Classification of military aircraft. What types of planes are there? Regional and local

Main components of the aircraft

Airplanes belong to aircraft heavier than air, they are characterized by the aerodynamic principle of flight. Airplanes have lift Y is created due to the energy of the air flow washing the load-bearing surface, which is fixedly fixed relative to the body, and translational movement in a given direction is provided by the thrust of the aircraft's power plant (PS).

Different types of aircraft have the same basic units (components): wing , vertical (VO) and horizontal (GO) plumage , fuselage , power plant (SU) and chassis (Figure 2.1).

Rice. 2.1. Basic aircraft design elements

Airplane wing1 creates lift and provides lateral stability to the aircraft during flight.

often the wing is the power base for housing the landing gear and engines, and its internal volumes are used to accommodate fuel, equipment, various components and assemblies of functional systems.

To improve takeoff and landing characteristics(VPH) of modern aircraft, mechanization means are installed on the wing along the leading and trailing edges. Along the leading edge of the wing are placed slats , and on the back - flaps10 , interceptors12 And aileron-interceptors .

In terms of strength, the wing is a beam of complex structure, the supports of which are the power frames of the fuselage.

Ailerons11 are lateral controls. They provide lateral control of the aircraft.

Depending on the design and flight speed, geometric parameters, structural materials and structural-power scheme, the mass of the wing can be up to 9...14 % from the take-off weight of the aircraft.

Fuselage13 combines the main components of the aircraft into a single whole, i.e. provides closure of the aircraft power circuit.

The internal volume of the fuselage serves to accommodate the crew, passengers, cargo, equipment, mail, luggage, and means of rescuing people in case of emergencies. In the fuselages cargo planes Developed loading and unloading systems and devices for fast and reliable cargo mooring are provided.

The fuselage function of seaplanes is performed by a boat, which allows for takeoff and landing on water.

In terms of strength, the fuselage is a thin-walled beam, the supports of which are the wing spars, with which it is connected through the nodes of the power frames.

the weight of the fuselage structure is 9…15 % from the take-off weight of the aircraft.

Vertical tail5 consists of a fixed part keel4 And rudder (RN) 7 .

Keel 4 provides the aircraft with directional stability in the plane X0Z, and RN - directional controllability relative to the axis 0y.


Trimmer RN 6 ensures the removal of long-term stress from the pedals, for example, in the event of engine failure.

Horizontal tail9 includes a fixed or limitedly movable part ( stabilizer2 ) and the moving part – elevator (RV) 3 .

Stabilizer 2 gives the aircraft longitudinal stability, and the RV 3 - longitudinal controllability. The RV can carry a trimmer 8 to unload the steering column.

The weight of GO and VO structures usually does not exceed 1.3...3 % from the take-off weight of the aircraft.

Chassis airplane 16 refers to take-off and landing devices (TLU), which provide take-off, take-off, landing, run and maneuvering of an aircraft when moving on the ground.

The number of supports and their location relative to center of mass (CM) of an aircraft depends on the landing gear designs and operating features of the aircraft.

The landing gear of the aircraft shown in Fig. 2.1 has two main supports16 and one nose support17 . Each support includes a power rack18 and supporting elements - wheels15 . Each support can have several posts and several wheels.

Most often, the landing gear of an aircraft is made to be retractable in flight, so special compartments are provided in the fuselage to accommodate it. 13. It is possible to clean and place the main landing gear in special gondolas (or engine nacelles), fairings14 .

The landing gear ensures the absorption of kinetic energy of impact during landing and braking energy during the run, taxiing and when maneuvering the aircraft around the airfield.

amphibious aircraft can take off and land both from ground airfields and from the water surface.

Fig.2.2. Amphibious aircraft chassis.

on the body seaplane a wheeled chassis is installed and placed under the wing floats1 ,2 (Fig. 2.2).

The relative weight of the chassis is usually 4...6 % from the take-off weight of the aircraft.

Power point 19 (see Fig. 2.1), ensures the creation of aircraft thrust. It consists of engines, as well as systems and devices that ensure their operation in the conditions of flight and ground operation of the aircraft.

In piston engines, the thrust force is created by the propeller, in turboprop engines - by the propeller and partly by the reaction of gases, in jet engines - by the reaction of gases.

The control system includes: engine mounting units, nacelle, control system, engine input and output devices, fuel and oil systems, engine starting systems, fire and anti-icing systems.

The relative mass of the control unit, depending on the type of engines and their arrangement on the aircraft, can reach 14...18 % from the take-off weight of the aircraft.

2.2. Technical, economic and flight technical
aircraft characteristics

The technical and economic characteristics of the aircraft are:

Relative payload mass:

`m mon = m Mon /m 0

Where m mon - payload mass;

m 0 - take-off weight of the aircraft;

Relative mass of maximum toll load:

`m knmax = m knmah / m 0

Where m knmax mass of maximum payload;

Maximum hourly productivity:

P h = m knmax ∙ v flight

Where v flight - aircraft cruising speed;

Fuel consumption per unit of performance q T

The main flight characteristics of aircraft include:

Maximum cruising speed v cr.max;

Cruise economic speed V to p .ek;

Cruising altitude N to p;

Flight range with maximum paid load L;

Average lift-to-drag ratio TO in flight;

Rate of climb;

Load capacity, which is determined by the mass of passengers, cargo, luggage transported on an airplane at a given flight weight and fuel reserve;

Takeoff and landing characteristics (TLP) of the aircraft.

The main parameters characterizing the flight path are the approach speed - V salary; landing speed - V n;takeoff speed during takeoff - V omp; takeoff run length - l once; landing run length - l n.p.; the maximum value of the lift coefficient in the landing configuration of the wing - WITH y max p;maximum value of the lift coefficient in the take-off configuration of the wing WITH at max vzl

Aircraft classification

Aircraft are classified according to many criteria.

One of the main criteria for classifying aircraft is purpose criterion . this criterion predetermines the flight performance characteristics, geometric parameters, layout and composition of the aircraft’s functional systems.

According to their purpose, aircraft are divided into civilian And military . Both the first and second aircraft are classified depending on the type of tasks performed.

Below we consider the classification of only civil aircraft.

Civil aircraft designed for transporting passengers, mail, cargo, as well as for solving various national economic problems.

Aircraft are divided into passenger , freight , experimental , educational and training , as well as on airplanes target national economic purpose .

Passenger Depending on their flight range and payload capacity, aircraft are divided into:

- long-haul aircraft – flight range L>6000 km;

- medium-haul aircraft - 2500 < L < 6000 км;

- short-haul aircraft - 1000< L < 2500 км;

- aircraft for local airlines (MVL) - L <1000 км.

