Wednesday, March 18, 2020

Aircraft Systems

PLANE

Airplane; It is a motorized aircraft that can rise and advance by holding in the air due to the pressure difference between the upper and lower surfaces of the wing profile parts, especially the wings.Many aircraft with propeller or jet engines, fixed wings and heavier than air are included in the aircraft category. Today, the most basic aircraft types are known as passenger aircraft, fighter aircraft, cargo aircraft, and there are also aircraft that are customized according to different geographical conditions.

The main parts of the aircraft are the wings, which provide the ability to hold in the air, the tail for keeping the wings in balance,control surfaces that change the position and position of the aircraft, and the engine and propeller that provide the necessary propulsion. The body that houses the passengers and the cargo, and the cockpit, which houses the flight crew and flight controls, is one of the main parts of the aircraft.



ELECTRİC SYSTEMS

- Electric Power Sources -

Batteries: Provides electricity for the initial operation of the engine or auxiliary power supply (APU). It is also available as a backup energy source in emergencies.
Generators: They convert the rotating motion they receive from the engine or APU into direct current electricity and feed the systems of the aircraft.
Alternators: They convert the rotation movement of the aircraft from the engine and APU, if any, to alternating current electricity. Alternators provide stable, reliable energy in different circuits of motors. Alternators are the main manufacturers in today's modern aircraft.

ELECTRİC CURRENT CONVERTERS, REGULATORS

Alternating current is converted to direct current, they prevent voltage changes.

Electricity Distribution Systems

Distribution bars (BUS bar): It is the central distribution line that delivers electricity to the devices.
Cables, cable groups (electical hardness)

- Insurance -

It protects the devices from overcurrent. The fuses, which were previously push-pull button-shaped, can be seen on the screens in front of the pilot in modern aircraft with advanced glass cockpit, a fault message is given, and can be reset electronically with the keys attached to the screen without being displaced by the pilot. Classic fuses are located in or near the pilot cabin on large-scale aircraft, and on external covers in small aircraft.




INTERNATIONAL AVIATION (ICAO) ALPHABET

A: alpha 
B: bravo
C: charlie
D: delta
E: echo
F: foxtrot
G: golf
H: hotel
İ: india
J: juliet
K: kilo
L: lima
M: mike
N: november
O: oscar
P: papa
Q: quebec
R: romeo
S: sierra
T: tango
U: uniform
V: victor
W: whiskey
X: xray
Y: yankee
Z: zulu

- PLANE TYPES - 

 Aircraft Types By Number Of WingsTypes Of Aircraft By Number Of Engines

 Types Of Aircraft According To Their Intended Use
 Types Of Aircraft By Engine Types
 Aircraft Types According To Other Specifications
    - AİRCRAFT TYPES BY NUMBER OF WİNGS - 

    Monoplane
    Biplane
    Three Winged

     - TYPES OF AİRCRAFT BY NUMBER OF ENGİNES - 

    Single Engine
    Two Motors 
    Three Motor
    Four Motor
    Six Motor
    Eight Engine
    Ten Engined

    - TYPES OF AİRCRAFT ACCORDİNG TO THEİR INTENDED USE -

    Passenger Aircraft
    Transport Aircraft
    Freight+Passenger
    Agricultural Spraying Aircraft
    Training Aircraft
    Surveillance Aircraft
    Reconnaissance Aircraft
    Submarine Aircraft
    Bomber Aircraft
    Firefighting Aircraft
    Offensive Aircraft
    Unmanned Aerial Vehicles
    Unmanned Combat Aircraft
    Spy Planes
    Command And Control Aircraft

    - TYPES OF AİRCRAFT BY ENGİNE TYPES -


    Turbojet

    Turbofan

    Ramjet

    Pulsejet

    Rocket Motor

    Scramjet

    Turboprop

    Piston Engined

    Wankel Engined

    Ductedfan

    - AİRCRAFT TYPES ACCORDİNG TO OTHER SPECİFİCATİONS - 


    Seaplane

    Different Design

    To Land And Water

    Fixed Wing

    Rotary Wing

    Very Small Aircraft



    LANDİNG GEAR, BRAKE SYSTEM AND TİRES


    What are the main tasks of the landing gear?

    Landing gear provides aircraft mobility on the earth,
    ensures that no other part of an aircraft is in contact with the ground during landings and departures,
    It prevents the formation of deformation in the body of the aircraft by absorbing the energy greatly during the landing of the wheels during the landing,
    It helps the plane maintain its balance on runway during take-off and landing in weather with strong side winds.


