Automatic refrigeration system for aircraft brakes

International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –
6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 3, March (2014), pp. 47-55, © IAEME
47
AUTOMATIC REFRIGERATION SYSTEM FOR BREAK SYSTEM OF
AIRCRAFT
Yousif Khudhair Abbas
Assistant lecturer- Technology College Kirkuk
ABSTRACT
Explosions in airplane tires were investigated. It was found that main reason had been the
excessive heat generated from friction in the brake system due to improper use by the pilots during
landing. I designed and added an auxiliary system which operated automatically to cool down the
plane tires and consequently reduces the brake temperature.
1) INTRODUCTION
Airlines are considered of great importance to most countries in the world at present for its
great and fast services and in the transport service compared with the rest of transportation services.
Despite of the interested efforts in this field the researcher believes the need for the installation of the
system he designed and installed on the Brazilian airplane Tucano 27. The system is called the self-
cooling system of the wheels and it lowers temperature of the brakes, which in turn leads to reduce
the phenomenon of plane tires burst and reduces the human and material losses.
2) BRAKE
The brake system is considered of the important systems in airplanes as the safety of the
passengers, the plane itself and property of airports depend on the reliability of the brakes.
3) PRINCIPLE BRAKES WORK
First, we must know that the brakes stop the wheels, not the plane and this is the function of
brakes. The friction between tires and the road is what stops the movement. The purpose of the brake
system is to stop the plane by stopping the wheels as:
- To stop the plane we must be dispose of kinetic energy = 0.5 × mass × speed2
- But (Energy can be neither created nor destroyed).
INTERNATIONAL JOURNAL OF ADVANCED RESEARCH IN ENGINEERING
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ISSN 0976 - 6480 (Print)
ISSN 0976 - 6499 (Online)
Volume 5, Issue 3, March (2014), pp. 47-55
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48
- Solution: convert kinetic energy into another form of energy, and thus the plane would lose its
kinetic energy.
- Converting kinetic energy into thermal energy (by friction in the wheels).
- The heat generated has many downsides that would be mentioned and we would overcome
these downsides through our research.[1, 2]
4) PRESSURE
Is the force acting on the unit area? The surface pressure is measured by dividing the for
acting on the surface by its area and it is measured in units of Newton / m 2 (N/m2) which is called
Pascal (Pa) in honor of the scientist Blaise Pascal.
F
P
A
=
P = pressure in the liquid parts
F = force acting on the unit area
A = unit area
If we assume that (f) and (a) are force and area of the small piston and (F) and (A) are the
force and area of the large piston then the pressure would be:
From this relationship it is clear that if we applied a force f on the small piston a larger force
is generated on the large piston force (F). The ratio F/f is called the automatic or mechanical benefit
ratio of the piston and denoted by the symbol (e):
A F
e
a f
= =
This means that the gain of the piston mechanism is the ratio between the forces we have
obtained to the force applied. In the case of an ideal piston (which is efficient 100%) the gain is
given by the ratio of the area of the large piston to the area of the small piston.
The Pascal rule operates on
- Converting the force used in brakes to fluid pressure transmitted by pipelines to the stopping
compound in the wheel.
- The force of the fluid pressure in the stopping compound of the wheel turns into a force to push
the plunger toward the friction linings to produce friction.
- Friction converts kinetic energy into thermal energy to stop the wheel. [3, 4, 5]

49
5) KINETIC ENERGY (KE)
Kinetic energy is the energy of the plane in which attempts to keep the plane in motion
(Inertia). It depends on the mass and speed of the plane, the higher the speed of the plane or mass or
both the higher Kinetic energy of the plane.
KE = kinetic energy (Gul)
m = mass of the aircraft (kg)
v = speed of the aircraft (m / s)
The difference between a stationary plane and a plane in motion is that the plane in motion
contains kinetic energy and a stationary plane does not contain kinetic energy and stop a moving
plane we simply need to get rid of the kinetic energy until the plane is without kinetic energy and
stops. As we know that (Energy can be neither created nor destroyed) but transforms from one form
to another and therefore we cannot simply get rid of the kinetic energy to stop the plane. the best
solution is instead to get rid of the energy we resort to converting kinetic energy into another form of
energy that is we transform kinetic energy of the plane into a form another form in order to stop the
plane. Therefore, what is required to stop the plane is designing a system that works to transform the
kinetic energy into another type of energy and this must take place in a short time. This system is the
brake system [6, 7].
6) FRICTION
When you use the brake the friction linings come into contact with the surface of the rotating
wheel of the plane. the pressure is a result of the impact of perpendicular forces to the surfaces
generated by the brake system and whether the brake system hydraulic or pneumatic this friction
between the surfaces of the linings installed on the plane and surface of wheels generates friction in
reverse to the direction of rotational motion of the wheels. In return this produces heat and kinetic
energy of the aircraft is transformed to heat energy and as a result of decreasing the kinetic energy
the speed of the plane decreases until all the kinetic energy of the aircraft is transformed into thermal
energy produced by friction.
The friction depends on
- the type of the material of contacting surfaces
- Condition of surfaces
- force between two surfaces
So, the benefit of friction is to halt the plane via the heat generated. This heat generated has
disadvantages which will be mentioned as well as how to overcome them.
The coefficient of friction between the friction surfaces:
Affect the value of the coefficient of friction between the surfaces on the amount of friction
force needed to brake the plane known as the coefficient of friction (µ) as the ratio between the force
required to move the surface to another surface (friction force) and the vertical force between the
surfaces and increases the frictional force increase vertical force and increase the coefficient of
friction.
21
2
KE mv=

