three seats located next to each other: for pilots (two outer ones) and a passenger

25

Fundamentals of design and design of vibrating mixers [monograph]

Based on known designs and research results, the monograph proposes principles for designing vibrating mixers that ensure the preparation of promising building materials with the necessary physical and chemical characteristics.

;  angle of inclination of the blade to the horizon.<...>Blade concrete mixers: N k FR   , where F is the frontal area of ​​the blade; R blade installation radius<...>;  angular velocity of the blade; k is the coefficient of resistance of the mixture to the rotation of the blades.<...>and the mass of the batch; z number of blades; R r, respectively, the radii of the end and beginning of the blade;  speed<...>, L is the width of the blade, h is the gap between the edge of the blade and the wall of the mixing chamber, V is the volume of the mixture.

26

No. 1 [Scientific and Technical Bulletin of Bryansk State University, 2018]

The journal specializes in the publication of scientific articles containing new scientific results in the field of theoretical and applied research and relevant to the following branches of science from the Nomenclature of Specialties of Scientific Workers: 02 – chemical sciences; 05 – technical sciences; 25 – Earth sciences.

blades 32 using clamps 33 and locking screws 34.<...>To seal the gaps between the mating surfaces of the blades and the inner surface of the shell<...>Each blade has a groove 37 for installing a sealing element 38.<...>with the number of installed partitions (blades).<...>The use of various layouts of aisles in a warehouse for packaged cargo / D.I.

27

Cooling systems for piston internal combustion engines, textbook. allowance

Publishing house SSAU

Cooling systems for piston internal combustion engines. Programs used: Adobe Acrobat. Works of SSAU employees (electronic version)

The blades can be rotatable.<...>tubes at an angle to the air flow, 2 staggered tubes, 3 rows of tubes<...>The operation of the fan is affected by its depth position in the casing.<...>But the location of its blades should be more accurate, since due to a possible mismatch of vectors<...>with blades bent back.

28

The article “Blade bit with reinforced peripheral equipment” is devoted to the substantiation of a number of the most important parameters of the blade bit of the cutting-shearing principle of operation - increasing the performance of the peripheral and central equipment of the bit

In this case, a prerequisite is the location of these elements at different levels relative to<...>The practice of testing blade bits indicates that the nature of wear of the equipment located on<...>The volumetric work of destruction of peripheral cutters is much greater than the volumetric work of cutters located on<...>Location of paired cutters on the periphery of the blade To ensure the possibility of placement on the peripheral<...>blades

29

Axial and centrifugal pumps for thermal power plants, textbook. allowance

M.: FLINTA

The manual discusses the principles of operation, energy characteristics and designs of axial and centrifugal pumps, as well as their elements. The classification of pumps and the features of their operation as part of pumping units and networks are presented. The characteristic damage to pump elements that occurs during operation is considered. Methods for determining the hydraulic and geometric parameters of designed pumps and features for selecting serial pumps for the required conditions are presented.

<...> <...>and vertical shaft arrangement.<...>impeller; OP – with rotating impeller blades; B – with vertical shaft arrangement<...>The location of the paws here is lower.

30

A structural and technological method is proposed to increase the wear resistance and durability of mixer blades, which consists of surfacing wear-resistant rollers arranged in a chevron pattern to form a protective layer of technological mass on the friction surface, providing a “shadow effect” - shielding the working surface of the blades from the effects of abrasive particles.

mixer, which consists in surfacing wear-resistant rollers arranged in a chevron pattern to form<...>The layout of the deposited beads provides for the implementation of the so-called shadow effect [<...>; 4 – blade holder; 5 – upper mixing blade; 6 – bottom mixing blade Yu.I.<...>the location of the beads, the width and height of the beads, as well as the corresponding deposition pitch.<...>rollers arranged in a chevron pattern can increase the durability of the blades by 1.3–1.5 times compared

31

Wind turbines textbook. allowance

M.: Publishing house of MSTU im. N.E. Bauman

The principles of operation and design of wind turbines of various types, as well as the features of their regulation (control) are considered.

As a result, when large wind turbines are located at a distance of no closer than 250 m from residential buildings, the noise level is not<...>to the direction of the wind (top view): a – using the tail; b – using Windrose; c – location<...>They are small wind wheels located perpendicular to the plane of rotation of the main<...>Orientation by placing the wind turbine behind the vertical axis of its rotation is based on<...>The rotation mechanism can be controlled by a centrifugal regulator located on the main vertical

32

Theoretical and experimental studies of mixing dry components and microadditives in a paddle mixer. Theory, design, calculation monograph

RIO PGSHA

The monograph summarizes the results of theoretical and experimental studies of the process of mixing dry components in a microadditive mixer. Indicators characterizing the quality of the prepared mixture and the energy intensity of the mixing process are given. A new design scheme for a microadditive mixer has been developed, and the optimal parameters of the mixer design to minimize the mixing energy intensity have been substantiated.

Through the receiving neck located under the unloading chute 9, the component enters the loading screw<...>The components are loaded with the mixer body positioned vertically through one of the external holes<...>The resulting mixture is discharged through the lower opening of the housing when the micromixer is positioned vertically<...>The mixing devices themselves are made in the form of horizontally located shafts with blades.<...>showed the presence of two zones of the expected location of the minimum energy intensity.

33

Road construction machines and complexes

The fundamentals of theory and design, features of the calculation and design of machines for the construction and maintenance of roads, airfields and municipal services, restoration and repair of road surfaces are outlined.

This requirement is more or less satisfied by the current arrangement of the blades.<...>In twin-shaft trough mixers, counter-rotating shafts with blades arranged<...>The height of the blades is different for different points of the blade along its length.<...>blades, m).<...>blades, m; y is the angle between the plane of the blade and the axis of the shaft; RH, Re outer and inner radii of the blade

34

The failures and energy characteristics of rotary-blade turbines that have long exceeded their standard service life are analyzed. The feasibility of replacing obsolete and physically worn rotary-vane impellers with new radial-axial wheels is substantiated

The underground Ust-Khantayskaya hydroelectric power station with its turbine room located at a depth of 47 m is one of such cases.<...>Diagram of the location of damage to the axial turbine blades Fig. 2.<...>zNA is the number of guide vane blades, frev is the turbine rotation frequency), which is caused by the proximity of the location<...>Actual “blade-chamber” gap of Ust-Khantayskaya HPP turbines Unit Turbine blade number Average<...>Selecting parameters for new equipment B climatic conditions location of the underground Ust-Khantayskaya

35

Identifier of trees and shrubs of European Russia, Crimea and the Caucasus by leaves and flowers with numerous numbers. rice. in the text

Berezovsky V. A., Ilyin A. A., Karbasnikov N. P. Orlov A. V.

Guide to trees and shrubs European Russia, Crimea and Caucasus by leaves and flowers

blade<...>A tree with ring-shaped branches.<...>N * S p R a v ™ ° transversely located, * G m e l U 1 r?<...>Buds and leaves are double-rowed and spirally arranged.<...>The stems and leaves are oppositely located.

36

Equipment for processing industries workshop

RIC SSAA

The workshop examined machine and hardware diagrams of lines and basic equipment for the production of flour, cereals, feed, bakery products and vegetable oils, as well as technological equipment for processing livestock products.