    What are the most used types of landing gear?

    1) Landing gear in the style called Tandem Configuration.

    This kind of landing gear is not used in passenger planes, it is generally preferred in narrow-body bombers, gliders. In tandem-style landing gear, both front and rear wheels share the total weight of the plane by approximately 40% and share it with 60% back. There are the same landing gear both at the front and at the back. There are supporting wheels for the plane not to tip over.


    2) The most commonly used landing gear, called three-point landing gear, is the main landing gear and one that is either front or rear balancing landing gear. Three-point landing gear is divided into two among themselves:

    2a) Configuration where the main landing gear is at the front and the supporting landing gear is at the back:
    It was mostly used in the period before jet engine aircraft. The weight distribution falls on the main landing gear, which is 80% to 90%, and the main landing gear remains in front of the aircraft's center of gravity (indicated by the letter "G" in the picture).


    2b) The most commonly used style in aircraft, especially passenger aircraft, is that the main landing gear is behind the supporting wheels at the front. The weight distribution falls 80% to 90% on the main landing gear at the rear, and the main landing gear remains behind the aircraft's center of gravity (indicated by the letter "G" in the picture).


    What are the advantages of three-point landing gear compared to being ahead of the main landing gear as it is used today?

    By providing the plane to stand horizontally, it has a positive effect both on passenger comfort and on the pilots' viewing angles on the apron.

    During hard braking, in the configuration with the main landing gear at the rear, there is no danger of the rear part of the aircraft being blown up as it is at the front.

    One of the most important advantages is that the main landing gear behind the plane is offset after landing on the runway is the supporting factor. I want to open this a little more:
    Airplanes do not always put their noses in parallel direction to the runway during landing, for example, under the influence of side winds. In such a case, the main landing gear behind the plane that puts the track on the runway plays a supportive role in the orbit of the plane. Let's examine the reason in the drawing below.

    The drawing above shows the situation where the main landing gear is, therefore, the center of gravity in front of the aircraft. For example, an aircraft that could not put the direction of movement parallel to the runway due to the side winds, braking forces * affect when all the wheels are seated on the runway. The main landing gear brakes the wheels in the opposite direction of movement, while applying force (both the friction force arising from the braking system of the aircraft and between the wheels and the runway surface before the braking system is activated), force is applied in the direction of movement due to the kinetic (motion) energy of the aircraft. Since the center of gravity is geometrically behind the braking forces *, the main landing gear, which is applied in the direction of movement from the main landing gear, which applies the braking force, and a moment that creates a tendency for the tail of the plane to turn around the main landing gear left behind.

    Brake system used in aircraft

    Disc brakes are used in airplanes, but a brake like in automobiles does not consist of a single disc, a single brake has more than one disc, depending on the weight of the aircraft. The steel brakes used to be replaced by carbon brakes today for both heat resistance and weight savings. It is possible to reach an average of 1000 landings with steel brakes and 1500 landings with carbon brakes. Moreover, a weight of up to 500 kg is saved on a large aircraft. Steel brakes become unusable at 2000 degrees, while carbon brakes can last up to 3000 degrees.



    In planes, there is a system similar to the ABS system we know from cars, but it is called Anti Skid. The purpose of the system is to prevent the wheels from locking. Because the locked wheels only apply less braking force than is possible because they are affected by the kinetic friction coefficient **. In summary, the working principle of the Anti Skid system is as follows;
    When the braking systems in the main landing gear of the aircraft are activated at the maximum level, the sensors measure the speed of movement of the aircraft by means of non-braking front wheels and compare this speed with the speed of the braking wheels. If the difference between them is less than approximately 0.85, the braking pressure on the braking wheels is reduced in such a way that the optimal coefficient of difference around 0.85 is reached again. For example, if the plane is traveling at 100k speed on the runway and the braking wheels are rotating at 70k speed, the brake pressure is reduced to decrease to approximately 85k speed. This means that making the braking wheels turn on average 15% less than the non-braking wheels, more precisely, to get them into a slight friction with the runway surface. This is because an average of 15% friction determined between aircraft tires and the runway gives the maximum braking force. Brake pressure may drop completely for a short time to reduce the friction of the wheels, as more than 30% friction will cause the wheels to lock.