Long-haul aircraft(Fig. 2.3) with a flight range of more than 6000 km are usually equipped with a propulsion system consisting of four turbofan engines or propfan engines, which improves flight safety in the event of failure of one or two engines.

Medium-haul aircraft(Fig. 2.4, Fig. 2.5) have a control system of two or three engines.

Short haul aircraft(Fig. 2.6) with a flight range of up to 2500 km, they have a control system of two or three engines.

Airplanes of local airlines (LDL) are operated on air routes less than 1000 km long, and their power supply can consist of two, three or even four engines. The increase in the number of engines to four is due to the desire to ensure a high level of flight safety with the high intensity of takeoffs and landings characteristic of international airliners.

International airlines include administrative aircraft, which are designed to carry 4...12 passengers.

Cargo aircraft provide transportation of goods. Depending on their flight range and payload capacity, these aircraft can be classified similarly to passenger aircraft. transportation of goods can be carried out both inside the cargo compartment (Fig. 2.7) and on the external suspension of the fuselage (Fig. 2.8).

Training aircraft provide training and training for flight personnel in educational institutions and civil aviation training centers (Fig. 2.9) Such aircraft are often made with two seats (instructor and trainee)

Experimental aircraft are created to solve specific scientific problems, conduct field research directly in flight, when it is necessary to test put forward hypotheses and design solutions.

Aircraft for national economic purposes Depending on the intended use, they are divided into agricultural, patrol, observation of oil and gas pipelines, forests, coastal zones, road traffic, sanitary, ice reconnaissance, aerial photography, etc.

Along with aircraft specially designed for these purposes, low-capacity MVL aircraft can be converted for target missions.

Rice. 2.7. Cargo plane

In accordance with the Fédération Aéronautique Internationale code, aircraft are divided into classes, for example:

Class A- free balloons;

Class IN- airships;

Class WITH- aircraft, helicopters, seaplanes, etc.;

Class S- space models.

Besides this, class WITH is divided into four groups, depending on the power plant. Also, all civil aircraft are grouped into classes depending on their take-off weight:

First class - 75 t or more;

Second class - 30-75 T;

Third class - 10-30 T;

Fourth grade - up to 10 T.

Classification by aircraft types.

An aircraft is an aircraft maintained in the atmosphere by its interaction with air other than the interaction with air reflected from the earth's surface.

An airplane is a heavier-than-air aircraft for flight in the atmosphere with the help of a power plant that creates thrust and a fixed wing, on which aerodynamic lift is generated when moving in the air.

Aircraft can be classified according to many criteria, but they are interconnected and form a single system of aircraft, which is in constant motion under the influence of many market factors.

Depending on the nature of operation, civil aviation aircraft can be classified into:

1) general aviation aircraft (GA);

2) commercial aviation aircraft.

Aircraft that are in regular operation, that is, in the field of activity of commercial airlines that transport passengers and cargo on a schedule, are classified as commercial aviation. The use of an aircraft for personal or business purposes classifies it as general aviation.

In recent years, there has been an increase in the popularity of general purpose aircraft, as they are capable of performing tasks unusual for commercial aviation - transportation of small cargo, agricultural work, patrolling, pilot training, aviation sports, tourism, etc., and also significantly save time for users . The latter is achieved due to the ability to fly unscheduled, the ability to use small airfields for takeoff and landing, and the user does not waste time issuing and registering air tickets and has the ability to choose a direct route to the destination. As a rule, GA aircraft are aircraft with a take-off weight of up to 8,6 t. However, it is also possible to use a larger aircraft.

Depending on the purpose, two main groups of aircraft can be distinguished, regardless of operating conditions - multi-purpose and specialized aircraft.

Multi-role aircraft are designed to solve a wide range of missions. This is achieved by converting and re-equipping an aircraft to meet a specific mission with minimal or no design changes. Depending on the ability to take off and land not only on airfields with artificial turf, but also to use the water surface for these purposes, multi-purpose aircraft can be ground-based or amphibious.

Specialized aircraft are focused on performing a single task.

Classification of aircraft is possible depending on the characteristics of the aerodynamic design, which is understood as a certain system of load-bearing surfaces of the aircraft. The system of lifting surfaces has main surfaces - wings, which create the bulk of the aerodynamic lift force, and auxiliary surfaces - tail surfaces, designed to stabilize the aircraft and control its flight. The following types of aerodynamic designs are distinguished, in accordance with Figure 2.10.

Figure 2.10 - Aerodynamic designs of aircraft

Aircraft based on individual characteristics of the aerodynamic design are classified primarily by the structural characteristics of the wing, in accordance with Figure 2.11.

Also, aircraft can be classified according to the fuselage scheme - depending on the type of power elements, depending on the design characteristics of the landing gear - which are distinguished by the location of the landing gear, by the power plant - depending on the type of engine, the number of engines and their location.

Figure 2.11 - Structural characteristics of an aircraft wing

Of particular importance for civil aviation is the classification of aircraft depending on their flight range, in accordance with Figure 2.12:

Short-haul (major airline) aircraft, with a flight range of - 1000-2500 km;

Medium long-haul aircraft, with a flight range - 2500-6000 km;

Long-haul aircraft with a flight range of over 6000 km.

Figure 2.12 - Aircraft classification
depending on range zones

Representative of business aviation.

Long gone are the days when an airplane (later an airplane) was just a plane. As they say in itself and for itself. People's needs change, technological progress does not stand still at all, and planes practically do not fly for fun, extreme sports, or anything like that. Although, of course, in fairness it should be said that this also occurs. However, the mercantile-useful use of aviation still prevails. And since in the modern world there are already quite a lot of areas of its application, its diversity is quite large.

So, . They are determined in accordance with regulatory documents. There is such a serious (by appearance :-)) document: the Air Code of the Russian Federation. So it defines that aviation has three types: civil, state And experimental . Civil includes civil, civil commercial and general aviation. With the first two, I think it’s clear, but “general purpose” is all kinds of useful work, such as: agricultural work, medical assistance, police assistance, private and corporate flights, training, etc. Experimental aviation is used to carry out various experimental work and test equipment (including aviation). And the state one is military aviation and state aviation special purpose , such as, for example, the aviation of the Ministry of Emergency Situations or there is also the aviation of the Ministry of Internal Affairs to carry out various special tasks. Interestingly, both government and experimental aircraft can also be used for commercial purposes. This is defined in the above code.