The relative position of the riffles.<...>In this case, the ribbed arrangement “back to back” is used.<...>a blade performing a curvilinear flat movement; d – with a kneading blade making a curvilinear<...>The blade undergoes planetary motion.<...>, paired Z-shaped cylindrical blades (TM-63, RZ-KhTI-3), with a kneading blade in the form of a polygonal

37

Calculation of helicopter parameters at the preliminary design stage of training. allowance

The training manual outlines methods for calculating the main parameters of a helicopter at the preliminary design stage: calculation of aerodynamic drag, take-off weight, mass of units, power of the propulsion system, issues of layout and alignment.

Based on the installation angle φ07 of the blade section located at the design radius r07, the overall pitch is determined<...>Geometric twist of the blade, which determines the angular position of a number of blade sections located along<...>For sections located closer to the end of the blade, it is recommended to use TsAGI type velocity profiles<...>In this case, the sections of the blade located closer to the axis of rotation and having low peripheral speeds operate<...>The blade twist is represented as a series of angles φi of installation of section profiles located at different

38

The article “Blade bit operating in the lateral shear mode of rock” is devoted to the substantiation of a number of the most important parameters of the blade bit of the cutting-shearing principle of operation

operating experience of blade bits, the following basic requirements for their design have been determined: 1) location<...>This creates an additional exposure plane for the adjacent incisor.<...>the working elements of the blade could dump the destroyed rock.<...>But with this variant of the blade, the peripheral cutter should be ahead of the nearby cutter by some<...>This arrangement of the peripheral cutter can only be used when drilling soft rocks,

39

Mechanical equipment and technological complexes textbooks. allowance

The basic theoretical information, fundamentals of calculation and design of machines and equipment are presented; a description of the designs of machines and equipment, the principle of their operation is given; the selection and calculation of technological lines and equipment complexes is proposed.

The block usually has seven cylinders arranged around its circumference.<...>Blade 7 is intended for cleaning the walls of the housing, and blade 4 is intended for cleaning the shell of the inner cup<...>Attached to the traverse are blade 21, which rake the mixture under the blades, and blades 24 and 23, which clean the walls.<...>; α is the angle between the blade plane and the shaft axis; δ is the number of blades within one propeller pitch.<...>Describe the arrangement of mixers in mixing compartments. 10.on the sides of the umbrella, have a rounded outline.

The textbook is intended for students in the training profile “Technology of baking, pasta and confectionery production” of all forms of study when studying the discipline “Technological equipment of industry enterprises”, as well as during coursework and diploma design.

Located parallel in a horizontal plane.<...>Inside the chamber, four blades are mounted on a horizontal shaft, located one relative to the other<...>The required processing time at the appropriate speed is set using a relay located<...>blades 10.<...>2, located in the bottom of the trough.

43

Pumps, fans, compressors. Calculation and selection of superchargers method. instructions for completing coursework in the discipline “Pumps, fans, compressors”

FSBEI HPE "Saratov State Agrarian University named after N.I. Vavilov"

The guidelines contain a number of theoretical materials on the topic “Pumps, fans, compressors.” Here we consider the main issues of calculation and selection of compressors of the required pressure and power. A detailed analysis of the calculation of pumping systems is given, in particular the calculation of a centrifugal pump and its impeller, which will allow students to independently select and calculate the impeller and present it in graphical form. The guidelines offer options for implementation course work.

: channel width in meridian section 1b, location of the leading edge of the blade and the radius of its midpoint<...>r1, as well as the blade entry angle β1.<...>, which is most often chosen equal speedύ0, 11 1 1 2 mvr Q b     (13) Location of input<...>channel mvr Q b    2 (27) Having found the channel width b as a function of the length of the center line S, from a number of points located<...>Blade profiling.

44

A method has been developed for selecting a rational angle of inclination of the auger blade of a vertical screw conveyor, which allows taking into account the physical and mechanical properties and geometric characteristics of the cross-section of the flow of transported material, as well as the processes occurring on the contact surfaces of the material with the working parts of the conveyor, taking into account the imposed restrictions and optimization criteria

. No. 5 55 UDC 621. 867. 1/3 (06) METHOD FOR SELECTING A RATIONAL INCLINATION ANGLE OF THE AUGER BLADE OF A SCREW CONVEYOR<...>auger blade has been little studied due to many factors influencing this value.<...>The input parameters are the blade radius R and the helix angle α.<...>formula vit 0 2/Q V k   , (2) where 0 is the angular velocity of the screw shaft, s –1; Vvit – volume of material, located If necessary, it is possible to remove the force from the control handle and pedals by pressing a button. Currently, the hydraulic turbines of the Rybinsk hydroelectric station, which have operated for more than 60 years, are being reconstructed. The purpose of the reconstruction: increasing power, efficiency and ensuring environmental friendliness. The refurbishment includes mechanical and hydraulic designs, strength studies, model testing and delivery. The impeller is environmentally friendly, without oil in the housing. The article by specialists from the Gidroturbomash design bureau of OJSC Power Machines reflects the stages of reconstruction, the parameters of the hydraulic turbine before and after reconstruction

<...>their supporting surfaces rotate in bushings and thrust rings located in the outer and inner<...>repair - at least 20 years. to prevent the entry of solid particles and water from the flow path into the location area<...>made of cavitation-resistant stainless steel, blade rotation mechanism, servomotor located<...>their supporting surfaces rotate in bushings and thrust rings located in the outer and inner

47

Mechanization of the technological process of milk separation

RIO PGSHA

Basic information about the problem associated with the mechanization of milk separation is provided. The methods, equipment and instrumentation of experimental studies in laboratory and production conditions of a cream separator with a paddle plate holder are described. A theoretical and experimental substantiation of the design, kinematic and technological parameters of a cream separator with a paddle plate holder was carried out.

Table 1.2 presents the main fatty acids of milk fat in order of their location from the periphery<...>Consists of a frame 17 (Figure 1.8) with an oil level indicator 2 and a drain plug located on it<...>the end of the blade, internal and external, respectively, m; 3R – radius of the outlet hole axis<...>blade profile arc angle – (2.39); blade profile length – (2.40).<...>; radius of curvature of the blade profile; central angle of the arc of the radius of curvature of the blade; blade length.

48

Until recently, the destruction of turbine cover fasteners was considered only for high-pressure radial-axial turbines (Sayano-Shushenskaya, Nurek hydroelectric power station). Further study of the problem revealed that fastener failure also occurs on rotary-blade turbines. Thus, during a major overhaul in 2011 of a unit at the Uch-Kurgan hydroelectric power station (rated turbine power Nt = 45 MW at design pressure Hp = 25.8 m), 26 destroyed studs out of 72 were discovered. A major accident involving the tearing off of the turbine submarine cover (station number 1) occurred on March 10, 1992 at the Grand Rapids hydroelectric station (Canada). Three other units were also flooded. The extent of destruction at the station was quite significant. More than $2 million was spent on clearing the rubble in the turbine hall alone. Let's take a closer look at this accident.