    (*) Braking forces = As soon as the main landing gear of the aircraft lands on the runway, it does not brake with the landing gear, but a braking force occurs between the wheels and the surface of the runway. The word "Braking forces" in the article covers both forces, whether this is the natural braking force or the braking force that occurs when the landing gear's braking systems are activated.

    (**) There are two types of friction coefficient in physics. One of them is the coefficient of friction, which is called the static friction coefficient, which has a large value to prevent slippage between the surfaces of two objects that contact each other, and the other is the friction coefficient, which is called the kinetic friction coefficient that occurs when the sliding begins between the surfaces of the same two bodies. The best example is when we try to push a box on the ground again. The static friction coefficient affects the box until it moves, and as soon as we move it, we need less force as we start dragging on the ground because we have now switched from the static friction coefficient to the lower value kinetic friction coefficient.


    Aircraft engine is a component that produces mechanical power to provide propulsion power to the aircraft. Aircraft engines mostly consist of light piston engines or gas turbine engines.

    DEVELOPMENT HİSTORY OF AİRCRAFT ENGİNE

    1848: Although John Stringfellow may seem trivial, he built a steam engine with exemplary power capacity.
    1903: Charlie Taylor built a 12-horsepower sequential engine for Wright Flyer.
    1903: Manly-Balzer engine project, which will set the standard for star type engine, started.
    1906: Léon Levavasseur adapts the successful cooling V8 engine for use in aircraft.
    1908: René Lorin patents the first reactive jet engine.
    1908: Production of Gnome Omega, the world's first Doner engine, started. In 1909, the Gnome powered Farman III plane traveled 180 kilometers without stopping and set a world record. For this reason, Grande Semaine d'Aviation de la Champagne won the endurance award.
    1910: Coandă-1910 aircraft with piston engine and ducted fan was exhibited in the Paris Aero Hall. The aircraft flew in this way, but the patent received was due to the exhaust gas being fed into the duct to increase thrust.
    1914: Auguste Rateau recommends the use of an exhaust-powered compressor - a turbo - to improve high altitude performance, and its recommendations are not accepted as a result of tests.

    AİRCRAFT ENGİNE TYPES

    - SHAFT MOTORS - 

    Internal combustion engines

    Internal combustion engines are the machines created by the burning of the fuel inside the engine in a limited area called the combustion chamber, moving the part called the piston.

    The reason why these engines are called internal combustion engines is because the combustion occurs in the engine. External combustion engines, on the other hand, were called external combustion engines, since external combustion occurred. For example: Steam generator engines.

    In the internal combustion engines, by moving the combustion chamber into the engine, very compact engines were produced and automobiles were created.

    The machine that converts an energy form (electricity, chemical energy ... gasoline, thinner, LPG etc.) into mechanical energy is called an engine.

    Working principle

    Fuel is mixed with carburetor or fuel injection system with a certain amount of air and sent into the cylinder called combustion chamber. The mixture is compressed by the piston and ignited with the help of spark plugs. In diesel engines, ignition is done by compression under high pressure instead of spark plug. The mixture turns into CO2 and CO. This reaction creates volume and heat. This is done by converting the swing movement of the pistons into mechanical energy with the help of the crankshaft. Today, kerosene was used as fuel, but today, gasoline, diesel oil and LPG (Liquefied Petroleum Gas) are quite common. In today's technology, "hybrid" cars started to be produced, these cars have two different types of engines. So the hybrid name comes from the fact that it has two types of engines, one of which is combustion and the other is electric.



    1. Intake: The mixture of fresh air and gasoline is taken into the cylinder by opening the valve in the suction channel on the right side and the downward movement of the piston.
    2. Compression: The mixture of air and fuel taken into the cylinder is compressed by the upward movement of the piston, and both its temperature and pressure are raised and trapped in a very small volume. Meanwhile, both valves are fully closed and insulation is provided.
    3. Combustion: Combustion of the compressed gasoline and air mixture is ignited by the spark plug located in the middle of the valves. The power that provides the movement of the vehicle is produced at this moment.
    4. Exhaust: When the piston comes back up after combustion, the burnt residual gases are thrown out by opening the exhaust valve located on the upper left side. Then, while the piston comes down again, the 1st cycle, the suction phase, begins again.

    Energy efficiency

    If the energy efficiency is defined as the ratio of the chemical energy of the fuel consumed to the mechanical energy produced, the approximate efficiency of modern turbocharged engines is 20%.

    Given that the theoretical maximum efficiency of the internal combustion thermodynamic event is 35%, the remaining 15% energy loss is spent on compression of fuel, friction of pistons, and other processes.

