Performance Chapter 11. Aim To determine aeroplane performance using flight manual data.

PerformanceChapter 11

Aim

To determine aeroplane performance using flight manual data

Objectives1. Define Performance2. State terms and definitions3. State factors affecting take-off and landing

performance4. Calculate Pressure and Density altitudes5. Calculate take-off performance6. Calculate landing performance

BackgroundDefine the followingMax take-off weight (MTOW) –

Max landing weight (MLW) -

Basic empty weight (BEW) -

Centre of Gravity (CoG) -

Maximum permitted take-off weight

Maximum permitted landing weight

Weight of aircraft without any payload, includes un-useable fuel and full oil

Point where all the weight is said to act. Also the point about which the aircraft pivots

1. Define PerformanceDefinition

Understanding performance data allows us to make practical use of the airplane’s capabilities and limitations

2. Terms and DefinitionsTake-Off Distance Required (TODR) - Distance required to take-off

and reach a screen height (usually 50ft) above the runway at take-off safety speed

Take-Off Run Required (TORR) - Actual Ground Run Required

Take-Off Safety Speed (TOSS) - Speed which gives an adequate margin above the stall speed in the take-off configuration. Must not be less than 1.2Vs

TORRTODR

Screen Height

2. Terms and DefinitionsClearway – Defined area on the ground or over water that is free

of obstacles, over which an aircraft may make its initial climb

Take-Off Run Available (TORA) – Length of the runway available and suitable for the ground run of an aircraft taking off

Take-Off Distance Available (TODA) – Length of take-off run available plus any clear way

TORATODA

Screen Height

Clearway

2. Terms and DefinitionsStopway – Defined area on the ground at the end of a runway

suitable area in which an aircraft may stop in an emergency

Accelerate Stop Distance Available (ASDA) – Distance specified as being the effective length available for use by an aircraft executing an aborted take-off, including any Stopway

ASDAStopway

2. Terms and DefinitionsLanding Distance Required (LDR) - Distance required to land from

a height of 50ft above the threshold to where the aircraft comes to a complete stop

Landing Run Required (LRR) - Actual Ground Roll Required

Landing Distance Available (LDA) – Length of runway suitable for the ground roll of an aircraft beginning at the threshold or displaced threshold

LRRLDR

50’

LDA

3. Factors Affecting Perf.

The pilot in command of an aircraft must ensure the TODR does not exceed the TODA

When calculating TODR the PIC must take into account:

• TORA• Wind component• Pressure Altitude• Temperature

Take-Off

• Aircraft Weight• Slope• Surface

3. Factors Affecting Perf.Take-Off - Wind

Nil Wind


Head Wind


Tail Wind


Tail Wind

Head Wind

Nil Wind

3. Factors Affecting Perf.Take-OffFactorWindAltitude

Temp.

WeightSlopeFlaps

Surface

Affect on TODRH/W – T/W –

ReasonGroundspeed changedLower engine efficiency, greater TAS required

More inertiaNeed to accelerate uphillSome aircraft have take-off flap settings, allowing then to get airborne faster but reducing their overall climb performance

Friction

Increase in temperature decreases air density giving a lower performance


The pilot in command of an aircraft must ensure the LDR does not exceed the LDA

When calculating LDR the PIC must take into account:

• LDA• Wind• Elevation/Altitude

Landing

• Aircraft weight• Slope• Surface

3. Factors Affecting Perf.Landing - Wind

Nil Wind


Head Wind


Tail Wind


Head Wind Nil Wind Tail Wind

3. Factors Affecting Perf.LandingFactorWindAltitudeWeightSlopeFlapsSurface

Affect on LDRH/W – T/W –

ReasonGroundspeed changedGreater TASIncreased momentumUpslope helps decelerationLower approach speed, Increase in dragBitumen increases braking efficiency


Subject to paragraph 6.3, the take-off distance required is the distance to accelerate from a standing start with all engines operating and to achieve take-off safety speed at a height of 50 feet above the take-off surface, multiplied by the following factors:

(a) 1.15 for aeroplanes with maximum take-off weights of 2 000 kg or less;

(b) 1.25 for aeroplanes with maximum take-off weights of 3 500 kg or greater; or

(c) for aeroplanes with maximum take-off weights between 2 000 kg and 3 500 kg, a factor derived by linear interpolation between 1.15 and 1.25 according to the maximum take-off weight of the aeroplane.