50
r
n
F
F
µ =
µ =Coefficient of friction
rF = Friction force
nF = Vertical force
Friction and heat
During the process of braking there is a change in kinetic energy causing more reduction in
the kinetic energy and increase in thermal energy. This thermal energy is transmitted to the brake
parts as a result of friction, such as disk and circuit lining friction and as a result the temperature of
those parts increases and this excess heat leads to:
- Damaging brake parts
- Damaging the lining of friction which become more solid with the increase in temperature thus
decreasing the coefficient of friction
- Causing decay of the brake
- Causing closing wheels
The decay of the brake
- the heat generated because of friction lower the value of the coefficient of friction between the
lining and the rotor
- Damage to parts of the compound of braking as a result of heat , including Gasket and booklet
Downloads
- Excess heat lead to increased kinetic energy of the gases in the tire which in return
increases the pressure of the tire more than the allowed and this excess pressure may lead to
explosion of the tire so as to prove the size of the frame, the increase in temperature leads to
an increase tire pressure by process (Isochoric) in a dynamic thermal [8, 9]
7) (ABC) ANTILOCK BREAK SYSTEM
During braking suddenly or on a slippery ground (the case of presence of water or snow on
the runway) this may lock a wheel or more which causes to slip on the surface, therefore, the system
automatically apply to cancel the braking by removing and applying pressure more than 20 times per
second in order to avoid the process of slipping but this has the disadvantage of increasing the
stopping distance [10].
8) CONSTANT OF THE GASES(R)
Constant to gases sometimes called molar constant of gases is given by multiplying the
number of Avogadro (NA) by Boltzmann constant (KB).
The value of the constant gases in accordance with the data of Science and Technology
Committee

51
Scientists have arrived at a fixed value of constant of gasses the constant (R) in the ideal gas
equation :
It links between functions of gas, temperature (T), quantity of the mass (n), pressure (P) (V).
it is also used in a large number of applications and mathematical formulas on the properties of gases
9) ISOCHORIC
In Thermodynamics (isochoric) is an action or experiment where the volume is constant,
such as the volume of gas
According to the law of Gay-Lussacs or law of ideal gas we apply the equation:
And we can deduce from this equation that the relative change in pressure (P) is accompanied
by relative change in temperature (T) of the system when maintaining the volume of the system
unchanged.
Thus:
Where:
p1: pressure Bar after raising system temperature
p2: the pressure in the system before raising the temperature
T1: the temperature before raising system temperatures
T2: System temperature after raising the temperature
The graph below of volume and pressure. The pressure changes as the temperature changes
but the volume remains constant [11, 12, 13].
10-COMPONENTS OF AUTOMATIC REFRIGERATION SYSTEM FOR BREAK SYSTEM
OF AIRCRAFT
1) The container
Capacity of the container is five liters containing a mixture of (1) liter acetone and (4) liters
of distilled water (in order to increase the speed of evaporation and avoid leaving residue on the
braking compound),
The container has an upper aperture used to fill it and a side one to connect it with the
compound. The container has a glass ruler which enables us to determine the level of liquid in it,

52
From experience amount of fluid is sufficient for (3-4) trips. As shown figure (1)
2) Electric pump
Electric pump consists of two parts
- Mechanical part and consists of a core equipped with a number of feathers
- Electrical par to rotate the feathers. It operates to take fluid from the container and push it with
pressure to the system as in figure (2)
- The pump is connected to an electric circuit with a switch and green light whose purpose is to
examine the system during control check before takeoff by ground engineer and log the
examination in the record of the plane) (the plane log is used to record all engineering
maintenance performed on the plane such as check, repair, parts replacement and periodic
inspection).
- Pump is connected to the braking paddle such that when applied by the pilot it operates
automatically by pushing the coolant fluid to the system.
3) Electric solenoid valve
Consists of two parts
- mechanical part consists of a valve and a spring. The spring works push the valve forward to
shut down the system when not in use
- Electric part:
Aperture to system
Glass ruler
Container
Aperture with
cover
Exit Entry
Figure 2
Motor
feathers
Figure 1