    Piston engine

    Piston (replenishment), disc-shaped piece placed in a cylinder with 7 cavities per 1000. It is used in machines such as engine, pump and compressor depending on the piston rod extending from the cylinder (connecting rod). It is the mechanism that converts chemical energy (gasoline, diesel, lpg etc.) into mechanical energy in motor vehicles.

    Past

    When the fuel-air mixture is ignited in the cylinder in an automobile engine, the expanding gases push down the piston and rotate the crankshaft connected to the piston rod (connecting rod). It provides the conversion of combustion energy into mechanical energy. In a steam engine, high-pressure steam enters from one end of the cylinder, pushing the piston. This advance movement is converted into a rotational movement by means of the crank-connecting rod mechanism connected to the piston. It is used to move water or liquids by pressing the piston in a pump by hand or by a machine or to press it high. It enables the compression of air or other gases in the cylinder at a higher pressure by operating the machine or engine piston in a compressor. Thus, it also acts as a filter.

    structure

    The piston consists of the body, the sealing rings and the connecting rod that connects with the connecting rod. Body and rings are made of long-life alloy steel to withstand high temperatures in explosive engines. Circlips can be made from hemp, felt, cast iron, steel, bronze, leathery and rubber, depending on the type and temperature of the machine and fluid. In hydraulic devices, segments made of rubber and leather are used to ensure sealing. The most important problem in the pistons is that they lose their tightness due to the wear of their bodies and rings. For this reason, the surfaces of the engine pistons, which operate at high pressure, are hardened by heat treatment by thoroughly treating and polishing the surfaces. Mechanical wear occurs on the piston due to the temperature rising while the engine is running. To eliminate these wear, the piston is given an oval form. This oval form varies from piston to piston. The oval form is as small as a few microns in line with the piston pin holes (1 micron is 1 in 1000 of 1 millimeter). This oval form minimizes wear and increases the life of the engine. Very precise CNC machines are used to give the oval form. Where the fuel called as the head of the pistons is sprayed, the temperature is warmer than the side near the crankshaft, which is called the skirt, and the head side of the piston is machined to a smaller diameter than the skirt side, so that this difference does not affect the performance while the engine is running. is an engine part.

    Wankel engine

    Wankel engine; It is an internal combustion engine with excentric rotary design that converts combustion pressure into rotary motion. Unlike other internal combustion engines, these engines use triangular rotary pistons with flattened edges. Their structure is less complicated than other engines, thanks to the fact that the power transmission is carried out directly with the help of the shaft connected to the piston.


    Structure and work

    The Wankel engine has a much simpler structure than a normal engine. It is a rotating rotor (rotating piston) in an oval body (it may be 2-3-4 rotors according to the design) and the camshaft (the camshaft does the work of the crankshaft in 4-stroke engines).

    The Wankel engine has much less complex moving parts than today's engine with 4 cylinders, 16 valves, and 2 camshafts. The rotor is connected to the main shaft of the motor with the help of an internal and an external gear. As long as the engine is running, suction, compression, work and exhaust times occur around the rotor. The biggest difficulty of the engine is also due to this. Due to the wear of the rotor around very quickly, it must be replaced frequently. A suitable material that can solve the problem of wear of rotor edges, usually made of polymer material, has not been produced yet.

    The Wankel engine operates on four time principles. At each full revolution of the rotor, a job occurs according to the four-stroke engine in each chamber. The camshaft turns three revolutions at this time.

    The control of the engine is provided through the channel in the housing body. The rotor is mounted on a cam of the camshaft. The pinion, which is fixed inside the casing body, is in engagement with the gear opened to the inside of the rotor. The rotor is rolled on the fixed pinion gear. It generates a rotating force on the camshaft while rolling. This rotational movement in the camshaft is transmitted to the gearbox. The spark plugs are located on one side of the water-cooled engine body and on the opposite side of the exhaust ducts.



    The biggest problem with the Wankel engine today is the high speed required to capture torque. Parallel fuel consumption is also quite high. Based on Mazda Rx-8, one of today's wankel cars, it has been reported by some users that the car spends around 20 liters of fuel per 100 km, except for quiet use.


    Turbine engine

    Turbine engines burn fuel and air like piston engines, but instead of moving the piston up and down, a group of fan blades called turbines rotate at high speed. Turbine engines are the first in II. It was used in aircraft during World War II. There are many types of turbine engines. The most common is the turbofan engine.