Transportnik AN-12

The well-known passenger Boeing 737

This is how it all sounds officially. And now, without looking at the regulatory documents, I will add something else on my own. With civil aviation, everything is more or less clear. These are passenger, transport and cargo-passenger. Their functions are clear to everyone. And their brightest representatives are, for example, the hard workers TU-154 and Boeing-737, An-12 and Il-76.
As for general aviation, although this name is spelled out in the code, there are other definitions next to it, and sometimes it is not always clear which of them includes the other. We won’t go into this, I’ll just mention a few, or rather their names, that are now used in aviation practice.

Business aviation aircraft cabin interior.

It has existed abroad for quite a long time, but in Russia the so-called business aviation or “Business aviation” in the Anglo-American version. These are usually special aircraft (and, of course, their technical maintenance complex) with low capacity, but quite a lot of comfort :-). They are used for individual and corporate flights and, of course, for providing special services. One of the representatives is the Gulfstream G500.

Airplane Yak-52.

Sports Yak-55M

Sports SU-26M.

Honored AN-2

Further, we can distinguish sports aviation and initial training aviation. In other words, the Aero Club one. These are the airplanes and helicopters on which people learn to fly and further improve their flying skills. In Russia, the system of flying clubs was thoroughly destroyed during the process of revolutionary transformations, from perestroika onwards. But something remains and is now even slowly developing. Our representatives of this type of aviation are mainly the Yak-52, Yak-55, SU-26 and the hard worker Yak-18T. Of course, the AN-2 is also used in this system (mainly for auxiliary purposes, for example, for the removal of paratroopers). Abroad, these are most often the Cessna-172, Piper PA-28 Warrior and Robinson R-22.

Piper PA-28 Warrior

Robinson R-22 helicopter

Naturally, all these aircraft are also used for commercial cargo and passenger purposes. After all, flying clubs are mostly private. And just one plane can be privately owned. Then a person who has a private pilot's license can fly it for his own purposes (even just for fun :-)). But this, however, applies more to the USA and Western countries. In Russia, there is neither a legislative framework nor technical and financial capabilities for this yet. What a pity... It would be nice to have such a “family airplane” and fly on it on weekends to visit another city :-).

In connection with the above, it must be said that in general, such a concept as small aircraft . This concept is not clearly defined by law (although, in my opinion, it is closest to general aviation), but usually small aircraft have a low take-off weight (usually up to 9000 kg) and carry no more than 18 passengers. Of course, small aviation also includes the entire service infrastructure, i.e. airfields, air traffic control systems, maintenance. There are now more and more small aircraft around the world. In the USA, for example, there are already more than 280 thousand of them registered. Accordingly, the number of runways and sites is growing. According to statistics, more than 80% of everything that flies in the world operates in small aviation. That is, small aviation is conquering the world :-). That's how things are. But let's leave it alone and get back to serious things :-).

Although I, in fact, have already listed everything. But it is definitely worth saying that some people stand apart from this division military aviation(even though it is part of the state). The fact is that she herself also has species, and in addition, some of them are also divided into genera. Quite an interesting division and this is the topic of another article, or rather the second part of the article about types of aviation.

Photos are clickable.



Plan:

    Introduction
  • 1 Aircraft classification
    • 1.1 Intended use
    • 1.2 By take-off weight
    • 1.3 By type and number of engines
    • 1.4 According to the layout diagram
    • 1.5 By flight speed
    • 1.6 By type of planting organs
    • 1.7 By type of takeoff and landing
    • 1.8 By type of traction sources
    • 1.9 In terms of reliability
    • 1.10 By control method
  • 2 Aircraft design
  • 3 Aircraft history
  • 4 Interesting facts
  • Literature

Introduction

Airplane(aka airplane) - an aircraft with an aerodynamic method of generating lift using an engine and fixed wings (wings) and used for flights in the Earth's atmosphere. (Later in this article the term airplane interpreted only in this sense.)

The aircraft is capable of moving at high speeds, using the lift of the wing to maintain itself in the air. A fixed wing distinguishes an airplane from an ornithopter (machine) and a helicopter, and the presence of an engine distinguishes it from a glider. What distinguishes an airplane from an airship is the aerodynamic method of creating lift - the airplane wing creates lift in the oncoming air flow.

The above definition is “classical” and relevant for aircraft that existed at the dawn of aviation. In relation to modern and promising developments in aviation technology (integrated and hypersonic aerodynamic configurations, the use of variable thrust vector, etc.), the concept of “aircraft” requires clarification: Airplane- an aircraft for flights in the atmosphere (and outer space (for example, orbital aircraft)), using the aerodynamic lift of the airframe to keep itself in the air (when flying within the atmosphere) and the thrust of the power (propulsion) installation for maneuvering and compensating for losses of full mechanical energy on drag.


1. Aircraft classification

The classification of aircraft can be given according to various criteria - by purpose, by design features, by engine type, by flight performance parameters, etc., etc.

1.1. By purpose


1.2. By take-off weight

Light aircraft MAI-223

  • 1st class (75 tons or more)
  • 2nd class (from 30 to 75 tons)
  • 3rd class (from 10 to 30 tons)
  • 4th class (up to 10 tons)
  • light-engine
  • ultra-light (up to 495 kg)

The class of an aircraft is associated with the class of an airfield capable of receiving an aircraft of this type.


1.3. By type and number of engines

Cross-section of a star engine

Compressor of a turbojet engine (TRE)

  • By type of power plant:
    • piston (PD) (An-2)
    • turboprop (TVD) (An-24)
    • turbojet (turbojet) (Tu-154)
    • with rocket engines
    • with a combined power unit (CPU)
  • By number of engines:
    • single-engine (An-2)
    • twin-engine (An-24)
    • three-engine (Tu-154)
    • four-engine (An-124 “Ruslan”)
    • five-engine (He-111Z)
    • six-engine (An-225 "Mriya")
    • seven-engine (K-7)
    • eight-engine (ANT-20, Boeing B-52)
    • ten-engine (Convair B-36J)
    • twelve-engine (Dornier Do X)

1.4. According to the layout diagram

Classification according to this criterion is the most multivariate). Some of the main options are offered:

  • By number of wings:
    • monoplanes
    • one-and-a-half plans
    • biplanes
    • triplanes
    • polyplanes
  • By wing location (for monoplanes):
    • high-wing aircraft
    • mid-shots
    • low-wing aircraft
    • parasol
  • By tail position:
    • normal aerodynamic design (tail at the rear)
    • flying wing (tailless)
    • tailless
    • "duck" type (front plumage);
  • By fuselage type and size:
    • single-fuselage;
      • narrow-body;
      • wide-body;
    • two-beam scheme (“frame”);
    • fuselageless (“flying wing”).
    • Double deck aircraft
  • By chassis type:
    • Land;
      • with wheeled chassis;
        • with tail support;
        • with front support;
        • bicycle type support;
      • with ski chassis;
      • with tracked chassis;
    • Seaplanes;
      • amphibians;
      • float;
      • "flying boats"

