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Aircraft Characteristics

Type of Propulsion

Size of Aircraft

Minimum Turning Radius

Minimum Circling Radius Speed of Aircraft

Capacity of Aircraft

Aircraft Weight and Wheel Configuration Jet Blast and Noise

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Type of Propulsion Propeller driven Piston Engine (P)

Thrust is generated by propeller which is powered by gasoline fed

reciprocating engine (Cesna Aircrafts) Turbo Prop (TP)

Thrust is generated by propeller which is powered by turbine engine. Itsturbine uses almost all the engine's energy to turn its compressor andpropeller, and it depends on the propeller for thrust, rather than on thehigh-velocity gases going out of the exhaust. (ATR, Dornier)

Turbo Jet (TJ) Dont depend on propeller for thrust. Thrust is directly obtained from

turbine engines (Concorde)

Turbo Fan (TF)

Similar to turbo jet, but with a small fan attached to the turbine engine.The fan causes more air to flow around (bypass) the engine. Thisproduces greater thrust and reduces specific fuel consumption. Thispropulsion system is the most efficient. (most of the present dayprincipal transport aircrfats Airbus, Boeng, McDonnell-Douglas)

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Turbo Prop

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Turbojet

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Turbo Fan

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Size of Aircraft Wing span

Distance between two wing tips. Determines separation clearance

between two parallel taxiways, size of gates, turning radius, etc. Fuselage length

The overall length of aircraft from tip of nose to the tail. Determines sizeof gate, turning radius, etc.

Height

Determines the vertical clearances required in hangar and other serviceareas

Wheel base Centre to centre distance between nose gear and landing gear.

Determines the minimum turning radius

Wheel tread / Outer main gear wheel span The centre to centre distance between the two landing gears is wheel

tread. The outer to outer distance between the two landing gears isouter main gear wheel span.

These dimensions effect the minimum turning radius, width of taxiway,etc.

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Size of Aircraft (B-747)

Height

Wing span

Fuselage Length

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Minimum Turning Radius This dimension is important for establishing the

geometry of movement of the aircraft. The exact position of the aircraft adjacent to theterminal building and the path of the aircraft atother locations is determined based on the

turning radius. Turning radius is a function of nose gear turning

angle (caster angle). The maximum turningangle varies between 600 800.

However, while working out minimum turningradii, moderate caster angle (50) is used tominimize the wear and tear of nose gear.

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Determining Minimum Turning Radius

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Minimum Circling Radius

This is the minimum radius with which

aircraft can take turn in space.

Depends on type of aircraft, air traffic

volume, weather condition, etc. Determines the spacing between two

airports

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Typical Values for MinimumCircling Radii

Small general aviation aircrafts

operating under Visual Flight Rules Bigger aircrafts operating under

Visual Flight Rules

Piston Engine aircrafts operatingunder Instrument Flight Rules

Jet Engine aircrafts operating under

Instrument Flight Rules

1.6 km

3.2 km

13 km

80 km

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Speed of Aircraft Speed of aircraft is measured either with respect

to ground (termed as cruising speed or groundspeed) or relative to wind (termed as air speed)

Speed of aircraft is reported in Nautical Miles per

hour (1 nautical mile = 1.85 km) Approach speed, touchdown speed, exit speed

and allowable deceleration values determine the

location and design of exit taxiways.

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Aircraft Weight Operating Empty Weight (OEW)

Weight of aircraft excluding payload and fuel, but including crewand necessary gear required for flight

Zero Fuel weight (ZFW) The weight above which all additional weight must be in terms of

fuel, so that, when the aircraft is in flight, the bending momentsat the junction of wing and fuselage do not become excessive.

Payload This is the total revenue producing load: passengers + baggage

+ mail + cargo

Maximum Structural Payload The maximum payload the aircraft is certified to carry.

Theoretically, Maximum Structural Payload = ZFW - OEW Actual payload often is less than this as much of space is

occupied by seats, etc.

