The invention of the aircraft made it possible not only to realize the oldest dream of mankind - to conquer the sky, but also to create the fastest mode of transport. Unlike balloons and airships, airplanes are little dependent on the vagaries of the weather, able to travel long distances at high speed. The components of the aircraft consist of the following structural groups: wings, fuselage, plumage, takeoff and landing devices, power plant, control systems, various equipment.
Operating principle
Aircraft - an aircraft (LA) heavier than air, equipped with a power plant. With the help of this crucial part of the aircraft, the thrust necessary for the flight is created - the acting (driving) force, which the motor develops on the ground or in flight (propeller or jet engine). If the screw is located in front of the engine, it is called pulling, and if behind, it is called pushing. Thus, the engine creates a translational movement of the aircraft relative to the environment (air). Accordingly, a wing moves relative to the air, which creates a lifting force as a result of this translational motion. Therefore, the device can stay in the air only if there is a certain flight speed.
What are the parts of the aircraft
The housing consists of the following main parts:
- The fuselage is the main body of the aircraft, connecting the wings (wing), plumage, power system, landing gear and other components into a single whole. The fuselage houses the crew, passengers (in civil aviation), equipment, payload. It can also accommodate (not always) fuel, chassis, motors, etc.
- Engines are used to propel aircraft.
- Wing - a work surface designed to create lift.
- The vertical tail is designed for controllability, balancing and directional stability of the aircraft relative to the vertical axis.
- The horizontal tail is designed for controllability, balancing and directional stability of the aircraft relative to the horizontal axis.
Wings and fuselage
The main part of the aircraft structure is the wing. It creates the conditions for fulfilling the main requirement for the possibility of flight - the presence of lifting force. The wing is attached to the hull (fuselage), which may have one form or another, but if possible with minimal aerodynamic drag. To do this, they provide him with a conveniently streamlined droplet shape.
The front of the aircraft is used to accommodate the cockpit and radar systems. In the back is the so-called tail. It serves to provide controllability during the flight.
Plumage design
Consider the average aircraft, the tail of which is made according to the classical scheme, characteristic of most military and civilian models. In this case, the horizontal plumage will include the fixed part - the stabilizer (from the Latin Stabilis, stable) and the mobile - elevator.
The stabilizer serves to stabilize the aircraft relative to the transverse axis. If the nose of the aircraft drops, then, accordingly, the tail of the fuselage, together with the plumage, rises up. In this case, the air pressure on the upper surface of the stabilizer will increase. The created pressure will return the stabilizer (respectively, and the fuselage) to its original position. When lifting the fuselage nose up, the air flow pressure will increase on the bottom surface of the stabilizer, and it will again return to its original position. This ensures automatic (without pilot intervention) aircraft stability in its longitudinal plane relative to the transverse axis.
The rear of the aircraft also includes vertical tail. Like the horizontal, it consists of the fixed part - the keel, and the moving - rudder. The keel gives stability to the movement of the aircraft relative to its vertical axis in the horizontal plane. The principle of operation of the keel is similar to the action of the stabilizer - when the nose deviates to the left, the keel deviates to the right, the pressure on its right plane increases and returns the keel (and the entire fuselage) to its previous position.
Thus, with respect to two axes, flight stability is ensured by plumage. But one more axis remained - the longitudinal one. To provide automatic stability of movement relative to this axis (in the transverse plane), the glider wing consoles are placed not horizontally, but at a certain angle relative to each other so that the ends of the consoles are tilted up. This placement resembles the letter "V".
Control systems
Steering surfaces are important parts of an aircraft designed to control an aircraft. These include ailerons, rudders and heights. Control is provided with respect to the same three axes in the same three planes.
The elevator is the movable rear of the stabilizer. If the stabilizer consists of two consoles, then accordingly there are two elevators that deviate down or up, both synchronously. With it, the pilot can change the flight altitude of the aircraft.
The rudder is the movable rear of the keel. When it is deflected in one direction or another, an aerodynamic force arises on it, which rotates the plane relative to the vertical axis passing through the center of mass, in the opposite direction from the direction of steering deviation. The rotation occurs until the pilot returns the steering wheel to a neutral (not deviated position), and the aircraft will move in a new direction.
Ailerons (from the French. Aile, wing) - the main parts of the aircraft, which are the moving parts of the wing consoles. Serve to control the aircraft relative to the longitudinal axis (in the transverse plane). Since the wing consoles are two, then there are also two ailerons. They work synchronously, but, unlike elevators, they deviate not in one direction, but in different directions. If one aileron deviates up, then the other down. On the wing console, where the aileron is tilted up, the lift decreases, and where down it increases. And the fuselage of the aircraft rotates in the direction of the raised aileron.