1.5. By flight speed

  • subsonic (up to Mach 0.7-0.8)
  • transonic (from 0.7-0.8 to 1.2 M)
  • supersonic (from 1.2 to 5 M)
  • hypersonic (over 5 M)

1.6. By type of planting organs

  • land
  • ship
  • seaplanes
  • Flying submarine

1.7. By type of takeoff and landing

  • vertical (GDP)
  • short (KVP)
  • normal takeoff and landing

1.8. By type of traction sources

  • screw
  • reactive

1.9. In terms of reliability

  • experimental
  • experienced
  • serial

1.10. By control method

  • piloted
  • unmanned

2. Aircraft design

Main elements of the aircraft:

  • Wing - creates the lifting force necessary for flight during the forward movement of the aircraft.
  • The fuselage is the “body” of the aircraft.
  • The tail is the load-bearing surfaces designed to ensure stability, controllability and balancing of the aircraft.
  • Landing gear is the take-off and landing device of an aircraft.
  • Power plants - create the necessary traction.
  • On-board equipment systems are various equipment that allows you to fly under any conditions.

3. History of aircraft

Viktor Vasnetsov “Flying Carpet”, 1880

Vimana flying machines are described in ancient Indian literature. There are also references to flying machines in the folklore of different nations (flying carpet, stupa with Baba Yaga).

The first attempts to build an airplane were made back in the 19th century. The first life-size aircraft built in 1882 and patented is the aircraft of A. F. Mozhaisky. In addition, aircraft with steam engines were built by Ader and Maxim. However, none of these structures were able to take off. The reasons for this were: too high take-off weight and low specific power of the engines (steam engines), lack of theory of flight and control, theory of strength and aerodynamic calculations. In this regard, aircraft were built “at random”, “by eye”, despite the engineering experience of many aviation pioneers.

The first aircraft that was able to take off the ground independently and perform controlled horizontal flight was Flyer 1, built by the brothers Orville and Wilbur Wright in the USA. The first flight of an airplane in history was carried out on December 17, 1903. The Flyer stayed in the air for 59 seconds and flew 260 meters. The Wrights' brainchild was officially recognized as the world's first heavier-than-air vehicle to make a manned flight using an engine.

Their aircraft was a canard-type biplane - the pilot was located on the lower wing, the rudder was at the rear, and the elevator was at the front. The double-spar wings were covered with thin unbleached muslin. The Flyer's engine was four-stroke, with a starting power of 16 horsepower and weighed only (or as much as, if assessed from a modern point of view) 80 kilograms.

The device had two wooden screws. Instead of a wheeled chassis, the Wrights used a launch catapult consisting of a pyramidal tower and a wooden guide rail. The catapult was driven by a falling massive load connected to the aircraft by a cable through a system of special blocks.

In Russia, the practical development of aviation was delayed due to the government's focus on creating aeronautical aircraft. Based on the example of Germany, the Russian military leadership relied on the development of airships and balloons for the army and did not timely appreciate the potential capabilities of the new invention - the airplane.

The story of V.V. Tatarinov’s “Aeromobile” also played its negative role in relation to heavier-than-air aircraft. In 1909, the inventor received 50 thousand rubles from the War Ministry to build a helicopter. In addition, there were many donations from individuals. Those who could not help financially offered their labor free of charge to implement the inventor's plan. Russia had high hopes for this domestic invention. But the idea ended in complete failure. Tatarinov’s experience and knowledge did not match the complexity of the task, and a lot of money was thrown away. This incident negatively affected the fate of many interesting aviation projects - Russian inventors could no longer obtain government subsidies.

In 1909, the Russian government finally showed interest in airplanes. It was decided to reject the Wright brothers' offer to buy their invention and build the aircraft on their own. Aeronautical officers M.A. Agapov, B.V. Golubev, B.F. Gebauer and A.I. Shabsky were entrusted with designing the aircraft. We decided to build three-seater aircraft of various types, so that later we could choose the most successful one. None of the designers not only flew airplanes, but even saw them in real life. Therefore, it is not surprising that planes crashed while still running on the ground.

"Kudashev-1" - the first Russian flying aircraft

Winged Benz. A Russian airplane in the back of a truck on the Caucasian front of the First World War. 1916

The first successes of Russian aviation date back to 1910. On June 4, Prince Alexander Kudashev, a professor at the Kyiv Polytechnic Institute, flew several tens of meters in a biplane aircraft of his own design.

On June 16, the young Kiev aircraft designer Igor Sikorsky took his plane into the air for the first time, and three days later, engineer Yakov Gakkel’s plane, which was unusual for that time in the design of a biplane with a fuselage (bimonoplane), took off.


4. Interesting facts

  • In 1901, two professors from one of the US universities “proved” that a heavier-than-air aircraft would fundamentally never be able to get off the ground, that it was like a “perpetuum mobile.” The US Senate prohibited the Pentagon from funding developments, but three years later the Wright brothers' plane took off, which paved the way for aviation developments.
  • The X-43A hypersonic aircraft is the fastest aircraft in the world. The X-43A recently set a new speed record of 11,230 km/h, thereby exceeding the speed of sound by 9.6 times. By comparison, fighter jets fly at or only twice the speed of sound.

Literature

  • History of aircraft designs in the USSR - Vadim Borisovich Shavrov. History of aircraft designs in the USSR 1938-1950 // M. Mashinostroenie, 1994. ISBN 5-217-00477-0.
  • "THE THORNY ROAD TO NOWHERE. Notes of an aircraft designer." L.L. Selyakov

Main components of the aircraft

Airplanes are heavier-than-air aircraft and are characterized by an aerodynamic flight principle. Airplanes have lift Y is created due to the energy of the air flow washing the load-bearing surface, which is fixedly fixed relative to the body, and translational movement in a given direction is provided by the thrust of the aircraft's power plant (PS).

Different types of aircraft have the same basic units (components): wing , vertical (VO) and horizontal (GO) plumage , fuselage , power plant (SU) and chassis (Figure 2.1).

Rice. 2.1. Basic aircraft design elements

Airplane wing1 creates lift and provides lateral stability to the aircraft during flight.

often the wing is the power base for housing the landing gear and engines, and its internal volumes are used to accommodate fuel, equipment, various components and assemblies of functional systems.

