AIR TRANSPORT CHARASTERSTICS.

1. Weight and wheel distribution
– Pay load
• Load for which revenues are generated (passengers +
freight)
– Zero-fuel weight
• Air craft reaching destination and fuel is getting empty
Note: (maximum is taken considering biggest aircraft allowed at airport

2. Weight and wheel distribution
• Wheel configuration defines how the weight will
be transferred to the bottom
– More the no of wheels, lesser the stress, hence less
thickness enough.
– Different wheel combinations available based on size
of aircraft.
– Single tandem, duel tandem and multi axle tandems
are used based on the size and weight of air craft.
– Some wheel configurations are shown in the next
slide.

4. Minimum turning radius
• While making a turn, the nose gear is steered
and hence it makes an angle with the axis of
main gear called angle of rotation.
• The point of intersection of axis of main gear and
line through axis of steered nose gear is called
point of rotation.
• Max angle varies between 50 to 60 degrees
• The line joining the centre of rotation and the tip
of farthest wing of aircraft is known as minimum
turning radius.
• The amount depends on size of aircraft

5. Minimum turning radius

6. Minimum circling radius
• Related to movement of aircraft with in the air
• Radius in space required for the aircraft to take a
smooth turn
• It depends on
– Type of aircraft (size, power propulsion system etc.,)
– Air traffic volume
– Weather condition
• It is the total radius which is provided at the top
of the air port in which the aircraft will be circling
if it is not allowed to land.

7. Speed
• Air speed
– Speed of air craft in air relative to medium.
• Indicated speed
– Indicated by the instrument onboard
– 2% lower than actual true speed
– The reason is it is relative speed what is true, to
get the correct value of speed 2% is reduced for
resistance in air.

8. Capacity of air craft
• No of passengers and amount of cargo it can
handle
• Dependant on
– Size
– Propulsive power of aircraft
– Speed of air craft

9. Noise
• Big problem if nearer to developed areas
• Major sources of noises are
– Engine
– Machinery (more during landing)
– Primary jet (more during take-off)
• Disturbances are more during take off
• Since the inception of jet engines the noise
has been reduced to a great extent

10. Vortices at tail end
• Vortices form at tail when moving at high speed
• Have a tendency to break tail if they are heavy
and eddies are formed
• Vortices are made of 2 counter rotating
cylindrical masses of air extending along the path
• These are formed near tail ends of wings or tail
end of aircraft
• The velocity of wind in these vortices will be very
high

11. Jet blast
• This aspect belongs to aircrafts having jet engines
• This is the blast that comes out of jet engine at the
rear of air craft to provide a force for movement
• If we consider the case where air craft is standing and
jet blast is coming from back side, it is so hot and
creates severe conditions
• The severity depends on
– Height of tail pipe
– Angle of tail pipe
• Hence, blast fences are needed to control the damage
to the pavements

12. Fuel spillage
• Spilling of fuel occurs when the engine is
shutdown or loosing speed
• It is spilled fuel from the engine or other
locations into the aircraft. This may cost the
speed when it is moving on runways or
taxiways or apron.

13. Influencing characteristics of aircraft
on design of airport
• Engine type and propulsion
• Size
• Aircraft weight and wheel configuration
• Minimum turning radius
• Minimum circling radius
• speed capacity
• Noise
• Vortices at tail ends
• Jet blast
• Fuel spillage

14. Engine type and propulsion decides
• Size of the aircraft
• Speed
– length of the runway (more speed ->longer runway)
– Weight (more if bigger propulsion system)
– Carrying capacity (depends on size)
– Noise (depends on propulsion system)
– Circling radius (high power, and speed crafts have high
radius)
– Range (distance it can move without refueling)
– Maintenance facilities
– Ballast pads (required for jet propulsion)