CAO 20.7.4 – Take-Off


Subject to paragraphs 10.3 and 10.4, an aeroplane must not land unless the landing distance available is equal to or greater than the distance required to bring the aeroplane to a complete stop or, in the case of aeroplanes operated on water, to a speed of 3 knots, following an approach to land at a speed not less than 1.3VS maintained to within 50 feet of the landing surface. This distance is to be measured from the point where the aeroplane first reaches a height of 50 feet above the landing surface and must be multiplied by the following factors: (a) 1.15 for aeroplanes with maximum take-off weights of 2 000 kg or less;

(b) 1.43 for aeroplanes with maximum take-off weights of 4 500 kg or greater;

(c) for aeroplanes with maximum take-off weights between 2 000 kg and 4500 kg, a factor derived by linear interpolation between 1.15 and 1.43 according to the maximum take-off weight of the aeroplane.

CAO 20.7.4 - Landing


Some tables and charts will factor this in. READ THE CONDITIONS ON THE CHART

CAO 20.7.4

4. Pressure and Density Altitude

ISA provides a yardstick against which we can measure the effects of changing atmospheric conditions against performance figures produced by the aircraft manufacturer

Standard ISA conditions at sea level are:• QNH 1013 hPa• Lapse rate of 1 hPa per 30ft• Temperature 15⁰C• Lapse rate of 2⁰C per 1000ft• Density 1.225 Kg/M3

International Standard Atmosphere (ISA)


Pressure altitude is altitude corrected for pressure deviations from ISA

If our QNH is greater than ISA our pressure altitude will be less than our actual altitude and the aircraft will perform better

If our QNH is less than ISA our pressure altitude will be greater than our actual altitude and the aircraft will perform worse

To calculate pressure altitude we must:1. Determine pressure variation from ISA 2. Multiply variation by the pressure lapse rate, 30ft per 1 hPa3. Apply the variation to the aerodrome elevation

• If our QNH is greater than ISA our pressure altitude will be less than our actual altitude

• If our QNH is less than ISA our pressure altitude will be greater than our actual altitude

Pressure Altitude


For Example:

Elevation is 650ftQNH is 1020 hPaTemperature is 30⁰CWhat is the pressure altitude?

1. Determine pressure variation from ISA1013 hPa – 1020 hPa = -7hPa

2. Multiply variation by the pressure lapse rate, 30ft per 1 hPa-7 hPa x 30ft = -210ft

3. Apply the variation to the aerodrome altitudeSince QNH is greater than ISA, pressure altitude will be lower650ft – 210ft = 440ft

Pressure Altitude


Density altitude is the altitude which has the same density as ISA standard

If our density altitude is less than ISA the aircraft will perform better

If our density altitude is greater than ISA the aircraft will perform worse

To calculate density altitude we must:1. Determine pressure altitude2. Determine temperature variation from ISA at the pressure altitude 3. Multiply variation by the lapse rate, 120ft per 1⁰C4. Apply the variation to the pressure altitude

• If our temperature is greater than ISA our density altitude will be greater than our actual altitude

• If our temperature is less than ISA our density altitude will be less than our actual altitude

Density Altitude


For Example:

Pressure altitude is 4000ftQNH is 1020 hPaTemperature is 22⁰CWhat is the density altitude?

