The document discusses key characteristics of aircraft that are important for airport planning and design, including: 1) Type of propulsion, size, minimum turning/circling radii, speed, capacity, weight, wheel configuration, jet blast, fuel spillage, and noise, which all impact runway length, taxiway design, and more. 2) Common aircraft components like engines (piston, turbojet, turboprop, rocket), propellers, fuselage, wings, and controls (elevator, rudder, aileron, flaps). 3) Factors that determine an airport's layout and capacity such as aircraft sizes, speeds, weights, noise levels, and volumes of air traffic.

1. AIRCRAFT
CHARACTERISTICS
Dr. A. K. Singh

2. CHARACTERSTICS
 Aircraft and airport are dependent on each other in providing a service for the
passenger in conventional air transport system.
 In the past, the system evolved largely with separate planning of the airport, the
route structuring and the aircraft technology. With the advancement in
technology, the major factor in the growth of the mode, have been quickly
utilized by the airlines in expanding their route structures.
 Advancement in engine and airframe technology have also been found
significant in the reduction of real cost of air travel and at the same time have led
to improvements in system performances
 The improvement in speed, range, ticket price, comfort, and reliability led to the
high growth rates.
 In addition, the operating costs of the aircraft have continued about 85% of the
operating costs of the entire air transport system, the airports contribute 10%,
and the remaining 5%, goes for navigation charges and overheads of
governmental control
 This has resulted in a natural tendency for the airports to accommodate any
changes in aircraft design and performance that could maintain the trend to
lower the aircraft direct operating cost (DOC).

3. AEROPLANE COMPONENT
PARTS
The schematic
diagram of an aero
plane with its
various component
parts are shown in
the Figure:

4. Its essential parts are as given below:
 I Engine
 2 Propeller
 3 Fuselage
 4 Wings
 5 Three controls
 6 Flaps
 7 Tricycle under-carriage

5. Engine
 The main purpose of an aircraft engine is to provide a
force for propelling the aircraft through the air.
 Aircraft can be classified according to their propulsion
as follows
 (I) Piston engine
 (ii) Turbo jet
 (iii) Turbo fan or Turbo prop
 (iv) Rocket
 (I) Piston engine : It is powered by gasoline fed
reciprocating engine and is driven by propeller or
airscrew.

6. (ii) Turbo jet
 Here a compressor is rotated with a
motor. As the compressor gains its rated
speed. it sucks in air through the air
intake and compresses it in the
compression chamber. The air is ignited
here by a fuel like kerosine oil. The
expanding gases pass through the fan
like blades of the turbine. The turbine
extracts that much power from the gases
which is sufficient to keep the
compressor rotating. The compessor
rotates at the same speed as the turbine
because the two are fastened solidly to
one shaft. The hot gases, with the
remaining energy escape through the tail
pipe which becomes smaller in diameter
at the exit end. The hot exhaust gases,
having high velocity, give a forward thrust
to the engine. It has been reported that if
exhaust oases come out with a speed of
1600 kph (1000 mph), the forward thrust
may push the plane with the speed of
about 00 kph (500 mph).

7. (ii) Turbo prop
 It is similar to the turbo jet engine except that a propeller is provided in it. Main difference is in the design of turbines. The turbine in
turbo prop extracts enough power to drive both the compressor and the propeller. Only a small amount of power is left as a jet
thrust.
(iv) Ram jet:
 It is an engine with no moving parts. It must be operated at comparatively high speed if it has to function at all. It cannot operate
statically unless a continuous source of air is flown past the engine. Its principle of working is very simple. Air enters the air intake.
By shaping the tube with a diverging-converging configuration, as shown in the Figure, the air velocity is decreased in combustion
chamber with a consequent increase in the pressure. Fuel flow and combustion are continuous. A spark plug is used for starting
only. The heated air expends and rushes out of the exhaust nozzle at high velocity creating the thrust. The advantages of ram jet
are the simplicity of design and high speeds. But it requires the assistance of other types of power plants to reach the operating
speed and has a very high specific fuel consumption.
(v) Rocket engine
 The rocket produces its thrust in the same manner as the ram jet except for one outstanding difference. All the engines described
previously have definite ceilings, depending upon when they run out of oxygen necessary to support the combustion. But for
rocket engines, there is no limit on altitude since oxygen in the atmosphere is not relied ipon for the combustion. The engine
carries its own supply of oxygen placing it in the category of non- atmospheric engines. which had flown faster than the speed of
sound was powered by liquid-fuel rocket engine.