To improve takeoff and landing characteristics(VPH) of modern aircraft, mechanization means are installed on the wing along the leading and trailing edges. Along the leading edge of the wing are placed slats , and on the back - flaps10 , interceptors12 And aileron-interceptors .

In terms of strength, the wing is a beam of complex structure, the supports of which are the power frames of the fuselage.

Ailerons11 are lateral controls. They provide lateral control of the aircraft.

Depending on the design and flight speed, geometric parameters, structural materials and structural-power scheme, the mass of the wing can be up to 9...14 % from the take-off weight of the aircraft.

Fuselage13 combines the main components of the aircraft into a single whole, i.e. provides closure of the aircraft power circuit.

The internal volume of the fuselage serves to accommodate the crew, passengers, cargo, equipment, mail, luggage, and means of rescuing people in case of emergencies. The fuselages of cargo aircraft are equipped with developed loading and unloading systems and devices for fast and reliable cargo mooring.

The fuselage function of seaplanes is performed by a boat, which allows for takeoff and landing on water.

In terms of strength, the fuselage is a thin-walled beam, the supports of which are the wing spars, with which it is connected through the nodes of the power frames.

the weight of the fuselage structure is 9…15 % from the take-off weight of the aircraft.

Vertical tail5 consists of a fixed part keel4 And rudder (RN) 7 .

Keel 4 provides the aircraft with directional stability in the plane X0Z, and RN - directional controllability relative to the axis 0y.

Trimmer RN 6 ensures the removal of long-term stress from the pedals, for example, in the event of engine failure.

Horizontal tail9 includes a fixed or limitedly movable part ( stabilizer2 ) and the moving part – elevator (RV) 3 .

Stabilizer 2 gives the aircraft longitudinal stability, and the RV 3 - longitudinal controllability. The RV can carry a trimmer 8 to unload the steering column.

The weight of GO and VO structures usually does not exceed 1.3...3 % from the take-off weight of the aircraft.

Chassis airplane 16 refers to take-off and landing devices (TLU), which provide take-off, take-off, landing, run and maneuvering of an aircraft when moving on the ground.

The number of supports and their location relative to center of mass (CM) of an aircraft depends on the landing gear designs and operating features of the aircraft.

The landing gear of the aircraft shown in Fig. 2.1 has two main supports16 and one nose support17 . Each support includes a power rack18 and supporting elements - wheels15 . Each support can have several posts and several wheels.

Most often, the landing gear of an aircraft is made to be retractable in flight, so special compartments are provided in the fuselage to accommodate it. 13. It is possible to clean and place the main landing gear in special gondolas (or engine nacelles), fairings14 .

The landing gear ensures the absorption of kinetic energy of impact during landing and braking energy during the run, taxiing and when maneuvering the aircraft around the airfield.

amphibious aircraft can take off and land both from ground airfields and from the water surface.

Fig.2.2. Amphibious aircraft chassis.

on the body seaplane a wheeled chassis is installed and placed under the wing floats1 ,2 (Fig. 2.2).

The relative weight of the chassis is usually 4...6 % from the take-off weight of the aircraft.

Power point 19 (see Fig. 2.1), ensures the creation of aircraft thrust. It consists of engines, as well as systems and devices that ensure their operation in the conditions of flight and ground operation of the aircraft.

In piston engines, the thrust force is created by the propeller, in turboprop engines - by the propeller and partly by the reaction of gases, in jet engines - by the reaction of gases.

The control system includes: engine mounting units, nacelle, control system, engine input and output devices, fuel and oil systems, engine starting systems, fire and anti-icing systems.

The relative mass of the control unit, depending on the type of engines and their arrangement on the aircraft, can reach 14...18 % from the take-off weight of the aircraft.

2.2. Technical, economic and flight technical
aircraft characteristics

The technical and economic characteristics of the aircraft are:

Relative payload mass:

`m mon = m Mon /m 0

Where m mon - payload mass;

m 0 - take-off weight of the aircraft;

Relative mass of maximum toll load:

`m knmax = m knmah / m 0

Where m knmax mass of maximum payload;

Maximum hourly productivity:

P h = m knmax ∙ v flight

Where v flight - aircraft cruising speed;

Fuel consumption per unit of performance q T

The main flight characteristics of aircraft include:

Maximum cruising speed v cr.max;

Cruise economic speed V to p .ek;

Cruising altitude N to p;

Flight range with maximum paid load L;

Average lift-to-drag ratio TO in flight;

Rate of climb;

Load capacity, which is determined by the mass of passengers, cargo, luggage transported on an airplane at a given flight weight and fuel reserve;

Takeoff and landing characteristics (TLP) of the aircraft.

The main parameters characterizing the flight path are the approach speed - V salary; landing speed - V n;takeoff speed during takeoff - V omp; takeoff run length - l once; landing run length - l n.p.; the maximum value of the lift coefficient in the landing configuration of the wing - WITH y max p;maximum value of the lift coefficient in the take-off configuration of the wing WITH at max vzl

Aircraft classification

Aircraft are classified according to many criteria.

One of the main criteria for classifying aircraft is purpose criterion . this criterion predetermines the flight performance characteristics, geometric parameters, layout and composition of the aircraft’s functional systems.

According to their purpose, aircraft are divided into civilian And military . Both the first and second aircraft are classified depending on the type of tasks performed.

Below we consider the classification of only civil aircraft.

Civil aircraft designed for transporting passengers, mail, cargo, as well as for solving various national economic problems.

Aircraft are divided into passenger , freight , experimental , educational and training , as well as on airplanes target national economic purpose .

Passenger Depending on their flight range and payload capacity, aircraft are divided into:

- long-haul aircraft – flight range L>6000 km;

- medium-haul aircraft - 2500 < L < 6000 км;

- short-haul aircraft - 1000< L < 2500 км;

- aircraft for local airlines (MVL) - L <1000 км.

Long-haul aircraft(Fig. 2.3) with a flight range of more than 6000 km are usually equipped with a propulsion system consisting of four turbofan engines or propfan engines, which improves flight safety in the event of failure of one or two engines.

Medium-haul aircraft(Fig. 2.4, Fig. 2.5) have a control system of two or three engines.

Short haul aircraft(Fig. 2.6) with a flight range of up to 2500 km, they have a control system of two or three engines.

Airplanes of local airlines (LDL) are operated on air routes less than 1000 km long, and their power supply can consist of two, three or even four engines. The increase in the number of engines to four is due to the desire to ensure a high level of flight safety with the high intensity of takeoffs and landings characteristic of international airliners.

International airlines include administrative aircraft, which are designed to carry 4...12 passengers.