1. Determine temperature variation from ISA at the pressure altitude 15 ⁰C - (2x4)= 7 ⁰C

2. Multiply variation by the lapse rate, 120ft per 1⁰C22⁰C - 7 ⁰C = 15 ⁰C x 120ft = 3300ft

3. Apply the variation to the pressure altitudeBecause the temperature is greater than ISA our density

altitude will be greater than our actual altitude4000ft + 3300ft = 7300ft

Density Altitude

5. Calculate Take-Off Perf.

For Example, calculate the Maximum Take-Off Weight for the following conditions:

Pressure altitude 4000ftTemperature 25⁰CTake off Distance Available 800mSurface long dry grassNo slope15kt Headwind

Take Off Performance – Typical Cessna Chart


Method:

1. Enter the chart with 4000’ on the pressure altitude scale and plot a horizontal line to intersect 25⁰C

2. From this point plot a vertical line to the TODA of 800m. Also from the intersection of the climb weight limit line draw a horizontal line to the right. This gives us the climb weight limit of 1060kg



Method:

3. From the intersection of the TODA (800m) line plot a horizontal line to the reference line

4. From the reference line follow the lines in the window to the “Long dry grass” line. Plot a horizontal line from here into the slope graph



Method:

5. From the intersection of the horizontal line and the “Level” line plot a vertical line down into the wind graph to intersect 15kt headwind

6. From this point plot a horizontal line to the Take Off Weight scale. This gives us the runway performance weight limit of 1000kg



Method:

7. The Maximum Take Off Weight is the lesser of the climb weight limit (1060kg) and the runway performance limit (1000kg)



For Example, calculate the Take-Off Distance Required for the following conditions:

Pressure altitude 2000ftTemperature 20⁰CSurface Long dry grass2% Down slope5kt HeadwindTake-Off Weight 1000kg

Take Off Performance – Typical Piper Chart


Method:


1. Enter the chart with 25⁰C on the Temperature scale and plot a vertical line up to the Pressure altitude of 2000’. Also check the climb weight limit

2. From this point plot a horizontal line to the surface reference line. Follow the guide lines to the long dry grass line then proceed horizontally to the slope reference line


Method:


3. Follow the guide lines to the 2% down slope line then proceed horizontally to the wind reference line

4. Follow the guide lines to the 5kt headwind line then proceed horizontally to the take off weight of 1000kg


Method:


5. Follow the guide lines to determine the Take-Off Distance Required 750m

5. Calculate Landing Perf.

For Example, calculate the Landing Distance Required and Maximum Landing Weight for the following conditions:

Pressure altitude 7000ftTemperature 15⁰CNo slope10kt Headwind

Landing Performance – Typical Cessna Chart


Method:

1. Enter the chart with 7000’ on the pressure altitude scale and plot a horizontal line to intersect 15⁰C

2. From this point plot a vertical line into the Landing Distance Required Window



Method:

3. Enter the chart again from the wind component of 10kts and plot a vertical line up to the slope, in this case level

4. From this point plot a horizontal line to intersect the vertical line already in the Landing Distance Required window



Method:

5. Follow the guide lines to the left to determine the Landing Distance Required 550m

6. We also need to check the climb weight limit – in case of a Go-Around – In the climb weight limit window plot a horizontal line from pressure height to the reference line then straight down to read the climb weight limit of 910kg



For Example, calculate the Landing Distance Required for the following conditions:

Pressure altitude 4000ftTemperature 30⁰C2% Down slope10kt Headwind

Landing Performance – Typical Piper Chart


Method:


1. Enter the chart with 30⁰C on the Temperature scale and plot a vertical line up to the Pressure altitude of 4000’. Also check the climb weight limit

2. From this point plot a horizontal line to the slope reference line. Follow the guide lines to the 2% down slope line then horizontally across to the wind reference line

No climb weight limit with a pressure alt. of 4000’


Method:


3. Follow the guide lines to the 10kt headwind line then proceeded horizontally to read the Landing Distance Required of 690m

No climb weight limit with a pressure alt. of 4000’

Questions?

Performance Chapter 11. Aim To determine aeroplane performance using flight manual data.

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Transcript of Performance Chapter 11. Aim To determine aeroplane performance using flight manual data.