53
* When an electrical signal arrives a mechanism works to pull the valve back out in order to open
the way for the coolant to pass to the system.
* This part of is also connected with the braking system paddle, so that when pressed by the
pilot the valve opens allowing passage of coolant to the system, as in Figure (3).
4) Jet nozzles
The squirt coolant liquid coming from the cooling system on the braking system to cool it and
reduce temperature, as in Figure (4)
5) Electric circuit components
There are two electric circuits for cooling system as shown in figure (5)
A- Manual circuit:
To test the system by ground engineer for the system validity and record it in the
maintenance book.
B- Automatic circuit
When pilot press pedals of the aircraft its send two single one of it connected to electric
motor to turn on and second single to electric solenoid valve to open the way for coolant.
Motor
Exit
Figure 3
Entry
Valve
Nozzles
Entry
Figure 4

54
6) The working principle of system
When the aircraft landing on the ground and use system braking by the pilot sends Two
electric signals ,first to run electric pump which in turn withdraw fluid from container and second
electric soled valve to open the way for the coolant and go to spray the barking system assembly by
jet nozzles as shown in figure (6).
7) Testing and conclusions
I selected two aircrafts type Tucano 27 which it caused frequent accidents (Tucano 27 is
aircraft Brazilian-made dual seat used for many purposes and the main purpose is to train students in
the colleges of the Air Force and rehabilitation Aviation). i installed my cooling system on one of the
aircraft and made sure that both aircrafts fly in same time in day and night and under the same
weather conditions and during six months of follow-up , the test concluded that there are a
difference between aircraft equipped with cooling system and non equipped ,as shown in the
following table.
container
Motor
Electric valve
Jet nozzlesBrakes assembly
Figure 6
Figure 5

55
N Tocano aircraft equipped with
cooling system
Tocano aircraft non-equipped cooling
system
1 Reduce in temprature of barking
system assembly
rise in temperature braking system
assembly.
2 Increase the efficiency of friction
for braking system
Reduce the efficiency of friction for
braking system
3 Short distance of the runawy Increase distance of the runawy
4 Reduce tyre burst Increase tyre burst
5 Reduce changing the tyres Increase changing the tyres
6 Reduce changing gland and
bearing
Increase changing gland and bearing
11) RECOMMENDATIONS
1- Recommendation to install self-cooling system on plane wheels and other types of aircraft and
examine its impact on braking system.
2- recommendation to examine planes by modern methods such as
- Examination by wave's magnetic particle inspection branch circuit breaker.
- Examination by radiography.
- Examination by X-ray
9 REFERENCES
1. Birch, Thomas W, "Automotive Braking System", Delmar Publishers, 3rd Edition, 1990.
2. Hillier, V.A.W., "Fundamentals of Motor Vehicle Technology", Stanley Thornes (Publishers)
Ltd., 4 th
edition 1991.
3. Frank M. White, "Fluid Mechanics", university of Rhode Island, 4 th
edition McGraw –Hill
1997.
4. David A. Lombardo, "advanced aircraft system practical flying series", McGraw - Hill Prof
MedTech. 1993
5. Robert W. fox, Alan T. McDonald and Philip J. Pritchard, "Fluid mechanics ", copyright 2004
John Wiley & Sons, Inc.
6. Joseph E.Shigley, Chariest R, Mischief, "Standard Handbook of Machine Design" 3rd
Edition,
McGraw –Hill.
7. Harold A. Rothberg and Thomas H. Brown, "Mechanical Design Handbook", 2nd
Edition
2006, McGraw –Hill
8. J. L. Merriam and L. G. Krieg, "engineering mechanics dynamics ", 6th
edition
9. R.C. Hobbler, "engineering mechanics statics", 10th
edition 2004 by pearson education, Inc.
10. Lihue, Kalong. "Automotive Brakes and Antilock Braking System", West Publishing
Company 1995.
11. Myron Kaufman," principle of thermodynamic", 2002.
12. Yunus A, Engel, Michael A. Boles, "thermodynamics an engineering approach" 5th
Edition
13. Rowland S Benson," advanced engineering thermodynamics ", 1977.

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