Cargo aircraft provide transportation of goods. Depending on their flight range and payload capacity, these aircraft can be classified similarly to passenger aircraft. transportation of goods can be carried out both inside the cargo compartment (Fig. 2.7) and on the external suspension of the fuselage (Fig. 2.8).

Training aircraft provide training and training for flight personnel in educational institutions and civil aviation training centers (Fig. 2.9) Such aircraft are often made with two seats (instructor and trainee)

Experimental aircraft are created to solve specific scientific problems, conduct field research directly in flight, when it is necessary to test put forward hypotheses and design solutions.

Aircraft for national economic purposes Depending on the intended use, they are divided into agricultural, patrol, observation of oil and gas pipelines, forests, coastal zones, road traffic, sanitary, ice reconnaissance, aerial photography, etc.

Along with aircraft specially designed for these purposes, low-capacity MVL aircraft can be converted for target missions.

Rice. 2.7. Cargo plane

Rice. 2.10
Rice. 2.9
Fig.2.8

Rice. 2.8. Transportation of goods on an external sling

Rice. 2.9. Training aircraft

Rice. 2.10. Aircraft for national economic purposes

Aerodynamic layout The aircraft is characterized by the number, external shape of the load-bearing surfaces and the relative position of the wing, tail and fuselage.

The classification of aerodynamic configurations is based on two criteria:

- wing shape ;

- plumage arrangement I.

In accordance with the first feature, six types of aerodynamic configurations are distinguished:

- with straight and trapezoidal wings;

- with a swept wing;

- with a delta wing;

- with a straight wing of low aspect ratio;

- with an annular wing;

- with round wing.

For modern civil aircraft, the first two and partially the third type of aerodynamic configurations are practically used.

According to the second type of classification, the following three options for aerodynamic configurations of aircraft are distinguished:

Normal (classical) scheme;

Duck patterns;

Tailless scheme.

A variation of the “tailless” scheme is the “flying wing” scheme.

Aircraft normal scheme (see Fig. 2.5, 2.6) have a GO located behind the wing. This scheme has become widespread on civil aviation aircraft.

The main advantages of the normal scheme:

Possibility of effective use of wing mechanization;

Easy provision of balancing of the aircraft with the flaps extended;

Reducing the length of the forward fuselage. This improves the pilot's visibility and reduces the airspace area, since the shortened forward part of the fuselage causes the appearance of a smaller destabilizing travel moment;

The possibility of reducing the areas of the VO and GO, since the shoulders of the GO and GO are significantly larger than those of other schemes.

Disadvantages of the normal scheme:

GO creates negative lift in almost all flight modes. This leads to a decrease in the aircraft's lift. Especially during transitional flight conditions during takeoff and landing;

The GO is located in a disturbed air flow behind the wing, which negatively affects its operation.

To remove the GO from the “aerodynamic shadow” of the wing or from the “following stream” of the flaps during transitional flight conditions, it is shifted relative to the wing in height (Fig. 2.11, a), placed in the middle of the keel (Fig. 2.11; b) or on the top of the keel (Fig. 2.11, c).

Rice. 2.12
Rice. 2.11

Rice. 2.11 Horizontal tail layouts

A. VO., shifted relative to the wing in height;

b. VO is located in the middle of the keel (cruciform tail);

V. T-tail;

g. v - shaped tail.

In aircraft manufacturing practice, there are known cases of using a combined, so-called v-tail (Fig. 2.12). the functions of GO and VO in this case are performed by two surfaces spaced at an angle relative to each other. The rudders placed on these surfaces, when simultaneously deflected up and down, work as a rotary control, and when one rudder is deflected up and the other down, directional control of the aircraft is achieved.

Quite often, two-fin and even three-fin aircraft can be used on airplanes.

When the aircraft is aerodynamically configured according to duck pattern on GO they are placed in front of the wing on the forward part of the fuselage (Fig. 2.13)

The advantages of the "duck" scheme are:

Placement of GO in an undisturbed air flow;

The possibility of reducing the size of the wing, since the GO becomes load-bearing, i.e. participates in creating aircraft lift;

Fairly easy parrying of the resulting diving moment when the wing mechanization is deflected by deflecting the GO;

Rice. 2.13 Aircraft canard layout

The increase in the GO shoulder is more than 30% than that of the normal design, which makes it possible to reduce the wing area;

When large angles of attack are reached, flow stall on the GO occurs earlier than on the wing, which practically eliminates the danger of the aircraft reaching supercritical angles of attack and stalling into a tailspin.

In an aircraft made according to the "canard" configuration, the focus position shifts back when moving from M<1 к М>1 is less than that of aircraft with a normal design, so the increase in the degree of longitudinal stability is observed to a lesser extent.

The disadvantages of this scheme are:

Reduced wing load-bearing capacity by 10-15 % due to the flow bevel from the GO;

A relatively small airfoil arm, leading to an increase in airfoil area, and sometimes to the installation of two fins to increase directional stability. This compensates for the destabilizing moment created by the elongated forward fuselage.

Tailless scheme characterized by the absence of GO (see Fig. 1.13), while the functions of GO are transferred to the wing. Airplanes made according to this design may not have a fuselage, in which case they are called a “flying wing”. Such aircraft are characterized by minimal drag.

The tailless scheme has the following advantages:

Since such aircraft use delta wings, with large side rib sizes it is possible to reduce the relative thickness of the profile, ensuring rational use of the wing volume to accommodate fuel;

The absence of GO loads makes it possible to lighten the rear fuselage;

The cost and weight of the airframe are reduced, since there is no GO; for the same reason, the frictional resistance of the aircraft is reduced due to a decrease in the area of ​​the surface flown around by the air flow;

The significant geometric dimensions of the side rib make it possible to create the effect of an “air cushion” during aircraft landing;

Since the “tailless” design uses double-swept wings, during takeoff there is a significant increase in the lift coefficient.

Among the disadvantages of this scheme, the most significant are:

Inability to fully utilize the wing's load-bearing capacity during landing;

A decrease in the ceiling of the aircraft due to a decrease in aerodynamic quality, which is explained by keeping the elevons in the upper deflected position to achieve the highest angle of attack of the wing;

The difficulty, and sometimes the impossibility, of balancing the aircraft with the flaps extended;

It is difficult to ensure the directional stability of the aircraft due to the small airfoil arm, so sometimes three fins are installed (see Fig. 1.13).

In the practice of experimental aircraft construction, you can find options with a combination of basic schemes in one aircraft.

An option is possible when two GOs are used on an airplane - one in front of the wing and the second behind it. When implementing the “tandem” scheme, the aircraft has a wing and GO that are almost comparable in area. The "tandem" configuration can be considered as intermediate between the normal configuration and the "canard" configuration, due to which the operational range of alignments is expanded with relatively small losses in aerodynamic quality for balancing the aircraft.