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Aircraft Weight Contd. Maximum Ramp Weight

This is the maximum total weight of the aircraft authorised for ground

maneuver Maximum Structural Takeoff Weight

The maximum weight of the aircraft authorised at brake release fortakeoff. It excludes taxi and run-up fuel and includes, OEW, payloadand trip and reserve fuel.

Thus, the difference between ramp weight and takeoff weight isnominal.

Maximum Structural Landing Weight This is the weight for which the landing gear is designed. The total

weight of the aircraft can not exceed this while landing. Maximumstructural landing weight is less than the maximum structural takeoff

weight as aircraft loses weight en route by burning fuel. In case of abortive takeoff, the fuel is jettisoned so as not to exceed the

maximum structural landing weight

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Gear Configuration Aircrafts are supported by a nose gear and two main

landing gears located on the wing area on each side.

The distribution of the load between the main gears andthe landing gear depends on the type of aircraft and thelocation of the centre of gravity of the aircraft

However, for pavement design it is normally assumedthat 95% of the weight is supported on the two landinggears.

Maximum ramp weight is used while working out the

distribution of load for pavement design purposes.

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Gear Configurations

Single wheel Dual wheel

Dual-in-tandem

Double dual-in-tandem

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Gear Configuration Contd. Single wheel

Small aircrafts (Douglas DC-3)

Dual wheel

B 737, B 727 Dual-in-tandem

A300, A310, A320, B701, B720B, B757, B767

Double Dual-in-tandem

B747A, B747B

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Payload Vs Range Range of an aircraft is the maximum distance it can fly satisfying the

norms relating to reserve fuel and the maximum weight

characteristics. When the aircraft is loaded to its maximum structural payload (PA),the fuel tanks can not be completely filled to satisfy the requirementof maximum structural takeoff weight limiting the range (say to RA).

In order to maximise the range (say to RB), the payload has to be

reduced (say to PB) giving way for additional fuel filling the fuel tankscompletely. When the aircraft is not on a passenger flight, the requirements of

reserve fuel will not apply. The range worked out by consideringmaximum trip fuel and reserve fuel under zero payload is termed asferry range (RC).

The payload vs range curves are given by the manufacturer. Thesecurves are useful in the planning of airport.

Using these curves the exact weight characteristics of the aircraftscan be obtained by knowing their scheduled operations.

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Typical Payload versus Range Curve

0

5000

10000

15000

20000

25000

30000

35000

40000

0 1000 2000 3000 4000 5000 6000 7000

Range, Nautical miles

Payload,

kg

(RA, PA)

(RB, PB)

(RC, PC)

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Weight characteristics of an aircraft

34232 kgFuel capacity

25878 kgMaximum structural payload

56982 kgOperating empty weight

82860 kgZero fuel weight

89892 kgMaximum structural landing weight

99880 kgMaximum structural takeoff weight

Reserve fuel requirement: 1.25 hr in en route service

Average route speed: 869 km/hr

Average fuel burn rate: 6.43 kg/km

Prepare payload versus range relationship

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Other Aircraft Characteristics Capacity of aircraft determines the facilities with in and

adjacent to the terminal building. It also determines the

range of the aircraft Noise created by the aircraft influences the decisions on

airport layout and capacity. The noise contours are superimposed on the land use

map of the airport to get a noise footprint. Thesefootprints are used in optimizing the runway layoutsminimizing the adverse effect on the surroundingcommunities.

Jet blast of aircraft influences the design of blast pads atrunway ends and the parking configurations adjacent tothe terminals.

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Basic Runway Length Basic runway length is the length of runway

required based on the imposed performancerequirements of the critical aircraft understandard conditions

Basic runway length has to be determined forthe following three general cases Normal landing case

Normal Takeoff case

Engine failure case Continued takeoff

Aborted takeoff (Engine failure accelerated stop)

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Runway Components The three basic components of runway are:

Full strength pavement (FS)

Clearway (CL) Stopway (SW)

Full strength pavement should support the full weight of

the aircraft Clearway is a prepared area beyond FS, clear of

obstacles (max slope is 1.25%), allowing the aircraft toclimb safely to clear an imaginary 11 m (35) obstacle.