8. Propeller
 This is provided in the conventional piston engine aircrafts as well as in turbo prop engines.
 When engine and propeller are in front, the machine is described as a tractor types
 Sometimes, but not very often, the engine and airscrew are behind the wing and this is known as a pusher
installation.
Fuselage
 It forms the main body of the aircraft and provides for the power plant, fuel, cockpit, passenger, cargo etc.
Wings
 The purpose of an aircraft wing is to support the machine in the air when the engine has given it the
necessary forward speed.
Vertical Lift on the Cambered AerofoilVarious Parts of a Wing

9. Three Controls
 There are three axes about which an aircraft in
space may move. These axes and the possible
aircraft movements are shown in the Figure.
 The movement of aircraft about the X axis is
called lateral or rolling movement.
 The movements about Y and Z axes are called
pitching and yawing movements
respectively.
 To control these movements, the airplane is
provided with three principal controls, viz., (i)
elevator (ii) rudder and (iii) aileron.
 The first two controls which are provided at the
tail end of the fuselage are also known as
empennage. Each control can be operated by
the pilot from his cabin.
 (1) Elevator It consists of two flaps capable of
moving up and down through an angle of 50 to
60. They are hinged to a fixed horizontal surface
(called a tailplane or stabilizer) placed at the
extreme rear of the fusiliage. It controls the
pitching or up and down movements of the
aircraft. When the
Three Axes of
Movements

10. (i) Elevator
 It consists of two flaps capable of moving up and down through
an angle of 50 to 60. They are hinged to a fixed horizontal
surface (called a tailplane or stabilizer) placed at the extreme
rear of the fusilage. It controls the pitching or up and down
movements of the aircraft.
(ii) Rudder
 It Consists of a streamlined flap hinged to a vertical fine
provided at the tail end of the fuselage. It can be moved right or
left of the vertical axis through an angle of about 300 It is utilised
for the turning or yawing movement of the aircraft.
(iii) Aileron
 It is a hinged flap which is fixed in the trailing edge of the wing
near the wing tip, as shown n Figure 3.19. It is so rigged that
when aileron in one wing is pulled up that in other is pulled
down. The effect of pulling the aieron c1own is to increase the
camber and angle of incidence of the wing. This results in an
increased lift under the wing. Pulling an aileron up reduces the
lift on the plane.
Flaps
 These are somewhat similar to ailerons and are used for
increasing the lift on acrofoils, Like the other three controls,

11. Tricycle Under-Carriage
 It is a structure to support the
aircraft while it is in contact with
the ground, It has two principal
functions to perform as listed
below
 (i) To absorb landing shocks
while an aircraft lands,
 (ii) To enable the aircraft to
maneuver on ground

12. AIRCRAFT
CHARACTERISTICS
Aircraft characteristics are of prime importance to the airport
planner and designer. The following characteristics need to be
studied
 1 Type of propulsion
 2 Size of aircraft
 3 Minimum turning radius
 4 Minimum circling radius
 5 Speed of aircraft
 6 Capacity of aircraft
 7 Aircraft weight and wheel configuration
 8 Jet blast
 9 Fuel spillage
 10 Noise

13. Types of Propulsion
 The size of aircraft, its circling radius, speed characteristic,
weight carrying capacity, noise nuisance etc. depend upon the
type of propulsion of the aircraft.
 The performance characteristics of aircrafts, which determine
the basic runway length, also depend upon the type of
propulsion. That heat nuisance due to exhaust gases is a
characteristic of turbo jet and turbo prop engines.
Size of Aircraft
 The sizes o aircraft involves following important dimensions:
 (i) Wing span (ii) Fuselage length (iii) Height (iv) Distance
between main gears, i.e. gear tread (v) Wheel base and (vi) Tail
width. These are shown in Figure 3.22.
 The wing span decides the width of taxiway, separation
clearance between two parallel traffic ways, size of aprons and
hangars, width of hangar gate etc.
 The length of aircraft decides the widening of taxiways on
curves width of exit taxiway, sizes of aprons and hangars etc.
The height of aircraft, also called as empennage height, decides
the height of hangar gate and miscellaneous installations inside
the hangar.
 The gear tread and the wheel base affect the minimum turning
radius of the aircraft.