The main design features by which aircraft are classified are:

Number and arrangement of wings;

Fuselage type;

Type of engines, number and placement on the aircraft;

Landing gear diagram, characterized by the number of supports and their relative position relative to the aircraft CM.

Depending on the number of wings, monoplanes and biplanes are distinguished.

Scheme monoplane dominates in aircraft construction, and most aircraft are made precisely according to this design, which is due to the lower drag of a monoplane and the possibility of increasing flight speeds.

Airplane diagrams "biplane" (Fig. 2.16) are distinguished by high
maneuverability, but they are slow-moving, so this scheme is implemented for special-purpose aircraft, for example, for agricultural ones.

Fig 2. 16 Biplane aircraft

Depending on the location of the wing relative to the fuselage, aircraft can be designed according to the “low-wing” (Fig. 2.17, a), “mid-wing” (Fig. 2.17, b) and “high-wing” (Fig. 2.17, c) schemes.

Fig.2.17. Various wing layouts

Scheme "low-wing" the least advantageous in aerodynamic terms, since in the area where the wing meets the fuselage, the smoothness of the flow is disrupted and additional drag arises due to the interference of the wing-fuselage system. This disadvantage can be significantly reduced by installing fairings, eliminating the diffuser effect.

Placing the gas turbine engine in the root part of the wing allows the use
ejector effect from the engine jet, which is called active fairing.

A low-wing aircraft has a higher position of the lower contour of the fuselage above the ground surface. This is due to the need to prevent the tip of the wing from touching the runway surface during a banked landing, as well as to ensure the safe operation of the control system when placing engines on the wing. In this case, the process of unloading and loading cargo, luggage, as well as boarding and disembarking passengers becomes more complicated. This disadvantage can be avoided if the aircraft landing gear is equipped with a “squat” mechanism.

The “low-wing” configuration is most often used for passenger aircraft, since it provides greater safety compared to other options during an emergency landing on ground and water. During an emergency landing on the ground with the landing gear retracted, the wing absorbs the impact energy, protecting the passenger cabin. When landing on water, the aircraft is immersed in water up to the wing, which gives the fuselage additional buoyancy and simplifies the organization of work related to the evacuation of passengers.

An important advantage of the “low-wing” design is the smallest weight of the structure, since the main landing gear is most often associated with the wing and their dimensions and weight are smaller than those of a high-wing. In comparison with a high-wing aircraft, which has a landing gear on the fuselage, a low-wing aircraft has less weight, since it does not require weighting the fuselage associated with attaching the main landing gear to it.

A low-wing aircraft with the main supports on the wing retains the basic rule: the aircraft is supported by a load-bearing surface. This rule is observed in all operating modes, both in flight and during takeoff and landing. In the latter case, the wing rests on the landing gear during the run and take-off run. Thanks to this, it is possible to unify the power circuit, which determines the paths for transmitting maximum loads, and reduce the weight of the aircraft structure as a whole. The considered advantages became the reason for the dominant position of the “low-wing” design on passenger aircraft.

Scheme "mid-ground" (Fig. 2. 17, b) is most often not used for passenger and cargo aircraft, since the wing caisson (its power part) cannot be placed in the passenger or cargo cabin.

With the increase in take-off weights and aircraft parameters, it becomes possible to bring the wing layout of wide-body aircraft closer to a mid-wing one. In this case, the wing is raised to the level of the floor of the passenger cabin or cargo compartment, as is done on the A-300, Boeing-747, Il-96, etc. Thanks to this solution, the aerodynamic characteristics can be significantly improved.

In its pure form, the “mid-plane” design can be implemented on double-deck aircraft, where the wing practically does not interfere with the use of fuselage volumes to accommodate passenger cabins, cargo spaces and equipment.

The “high-wing” design (Fig. 2.17, c) is widely used for cargo aircraft, and is also used on international airliners. In this case, it is possible to obtain the shortest distance from the lower contour of the fuselage to the runway surface, since the high wing does not affect the choice of fuselage height relative to the ground.

When using the scheme "high-wing" it becomes possible to freely maneuver special vehicles during aircraft maintenance.

The transport efficiency of cargo aircraft is increased due to the lowest position of the cargo cabin floor, which allows for quick and easy loading and unloading of large cargo, self-propelled equipment, various modules, etc.

The service life of the engines increases, since they are located at a considerable distance from the ground and the likelihood of solid particles from entering the air intakes from the runway surface is sharply reduced.

The noted advantages of the high-wing aircraft explain the dominant position that this design occupied on transport aircraft in the domestic (An-22, An-124, An-225), foreign (C-141, C-5A, C-17 (USA), etc. .) practice.

The “high-wing” design easily provides a standardized safe distance from the runway surface to the end of the propeller blade or the lower contour of the gas turbine engine air intake. This explains the fairly frequent use of this scheme on international passenger aircraft (An-28 (Ukraine), F-27 (Holland), Short-360 (England), ATR 42, ATR-72 (France-Italy)).

The undoubted advantage of the “high-wing” scheme is the higher value WITH at max due to the preservation of a completely or partially aerodynamically clean upper surface of the wing above the fuselage, greater efficiency of the wing mechanization due to the reduction of the end effect on the flaps, since the side of the fuselage and the engine nacelle play the role of end “washers”.

However, the large mass of the airframe compared to other designs negatively affects either the payload or the fuel reserve and flight range. The weight of the airframe structure is explained by:

The need to increase the area of ​​the air defense by 15-20 % due to part of it falling into the shading zone from the wing;

An increase in fuselage mass by 15-20 % due to an increase in the number of reinforced frames in the area of ​​fastening the main landing gear, strengthening the structure of the lower contour of the fuselage in case of an emergency landing with the landing gear not extended, and due to strengthening of the pressurized cabin.

When attaching the main landing gear to the fuselage power base, difficulties arise in ensuring the required track.

The small track of the chassis increases the load on one concrete slab,
which may require a higher airfield class to operate the aircraft.

The desire to provide an acceptable track often makes it necessary to increase the overall width of reinforced frames in the area where the main supports are located, to form protruding landing gear nacelles and to increase the midsection of the aircraft, and hence its aerodynamic drag. Statistics show that in this case the drag of the chassis nacelles can reach 10-15 % from the total resistance of the fuselage.