Engines
All aircraft are equipped with a power plant that allows you to develop speed, and, therefore, to ensure the emergence of lift. Engines can be located at the rear of the aircraft (typical for jet aircraft), front (light vehicles) and on wings (civilian aircraft, transporters, bombers).
They are divided into:
- Reactive - turbojet, pulsating, double-circuit, direct-flow.
- Screw - piston (rotor), turboprop.
- Missile - liquid, solid fuel.
Other systems
Of course, other parts of the aircraft are also important. Chassis allow aircraft to take off and land from equipped airfields. There are amphibious aircraft, where instead of the chassis special floats are used - they allow take-off and landing in any place where there is a body of water (sea, river, lake). Known models of light-engine aircraft equipped with skis for use in areas with stable snow cover.
Modern aircraft are crammed with electronic equipment, communication devices and information transfer. Military aircraft use sophisticated weapons systems, target detection and signal suppression.
Classification
By designation, airplanes are divided into two large groups: civilian and military. The main parts of a passenger plane are distinguished by the presence of an equipped passenger cabin, occupying most of the fuselage. A distinctive feature is the portholes on the sides of the case.
Civil aircraft are divided into:
- Passenger - local airlines, long-haul short-range (range less than 2000 km), medium-range (range less than 4000 km), long-distance (range less than 9000 km) and intercontinental (range more than 11 000 km).
- Cargo - light (weight up to 10 tons), medium (weight up to 40 tons) and heavy (weight over 40 tons).
- Special purposes - sanitary, agricultural, reconnaissance (ice reconnaissance, fish exploration), fire-fighting, for aerial photography.
- Training.
Unlike civilian models, parts of a military aircraft do not have a comfortable cabin with portholes. The main part of the fuselage is occupied by weapons systems, equipment for reconnaissance, communications, engines and other units.
According to the purpose of modern military aircraft (given the combat missions that they perform), it can be divided into the following types: fighters, attack aircraft, bombers (missile carriers), reconnaissance, military transport, special and auxiliary purposes.
Aircraft
The design of aircraft depends on the aerodynamic scheme by which they are made. The aerodynamic design is characterized by the number of basic elements and the location of the bearing surfaces. If the nose of the aircraft is similar for most models, then the location and geometry of the wings and the tail can be very different.
There are the following aircraft device schemes:
- "Classical".
- The Flying Wing.
- "Duck".
- "Tailless."
- "Tandem".
- Convertible circuit.
- Combined circuit.
Classic airplanes
Consider the main parts of the aircraft and their purpose. The classical (normal) layout of components and assemblies is characteristic of most apparatuses in the world, whether military or civilian. The main element - the wing - operates in a clean undisturbed stream, which smoothly flows around the wing and creates a certain lifting force.
The nose of the aircraft is reduced, which leads to a decrease in the required area (and hence the mass) of the vertical tail. This is because the nose of the fuselage causes a destabilizing moment of travel relative to the vertical axis of the aircraft. Reducing the nose of the fuselage improves the visibility of the front hemisphere.
The disadvantages of the normal scheme are:
- The work of horizontal plumage (GO) in a beveled and perturbed wing stream significantly reduces its efficiency, which necessitates the use of plumage of a larger area (and, consequently, mass).
- To ensure the stability of the flight, the vertical tail (IN) must create a negative lifting force, that is, directed downward. This reduces the overall efficiency of the aircraft: from the magnitude of the lifting force that the wing creates, it is necessary to take away the force that is created on the GO. To neutralize this phenomenon, a wing of an increased area (and, consequently, mass) should be used.
The device of the aircraft according to the scheme "duck"
With this design, the main parts of the aircraft are placed differently than in the "classic" models. First of all, the changes affected the layout of the horizontal plumage. It is located in front of the wing. According to this scheme, the Wright brothers built their first aircraft.
Benefits:
- Vertical plumage works in an undisturbed flow, which increases its efficiency.
- To ensure flight stability, the plumage creates a positive lift, that is, it is added to the lift of the wing. This allows you to reduce its area and, accordingly, the mass.
- Natural "anti-stop" protection: the possibility of transferring wings to supercritical angles of attack for ducks is excluded. The stabilizer is set so that it gets a larger angle of attack than the wing.
- Moving the focus of the aircraft backward with increasing speed with the "duck" scheme occurs to a lesser extent than with the classic layout. This leads to smaller changes in the degree of longitudinal static stability of the aircraft, in turn, simplifies the characteristics of its control.