    TYPES

    Turbofan engine

    These types of engines are used in jet passenger aircraft, military cargo aircraft and many other jet aircraft. One of the most famous is the Rolls Royce RB211-535. This large and powerful turbofan engine was made by Rolls Royce, a British company. A single engine produces a 19,200-kilogram thrust. This power is more than the total power that 50 passenger cars can produce. This engine is embedded in many modern jet airliners such as Tupolev Tu204.

    Turbofan engines have the ability to split air. Some of the air entering the engine enters the combustion section and 10 times as much as the passage channels. Air entering the sideways channels allows the engine to cool. 75% of the power produced by the engine is generated by the eccentric channels. Mode of operation: There is a fan in the front section of the motor, reaching 2 meters in diameter. The blades of this fan are made of alloy. Its task is to draw the air into the engine. 1 in 11 of the total air entering the engine enters the hub of the engine. This air is compressed by a series of fans and goes into the combustion chamber. The air coming to the combustion chamber has reached 30 times the pressure of the outside air. Here it is mixed with fuel and turns the propellers behind the engine at very high speeds, driving the engine.

    Turbojet engine

    These types of engines are the simplest of turbine engines. Impulse is provided by hot gases emitted from the back of the engine. Although the turbojets provide very high speed, they are noisy and consume a lot of fuel. They are used in fast jet aircraft. For example, Concorde uses 4 Olympos 593 turbojet engines.

    Turboprop engine

    Engines of this type have an extra turbine used to rotate a propeller, much of the impulse created by the engine. Turbopropes consume less fuel than other turbine engines, they are much quieter, but they cannot exceed 800 km / h. For example, Foker F27 has 2 turboprop engines.

    Turboprop

    Turboprop is a type of motor that turns a propeller with the power it takes from a turbojet engine running behind it. It provides high efficiency at low speeds. For this reason, it is still in use in large cargo aircraft.

    Turboshaft


    EXTERNAL COMBUSTİON ENGİNES

    The external combustion engine is a motor that converts energy through that fluid by heating a different fluid that will work in the system by combustion of fuel (eg steam engine and Stirling engine).

    External combustion engines have a lower power and more space occupation than internal combustion engines, but sometimes they can be more efficient and contain less harmful particles as a result of combustion. They tend to be more environmentally friendly due to the fact that they produce less harmful exhaust gases due to their low combustion temperature and pressures.

    Mechanical energy and heat energy are linked. For example, by friction between the moving parts of the machine, mechanical energy turns into heat energy. Heat energy can also be converted into mechanical energy with heat engines.

    Heat engines are divided into two groups;

    - External combustion engines
    - Internal combustion engines

    In external combustion engines, they transfer heat energy from hot gases generated by combustion to another fluid and the heat energy in this fluid turns into mechanical energy. These engines contain gas and steam turbines. In internal combustion engines, the heat energy of hot gases formed by combustion is directly converted into mechanical energy.

    A steam turbine can be a good example of external combustion engines. Heat from fuel combustion or from a nuclear reactor turns the water into steam with a boiler. The pipes carry the steam into the turbine with fins attached to a shaft. The high temperature steam expands and compresses along the turbine, pushing the fins and causing the shaft to turn. The rotating shaft can provide power for an electric generator, a ship propeller, or other business.

    Steam powered engines

    The steam engine is an external combustion engine that converts the heat energy present in the steam into mechanical energy. It can be steam machines, locomotives, steamships, pumps, steam tractors and industrial circuits.

    A steam engine needs a boiler to boil water to produce steam under pressure. Any heat source can be used, but generally fires from burning wood, coal or petroleum fuels are used. [1]

    As a working principle, the water that takes the heat energy expands by evaporation and is taken into a chamber. When the chamber is cooled, the liquid, which becomes liquid, creates a vacuum, so that the mechanisms move into mechanical energy, that is, work.

    REACTİVE ENGİNES

    Turbine engine

    Turbine engines burn fuel and air like piston engines, but instead of moving the piston up and down, a group of fan blades called turbines rotate at high speed. Turbine engines are the first in II. It was used in aircraft during World War II. There are many types of turbine engines. The most common is the turbofan engine.

    Types

    Turbofan engine

    These types of engines are used in jet passenger aircraft, military cargo aircraft and many other jet aircraft. One of the most famous is the Rolls Royce RB211-535. This large and powerful turbofan engine was made by Rolls Royce, a British company. A single engine produces a 19,200-kilogram thrust. This power is more than the total power that 50 passenger cars can produce. This engine is embedded in many modern jet airliners such as Tupolev Tu204.

