BREAKS SYSTEM AIRCRAFT
BREAKS SYSTEM ON AIRCRAFT
Abstract
Aerospace industry is growing rapidly. Previously, aircraft relied more on slower speeds and grassy runways than brakes to stop. With the advent of new and more powerful high-speed aero vehicles, the need for a more reliable and stronger braking system is increasing, a braking system that ensures minimum stopping distances, easy plane maneuverability and better heat dissipation. The paper presented provides an overview of the methods used for effective braking in aircraft. This system mainly consists of a number of interacting elements such as disc brakes, thrust reversers, air brakes and spoilers. disc brakes change the excess kinetic energy into heat due to friction. Thrust reversers direct the airflow to increase the thrust in the opposite direction of the flight, thereby helping to slow down the vehicle. Spoilers and airbrakes are structures that help improve drag. These elements are equally responsible for providing the necessary slowing forces to the aircraft.
Keyword
Spoiler, Disc Brake, Thrust Reverser, Airbrake.
I. INTRODUCTION
4 Basic Force
An aircraft is under the influence of many styles. The four main forces acting on a straight and flattened plane are gravity, lift, thrust and drag.
Fig. 1: gaya pada pesawat
weight is defined as the force acting on the plane due to gravity. Lifestyle is a force that works perpendicular to relative motion and against weight. Airplane wings arched above but flat at the bottom. The transverse shape of this wing is known as airfoil. When this form moves through the air at high speed, the air velocity is higher on the upper surface of the wing than the bottom. This causes the pressure above the wing to be lower than the pressure at the bottom of the wing. This pressure difference produces lift and increases with increasing angle of attack (this is the angle between relative wind and airfoil chord). The thrust force is the forward force created by the propeller or the engine and is responsible for forward movement. airplane. The inhibitory force is the force acting in the opposite direction. There are two types of drag styles: parasitic and induced. The drag parasite is caused due to air resistance to the surface of the aircraft and its components. The induced resistance is an inevitable part of the elevator caused by the transfer of air by the wings. The larger the angle of attack, the greater the induced resistance. For certain aircraft the higher the speed the lower is the required angle of attack
to maintain its level. Induced drag is inversely proportional to the square of the velocity. Parasitic drag on the other hand increases with speed. The aerodynamic efficiency of an aircraft is maximum at the speed at which the overall drag (the amount of drag induced and parasite drag minimum.
Breaks system
Brakes are responsible for converting excess kinetic energy to thermal energy by increasing friction. Increasing the amount of friction (ie the resistance offered on the motion of the vehicle) reduces the speed of motion of the vehicle. The braking system uses this principle to slow or stop the vehicle. The airplane design system consists of three basic types: mechanical, hydraulic and pneumatic brakes.
The mechanical brake is operated by the use of the connection, lever etc. Hydraulic brakes use fluid pressure for pressure transmission to the braking components while Pneumatic brake brakes use air pressure to transmit braking power. This system can increase the absorbency of air around it with the help of airbrakes, spoilers, flaps, reverse thrusters, drag chutes, etc. or add ground drag using anchors, glide etc for effective braking. The different types of entities used for braking have been described further in this paper.
II. Spoilers and Airbrake
Spoilers are devices used to destroy airplanes. Structures such as rectangular rectangular sections whose front ends are dependent on the wings (at an angle) interfere with efficient air flow thus changing the number of lifts. The net style on the plane in the vertical direction is equal to the weight of minus lift. So, when the spoiler is installed the lift will decrease due to the down-down force that works on the rising body. Spoilers are of two types: flight spoilers and ground spoilers.
Fig.
2: Spoiler Hinged on Wings
Flight spoiler is used to reduce the elevator, without increasing the speed to a very high level. This allows easier descent of the aircraft. Ground spoilers are also known as lift dumpers deployed on landing. They slow down the vehicle by increasing its attractiveness and also lower the lift dramatically. As a result, the weight of the aircraft is transferred from the wing to the undercarriage. This results in ease of braking and also reduces the possibility of skidding.
The maximum angle of the spoiler is kept around 50 ° -60 ° from the flush position. Spoilers are generally used for rolling purposes, not ailerons mainly because spoilers let the wing trailing edge be freed for other uses. As the pilot moves the control wheel to the right, the right wing spoiler extends and the right wing loses lift. The plane then rolls to the right. Similarly for the left roll, the left wing spoiler widened. Spoilers can also be used in refusal to take off when the aircraft's takeoff is canceled due to some technical failure or other reasons.
Air brakes also known as dive brakes are devices consisting of a series of metal strips that when activated increases the attractiveness of the aircraft. They are used in high performance aircraft and are above or below the wing or near the fuselage. Air brakes are different from spoilers so they have minimal effect on elevators. Rather they increase the attractiveness by biting the air. Another difference is that Air brakes are completely stored or fully installed, while spoilers can be used in different positions. Both Air brakes and spoilers when deployed ensure optimum power available to the engine to prevent it from the danger of shock cooling (due to rapid descent).
III. Thurst Reverse
In addition to normal brakes, Thurst Reverse is used to slow down the plane after touchdown especially when runways are covered in snow or cold. Thurst Reverse works on the principle of gas flush reversal or altering the propeller pitch in order to create a tensile force against aircraft motion. Thurst Reverse is mainly used to reduce stopping distances. This allows landing on smaller runways, reduction of brake wheel wear and cab distance. It is also used in case of take off Rejected.