Stop way is a paved surface that allows an aircraftoverrun to take place without harming the vehiclestructurally (cannot be used for takeoff)

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Stopway

Direction of operation

Departure end

of runway

Stopway

Source: FAA AC: 150/5300-13 (1989)

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Clearway

Direction of operation

Departure end of runway

Maximum Upward

Slope (1.25%)

150m

ClearwayLength

Clearway

Source: FAA AC: 150/5300-13 (1989)

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Runway ComponentsEach runway end has to be considered individually for

runway length analysis

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Nomenclature FL = field length (total amount of runway needed)

FS = full strength pavement distance CL = clearway distance

SW = stopway distance

LOD = lift off distance

TOR = takeoff run

TOD = takeoff distance

LD = landing distance

SD = stopping distance D35 = distance to clear an 11 m (35 ft.) obstacle

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Normal Landing Case Pilot approaches with proper speed and crosses the threshold of

the runway at a height of 15m

The demonstrated distance to stop an aircraft should be within 60%

of landing distance

LD = 1.667 * SD

FSland = LD

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Normal Takeoff Case The length of runway depends on

Lift off distance (LOD) Distance to reach a height of 35 feet (~11 m) (D35)

Take of Distance (TOD) is taken as 1.15 times the D35

The entire length of TOD need not be of full strength pavement.

The regulations permit the use of Clearway at the end of fullstrength pavement

Clearway Length (CL) = 0.5(TOD-1.15LOD)

The full strength runway, which is TOD-CL, is alsotermed as Take off Run (TOR)

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Normal Takeoff Case

RELATIONSHIPS:

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Engine Failure Continued

Takeoff Case Engine failure continued takeoff

TOD and LOD will be longer than those in normaltakeoff case

TOD is taken as D35 with no percentage applied

Regulations permit the use of clearway at the end Length of Clearway (CL) is half the difference

between TOD and LOD

FS = TOR = TOD-CL

FL = FS + CL

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Engine Failure Aborted

Takeoff Case The length of runway should be sufficient to

bring the plane to a stop

The distance required by an aero plane foraccelerating, decelerating and coming to a stop,in such a situation, is termed as Distance to

Accelerated Stop (DAS) For piston engine aircrafts, full strength

pavement is used for the entire DAS

For turbine engine aircrafts, regulations permitthe use of Stopway for portion of DAS beyondTOR.

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Engine Failure Case

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Example Problem Determine the runway length requirements according to the

specifications for a turbine powered aircraft with the following

performance characteristics: Normal Landing:

SD = 2540 m

Normal Takeoff:

LOD = 2134 m

D35 = 2438

Engine Failure Continued Takeoff:

LOD = 2500 m

D35 =2774 m

Engine Failure Aborted Takeoff:

DAS = 2896 m

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Solution Normal landing:LD = 1.667*SD = 1.667*1524 = 2540 m

Normal takeoff:

TOD = 1.15 (D35) = 1.15*2438 = 2804 mCL = 0.5(TOD-1.15LOD) = 0.5(2804-1.15*2134) = 175 m

TOR = TOD CL = 2804 -175 = 2629 m

Engine failure take off:

TOD = D35 = 2774 mCL = 0.5(TOD-LOD) = 0.5(2774-2500) =137 m

TOR = TOD CL = 2774 137 = 2637 m

Engine failure aborted take off:

DAS = 2896 m

Summary:FL =max (LD, TOD, DAS) = 2896 m

FS = max (TOR, LD) = 2637 m

SW = (DAS FS) = 259 m

CL = FL (FS+SW) = 2896 2896 = 0

259 m2637 m259 m

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Environs at the Airport Basic runway length is valid under the following

assumed conditions at the airport Altitude is at sea level

Temperature at the airport is standard

Runway is level in the longitudinal direction No wind is blowing on runway

Aircraft is loaded to its full loading capacity

No wind is blowing en route to the destination En route temperature is standard

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Corrections to Basic Runway Length

The basic runway length is corrected for

the actual conditions at the airport

The following corrections are applied:

Correction for elevation Correction for temperature

Correction for gradient

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Correction for Elevation High altitudes reflect low air densities, resulting in lower output of

thrust.

Therefore, higher the altitude the longer the runway required.

The increase in runway length with altitude is not linear and it varieswith weight and temperature.

The rate of increase at higher altitudes is higher than at loweraltitudes.

ICAO, however, recommends that the basic runway length shouldbe increased at the rate of 7% per 300 m rise in elevation above

mean sea level. There is exception for high temperature and high altitude areas,

where the increase could be up to 10%.

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Correction for Temperature

Higher temperatures reflect lower air densities resultingin lower out put of thrust.

Therefore, higher the temperature the longer the runwayrequired.

The increase in runway length with temperature is notlinear.

The rate of increase at high temperatures is greater thanat lower temperatures.

ICAO, however, recommends that the base runway

length after having been corrected for elevation, shouldbe further increased at the rate of 1% for every 1oC riseof airport reference temperature above the standardatmospheric temperature at that elevation.

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Airport Reference TemperatureIf,

T1 = Mean of the mean daily temperaturesfor the hottest month

T2= Mean of the maximum dailytemperatures for the hottest month

Then, airport reference temperature (T) is

found out asT = T1 + (T2T1)/3

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Standard Atmospheric

Temperature The standard temperature at mean sea

level is 15o

C. The temperature gradient of the standard

temperature from the mean sea level to

the altitude at which the temperaturebecomes -15.5oC is 0.0065oC per metre.

The temperature gradient becomes zero at

the elevation above the altitude at whichthe temperature is -15.5oC.

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Check for Correction The total correction in basic runway length

for elevation and temperature should notexceed 35%.

If this correction exceeds 35% furtherchecks are needed using model studies.

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Correction for Gradient If the runway is on gradient, the aircraft

has to overcome the grade resistance. More runway length is required to achieve

the required speed for liftoff.

Studies indicate that the runway lengthvaries linearly with the gradient.

Airport design criteria limits the runwaygradient to a maximum of 1.5%

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Effective Gradient For applying correction to runway length for

gradient, FAA uses effective gradient. Effective gradient is defined as the maximum

difference in elevation between the highest and

the lowest points of runway divided by the totallength of runway.

Effective gradient = (h4 h3)/L

L

h1 h2 h3

h4

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Correction for Gradient FAA recommends that the runway length

after having been corrected for elevationand temperature should be furtherincreased at the rate of 20% for every 1%

effective gradient.

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Example Problem Determine the actual length of runway to be provided for the following data

Basic runway length: 1500 m

Elevation of the runway: 110 m +MSL Mean of average daily temperatures for the hottest month: 18oC

Mean of maximum daily temperatures: 30oC

The construction plan includes the following data:

-0.31800 - 2100

-0.51500 18001.0900 1500

-0.3300 900

0.50 300

Gradient (%)Station to Station

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Solution Correction for elevation = (7/100)(110/300)(1500) = 38.50 m

Corrected length = 1500 + 38.50 = 1538.50 m

Correction for temperature:

Standard temperature = 15 0.0065110 = 14.2850C

Airport reference temperature = 18+(30-18)/3 = 220C

Correction = 1538.5(22-14.285) (1/100) = 118.7 m Corrected length = 1538.5 + 118.7 = 1657.2 m

Check for elevation and temperature correction

Increase in runway length = (1657.2-1500)/(1500/100) = 10.48%

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Solution Contd. Correction for gradient

Station 0 300 900 1500 1800 2100

Elevation 100 101.5 99.7 105.7 104.2 103.3

Effective gradient = [(105.7 99.7)/1657.2] 100 = 0.362%

Correction = 1657.2 (0.362 20)/100 = 120 m

Corrected length = 1657.2 + 120 = 1777.2 m

Actual runway length at the airport = 1780 m.