<...>pin tightness). when the fasteners are loosened, the vibration of the turbine cover should be greater than the vibration of the one located nearby<...>Location of sensors for measuring vibration velocities (a) and experimental pin (b) Fig. 3.<...>Layout of sensors for measuring vibration velocities and a sketch of an experimental pin with installation location<...>Layout of sensors for measuring vibration velocities and a sketch of an experimental pin with installation location

49

Conodonts from Carboniferous and Lower Permian deposits of the Zaladu section, which is located in the eastern part of Iran, near the village of Gushkamar, were studied. About 50 conodont elements have been identified, on the basis of which, for the first time in Iran, conodont complexes of the lower Bashkirian, the upper part of the Moscovian stage, the lower part of the Kasimovian stage, the upper part of the Gzhelian and the base of the Asselian have been established. In a single section, the position of the Carboniferous-Permian boundary is outlined based on the appearance of S. nodulinearis and S. isolatus. 12 species of conodonts belonging to 4 genera have been identified, 9 forms have been identified in the open nomenclature, most of them are described and depicted.

An additional blade located on the inside protrudes beyond the contour of the platform and carries the sculpture<...> <...>There are no additional blades.<...>, located outside the platform parallel to the axial ridge.<...>located parallel to the axial ridge.

50

Informatization of technological equipment of ship engineering

Northern (Arctic) Federal University named after M.V. Lomonosov

Most considered actual problems informatization of modern engineering production and proposed optimal methods and ways to solve them in the existing economic conditions. The proposed technical solutions for the modernization of various technological equipment make it possible to give obsolete equipment new technological capabilities, increase the accuracy class of technological equipment, expand the functionality of machines and the range of processed products, reduce the labor intensity of processing, increase the efficiency and accuracy of control, and improve the quality of technological operations.

The movement of the caliper is monitored by signal lamps located on the control panel<...>Disabling copying is done by pressing the Kn5 button located on the copy console.<...>The layout of the functional blocks of the CSUI of the machine is shown in Fig. 4.9.<...>Layout of functional blocks of the CSUI: 1 – vertical column of the machine; 2 – spindle head<...>First of all, the number and relative position of the points is determined (aboutCopyright OJSC "CDB "BIBKOM"

The use of alternative energy sources is one of the main trends of our time. Clean, affordable wind energy can be converted into electricity even in your home by building a wind turbine and connecting it to a generator.

You can build blades for a wind generator with your own hands from ordinary materials, without using special equipment. We will tell you which blade shape is more efficient and help you choose the appropriate drawing for a wind power plant.

A wind generator is a device that allows you to convert wind energy into electricity.

The principle of its operation is that the wind rotates the blades, sets in motion the shaft, through which the rotation is supplied to the generator through a gearbox, which increases the speed.

The operation of a wind power plant is assessed by KIEV - wind energy utilization factor. When a wind wheel rotates quickly, it interacts with more wind, which means it takes more energy from it.

There are two main types of wind generators:

• horizontal.

Vertically oriented models are built so that the propeller axis is perpendicular to the ground. Thus, any movement of air masses, regardless of direction, sets the structure in motion.

This versatility is an advantage of this type of wind turbine, but they are inferior to horizontal models in terms of productivity and operating efficiency.

A horizontal wind generator resembles a weather vane. In order for the blades to rotate, the structure must be turned in the desired direction, depending on the direction of air movement.

To monitor and capture changes in wind direction, special devices are installed. The efficiency with this screw arrangement is significantly higher than with a vertical orientation. For domestic use, it is more rational to use wind generators of this type.

What blade shape is optimal?

One of the main elements of a wind generator is a set of blades.

There are a number of factors associated with these parts that affect the efficiency of the windmill:

• size;
• form;
• material;
• quantity.

If you decide to design blades for a homemade windmill, you must take all these parameters into account. Some believe that the more wings on a generator propeller, the more wind energy can be produced. In other words, the more the merrier.

However, this is not the case. Each individual part moves against air resistance. Thus, a large number of blades on a propeller requires more wind force to complete one rotation.

In addition, too many wide wings can cause the formation of a so-called “air cap” in front of the propeller, when the air flow does not pass through the windmill, but goes around it.

Form matters a lot. The speed of the propeller depends on it. Poor flow causes the formation of vortices that slow down the wind wheel

The most efficient is a single-blade wind generator. But building and balancing it with your own hands is very difficult. The design turns out to be unreliable, although with a high efficiency. According to the experience of many users and manufacturers of wind turbines, the most optimal model is a three-bladed one.

The weight of the blade depends on its size and the material from which it will be made. The size must be selected carefully, guided by calculation formulas. It is better to process the edges so that there is a rounding on one side and a sharp edge on the opposite side.

The correctly selected blade shape for a wind generator is the foundation for its good operation.

The following options are suitable for home production:

• sailing type;
• wing type.

The sail type blades are simple wide stripes, like those on a windmill. This model is the most obvious and easiest to make. However, its efficiency is so low that this form is practically not used in modern wind generators. The efficiency in this case is about 10-12%.

A much more effective form is the blades of the winged profile. It involves the principles of aerodynamics that lift huge aircraft into the air. A screw of this shape is easier to set in motion and rotates faster. The flow of air significantly reduces the resistance that the windmill encounters along its path.

The correct profile should resemble an airplane wing. On one side the blade has a thickening, and on the other there is a gentle slope. Air masses flow around a part of this shape very smoothly

The efficiency of this model reaches 30-35%. Good news The idea is that you can build a winged blade with your own hands using a minimum of tools. All basic calculations and drawings can be easily adapted to your windmill and use free and clean wind energy without restrictions.

What are blades made from at home?

Materials that are suitable for the construction of a wind generator are, first of all, plastic, light metals, wood and a modern solution - fiberglass. The main question is how much labor and time you are willing to spend on making a windmill.

PVC sewer pipes

The most popular and widespread material for making plastic blades for wind generators is an ordinary PVC sewer pipe. For most home generators with a screw diameter of up to 2 m, a 160 mm pipe is sufficient.

The advantages of this method include:

• low price;
• availability in any region;
• ease of operation;
• a large number of diagrams and drawings on the Internet, extensive experience in use.

Pipes are different. This is known not only to those who make homemade wind power plants, but to everyone who has encountered the installation of sewerage or water supply. They differ in thickness, composition, and manufacturer. The pipe is inexpensive, so there is no need to try to reduce the cost of your windmill even more by saving on PVC pipes.

Poor-quality material of plastic pipes can lead to the fact that the blades will crack during the first test and all the work will be done in vain

First you need to decide on the pattern. There are many options, each form has its own disadvantages and advantages. It might be worth experimenting first before cutting out the final version.

Since the price of pipes is low, and you can find them in any hardware store, this material is perfect for the first steps in modeling blades. If something goes wrong, you can always buy another pipe and try again; your wallet won’t suffer much from such experiments.

Experienced wind energy users have noticed that it is better to use orange rather than gray pipes to make wind turbine blades. They hold their shape better, do not bend after the wing is formed and last longer

Amateur designers prefer PVC, since during testing a broken blade can be replaced with a new one, made in 15 minutes right on the spot if a suitable pattern is available. Simple and fast, and most importantly – affordable.

Aluminum – thin, light and expensive

Aluminum is a lightweight and durable metal. It is traditionally used to make blades for wind turbines. Due to its low weight, if you give the plate the desired shape, the aerodynamic properties of the propeller will be excellent.

The main loads that a windmill experiences during rotation are aimed at bending and breaking the blade. If the plastic quickly cracks and fails during such work, you can count on an aluminum screw for much longer.