    Turbofan engines have the ability to split air. Some of the air entering the engine enters the combustion section and 10 times as much as the passage channels. Air entering the sideways channels allows the engine to cool. 75% of the power produced by the engine is generated by the eccentric channels. Mode of operation: There is a fan in the front section of the motor, reaching 2 meters in diameter. The blades of this fan are made of alloy. Its task is to draw the air into the engine. 1 in 11 of the total air entering the engine enters the hub of the engine. This air is compressed by a series of fans and goes into the combustion chamber. The air coming to the combustion chamber has reached 30 times the pressure of the outside air. Here it is mixed with fuel and turns the propellers behind the engine at very high speeds, driving the engine.



    Turbojet engine

    These types of engines are the simplest of turbine engines. Impulse is provided by hot gases emitted from the back of the engine. Although the turbojets provide very high speed, they are noisy and consume a lot of fuel. They are used in fast jet aircraft. For example, Concorde uses 4 Olympos 593 turbojet engines.

    Turboprop engine

    Engines of this type have an extra turbine used to rotate a propeller, much of the impulse created by the engine. Turbopropes consume less fuel than other turbine engines, they are much quieter, but they cannot exceed 800 km / h. For example, Foker F27 has 2 turboprop engines.

    Turbojet

    Turbojet is an air-breathing jet engine used in the aviation industry. Although the engine's thermodynamic cycle patent was obtained by Brayton in the 19th century, working prototypes were developed independently of each other in the late 1930s by Frank Whittle in England and Hans von Ohain in Germany.

    Turbo means "rotating at high speed" in Latin. Jet means "throwing" in Latin. Under Newton's Law 3, he pushes gases back at high speed, creating a reverse force.

    Turbofan

    Turbofan is a reliable and easy-to-maintain jet engine type that is supplied with the thrust exhaust gas as well as the large fan at the front. The front part is large, the back part is cone shaped and smaller. It is generally used in passenger aircraft.

    The air sucked in through the turbine in the front is taken into the combustion chamber by the compressor propellers, where when the condensed air is burned simultaneously with fuel (some water is mixed in some engines), a great thrust is created. We can also call this rocket acceleration. This created thrust force is sent out through the turbines in the exhaust outlet, all this system is a mechanism connected to the same shaft.

    Propfan

    Rocket powerful engines

    Rocket is the name given to a motor that can create a high-energy effect. As a result of the spraying of hot gases at high speeds, rockets gain forward motion. It is also the type of engine used in space shuttles. They can work in an oxygen-free environment. In this way, they can be used in space.

    Rockets are classified according to fuel injection rate and fuel burning rate. They work according to the momentum principle. The main production aim of the rocket is to be asked to operate outside the atmosphere and to obtain short-term high speed and power. This can be for military or civilian purposes.

    According to the ballistic laws with the speed it gained after the fuel is finished, the rocket ensures that the cargo carried according to its purpose continues without leaving or leaving the load it carries. (In this section, we can give an example of a bullet that comes out of the gun.)

    Rockets keep the burner (types of oxygen, etc.) that can burn the fuel in its liquid or solid state depending on its type. Rockets are divided into two as liquid and solid fuel.

    Termojet

    Responsive engine with an air vent in the front. In this engine, the air sucked in is fed to the combustion chamber through a compressor, where it is mixed with fuel and burned; The expanding air is expelled at a high speed. The first application was made in 1910 by Henri Coanda.

    Pulsejet

    Pulse jet engine, in the simplest sense, are jet engines that take advantage of the effect caused by combustion. These engines can consist of a small number of moving parts as well as completely still parts and can operate statically.

    Since the early 1900s when they were first invented, they have remained in the background compared to other jet engines. After its use in German cruise missiles during World War II, a lot of false and exaggerated information about pulse jets was spread. This incorrect and exaggerated information still continues as propaganda purposes in some engineering books. This period is interpreted as the golden age of pulse jet engines, even though it is knitted for a conscious misinformation.

    Recently, scientists realized the practical benefits that developed depending on the characteristics of the pulse jet engines and increased their work on pulse jet engines. The line of these studies is mostly aimed at evaluating the examples of pulse detonated motors with more effective cost and small scale.