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Airport Configuration Airport configuration is defined as the number

and orientation of runways and the location of

the terminal area relative to the runways. Number of runways depends on air traffic

volume.

Orientation of runways depends on the directionof wind, size and shape of the area and land useand airspace use restrictions in the vicinity ofairport.

The terminal building should be located so as toprovide easy and timely access to runways.

Analysis of Wind for

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Analysis of Wind for

Orienting Runways Runways are oriented in the direction of

prevailing winds.

The data on the parameters of wind namely,intensity (speed), direction and duration areessential to determine the orientation ofrunways.

High intensity winds perpendicular to thedirection of runway cause wobbling effect andcause problems during landing and takeoff of

aircrafts. Smaller aircrafts are particularly effected bythese crosswinds.

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Analysis of Wind Cross wind component

The component of wind intensity perpendicular to the centre line

of runway is termed as cross wind component. Allowable cross wind component

This is the maximum cross wind component that is safe foraircraft operations. This depends on the size of aircraft, wing

configuration and the condition of the pavement surface. ICAO guidelines on cross wind component

18.5 km/hr1500

ACW Component (km/hr)Runway Length (m)

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Analysis of Wind Wind coverage

The amount of time in an year during which the cross wind component

is less than the allowable cross wind component FAA specifies that the system of runways at an airport should be

oriented in such a way to give at least 95% wind coverage.

If it is not possible to achieve the specified wind coverage with onerunway, a cross wind runway should be provided to achieve the same.

Calm Period

Percentage of time during which wind intensity is less than a small

value of wind speed (say 6.5 km/hr) which will not effect the operations.

Wind rose

A diagram where in the direction, duration and intensity are graphicallyrepresented.

Typical Wind Data for Wind Rose

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Typical Wind Data for Wind Rose

(Source: Horonjeff and Mckelvey,1993)

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Collection of Wind Data The wind information that is used in the analysis should be latest

and should accurately represent the situation. Preferably, wind data for the last 10 consecutive years should be

collected for carrying out the analysis. Wind data records for durations less than 10 years may be utilized

with caution. In some instances, it may be highly desirable to obtain and

assemble wind information for periods of particular significance. Indian Meteorological Departmentis the source for the collection of

wind data in India. FAA specifies that the wind summary for the airport site should be

formatted with the standard 36 wind quadrants and usual speedgroupings (0-4; 4-7; 7-11; 11-17; 17-22; 22-28; 28-34; 34-41; 41-47;over 47 knots)

At least 16 wind quadrants and suitable speed groupings should beused.

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Collection of Wind Data In the absence of wind data for a site, it is permissible to

develop composite wind data using wind information

obtained from two or more nearby recording stations.However, the terrain between the site and the recordingstations should be plain or rolling for developing thecomposite wind data.

In extreme cases, wind data should be collected for atleast one year at the site and the composite wind datafor the site should be prepared my merging the data fromnearby recording stations and augmented with personal

observations. Airport development should not proceed until adequate

wind data are acquired

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Wind Rose Construction


Graphical Representation of Wind

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Graphical Representation of Wind

Parameters

CWC

CWCV cos

Vsin

V V/

V/ cos

V/sin

Completed Wind Rose

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p


Wind Coverage of E-W Runway

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g y


WindCoverage =90.8 %

Wind Coverage of CW Runway

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Wind Coverage =84.8 %

Additional Wind

Coverage = 5.8%

Wind Coverage of the Runway System

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g y y


Wind Coverageof the runwaysystem = 96.6 %

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