However, if you compare aluminum and PVC pipes, metal plates will still be heavier. At high rotation speeds, there is a high risk of damaging not the blade itself, but the screw at the attachment point

Another disadvantage of aluminum parts is the complexity of manufacturing. If the PVC pipe has a bend that will be used to impart aerodynamic properties to the blade, then aluminum, as a rule, is taken in the form of a sheet.

After cutting out the part according to the pattern, which in itself is much more difficult than working with plastic, the resulting workpiece will still need to be rolled and given the correct bend. It will not be so easy to do this at home and without tools.

Fiberglass or fiberglass - for professionals

If you decide to approach the issue of creating a blade consciously and are willing to spend a lot of effort and nerves on it, fiberglass will do. If you have not previously dealt with wind generators, starting your acquaintance with modeling a windmill made of fiberglass is not a good idea. best idea. Still, this process requires experience and practical skills.

A blade made of several layers of fiberglass bonded with epoxy glue will be strong, light and reliable. At large area surface, the part turns out to be hollow and practically weightless

For production, fiberglass is taken - thin and durable material, which is available in rolls. In addition to fiberglass, epoxy glue is useful for securing the layers.

Work begins by creating a matrix. This is a blank that represents a mold for a future part.

The matrix can be made of wood: timber, boards or logs. The volumetric silhouette of half the blade is cut out directly from the massif. Another option is a plastic mold.

It is very difficult to make a blank yourself; you need to have in front of your eyes a ready-made model of a blade made of wood or other material, and only then a matrix for the part is cut out from this model. You need at least 2 such matrices. But, having made a successful shape once, it can be used many times and this way you can build more than one windmill.

The bottom of the mold is thoroughly lubricated with wax. This is done so that the finished blade can be easily removed later. Lay a layer of fiberglass and coat it with epoxy glue. The process is repeated several times until the workpiece reaches the desired thickness.

When the epoxy glue has dried, half of the part is carefully removed from the matrix. They do the same with the second half. The parts are glued together to form a hollow three-dimensional part. Lightweight, durable, and aerodynamically shaped, the fiberglass blade is the pinnacle of excellence for the home wind farm hobbyist.

Its main disadvantage is the difficulty of implementing the idea and a large number of defects at first, until the ideal matrix is ​​obtained and the creation algorithm is perfected.

Cheap and cheerful: wooden part for a wind wheel

A wooden blade is an old-fashioned method that is easy to implement, but ineffective at today's level of electricity consumption. The part can be made from a solid board of light wood, such as pine. It is important to choose a well-dried piece of wood.

You need to choose a suitable shape, but take into account the fact that the wooden blade will not be a thin plate, like aluminum or plastic, but a three-dimensional structure. Therefore, it is not enough to give the workpiece a shape; you need to understand the principles of aerodynamics and imagine the outline of the blade in all three dimensions.

You will have to use a plane to give the final look to the wood, preferably an electric one. For durability, the wood is treated with an antiseptic protective varnish or paint

The main disadvantage of this design is heavy weight screw To move this colossus, the wind must be strong enough, which is difficult to achieve in principle. However, wood is an affordable material. The boards suitable for creating a wind turbine propeller can be found right in your yard without spending a penny. And this is the main advantage of wood in this case.

The efficiency of a wooden blade tends to zero. As a rule, the time and effort that goes into creating such a windmill is not worth the result obtained, expressed in watts. However, as a training model or test piece, the wooden part has a place to be. And a weather vane with wooden blades looks impressive on the site.

Drawings and examples of blades

It is very difficult to make the correct calculation of a wind generator propeller without knowing the basic parameters that are displayed in the formula, as well as having no idea how these parameters affect the operation of the wind turbine.

It’s better not to waste your time if you don’t want to delve into the basics of aerodynamics. Ready-made drawings and diagrams with specified indicators will help you choose a suitable blade for a wind power plant.

Drawing of a blade for a two-blade propeller. Made from 110 diameter sewer pipe. The diameter of the windmill propeller in these calculations is 1 m

Such a small wind generator will not be able to provide you with high power. Most likely, you are unlikely to be able to squeeze more than 50 W out of this design. However, a two-blade propeller made of a light and thin PVC pipe will give a high rotation speed and ensure the operation of the windmill even in light winds.

Drawing of a blade for a three-bladed wind generator propeller made from a 160 mm diameter pipe. The estimated speed in this option is 5 with a wind of 5 m/s

A three-blade propeller of this shape can be used for more powerful units, approximately 150 W at 12 V. The diameter of the entire propeller in this model reaches 1.5 m. The wind wheel will rotate quickly and be easily started. The three-wing windmill is most often found in home power plants.

Drawing of a homemade blade for a 5-blade wind generator propeller. Made from PVC pipe with a diameter of 160 mm. Estimated speed – 4

Such a five-blade propeller will be able to produce up to 225 revolutions per minute with an estimated wind speed of 5 m/s. To build a blade according to the proposed drawings, you need to transfer the coordinates of each point from the “Front/rear pattern coordinates” columns to the surface of the plastic sewer pipe.

The table shows that the more wings a wind generator has, the shorter their length must be to produce a current of the same power

As practice shows, it is quite difficult to maintain a wind generator larger than 2 meters in diameter. If you need a larger windmill according to the table, consider increasing the number of blades.

You will become familiar with the rules and principles in this article, which outlines the process of performing calculations step by step.

Balancing a wind turbine

Balancing the blades of a wind generator will help make it work as efficiently as possible. To carry out balancing, you need to find a room where there is no wind or draft. Of course, for a wind wheel larger than 2 m in diameter it will be difficult to find such a room.

The blades are assembled into a finished structure and installed in the working position. The axis must be positioned strictly horizontally, level. The plane in which the propeller will rotate must be set strictly vertically, perpendicular to the axis and ground level.

A propeller that is not moving must be rotated 360/x degrees, where x = number of blades. Ideally, a balanced windmill will not deviate by 1 degree, but will remain motionless. If the blade has turned under its own weight, it needs to be adjusted a little, the weight reduced on one side, and the deviation from the axis eliminated.

The process is repeated until the screw is absolutely motionless in any position. It is important that there is no wind during balancing. This may skew test results.

It is also important to check that all parts rotate strictly in the same plane. To check, control plates are installed at a distance of 2 mm on both sides of one of the blades. During movement, no part of the screw should touch the plate.

To operate a wind generator with manufactured blades, you will need to assemble a system that accumulates the received energy, stores it and transmits it to the consumer. One of the system components is the controller. You will learn how to do this by reading our recommended article.

If you want to use clean and safe wind energy for household needs and do not plan to spend a lot of money on expensive equipment, homemade blades from ordinary materials will be a suitable idea. Don't be afraid to experiment, and you will be able to further improve existing models of windmill propellers.

All the most important indicators of a wind wheel, such as speed, power, and speed, depend on the correct installation angle of the blade. Calculating the installation angle of a wind generator blade is quite simple, but it will take some time to understand all this, so I’ll start in order.

When the blade is motionless, that is, the wind wheel is standing, the wind flows into it at the angle at which the blade is actually installed to it, but as soon as the blade begins to move, the angle of approach of the wind flow changes. For example, imagine that you are sitting in a car, the wind is blowing directly into the side window. As soon as you start moving, as you gain speed, the wind will blow obliquely at an angle and into the windshield, and if the speed is very high, then the wind will blow directly into the windshield.

