Embed Size (px)
Citation preview
Airfield Performance
For the aircraft the field performance is important due to the fact that the aircraft is required to land
and take off on unprepared, grass or asphalt runways of a short length.
Within the Scottish islands, there is a large variety of airfields each with its own field characteristics,
from sand to hardcore and of length from 467 metres to well over 2000 metres.
From the airfields within Scotland and also looking at several commercial routes needing a STOL, the
aircraft is required to have a maximum take off and landing distance up to the screen height of 10.7
metres of 450 metres with a runway surface of grass.
Take-Off Performance
A take-off is defined as the section of flight in which the aircraft starts from zero flight speed up to the
speed at which the aircraft has
enough lift to get the aircraft
airborne and set up in the initial
climb to a screen height of 10.5m
A typical take off profile is shown
in the following figure.
Equations used for the calculation
of the acceleration of the aircraft
within the take-off phase of flight.
Equation 1: Acceleration on the Ground
a x=V t =
T x−C D12V 2 SWING−mg−C L
12V 2 S WING
m
Figure 1: Take-Off Profile[7]
L
L1 L2 L3 L4
Ground Run
Ground Segment Airborne Segment
AB
Air Acceleration
ClimbV = 0 VLOF V2V2
Transition
L
L1 L2 L3 L4
Ground Run
Ground Segment Airborne Segment
AB
Air Acceleration
ClimbV = 0 VLOF V2V2
Transition
This is the acceleration of the aircraft
whilst it is travelling along the
ground and has the added drag force
due to the friction caused by the
wheels on the runway surface, this
friction force is proportional to the
force normal to the free stream
direction. Basically as the airspeed increases the aircraft will increase speed and therefore the wing
lift will increase and the force normal to the free stream direction will decrease and therefore the
friction force acting on the wheels will decrease.
Equation 2: Acceleration in the Air
Once the aircraft reaches the lift off speed, by definition, the aircraft will be airborne and there will be
no ground friction force acting on the wheels and therefore the only drag force is the aerodynamic
force applied to the aircraft.
Equation 3: Approximation of Real Time Velocity
This gives an approximation of the real time velocity by adding the acceleration multiplied to the time
difference to the previous velocity. If the time difference is made minimal then the error in the
velocity becomes very small, the reason for this is that the acceleration is not constant and is
constantly changing, if the time difference is reduced the actual acceleration at the velocity point
becomes very close to the approximation and approximated velocity is very close to the real time
velocity.
The distance that the aircraft travels during the time difference is given found by the following.
a x=V t =
T x−C D12V 2 SWING
m
V t≈V t− ta t− t t
Figure 2: Forces during the Ground Run[7]
T V
L
WFm Ff
NmNf
D T V
L
WFm Ff
NmNf
D
Equation 4: Increment of Distance during Take-Off
The total ground distance to which the aircraft travels during the take-off run is given by calculating
the sum of all the incremental distances.
Equations used to during calculations of the initial climb.
Equation 5: Lift Load Factor
The load factor in the initial climb can be found as a
constant due the fact that in the initial section of the climb
the climb velocity and the stall velocity will become
constant and the value will become fixed as shown.
Equation 6: Angle of Climb
The angle of climb is the angle between the horizontal and the flight path of the aircraft, this is a
given for the initial section of climb till at least the screen height.
Equation 7: Radius of Transition Arc
The transition arc is the point at which the aircraft changes
from horizontal flight to the initial climb flight path. The
radius of the transition arc is used both as a distance of the
aircraft travelled along the ground and the height achieved by the aircraft during the transition arc.
nL=L
mg=
V 2
V S
2
=1.22
r=V 2
2
g nL−cos
Figure 3: Transition Arc[7]
θ
θ
Vr
L3
h3
θ
θ
Vr
L3
h3
Figure 4: Climb Flight Path[7]
θ
V2
L4
h3
Hθ
V2
L4
h3
H
∆ l = V a . ∆ t =( V t + V t − ∆ t )
2. ∆ t
=arcsin T A−T R
mg
Equation 8: Height after the transition arc
Equation 9: Distance after Transition Arc
The initial climb horizontal distance is found by using trigonometry on the aircraft flight path, where
H is the take off screen height.
The ground run of the aircraft during take-off is given as the distance l1. By adding all the distance
found from the various equations, the total distance of the take off distance to the screen height is
given as:
Equation 11: TODR
The take off distance required is important due to the fact that this gives the distance from the point
that the aircraft applies full power to the point where the aircraft is established in the climb and
passing the screen height of 10.5m or 35 ft. This is gives the distance that the aircraft needs for a safe
take off even if there are obstacles near or within the airport boundaries.
Equation 10: Distance during climb
θtan3
4hHl −=
)cos1.(3 θ−= rh l 3 = r . s i n θ
l=l 1l 2 l3 l 4
Landing Performance
The landing phase of the aircraft's flight is to
get the aircraft from the approach
configuration to a stop on the runway. The
aircraft begins the landing phase in the
approach configuration, flaps deployed,
undercarriage down and with a flight speed of
VREF≈1.3Vs.