The disadvantages of the scheme "duck":
- When the flow is disrupted at the plumage, not only does the aircraft exit at lower angles of attack, but also its “subsidence” due to a decrease in its total lift. This is especially dangerous in take-off and landing modes due to the proximity of the earth.
- The presence of plumage mechanisms in the nose of the fuselage worsens the visibility of the lower hemisphere.
- To reduce the area of the front GO, the length of the nose of the fuselage is made significant. This leads to an increase in the destabilizing moment relative to the vertical axis, and, accordingly, to an increase in the area and mass of the structure.
Aircraft made according to the tailless pattern
In models of this type there is no important, familiar part of the aircraft. A photo of the tailless aircraft (Concord, Mirage, Volcano) shows that they have no horizontal tail. The main advantages of such a scheme are:
- Reducing frontal aerodynamic drag, which is especially important for aircraft with high speed, in particular cruising. At the same time, fuel costs are reduced.
- Greater torsional wing rigidity, which improves its aeroelasticity characteristics, high maneuverability characteristics are achieved.
Disadvantages:
- To balance on some flight modes, part of the mechanization of the trailing edge of the wing (flaps) and steering surfaces must be tilted up, which reduces the overall lift of the aircraft.
- The combination of aircraft controls relative to the horizontal and longitudinal axes (due to the lack of a rudder) worsens the characteristics of its controllability. The lack of specialized plumage makes the steering surfaces located on the trailing edge of the wing perform (if necessary) the duties of both ailerons and elevators. These steering surfaces are called elevons.
- The use of part of the means of mechanization to balance the aircraft affects its takeoff and landing characteristics.
"Flying wing"
With this scheme, there is virtually no such part of the aircraft as the fuselage. All volumes needed to accommodate the crew, payload, engines, fuel, equipment are in the middle of the wing. Such a scheme has the following advantages:
- Least aerodynamic drag.
- The smallest mass of construction. In this case, the entire mass falls on the wing.
- Since the longitudinal dimensions of the aircraft are small (due to the lack of a fuselage), the destabilizing moment relative to its vertical axis is negligible. This allows designers to either significantly reduce the area of HE, or even abandon it (in birds, as you know, there is no vertical plumage).
The disadvantages include the difficulty of ensuring the stability of the flight of the aircraft.
"Tandem"
The tandem pattern, when two wings are located one after the other, is used infrequently. This solution is used to increase the wing area at the same values of its wingspan and fuselage length. This reduces the specific load on the wing. The disadvantages of this scheme is the large aerodynamic drag, an increase in the moment of inertia, especially with respect to the transverse axis of the aircraft. In addition, with increasing flight speed, the longitudinal balancing characteristics of the aircraft change. The steering surfaces on such aircraft can be located either directly on the wings or on the plumage.
Combined circuit
In this case, the components of the aircraft can be combined using various structural schemes. For example, horizontal tail is provided in the nose and in the rear of the fuselage. They can be used the so-called direct control of the lifting force.
In this case, the horizontal nose with flaps creates additional lifting force. The moment of pitch that occurs in this case will be aimed at increasing the angle of attack (the nose of the aircraft rises). To counter this moment, the tail must create a moment to decrease the angle of attack (the nose of the aircraft drops). To do this, the force on the tail should also be directed upwards. That is, there is an increment of the lifting force on the nose GO, on the wing and on the tail GO (and, consequently, on the entire aircraft) without turning it in the longitudinal plane. In this case, the plane simply rises without any evolution relative to its center of mass. Conversely, with such an aerodynamic layout of the aircraft, it can carry out evolution relative to the center of mass in the longitudinal plane without changing the path of its flight.
The ability to carry out such maneuvers significantly improve the tactical and technical characteristics of maneuverable aircraft. Especially in combination with a system of direct control of lateral force, for the implementation of which the aircraft must have not only a tail, but also a nose plumage.
Convertible circuit
The device of an airplane built according to a convertible scheme is characterized by the presence of a destabilizer in the nose of the fuselage. The function of destabilizers is to reduce, within certain limits, or even completely eliminate the backward shift of the aerodynamic focus of the aircraft in supersonic flight modes. This increases the maneuverability of the aircraft (which is important for a fighter) and increases the range or reduces fuel consumption (this is important for a supersonic passenger aircraft).
Destabilizers can also be used in take-off / landing modes to compensate for the dive moment, which is caused by the deviation of the take-off and landing mechanization (flaps, flaps) or the nose of the fuselage. On subsonic flight modes, the destabilizer is hidden in the middle of the fuselage or set to the weather vane operation mode (freely oriented along the flow).