    Types

    Pulse jet engines have a unique design approach. There are basically two types of pulse jets. Both of them create propulsion using intermittent exhaust gases using resonant combustion and harness the expanding combustion feature.

    Pulsejet with valve

    Pulse jet scheme.

    The first type of pulsejet is the valve type pulsejet. Valve motors are pulsejets that use a mechanically controlled valve to control the flow and generate exhaust gases and generate impulse. The flow of hot gases of this type to the tail pipe only backwards, followed by fresh air in the front section, mixed with fuel and incinerated. V-1 used during World War II is one of the conventional examples of the “buzz bomb” valve type. In this engine, two channels are connected to the combustion zone where the explosion occurs. Generally, the short channel called “intake” and the long channel called “tailpipe” are mentioned. The function of the front air intake is to supply fresh air for combustion. In small versions of this type of engine, air-fuel mixture is also provided in this section. The purpose of the tail pipe is to control the flow of the air mass in a controlled manner and utilize the thrust force. Combustion section and "tailpipe" constitute the main tube part of the engine. A flexible one-way low flow valve separates the combustion zone and the "intake" part.

    The air must be drawn into the combustion zone at the beginning of each cycle. At the end of each cycle, it should be emptied with strong flow from the tail pipe to the atmosphere due to its aerodynamic structure. Since these two basic actions were defined by Kadenacy for the first time, they were named as Kadenacy effect. Also, the combustion product is thrown from the tail pipe at the same time. During this process, as the pressure starts to rise again, the valve closes quickly and a new cycle begins.

    Pulsejet without valve

    Valveless pulsejets work on the same principle as the valve pulsejets. However, due to the geometric structure of the engine instead of any mechanically controlled valve of this type, the air flow applies the same principle by showing a valve feature.

    This type of fuel is injected either into the air inlet or directly into the combustion chamber as gas or steam at high temperature. The first start of the engine is done by using spark plug with air drive. In modern engines, this process starts with the procedure of ignition and self-cycling, creating a rich mixture instead of compressed air. The cycle is then maintained with the fuel boost.


    Ramjet:Ramjet, sometimes called stove pipe jet, is a type of jet engine that doesn't use moving parts. It is a simple engine used at high speed. Thanks to this advantage, it has been used in missile systems.

    Ramjet is a jet engine type without forward thrust compressed air intake rotary damper. Since it does not generate impulses at low speeds, it cannot activate an aircraft that is on the ground. It is suitable for high speed flights. It is a type of engine that does not have moving parts such as a compressor or turbine. Ramjets need a pre-speed to work and they can start working at supersonic speeds (M> 1). This type of engine runs up to 5 Mach speed. Scramjet engines are needed to accelerate to higher speeds. They are used in applications that require high speed, gun makers have increased their range by adding a ramjet to heavy weapons with outer shells.

    Scramjet

    Scramjet (supersonic combustion ramjet) is a type of ramjet and has a supersonic combustion chamber. It has a combustion chamber where air is compressed and the fuel is burned and a nozzle, where the exhaust leaves faster than the inlet speed. Commercial jet engines use a compressor to intake and compress air into the engine, then sprayed fuel fires with compressed air to go backwards and form thrust. The Scramjet uses the speed of the plane to compress the air, meaning it requires very few moving parts.

    Others

    - Electricity
    - Human strong
    - Hydrogen
    - Nuclear

    - AİRCRAFT SPEEED AND WEİGHT - 

    Aircraft speed

    Speed in aircraft is measured by the "Pitot static" system. This system shows speed by taking advantage of the difference between the pressure caused by the air flow caused by the velocity to the hole at the end of a pipe called the "Pitot tube" and the static (static air) pressure on the side surfaces of the same tube or around the aircraft. Air 
    the actual velocity is difficult to find because its pressure varies depending on altitude and temperature. There are therefore four types of speeds used in aircraft.

    IAS (Indicated Air Speed) 

    Shown Airspeed
    It is the speed that the indicators point to the pilot.

    CAS (Calibrated Air Speed)

    Calibrated Airspeed
    Speed sensor and speed indicator errors by correcting the reflecting speed information.

    TAS (True Air Speed)

    True Airspeed
    CAS speed is calculated by taking into account the air density and altitude in the flying environment. Normal indicators can only show true speed at sea level and in standard conditions. Advanced computer devices directly indicate the actual speed.

    GS (Ground Speed)

    Ground Speed
    It is the speed at which the plane's shadow on the ground is relative to the ground. It determines how long it takes.