14. Minimum Turning Radius
 In order to decide the radius of
taxiways, the position of aircrafts in
loading aprons and hangars and to
establish the path of the movement
of aircraft, it is very essential to
study the geometry of the turning
movement of aircrafts. The turning
radius of an aircraft is illustrated in
the Figure.
 To determine the minimum tuning
radius, a line is drawn through the
axis of the nose gear when it is at its
maximum angle of rotation The
point, where this line intersects
another line drawn through the axis
of the two main, gears, is called the
centre of rotation. Turning Radius of Aircraft

15. Minimum Circling Radius
 There is certain minimum radius with which the aircraft can take turn in space. This radius
depends upon the type of aircraft air traffic volume and weather conditions. The radii
recommended for different types of aircrafts are as follows
 (i) Small general aviation aircrafts under UFR conditions, 1.6 km (1 mile)
 (ii) Bigger aircrafts, say two piston engine under VFR conditions = 32 km (2 mile)
 (iii) Piston engine aircrafts under IFR conditions. = 13 kin (8 miles)
 (iv) Jet engine aircrafts under IFR conditions= 80 km (50 mites)
 The two nearby airports should be separated from each other by an adequate distance so
that the aircrafts simultaneously landing on them do not interfere with each other. If the
desirable spacing between the airports cannot he provided, the landing and takeoff aircrafts
in each airport will have to be timed so as to avoid collision.
Speed of Aircrafts
 The speed of aircraft can be defined in two ways viz. cni,’iig ‘d or ground speed and air
peed Cruising speed is he rc’cd f aircrafis with respect to the ground when the ui rah i fling
in air at its maximum speed. Air spned is the steed of aircraft relative to the wind. Thus, if
the aircraft is fis üg at a speed of 500 kph and there is a head wind of 50 kpl’, air speed will
be 450 kph.

16. Aircraft Capacity
 The number of passengers, baggage, cargo and fuel that can he
accommodated in the aircrafts depends upon the capacity of aircraft.
the capacity of aircraft using an airport have an important effect on the
capacity of runway systems as well as that of the passenger processing
terminal facilities.
Weight of Aircraft & Wheel Configuration
 Weight of the aircraft directly influence the length of the runway as well
as the structural requirements i.e. the thickness of the runway, taxiway,
apron & hangars. It depends not only on the weight of the passenger
baggage, cargo and fuel it is carrying and its structural weight, but also
on the fuel which is continuously decreasing during the course of the
flight. The details of the weight component is given in article 3. Table
3.1 b and 3.1 c shows the maximum take-off, maximum landing and
empty operating weights. The various possible wheel configuration are
shown in Figure.

17. Jet Blast
 At relatively high velocities, the aircrafts eject hot exhaust gases, The velocity of
jet blast may be as high as 300 kmph. This high velocity cause inconvenience to
the passengers traveling in the aircraft. Several types of blast f nces or jet blast
deflector are available to serve as an effective measure for diverting the smoke
ejected by the engine to avoid the inconvenience to the passengers. Since, the
bituminous (flexible) pavements are affected by the jet bust, therefore, it s
desirable to provide cement concrete pavement at least at the touch down
portion to resist the effect of the blast in preference to the bituminous
pavements. The effect of the jet blast should also be considered for determining
the position, size and location of gates.
Fuel Spillage
 At loading aprons and hangars, it is difficult to avoid spillage completely, but
effort should be made to bring it within minimum limit. The bituminous (flexible
pavements are seriously affected by the fuel spillage and therefore, it is
essential that the areas of bituminous pavements under the fueling inlets, the
engines and the main landing gears are kept under constant supervision by the
airport authorities.

18. Noise
 Noise generated by aircraft create problems in
making decisions on layout and capacity.
 The correct assessment of future noise patterns to
minimize the effect of surrounding communities, is
essential to the optimal layout of the runways.
 The FAA noise regulations came into force in 1969
for jet-powered aircraft with bypass ratios greater
than 2.
 In 1973, they were modified to apply to all aircraft
manufactured after that date.