In the case of a wet or cold runway layer of water acting like a lubricating film between the wheel surface and the base (Hydroplaning). As a result, friction decreases. Thurst Reverse Spreading apart from surface friction allows better braking under such conditions.
Because the Reverse Thurst power is most effective at high speeds, it is important to start the initial round on the landing and immediately raise the thrust right to the recommended limits for a special aircraft model [1]. Thurst Reverse should be done only after touchdown and they have minimum speed requirements below which there is a danger of reinjection of exhaust gas to the engine. Generally Thurst Reverse is recalled under a speed of 70mph.
At Thurst Reverse the propeller of the plane is done by changing the angle of the blade of the blades to produce drag. This involves the use of a mechanical hydro system for actuation to slow down aircraft. On turbojets and turbofan water thrust reversal is achieved by directing the exhaust gas airflow from the engine. Due to aerodynamic restrictions, the release angle is maintained at 45 degrees and consequently, the drag generated for both systems is 40-60% forward drive.
There are several methods for Thuring Reverse on a turbojet or turbofan engine:
• Clam shell type
• Bucket Target type
• Cascade type
Clam shell is a Theres Reversal system that is operated pneumatically. In this system, the doors remain closed during flight so that the exhaust from the engine flows straight out from behind. After being activated by the Thurst Reverse lever, the deflector door on the back of the engine spins and closes the normal flow of the gas flow and directs the air toward the front through the cascade vane. As a result, drag increases.
Fig. 3: Clam-Shell Type Thrust Reverser
The type of bucket target is a hydraulically operated Thurst Reversal mechanism that diverts heat exhaust from the engine. The Thurst Reversal door is driven using a conventional pushrod system [4]. The target door is located on the outer surface of the engine nacelle, and when activated, the lift is out and back to back of the engine forming a convergent divergent nozzle. This system is relatively more efficient than the other Thurst Reversal because this geometry allows for maximum thrust to be reversed.
Fig. 4: Bucket-Target Thrust Reverser
Cascade type consists of a series of blades that are covered by a blocking door under normal conditions to allow airflow from the engine. When Thurst Reverse is moved, the blocking door slides toward the tail. It shows the cascade propellers, directing the airflow toward the front. As a result Thurst Reverse increases. Refrigerated Thurst Reverse systems can be used for cold and hot air flow. Although this system is used in larger commercial aircraft due to the ease of integration with conventional engine nacelles but due to its severe weight and complexity, the cost of maintenance and fuel is high.
Fig. 5: Cascade Type Thrust Reverser
The main disadvantage of using Thurst Reverse on turbojets and turbofan engines is that reverse airflow causes a large amount of noise associated with it due to increased turbulence.
IV. Disc Brakes
Aircraft typically use discs and multi-discs. Mainly consists of rotating discs mounted on the wheel unit, brake calipers held silently and containing brake pads made of materials such as asbestos, ceramics, carbon etc. When the brake pedal is pressed. , Brake fluid under pressure flows from the master cylinder to the slave cylinder through the tube. The slab cylinder consists of a piston that is driven by an incoming fluid pressure force. Pistons force brake pads into rotating discs. Friction between the brake pads and the surface of the disc, hold the spinning motion and stop it. Disc brakes that are used lately are differential types ie left and right units are not interdependent with each other. It also increases maneuverability.
Fig. 6: Disc Brakes
Some disc brakes are composed of a series of discs, a steel stator which is a stationary unit locked on the bearings and the rotor forms a rotating and locked portion of the wheel. Automatic adjuster is used to provide clearance between the rotor layer and the stator. Under hydraulic pressure, this diskette circuit is compressed, forcing the wheel to slow down due to friction. Currently the discs are equipped with slots for better heat dissipation at high temperatures. Also, carbon fibers are widely used as a rotor brake because of their weight which is low and the ability to withstand heat and high temperature. Although it requires lower maintenance than conventional brakes but the cost of manufacture is relatively high.
V. Kesimpulan
Braking system is one of the important elements in the aviation sector. The advent of technologies such as reverse thrust, spoilers, disc brakes etc. have transformed commercial and also military flights extensively. Their use ensures better utilization of energy that otherwise would be in vain and also reduces the risk of accidents due to skidding and shock cooling. These days materials with better thermal and mechanical properties are used such as carbon fiber, ceramics etc. This ensures longer life brake parts, increased reliability and safety. Although it requires proper adjustment, inspection and maintenance of the system over time is essential for effective operation.
Referensi
[1] Slippery Runways, [Online] Available: http://www. smartcockpit.com/aircraft-ressources/Slippery_Runways. html
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[Online] Available: https://www.faa.gov/regulations_
IJRMET Vol. 4, IssuE 1, NoV 2013 - ApRIl 2014
policies/handbooks_manuals/aircraft/amt_airframe_ handbook/
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[5] Michael Kroes, James Rardon,"Aircraft Basic Science”, seventh edition, Tata McGraw-Hill Education, 2010.
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[9] “Thrust Reversing”, [Online] Available: https://engineering. purdue.edu/~propulsi/propulsion/jets/basics/reverse.html
[10] Mohd Anees Siddiqui, Md Shakibul Haq,“Review of Thrust Reverser Mechanism used in Turbofan Jet Engine Aircraft”, International Journal of Engineering Research and Technology. Vol. 6, No. 5, 2013, pp. 717-726.
[11] “Thrust Reversers”, [Online] Available: http://www.pilotoutlook.com/airplane_flying/thrust_reversers
[12] “Aircraft Braking System”, [Online] Available: http://en.wikipedia.org/wiki/Aircraft_Braking_Systems
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