It’s the same with a blade; as the rotation speed increases, the actual angle of attack of the blade also changes. To calculate this angle you need to know the speed of the blade. For example, we have a wind of 10 m/s, the speed of the propeller is Z5, which means the speed of the tip of the blade is five times greater than the wind speed of 5*10=50 m/s.

Now we need to build right triangle with legs 5 and 50. Next, we need to determine the angle between the hypotenuse and the long leg; to do this, we need to divide the opposite leg by the adjacent one and we will get the tangent of this angle. 5:50=0.1. To derive the angle from this 0.1, we must take the inverse function of the tangent, that is, the arctangent.

The arctangent of a number can be calculated in special calculators, or use online services, For example >>online calculator. Arctangent 0.1=5.7 degrees. 5.7 degrees is the actual angle of flow on the plane of rotation of the propeller in the Z5 speed zone. But since the blade has different speeds along its radius, the actual angle of attack will be different and will be different in each section. For example, in the middle of the blade the speed is Z2.5, which means the angle of the wind flow is twice as large.

Now you need to find out what true wind is.

Now let's remember the angle of approach of the wind flow, which we obtained above, it is equal to 5.7 degrees. Does it correspond to the actual oncoming wind on the blade - No!, since the wind speed is 33% weaker. Then you need to take the wind not 10 m/s, but 6.6 m/s and everything will fall into place. 6.6 m/s*Z5=33, 5:33=0.15, arctangent 0.15=8.5 degrees. This means that the wind actually hits the plane of the blade in the Z5 speed zone at an angle of 8.5 degrees.

Further, if the aerodynamic quality of the blade, the polars of the blade, and the wedging angle at which its maximum qualities are manifested are not known, then the wedging angle of the blade can be taken equal to 5 degrees. This means the blade needs to be installed at an angle of 5 degrees to the wind flow actually flowing onto the plane of rotation, then 8.5-5 = 3.5 degrees. It turns out that the angle of the blade tip should be set to 3.5 degrees, then with a wind of 10 m/s and speed Z5 there will be maximum thrust and blade power, that is, maximum wind energy utilization factor (WEE).

The blade also has local speed, and the angle must be calculated separately for each section of the blade. If the tip of the blade is set to Z5 speed, then the middle of the blade will be Z2.5.

Under all other conditions, the blade will take much less energy from the wind and therefore its KIEV and shaft power will be less. For example, the generator is too powerful and will not allow the blades to reach their speed. Or the wind speed is not the same as the blade angles were set to. Therefore, the blade can be configured and manufactured for a certain wind, for example 5 m/s, then its maximum power will only be at this wind and speed corresponding to its speed. In order for the blade to operate with maximum efficiency in a wide range of winds, you need to have a wind wheel with an adjustable blade angle. The speed of the blades and the degree of braking depend on a bunch of factors, on the thickness of the blade, its width in different areas, on the number of blades, on the coefficient of filling the area swept by the blades, so actually made homemade blades with rough calculations may behave differently. If you calculated the angles for the speed of the Z5, this does not mean that the maximum power will be at this speed, for example, if the blades are wide, then the drag will be very large at high speeds and most of the power will be lost on this resistance.

An example of calculating blades for a specific generator.

For example, a generator produces 200 watt/hour of power at 180 rpm, and you want to get this power in a wind of 6 m/s. This means the propeller must take 400 watts from the wind and have 180 rpm. The average KIEV of the three-blade propeller is 0.4 and the speed is Z5. If, for example, the propeller is six-bladed, then its KIEV will be lower and its speed will also be lower, approximately KIEV 0.3 and speed Z3.5. More accurate data can only be obtained from specific profiles that were blown in a wind tunnel, and if there is no blowing data, then only such approximate data can be taken. I also want to note that without a load the propeller can accelerate to high speed values, but its power will be significantly less, and the maximum power will only be at the design power.

For the propeller to take 400 watts, the wind must have an energy of about 1000 watts. At 6 m/s, the wind has a power (see other articles on calculating the wind wheel formula) 0.6 * 1 * 6 * 6 * 6 = 129.6 watts per square meter. 129.6 * 8 square meters equals 1036.8 watts, the area swept by the blades should be 8 square meters. The propeller with a diameter of 3.2 meters has a swept area of ​​8 m. square. Now we know the diameter of the wind wheel.

Next you need to find out the speed of the wind wheel. The circumference of a 3.2 m propeller is 10 m, which means that in one revolution the blades will travel a distance of 10 meters. Now you need to find out the speed of the tips of the blades with a wind of 6m/s and speed Z5, 6*5=30m/s, that is, in a second the blades will make 30:10=3rpm, which is equal to 3*60=180rpm. From the calculations it became clear that a wind wheel with a diameter of 3.2 m and a speed of Z5, with a wind of 6 m/s, will have 180 rpm and a shaft power of 400 watts. If the efficiency of the generator is 0.5, then the output will be 200 watt/hour electrical, but if the efficiency of your generator at these speeds is 0.8, then the output will be 320 watts. Also, if the increase in speed does not cause the KIEV to sag significantly, then perhaps the power will increase a little more due to the revolutions.

As you know, when the wind speed doubles, its power increases 8 times, therefore the propeller power will also increase by about 8 times, therefore the dependence of the output power on the speed should also be quadratic. At 6 m/s we will have about 250 watts from the generator, and at 10 m/s the generator should produce up to 2 kW and load the wind wheel accordingly. If the generator turns out to be weak, the wind wheel will go into disarray. strong wind and will spin up to high speeds, hence strong noise, vibrations and possible destruction of the wind generator. Therefore, the generator must have a power synchronous with the power of the wind wheel.

All these data are of course inverted and have a fairly rough calculation; a more accurate calculation can be made independently knowing all the necessary parameters of the generator and knowing the aerodynamic properties of the blade profile used. But for a home windmill, a simple calculation of the installation angles of the blades and the wind wheel as a whole is sufficient. If you have any questions or notice gross inaccuracies in my presentation of the calculation, then write in the comments below about this to everyone and I will answer all questions. For other materials on blade calculations, see the "VG Calculations" section.

The helicopter's main rotor blades must be built in such a way that, while creating the necessary lifting force, they can withstand all the loads placed on them. And they would not just withstand, but would also have a margin of safety for all sorts of unforeseen cases that may occur in flight and during helicopter maintenance on the ground (for example, a sharp gust of wind, an upward air flow, a sharp maneuver, icing of the blades, inept rotation of the propeller after launch engine, etc.).

One of the design modes for selecting a helicopter main rotor is the vertical climb mode at any height chosen for the calculation. In this mode, due to the lack of translational speed in the plane of rotation of the propeller, the required power is greater.

Knowing approximately the weight of the helicopter being designed and setting the size of the payload that the helicopter will have to lift, they begin to select the propeller. The selection of a propeller comes down to choosing the diameter of the propeller and the number of its revolutions per minute at which the design load could be lifted vertically by the propeller with the least expenditure of power.

It is known that the thrust of the main rotor is proportional to the fourth power of its diameter and only to the second power of the number of revolutions, i.e., the thrust developed by the main rotor is more dependent on the diameter than on the number of revolutions. Therefore, it is easier to obtain a given thrust by increasing the diameter than by increasing the number of revolutions. So, for example, by increasing the diameter by 2 times, we obtain a thrust 24 = 16 times greater, and by doubling the number of revolutions, we obtain a thrust only 22 = 4 times greater.