In the decent, the ground distance is found by trigonometry and is given by:
Θ is the decent angle of which the aircraft flies during the approach.
The flare is the section of the landing where the aircraft's vertical
velocity is reduced in order to get a safe touchdown speed for
safety and comfort. The flare is given as a constant radius arc and
the equations used during this stage of the landing are similar to
the transition in the take-off phase and are found using simple
geometry of a circular arc.
Equation 13: Flare Load Factor
Equation 14: Flare Radius
Figure 5: Landing Phase Profile[7]
Air Phase Ground Phase
Descent
Flare
Holding Ground Run
VREF VREF VTD V = 0
AB
L1 L2 L3 L4
L
Air Phase Ground Phase
Descent
Flare
Holding Ground Run
VREF VREF VTD V = 0
AB
L1 L2 L3 L4
L
Equation 12: Decent Ground Distance
θtan1
1hHl −=
Figure 6: Flare Geometry[7]
Vref
L1 L2
r
∆ H
h1
H
θ
θ
Vref
L1 L2
r
∆ H
h1
H
θ
θ
n L =L
m . g= (
V A
V S 0
) 2 = 1 . 3 2r =
V A2
g . ( n L − c o s θ )
Equation 15: Ground Distance of Flare
Equation 16: Height at Start of Flare
During the flare, the aircraft's speed will decrease due to the fact that the aircraft has to increase lift,
and hence drag, to reduce the vertical velocity. After the flare is completed, the aircraft's velocity is
given by VF.
Equation 17: Velocity after the Flare
This velocity is usually greater than the aircraft's stall speed so a hold-off is required to get the aircraft
to touchdown. In the hold-off, the aircraft's drag is greater than the thrust that is generated therefore
the aircraft will decelerate if a constant height is maintained.
The aircraft's deceleration is calculated in the same way as for the air acceleration for the take-off,
however the thrust that is generated by the aircraft's engines will be much smaller than the
aerodynamic drag that acts on the aircraft. Once the aircraft has reached the stall speed the aircraft
will touchdown. When the aircraft is on the ground, friction acts on the gear and therefore the
deceleration will be higher.
The distance during the deceleration of the aircraft both in the air and on the ground are given in a
similar manner to that of the take-off.
By adding all the ground distances together, the total landing distance required (LDR) can be found.
Accelerate Stop Distance
The accelerate stop distance used in the performance charts is the absolute maximum accelerate stop
distance as it is taking the decision speed as the speed at which the aircraft will become airborne at. If
the aircraft is able to operate at these conditions then the aircraft when fully operational will be able to
operate without problems, due to the fact that the decision speed is usually much slower than the lift-
θsin.2 rl = h 1 = r . ( 1 − c o s θ )
V F = V A2 − 2 . g . h 1
off speed. Therefore the ASD is the ground run on the take off to the point of the stall speed and then
the ground run during the landing for the deceleration from stall speed to zero forward speed.
Out of the TODR, LDR and ASDR, the distance that is the longest will be the limiting distance for the
use of the airfield with the aircraft's parameters given.
Rate of Climb
A climb is able to occur due to the fact there is an excess in thrust. The rate of climb is the vertical
velocity of the aircraft and is given by the following equation.
Equation 18: Rate of Climb
The required gradient of the climb given by JAR 23 must be 4% given that all engines are operating
at take-off power and flaps are at take-off setting and at least 0.75% with one engine inoperative with
the propeller feathered and the operating engine being run at or below maximum continuous power.
This therefore requires that the ratio of excess thrust to weight must be equal to or greater than 0.04
for all engines operating and 0.0075 for single engine climb. For the aircraft at maximum take-off
mass of 7995kgs, the excess thrust must therefore be equal to or greater than 3137N, for both engines
operating and 588N, for single engine climb.
V c=T a−DV
mg
Range and Endurance
The range of aircraft is defined as the distance of which the aircraft will fly during its flight sector.
By using the Brequet Range Equation, the cruise distance can be found.
Equation 19: Brequet Range Equation
In the equation k is denoted as the
aerodynamic efficiency, Csp is the
specific fuel consumption for the aircraft's engines and mi is the initial mass of the aircraft during the
phase of flight, mf is the final mass of the aircraft.
An aircraft's endurance is the maximum time for which an aircraft can maintain a cruise at.
Equation 20: Brequet Endurance Equation
Where V is the aircraft's flight velocity.
The Brequet equation give some indication to the types of missions that the aircraft can be able to
perform, as is show the equations are directly proportional to the aerodynamic efficiency of the
aircraft and inversely proportional to the specific fuel consumption of the engines. The theoretical
range of the aircraft can be extended by reducing the aircraft's drag, since lift cannot be altered due to
the relatively constant mass, or using a more fuel efficient engine, therefore reducing the specific fuel
consumption.