    EAS (Equivalent Air Speed)

    Equivalent Airspeed

    It is found by adding density ratio to the airspeed shown.

    Mach Number

    Speed Of Sound
    It is the ratio of the speed of the aircraft to the speed of sound in the air, which is relative to the altitude and ambient temperature at which it flies. Pilots use this indicator because air density decreases at high altitude.

     - WEIGHT -

    It is in the opposite direction of the lifting force and is always perpendicular to the center of the Earth. In Normal horizontal flight, buoyancy equals weight. Gravity acceleration: the G effect increases the load on the aircraft, however, in Incline sharp turns and circular acrobatic manoeuvres perpendicular to the ground (loop).

    Gross weıght

    The empty weight of the aircraft is the sum of fuel, oil, weight of detachable equipment, weight of flight crew, passenger baggage and cargo.

    Center Of Gravıty

    It is the imaginary point at which an aircraft can stand in equilibrium on three axes (transverse, longitudinal and Perpendicular) when suspended from one point.

    Weıght And Balance

    The importance of weight and center of gravity (CG) in aircraft was explained. For this reason, it is done after the production of the aircraft is finished and before the first flight, and after a major renovation which will affect weight or CG when using it in service. This process is usually from three-point aircraft, mostly lifted from the landing gear and are brought to a position parallel to the ground with a jack and level adjustment is made after the jack at the top of the detector and the electrical signals from the electronic load device is assessed by the total weight of the plane, the location of the center of gravity in the horizontal and vertical planes is calculated. In another system, the aircraft is hoisted onto three separate portable platforms with load sensors on them without being jacked, and the same weighing and balancing operations are carried out by bit Portable Computer. If the resulting center of gravity is outside the limits, special weights called "ballast: bile" are added to the plane and the weight of the merlezin is drawn into the limits.


    Load Factor

    The ratio of the load carried by the wings to the total weight of the aircraft.

    FACTORS AFFECTING THE LIFTING FORCE

    THE WING PROFILE
    ANGLE OF ATTACK
    THE SPEED OF THE AIRCRAFT
    WING SURFACE AREA
    WING SHAPE
    THE OPENNESS RATIO
    AIR DENSITY

    REMOVİNG STRENGTH

    It is a force that allows aircraft and helicopters to take off and keep them in the air. In all aircraft the principal buoyancy is obtained from the wings. In helicopters, lift is also obtained from Wings revolving around an axis. For this reason, helicopters are also called rotating wing aircraft. In some advanced aircraft, buoyancy is achieved from the fuselage and horizontal tail surfaces in addition to the wings. It is based on the Bernoulli principle of "buoyancy", the principle of flying of all fixed-wing and rotary-wing (helicopters) aircraft;

    BERNOULLI PRINCIPLE

    The pressure of a fluid (gas or liquid) decreases as the velocity increases.The “wing profile”, which looks like an elongated and corrected water drop, translates the forward motion of the aircraft to the lifting force, while the effect of the air flow generated by rotation in the helicopters. The wing sections are designed to provide minimum air resistance / drag back Force and maximum lift force, and the wings and control surfaces of the aircraft are formed by combining these sections in different sizes and shapes. In aircraft, the shapes of the wings, tail rudders and fuselage are also designed using aerodynamics.

    AERODYNAMIC

    THE FORCE OF AN OBJECT ON A MOVING SOLID IN A STATIONARY AIR AND THE STATE OF THE AIR FLOW IS A BRANCH OF SCIENCE THAT STUDIES THE MOTION OF THE AIR CURRENT SURROUNDING AN OBJECT.


    When airflow is generated above a certain speed around an Aircraft Wing ( by moving or rotating the wing forward), lower pressure occurs on the upper surface of the wing than on the lower surface of the wing. When the pressure on the lower surface is greater than the pressure on the upper surface, buoyancy is obtained. If we think of air molecules as human beings, the people on the lower surface of the wing will be able to walk the straight distance between the front edge and the rear edge of the wing, and the man on the top will have to run in order to cross the upper surface, which is longer due to its curved shape, in the same time.

    In order for the lifting force on the wing of an aircraft to hold that aircraft in the air;In flat flight the lifting force is equal to the weight of the aircraft,

    In order to make it rise while flying horizontally on the ground, the lifting force must be greater than the weight of the aircraft.

    Therefore, the lifting force must be controlled.

    FORCES ACTİNG ON AİRCRAFT


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