Knowing the power of the engine that will be installed on the helicopter to drive the rotor, first select the diameter of the rotor. For this, the following ratio is used:

The rotor blade operates under very difficult conditions. It is acted upon by aerodynamic forces that bend it, twist it, tear it, and tend to tear the skin away from it. To “resist” such aerodynamic forces, the blade must be strong enough.

When flying in rain, snow or clouds with conditions conducive to icing, the operation of the blade becomes even more difficult. Raindrops hitting the blade at enormous speeds knock off the paint. When icing occurs on the blades, ice growths form, which distort its profile, interfere with its swing motion, and make it heavier. When storing a helicopter on the ground, sudden changes in temperature, humidity, and sunlight have a destructive effect on the blade.

This means that the blade must not only be strong, but it must also be immune to the influence of the external environment. But if only this! Then the blade could be made all-metal, covering it with an anti-corrosion layer, and the problem would be solved.

But there is one more requirement: the blade, in addition to this, must also be light. Therefore, it is made hollow. The design of the blade is based on a metal spar, most often a steel pipe of variable cross-section, the area of ​​which gradually or stepwise decreases from the root part to the end of the blade.

The spar, as the main longitudinal force element of the blade, absorbs shear forces and bending moment. In this respect, the operation of a blade spar is similar to that of an aircraft wing spar. However, the blade spar is also subject to centrifugal forces as a result of rotor rotation, which is not the case with an aircraft wing spar. Under the influence of these forces, the blade spar is subject to tension.

Steel flanges are welded or riveted to the spar to attach the transverse force set - the ribs of the blade. Each rib, which can be metal or wood, consists of walls and shelves. Metal sheathing is glued or welded to metal shelves, plywood sheathing is glued or welded to wooden shelves, or plywood sheathing is glued to the toe and canvas sheathing is sewn to the tail, as shown. In the bow part of the profile, the rib flanges are attached to the front stringer, and in the tail part - to the rear stringer. Stringers serve as auxiliary longitudinal strength elements.

The skin covering the flanges of the ribs forms the profile of the blade in any section. The lightest is linen covering. However, in order to avoid distortion of the profile as a result of deflection of the fabric covering in the areas between the ribs, the ribs of the blade have to be placed very often, approximately 5-6 cm from one another, which makes the blade heavier. The surface of a blade with poorly stretched fabric covering looks ribbed and has low aerodynamic qualities, since its drag is high. During one revolution, the profile of such a blade changes, which contributes to the appearance of additional vibration of the helicopter. Therefore, the fabric covering is impregnated with dope, which, as it dries, strongly stretches the fabric.

When making plywood skins, the rigidity of the blade increases and the distance between the ribs can be increased by 2.5 times compared to blades covered with fabric. In order to reduce resistance, the surface of the plywood is smoothly processed and polished.

Good aerodynamic shapes and great strength can be achieved by making a hollow all-metal blade. The difficulty in its production lies in the manufacture of a spar of variable cross-section, which forms the bow of the profile. The tail part of the blade profile is made of sheet metal casing, the leading edges of which are welded flush to the spar, and the trailing edges are riveted together.

The helicopter rotor blade profile is selected in such a way that as the angle of attack increases, flow stall occurs at the highest possible angles of attack. This is necessary in order to avoid flow stall on the retreating blade, where the angles of attack are especially high. In addition, in order to avoid vibrations, the profile must be selected in such a way that the position of the center of pressure does not change when the angle of attack changes.

Very important factor for the strength and operation of the blade is the relative position of the center of pressure and the center of gravity of the profile. The fact is that under the combined action of bending and torsion, the blade is subject to self-excited vibration, i.e. vibration with an ever-increasing amplitude (flutter). To avoid vibration, the blade must be balanced relative to the chord, i.e., the position of the center of gravity on the chord must be ensured in a way that would prevent self-increasing vibration. The balancing task comes down to ensuring that the center of gravity of the profile of the constructed blade is in front of the center of pressure.

Continuing to consider the harsh operating conditions of the rotor blade, it should be noted that damage to the wooden skin of the blade by rain drops can be prevented by strengthening the sheet metal edging along its leading edge.

The fight against icing of blades is more difficult task. If such types of icing in flight as frost and hoarfrost do not pose a great danger to the helicopter, then glassy ice, gradually and imperceptibly, but extremely firmly growing on the blade, leads to weighting of the blade, distortion of its profile and, ultimately, to a decrease in lifting force, which leads to a sharp loss of controllability and stability of the helicopter.

The theory that existed at one time that the ice would chip off in flight due to the flapping movement of the blades turned out to be unfounded. Icing of the blade begins first at the root part, where the bend of the blade during its flapping movement is small. Subsequently, the layer of ice begins to spread further and further towards the end of the blade, gradually disappearing. There are known cases when the ice thickness at the root part reached 6 mm, and at the end of the blade - 2 mm.

There are two ways to prevent icing.

First way- this is a careful study of the weather forecast in the flight area, avoiding clouds encountered along the way and changing the flight altitude in order to get out of icing conditions, stopping the flight, etc.

Second way- equipping the blades with anti-icing devices.

A whole range of these devices are known for helicopter blades. To remove ice from the rotor blades, you can

An alcohol deicer should be used, which sprays alcohol on the leading edge of the propeller. The latter, when mixed with water, lowers its freezing point and prevents the formation of ice.

Ice can be chipped from the rotor blades by air, which is pumped into a rubber chamber laid along the leading edge of the rotor. The inflating chamber breaks up the ice crust, individual pieces of which are then swept away from the propeller blades by the oncoming air flow.

If the leading edge of the propeller blade is made of metal, then it can be heated either electrically or warm air, passed through a pipeline laid along the leading edge of the rotor.

The future will show which of these methods will find wider application.

For the aerodynamic characteristics of the main rotor, the number of main rotor blades and the specific load on the area swept by the rotor are of great importance. Theoretically, the number of rotor blades can be any, from one to an infinitely large number, so large that they ultimately merge into a spiral surface, as was supposed in the project of Leonardo da Vinci or in the helicopter-bicycle of I. Bykov.

However, there is a certain number of blades that is most advantageous. The number of blades should not be less than three, since with two blades large unbalanced forces and fluctuations in propeller thrust occur. The change in main rotor thrust around its average value during one rotor revolution for single-blade and two-blade propellers is shown. The three-blade propeller practically maintains the average thrust value throughout the entire revolution.

The number of rotor blades should also not be very large, since in this case each blade operates in a flow disturbed by the previous blade, which reduces the efficiency of the main rotor.

The more propeller blades, the larger part of the area of ​​the swept disk they occupy. The concept of fill factor o has been introduced into the helicopter rotor theory, which is calculated as the ratio of the total area

For the design operating mode of a helicopter main rotor (steep climb), the most favorable fill factor value is 0.05-0.08 (average value 0.065).

This load is average. A low load is a load in the range of 9-12 kg/m2. Helicopters carrying such a load are maneuverable and have high cruising speed.

General purpose helicopters have an average load ranging from 12 to 20 kg/m2. And finally, a large load, rarely used, is a load from 20 to 30 kg/m2.

The fact is that although the high specific load on the swept area provides a large payload for the helicopter, if the engine fails, such a helicopter will descend quickly in self-rotation mode, which is unacceptable, since in this case the safety of the descent is compromised.