The lower safety of a high-wing aircraft during an emergency landing on water and land sometimes makes it impossible to use this scheme on aircraft with a large passenger capacity, since during an emergency landing on the ground, the mass of the wing together with the engines tends to crush the fuselage and passenger cabin. When landing on water, the fuselage submerges to the lower edges of the wing and the passenger compartment may be under water. In this case, the organization of work to rescue passengers is significantly complicated and evacuation of people is possible only through emergency hatches in the upper part of the fuselage.

By fuselage type airplanes are divided into conventional ones, i.e. made according to a single-fuselage design (Fig. 2.18, a); according to the two-fuselage scheme and the "gondola" scheme (Fig. 2.18, b).

Rice. 2.18 Classification of aircraft by fuselage type

The most widespread is the single-fuselage design, which makes it possible to obtain the most advantageous configuration of the fuselage shape from an aerodynamic point of view, since the drag in this case will be the least compared to other types.

When placing the aircraft's tail not on the fuselage, but on two beams (Fig. 2.18, b) or replacing the fuselage with a gondola, the drag increases. The “gondola” configuration (Fig. 2.18b) is characterized by poor streamlining of the nacelles, which can lead to aircraft instability at high angles of attack. Therefore, the double-beam “gondola” design is rarely implemented in aircraft manufacturing practice, mainly on transport aircraft, where issues of transport efficiency become paramount. An example of such a solution is the Argosy cargo aircraft from Hawker Sidley.

Fig.2.19 Aircraft "Aggie Aircraft"

By engine type distinguish between aircraft with PD, turbojet engine, turbojet engine, etc.

By number of engines Airplanes are divided into one-, two-, three-, four-, and six-engine.

On passenger aircraft, to ensure flight safety, the number of engines should not be less than two. Increasing the number of engines beyond six turns out to be unjustified due to the difficulties associated with ensuring synchronization of the operation of individual control systems and the increase in time and labor intensity of maintenance work.

By engine location subsonic passenger aircraft can be classified into four main groups: engines - on the wing (Fig. 2.20, a), engines - in the root of the wing, engines - on the rear of the fuselage (b) and a mixed version (c) of the engine layout.

When choosing a location for installing engines, they take into account the features of the general layout of the aircraft, operating conditions and ensuring the maximum service life of the engines, strive to obtain the lowest drag of the control system, and minimize air losses in the air intakes.

Thus, on aircraft with three engines, it is advisable to use a mixed layout (Fig. 2.20): two engines under the wing and a third in the rear fuselage or on the fin.

Rice. 2.20 Schemes for installing engines on aircraft

On aircraft with two engines, the control system is placed on the wing or on the rear fuselage.

As the engine bypass ratio increases, its diameter increases. Therefore, when arranging engines under the wing, it is necessary to increase the height of the chassis to ensure a standardized distance from the contour of the engine nacelle to the surface of the earth. This increases the weight of the aircraft structure and creates a number of problems related to passengers, baggage and maintenance. First of all, this applies to international aircraft, which are often operated from airfields that do not have special equipment. At the same time, the effect of unloading the wing in flight due to the placement of engines on it is significantly reduced, since with increasing bypass ratio the specific mass of the turbojet engine decreases.

Figure 2.21 shows two aircraft, the design of which was created on the basis of the same requirements for payload, range, flight characteristics, fuselage midsection, etc. Figure 2.21 shows the difference between the two aircraft in the height of the wing and fuselage relative to the ground.

Fig. 2.21 The influence of engine bypass on the aircraft layout

By type of landing gear They are divided into wheeled, ski, float (for seaplanes), tracked and air-cushioned landing gear.

The wheeled chassis has become predominant, and a float chassis is often used.

According to the chassis diagram aircraft are divided into tricycle and
two-support

The three-support scheme is carried out in two versions: a three-support scheme with a nose support and a three-support scheme with a tail support. In most cases it is used on airplanes three-legged design with bow support. The second version of this scheme is found on light aircraft.

The two-wheel landing gear design is practically not used on civil aircraft.

On heavy, especially transport, aircraft, a multi-support landing gear design has become widespread. For example, the Boeing 747 aircraft uses a five-post landing gear, the An-225 aircraft uses a sixteen-post landing gear, and the passenger Il-86 uses a four-post landing gear.

2.4. REQUIREMENTS FOR THE DESIGN
AIRCRAFT

All requirements for aircraft design are divided into general , mandatory for all airframe components, and special .

General requirements include aerodynamic, strength and rigidity, reliability and survivability of aircraft, operational, maintainability, manufacturability of aircraft, economic and requirements, minimum weight of the airframe structure and functional systems.

Aerodynamic requirements boil down to ensuring that the influence of the aircraft’s shape, its geometric and design parameters correspond to the specified flight data obtained at the lowest energy costs. The implementation of these requirements involves ensuring the minimum resistance of the aircraft, the required characteristics of stability and controllability, high performance characteristics, and cruising flight performance.

Fulfillment of aerodynamic requirements is achieved by choosing the optimal values ​​of the parameters of individual units (parts) of the aircraft, their rational mutual arrangement and a high level of specific parameters.

Strength and rigidity requirements are applied to the airframe frame and its skin, which must withstand all types of operational loads without destruction, while deformations must not lead to changes in the aerodynamic properties of the aircraft, dangerous vibrations must not occur, and significant residual deformations must not appear. The fulfillment of these requirements is ensured by the choice of a rational power structure and cross-sectional areas of the power elements, as well as by the selection of materials.

Reliability and survivability requirements aircraft provide for the development and implementation of constructive measures aimed at ensuring flight safety.

Aircraft reliability represents the ability of a structure to perform its functions while maintaining performance indicators during the established interregulatory period, resource or other unit of measurement of operating time. Reliability characteristics are flight hours per failure, number of failures per flight hour, etc.

The reliability of an aircraft can be increased by selecting reliable structural elements and duplicating them (redundancy).

Aircraft survivability determined by the ability of the structure to perform its functions in the presence of damage. To ensure this requirement, constructive measures are necessary, for example, the use of statically indeterminate power circuits, effective fire protection measures and, mainly, redundancy. These requirements are especially important to ensure a given level flight safety .

Operational Requirements provide for the creation of such
structures that make it possible to provide technical support in a short time
aircraft maintenance with minimal material and technical costs.

The implementation of such requirements is possible by ensuring convenient access to units, standardization and unification of components, assemblies, aircraft parts and connectors, the use of built-in systems for automatic monitoring of the technical condition of aircraft systems and assemblies, effective troubleshooting systems and their elimination, increasing the service life and inter-regulatory service life.

Maintainability requirements predetermine the possibility of quickly and cheaply restoring failed (damaged) parts of the aircraft and promptly maintaining the size of the aircraft engine fleet. The importance of these requirements is increasing due to the constant complication of aircraft and equipment.