15. Size of aircraft
• Size of aircraft influences
– Load carrying capacity
– Other facilities like apron, terminal area etc.
– Bigger the size larger are facilities to be provided at airport
terminal building
– Wing span will increase with size
• It has effect on taxiway width
• Separation between traffic lanes
• Size of gate, apron size, width of hanger etc.
– Length
• Widening of taxiway on curves, apron, hangers, width of exit way
– Height : further influences height of hanger gate
– Wheel base, gear tread also changes

16. Aircraft wheel
• Aircraft wheel configuration
– Thickness of runway, taxiway, apron
– Distribution of load to ground
– Turning (difficult for more weight in case of sharp
curves)
– Stability (depends on the support system provided
and also depends on wheel configuration)

17. Aircraft wheel
• Minimum turning radius
– Radius of taxiways
• Taxiway is the connecting pavement which is provided between
the runways and aprons
• Minimum circling radius:
– Defines the minimum distance between 2 near by airports
– For larger aircrafts it will be in kms hence more distance is
required between 2 airports
– Adjustments of timings of landing and takeoff
– Airport capacity(decrease with increased air circle time)
– Zoning laws related to height of obstruction

18. Aircraft Characteristics
• Speed
– Reduces journey time
– Increase in frequency of operations
– Improving and broadening the air network system
• Capacity
– Processing terminals
– Passenger and baggage handling facilities
– Cargo processing
– Size of apron, special equipments etc.

19. Aircraft Characteristics
• Vortices at tail ends
– Hazardous to aircraft
– Stresses at fuselage and other joints
– Pressure under wings producing lifts and drags
• Jet blast
– Inconvenience to passengers
– May do harm to airport runways and other
components of airport
• Fuel slippage
– Badly effects bitumen pavements
– Causes slip of wheels

20. Selection of site for airport
– Air traffic potential
• Magnitude of passenger and freight traffic expected
– Adequate access
– Sufficient airspace
• Circling radius should be taken care
– Sufficient land
• Various facilities, terminal buildings, security systems
– Atmospheric and meteorological conditions
– Availability of land for expansion
– Availability of utilities

21. Selection of site for airport
– Development of surrounding area
– Ground accessibility
– Presence of other airports
– Regional plan
– Soil characteristics
– Surrounding obstructions
– Use of air port

22. Selection of site for airport
• Atmospheric and meteorological conditions
– Visibility
• Fog, smoke, haze
– Affected by wind
– Development of area (industrial)
• Causes reduction in frequency and hence in capacity
handling
– Wind
• Direction and intensity
• Associated topographical features (hills, valley)
• Windward/leeward side
• Locating development w.r.t site of airport

23. Selection of site for airport
• Availability of land for expansion
– Future prediction of air traffic
• Land for parking vehicles, providing facilities
– Land cost at later stage
– Availability of land at later stage
• Availability of utilities
– Water, power etc.,
– Sewerage, communication etc.

24. Selection of site for airport
• Development of surrounding area
– Residential or sensitive area
– Industrial development
• Height of development
• Zoning laws
– Noise pollution
– Movement of air pollution
– Birds and hits at engines

25. Selection of site for airport
• Economy of construction
– Alternate sites to be examined
– Availability of local construction material
– Terrain even or not
– Problematic areas
• Water logging areas
• Reclaimed areas

26. Selection of site for airport
• Ground accessibility
– Travel time in air vs on ground
– Easily approachable using all modes
– Proximity to areas of trip generation
– Facilities for private vehicle users
– Efficient transport system

27. Selection of site for airport
• Presence of other airport
– Traffic volume
– circling radius
– Types of air crafts in different airports
– Type of operating facility
• Instrumental flight rules, design flight rules
– Separation distance between radii
– May cause
• Accidents, reduction in capacity

28. Selection of site for airport
• Characteristics of soil
– Strength of soil sub grade
– Drainage of soil
– Level of water table and its impact
• Sub-soil drainage effects
– Valley side may have flooding
– Soil with good amount of pervious material like
sand or gravel is considered good