Recently, several things have happened in the world of helicopter technology. significant events. The American company Kaman Aerospace announced its intention to resume production of synchropters, Airbus Helicopters promised to develop the first civil fly-by-wire helicopter, and the German e-volo promised to test an 18-rotor two-seat multicopter. In order not to get confused in all this diversity, we decided to compile a short educational program on the basic diagrams of helicopter technology.

The idea of ​​an aircraft with a main rotor first appeared around 400 AD in China, but it did not go further than creating a children's toy. Engineers began seriously creating a helicopter at the end of the 19th century, and the first vertical flight of a new type of aircraft took place in 1907, just four years after the first flight of the Wright brothers. In 1922, aircraft designer Georgy Botezat tested a quadcopter helicopter developed for the US Army. This was the first consistently controlled flight of this type of equipment in history. Botezat's quadcopter managed to fly to a height of five meters and spent several minutes in flight.

Since then, helicopter technology has undergone many changes. A class of rotary-wing aircraft has emerged, which today is divided into five types: gyroplane, helicopter, rotorcraft, tiltrotor and X-wing. They all differ in design, method of takeoff and flight, and rotor control. In this material, we decided to talk specifically about helicopters and their main types. At the same time, the classification based on the layout and location of the rotors was taken as a basis, and not the traditional one - according to the type of compensation for the reactive moment of the rotor.

A helicopter is a rotary-wing aircraft in which the lifting and driving forces are created by one or more rotors. Such propellers are located parallel to the ground, and their blades are installed at a certain angle to the plane of rotation, and the installation angle can vary within a fairly wide range - from zero to 30 degrees. Setting the blades to zero degrees is called propeller idle or feathering. In this case, the main rotor does not create lift.

As the blades rotate, they capture air and throw it in the opposite direction to the propeller's movement. As a result, a zone of low pressure is created in front of the screw, and high pressure behind it. In the case of a helicopter, this creates lift, which is very similar to the lift generated by a fixed wing of an airplane. The greater the angle of installation of the blades, the greater the lifting force created by the rotor.

The characteristics of the main rotor are determined by two main parameters - diameter and pitch. The diameter of the propeller determines the helicopter's takeoff and landing capabilities, as well as partly the amount of lift. Propeller pitch is the imaginary distance that a propeller will travel in an incompressible medium at a certain blade angle in one revolution. The last parameter affects the lift and rotation speed of the rotor, which pilots try to keep unchanged for most of the flight, changing only the angle of the blades.

When a helicopter flies forward and the main rotor rotates clockwise, the incoming air flow has a stronger effect on the blades on the left side, which is why their efficiency increases. As a result, the left half of the propeller's rotation circle creates more lift than the right, and a heeling moment occurs. To compensate for this, the designers came up with a special system that reduces the angle of the blades on the left and increases it on the right, thus equalizing the lift on both sides of the propeller.

In general, a helicopter has several advantages and several disadvantages over an airplane. The advantages include the possibility of vertical takeoff and landing on sites whose diameter is one and a half times greater than the diameter of the main rotor. At the same time, the helicopter can transport large-sized cargo on an external sling. Helicopters are also distinguished by better maneuverability, since they can hang vertically, fly sideways or backwards, and turn on the spot.

Disadvantages include greater fuel consumption than airplanes, greater infrared visibility due to the hot exhaust of the engine or engines, and increased noise. In addition, a helicopter in general is more difficult to control due to a number of features. For example, helicopter pilots are familiar with the phenomena of ground resonance, flutter, vortex ring, and rotor locking effect. These factors may cause the machine to break or fall.

Helicopter equipment of any type has an autorotation mode. It refers to emergency modes. This means that if, for example, the engine fails, the main rotor or propellers are disconnected from the transmission using an overrunning clutch and begin to spin freely with the incoming air flow, slowing down the machine’s fall from a height. In autorotation mode, a controlled emergency landing of a helicopter is possible, and the rotating main rotor continues to spin the tail rotor and generator through the gearbox.

Classic scheme

Of all types of helicopter designs today, the most common is the classic one. With this design, the machine has only one main rotor, which can be driven by one, two or even three engines. This type, for example, includes the attack AH-64E Guardian, AH-1Z Viper, Mi-28N, transport-combat Mi-24 and Mi-35, transport Mi-26, multi-purpose UH-60L Black Hawk and Mi-17, light Bell 407 and Robinson R22.

When the main rotor rotates on classical helicopters, a reactive torque arises, due to which the body of the machine begins to spin in the direction opposite to the rotation of the rotor. To compensate for the moment, a steering device is used on the tail boom. As a rule, it is a tail rotor, but it can also be a fenestron (a propeller in a ring fairing) or several air nozzles on the tail boom.

A feature of the classical scheme is cross-connections in the control channels, due to the fact that the tail rotor and the main rotor are driven by the same engine, as well as the presence of a swashplate and many other subsystems responsible for controlling the power plant and rotors. Cross coupling means that when any operating parameter changes propeller, everyone else will change too. For example, as the main rotor speed increases, the steering speed will also increase.

Flight control is carried out by tilting the rotor axis of rotation: forward - the machine will fly forward, backward - backward, sideways - sideways. When the axis of rotation is tilted, a driving force arises and the lifting force decreases. For this reason, in order to maintain flight altitude, the pilot must also change the angle of the blades. The direction of flight is set by changing the pitch of the tail rotor: the smaller it is, the less the reaction torque is compensated, and the helicopter turns in the direction opposite to the rotation of the main rotor. And vice versa.

In modern helicopters, in most cases, horizontal flight control is carried out using a swashplate. For example, to move forward, the pilot, using an automatic machine, reduces the angle of the blades for the front half of the wing rotation plane and increases it for the rear. Thus, the lift force increases at the rear, and decreases at the front, due to which the tilt of the propeller changes and a driving force appears. This flight control scheme is used on all helicopters of almost all types, if they have a swashplate.

Coaxial scheme

The second most common helicopter design is coaxial. It does not have a tail rotor, but there are two main rotors - an upper and a lower one. They are located on the same axis and rotate synchronously in opposite directions. Thanks to this solution, the screws compensate for the reactive torque, and the machine itself turns out to be somewhat more stable compared to the classical design. In addition, coaxial helicopters have virtually no cross-connections in control channels.

The most famous manufacturer of coaxial helicopters is the Russian company Kamov. It produces shipborne multi-purpose helicopters Ka-27, attack Ka-52 and transport Ka-226. They all have two screws located on the same axis, one below the other. Machines of a coaxial design, unlike helicopters of a classical design, are capable, for example, of making a funnel, that is, flying around a target in a circle, remaining at the same distance from it. In this case, the bow always remains turned towards the target. Yaw control is carried out by braking one of the main rotors.

In general, coaxial helicopters are somewhat easier to control than conventional ones, especially in hovering mode. But there are also some peculiarities. For example, when performing a loop in flight, the blades of the lower and upper rotors may overlap. In addition, in design and production, the coaxial design is more complex and expensive than the classical design. In particular, due to the gearbox that transmits the rotation of the engine shaft to the propellers, as well as the swashplate, which synchronously sets the angle of the blades on the propellers.

