Transcript Performance Chapter 11 Aim To determine aeroplane performance using flight manual data Objectives 1. Define Performance 2.

Performance
Chapter 11
Aim
To determine aeroplane performance using flight manual
data
Objectives
1. Define Performance
2. State terms and definitions
3. State factors affecting take-off and landing
performance
4. Calculate Pressure and Density altitudes
5. Calculate take-off performance
6. Calculate landing performance
Background
Define the following
Max take-off weight (MTOW) – Maximum permitted take-off weight
Max landing weight (MLW) -
Maximum permitted landing weight
Basic empty weight (BEW) -
Weight of aircraft without any payload,
includes un-useable fuel and full oil
Centre of Gravity (CoG) -
Point where all the weight is said to act.
Also the point about which the aircraft
pivots
1. Define Performance
Definition
Understanding performance data allows us to make
practical use of the airplane’s capabilities and limitations
2. Terms and Definitions
Take-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
Screen
Height
TORR
TODR
2. Terms and Definitions
Clearway – 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
Screen
Height
Clearway
TORA
TODA
2. Terms and Definitions
Stopway – 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
Stopway
ASDA
2. Terms and Definitions
Landing 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
50’
LRR
LDR
LDA
3. Factors Affecting Perf.
Take-Off
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
• Aircraft Weight
• Slope
• Surface
3. Factors Affecting Perf.
Take-Off - Wind
Nil Wind
3. Factors Affecting Perf.
Take-Off - Wind
Head Wind
3. Factors Affecting Perf.
Take-Off - Wind
Tail Wind
3. Factors Affecting Perf.
Take-Off - Wind
Head Wind
Nil Wind
Tail Wind
3. Factors Affecting Perf.
Take-Off
Factor
Wind
Altitude
Temp.
Reason
Groundspeed changed
Affect on TODR
H/W –
T/W –
Lower engine efficiency, greater TAS
required
Increase in temperature decreases air
density giving a lower performance
Weight
Slope
Flaps
More inertia
Need to accelerate uphill
Surface
Friction
Some aircraft have take-off flap settings,
allowing then to get airborne faster but
reducing their overall climb performance
3. Factors Affecting Perf.
Landing
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
• Aircraft weight
• Slope
• Surface
3. Factors Affecting Perf.
Landing - Wind
Nil Wind
3. Factors Affecting Perf.
Landing - Wind
Head Wind
3. Factors Affecting Perf.
Landing - Wind
Tail Wind
3. Factors Affecting Perf.
Landing - Wind
Head Wind
Nil Wind
Tail Wind
3. Factors Affecting Perf.
Landing
Factor
Wind
Altitude
Weight
Slope
Flaps
Surface
Reason
Groundspeed changed
Affect on LDR
H/W –
T/W –
Greater TAS
Increased momentum
Upslope helps deceleration
Lower approach speed, Increase in drag
Bitumen increases braking efficiency
3. Factors Affecting Perf.
CAO 20.7.4 – Take-Off
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.
3. Factors Affecting Perf.
CAO 20.7.4 - Landing
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.
3. Factors Affecting Perf.
CAO 20.7.4
Some tables and charts will factor this in.
READ THE CONDITIONS ON THE CHART
4. Pressure and Density Altitude
International Standard Atmosphere (ISA)
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
4. Pressure and Density Altitude
Pressure Altitude
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 hPa
3. 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
4. Pressure and Density Altitude
Pressure Altitude
For Example:
Elevation is 650ft
QNH is 1020 hPa
Temperature is 30⁰C
What is the pressure altitude?
1. Determine pressure variation from ISA
1013 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 altitude
Since QNH is greater than ISA, pressure altitude will be lower
650ft – 210ft = 440ft
4. Pressure and Density Altitude
Density 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 altitude
2. Determine temperature variation from ISA at the pressure altitude
3. Multiply variation by the lapse rate, 120ft per 1⁰C
4. 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
4. Pressure and Density Altitude
Density Altitude
For Example:
Pressure altitude is 4000ft
QNH is 1020 hPa
Temperature is 22⁰C
What 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 1⁰C
22⁰C - 7 ⁰C = 15 ⁰C x 120ft = 3300ft
3. Apply the variation to the pressure altitude
Because the temperature is greater than ISA our density
altitude will
be greater than our actual altitude
4000ft + 3300ft = 7300ft
5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
For Example, calculate the
Maximum Take-Off Weight for
the following conditions:
Pressure altitude 4000ft
Temperature 25⁰C
Take off Distance Available 800m
Surface long dry grass
No slope
15kt Headwind
5. Calculate Take-Off Perf.
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
5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
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
5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
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
5. Calculate Take-Off Perf.
Take Off Performance – Typical Cessna Chart
Method:
7. The Maximum Take Off
Weight is the lesser of the
climb weight limit
(1060kg) and the runway
performance limit
(1000kg)
5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
For Example, calculate the TakeOff Distance Required for the
following conditions:
Pressure altitude 2000ft
Temperature 20⁰C
Surface Long dry grass
2% Down slope
5kt Headwind
Take-Off Weight 1000kg
5. Calculate Take-Off Perf.
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
5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
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
5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
Method:
5. Follow the guide lines to
determine the Take-Off
Distance Required 750m
5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
For Example, calculate the
Landing Distance Required and
Maximum Landing Weight for the
following conditions:
Pressure altitude 7000ft
Temperature 15⁰C
No slope
10kt Headwind
5. Calculate Landing Perf.
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
5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
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
5. Calculate Landing Perf.
Landing Performance – Typical Cessna Chart
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
5. Calculate Take-Off Perf.
Landing Performance – Typical Piper Chart
For Example, calculate the
Landing Distance Required for
the following conditions:
Pressure altitude 4000ft
Temperature 30⁰C
2% Down slope
10kt Headwind
5. Calculate Take-Off Perf.
Landing Performance – Typical Piper Chart
For Example, calculate the
Landing Distance Required for
the following conditions:
Pressure altitude 4000ft
Temperature 30⁰C
2% Down slope
10kt Headwind
5. Calculate Take-Off Perf.
Take Off 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’
5. Calculate Take-Off Perf.
Take Off Performance – Typical Piper Chart
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?