Longitudinal and transverse diagrams

The third most popular is the longitudinal arrangement of helicopter rotors. In this case, the propellers are located parallel to the ground on different axes and spaced apart from each other - one is located above the bow of the helicopter, and the other is above the tail. A typical representative of machines of this type is the American heavy transport helicopter CH-47G Chinook and its modifications. If the propellers are located at the tips of the helicopter's wings, then this arrangement is called transverse.

There are no serial representatives of transverse helicopters today. In the 1960-1970s, the Mil design bureau developed the heavy cargo helicopter V-12 (also known as the Mi-12, although this index is incorrect) with a transverse design. In August 1969, the B-12 prototype set a record for lifting capacity among helicopters, lifting a cargo weighing 44.2 tons to a height of 2.2 thousand meters. For comparison, the world's most heavy-duty helicopter, the Mi-26 (classical design) can lift loads weighing up to 20 tons, and the American CH-47F (longitudinal design) can lift loads weighing up to 12.7 tons.

In helicopters with a longitudinal design, the main rotors rotate in opposite directions, but this only partially compensates for the reaction moments, which is why in flight pilots have to take into account the resulting lateral force that takes the machine off course. The lateral movement is set not only by the inclination of the rotor axis of rotation, but also by different installation angles of the blades, and yaw control is carried out by changing the rotor speed. The rear rotor of longitudinal helicopters is always located slightly higher than the front rotor. This is done to eliminate mutual influence from their air flows.

In addition, at certain flight speeds of longitudinal helicopters, significant vibrations can sometimes occur. Finally, longitudinal helicopters are equipped with a complex transmission. For this reason, this screw arrangement is not very common. But helicopters with a longitudinal design are less susceptible to the appearance of a vortex ring than other machines. In this case, during the descent, the air currents created by the propeller are reflected upward from the ground, drawn in by the propeller and directed downward again. In this case, the lifting force of the main rotor is sharply reduced, and changing the rotor speed or increasing the angle of the blades has practically no effect.

Synchroptera

Today, helicopters built according to the synchropter design can be classified as the rarest and most interesting machines from a design point of view. Until 2003, only the American company Kaman Aerospace was involved in their production. In 2017, the company plans to resume production of such cars under the designation K-Max. Synchropters could be classified as transverse helicopters, since the shafts of their two rotors are located on the sides of the body. However, the axes of rotation of these screws are located at an angle to each other, and the planes of rotation intersect.

Synchropters, like helicopters with coaxial, longitudinal and transverse designs, do not have a tail rotor. The rotors rotate synchronously in opposite directions, and their shafts are connected to each other by a rigid mechanical system. This is guaranteed to prevent blade collisions under different flight modes and speeds. Synchropters were first invented by the Germans during the Second World War, but mass production was carried out in the USA since 1945 by the Kaman company.

The direction of flight of the synchropter is controlled solely by changing the angle of the propeller blades. In this case, due to the crossing of the planes of rotation of the propellers, and therefore the addition of lifting forces at the crossing points, a moment of pitching up occurs, that is, raising the bow. This moment is compensated by the control system. In general, it is believed that the synchroter is easier to control in hover mode and at speeds above 60 kilometers per hour.

The advantages of such helicopters include fuel savings due to the elimination of the tail rotor and the possibility of more compact placement of units. In addition, synchropters are characterized by most of the positive qualities of coaxial helicopters. The disadvantages include the extraordinary complexity of the mechanical rigid connection of the screw shafts and the swashplate control system. In general, this makes the helicopter more expensive compared to the classic design.

Multicopter

The development of multicopters began almost simultaneously with work on the helicopter. It is for this reason that the first helicopter to perform a controlled takeoff and landing was the Botezata quadcopter in 1922. Multicopters include machines that usually have an even number of rotors, and there should be more than two. In production helicopters today, the multicopter design is not used, but it is extremely popular among manufacturers of small unmanned vehicles.

The fact is that multicopters use propellers with a constant pitch, and each of them is driven by its own engine. The reactive torque is compensated by rotating the screws in different directions - half rotates clockwise, and the other half, located diagonally, in the opposite direction. This allows you to abandon the swashplate and, in general, significantly simplify the control of the device.

To take off a multicopter, the rotation speed of all propellers increases equally; to fly to the side, the rotation of the propellers on one half of the device accelerates, and on the other, it slows down. The multicopter is rotated by slowing down the rotation, for example, of screws rotating clockwise or vice versa. This simplicity of design and control was the main impetus for the creation of the Botezata quadcopter, but the subsequent invention of the tail rotor and swashplate practically slowed down work on multicopters.

The reason why there are no multicopters designed to transport people today is flight safety. The fact is that, unlike all other helicopters, machines with multiple rotors cannot make an emergency landing in autorotation mode. If all engines fail, the multicopter becomes uncontrollable. However, the likelihood of such an event is low, but the lack of autorotation mode is the main obstacle to passing flight safety certification.

However, the German company e-volo is currently developing a multicopter with 18 rotors. This helicopter is designed to carry two passengers. It is expected to make its first flight in the next few months. According to the designers' calculations, the prototype vehicle will be able to stay in the air for no more than half an hour, but this figure is planned to be increased to at least 60 minutes.

It should also be noted that in addition to helicopters with an even number of propellers, there are also multicopter designs with three and five propellers. They have one of the engines located on a platform that can be tilted to the sides. Thanks to this, the flight direction is controlled. However, in such a scheme it becomes more difficult to suppress the reactive torque, since two out of three or three out of five screws always rotate in the same direction. To level out the reaction torque, some of the propellers rotate faster, and this creates unnecessary lateral force.

Speed ​​scheme

Today, the most promising in helicopter technology is the high-speed scheme, which allows helicopters to fly at significantly higher speeds than modern machines can. Most often, this scheme is called a combined helicopter. Machines of this type are built in a coaxial design or with a single propeller, but have a small wing that creates additional lift. In addition, helicopters can be equipped with a pusher rotor in the tail or two pullers at the wingtips.

Attack helicopters of the classic AH-64E design are capable of speeds of up to 293 kilometers per hour, and coaxial Ka-52 helicopters - up to 315 kilometers per hour. For comparison, the combined technology demonstrator Airbus Helicopters X3 with two pulling propellers can accelerate to 472 kilometers per hour, and its American competitor with a pusher propeller, the Sikorksy X2, can accelerate to 460 kilometers per hour. The promising high-speed reconnaissance helicopter S-97 Raider will be able to fly at speeds of up to 440 kilometers per hour.

Strictly speaking, combined helicopters do not refer to helicopters, but to another type of rotary-wing aircraft - rotorcraft. The fact is that the driving force of such machines is created not only and not so much by rotors, but by pushing or pulling ones. In addition, both the rotors and the wing are responsible for creating lift. And on high speeds During flight, the controlled overrunning clutch disconnects the rotors from the transmission and the further flight proceeds in the autorotation mode, in which the rotors act, in fact, like an airplane wing.

Currently, several countries around the world are developing high-speed helicopters, which in the future will be able to reach speeds of over 600 kilometers per hour. In addition to Sikorsky and Airbus Helicopters, such work is being carried out by the Russian Kamov and the Mil design bureau (Ka-90/92 and Mi-X1, respectively), as well as the American Piacesky Aircraft. The new hybrid helicopters will be able to combine the flight speed of turboprop aircraft and the vertical takeoff and landing capabilities of conventional helicopters.

Photo: Official U.S. Navy Page / flickr.com