For calculation of the endurance in the performance program, the specific fuel consumption is
multiplied by the power of the engine to give the fuel consumption per engine per hour, this is then
Figure 7: Flight Profile[7]
V
Climb Level Flight Descent
H - Operational Altitude
V
Climb Level Flight Descent
H - Operational Altitude
f
i
sp mm
gCks lnη=
f
i
sp mm
VgCkt lnη=
further multiplied by the number of engines to give the fuel consumption for the total aircraft per
hour. The endurance of the aircraft is given as the ratio of the of the total usable cruise fuel on board
the aircraft to the fuel consumption of the aircraft for both engines. This endurance is only for the
level cruise at the cruise power settings and does not take into account further climbs and descents
during the cruise. During climbs and descents the aircraft will have a change in power and specific
fuel consumption therefore each climb and descent has to be taken into account separately.
The range of the aircraft is calculated by getting the endurance as calculated earlier and then
multiplying it by the cruise velocity of the aircraft.
Improving Field Performance
Various different sections have been design in order to improve the field performance from the base
aircraft in order to be able to operate from short fields and unprepared runways.
Spoilers
Spoilers are sections of the upper wings surface that
can be moved and rotated to change the geometry of
the wing. Spoilers improve performance in 2 ways,
firstly when they are deployed they increase the
overall drag of the aircraft and secondly they reduce
the wings lift producing capability. With the spoilers
being deployed during the landing run of the aircraft,
the spoilers act to increase the profile drag of the aircraft due to the fact that they increase the wetted
area of the aircraft. Also when the spoilers are deployed the wings cross section changes and the
aerofoil becomes inefficient at producing lift. With the lift that is produced by the wings being
reduced, the normal force acting upon the undercarriage is increased and therefore the frictional force
that act to retard the forward motion of the aircraft is increased. Both these increases in the aircraft's
drag will increases the deceleration rate and reduce the ground run.
Large Trailing Edge Flaps
Trailing Edge Flaps are trailing edge sections
of the wing that can be rotated downwards
and moved. Flaps increase the chord of the
wing and therefore the wing area, increasing
the amount of lift generated by the wing. Also the trailing edge of the wing is moved downwards and
therefore increasing the sections angle of attack, this increases the lift co-efficient of the wing. To
maintain the same amount of lift with the increased lift co-efficient and wing area, the aircraft's
Figure 8: Spoilers
Figure 9: Trailing Edge Fowler Flap[5]
velocity can be reduced. The touchdown velocity can be slower and with the same level of
deceleration, the landing ground run will be smaller and there will be less energy that will need to be
dissipated by the bakes during the ground run.
Efficient Anti-Skid Brakes
Anti-Skid Brakes stop the wheels from locking, stop rotating, during hard braking,
when the wheels lock the friction co-efficient of the gear reduces and the frictional
force that acts on the gear reduces and the deceleration reduces. Anti-skid brakes
benefit an aircraft that operates on grass due to the fact that wheels will lock easier
on grass, especially when wet, than concrete or asphalt surfaces. Using anti-skid
brakes therefore maintains the highest frictional co-efficient that is possible for the surface and
therefore the best deceleration that is possible occurs.
Reverse Thrust
Reverse thrust changes the direction in which the thrust operates to being in a forward direction and
therefore acts as another retarding force during the deceleration, therefore increasing the deceleration
of the aircraft. In a turbo-prop engine, the angle of the blades is turned in a negative direction and the
blade thrust act to prevent forward motion.
During the ground run of the landing, reverse thrust is used initially to reduce the speed of the aircraft
on runways where the length is not such an issue in order to reduce the wear on the brakes and allow
them to be able to be used over far more flight sectors than if only brakes were used during the
deceleration.
With the use of all the design additions, the aircraft has the ability to be able land and come to a stop
in the shortest available distance. Reducing the LDR will firstly give the aircraft the performance
required to operate from the shortest available runways and reach the more remote communities,
secondly when they are operated from the existing sectors the aircraft will be able to operate safer.
Figure 10: Anti-Lock Carbon Brakes[6]
Performance Graphs for the Aircraft
Figure 11
The figure above shows the force values for the take-off at the MTOM and how they vary as the take-
off proceeds. Initially the aircraft's thrust is maximum due to the fact that the static thrust from the
engines is maximum and as the aircraft's velocity increases the thrust will decrease. Also in the static
case the aerodynamic lift and drag that is generated by the aircraft is zero and therefore the only
retarding force that is applied initially to the aircraft is that off the frictional force of the wheels on the
runway surface. As the aircraft's velocity increases during the take-off run, the aerodynamic lift and
drag that the aircraft experiences increases, as the increases to the lift occurs the normal force to
which the gear applies to the ground becomes less and therefore the frictional force that occurs on the
gear will decrease. However, as the airspeed increases, the total drag that is being experienced by the
aircraft will increase and the net acceleration force will decrease and hence as the aircraft's
acceleration will reduce as the aircraft reaches the end of the take-off run.
0 5 1 0 1 5 2 0 2 5 3 0 3 5- 0 . 5
0
0 . 5
1
1 . 5
2
2 . 5
3
3 . 5x 1 0
4
V e l o c i t y m / s
Forc
e N
V e l o c i t y v s F o r c e s d u r i n g T a k e O f f R u n a t a l t i t u d e o f 0 m a n d a T a k e - o f f m a s s o f 8 0 0 0 k g s .
T h r u s t
N e t A c c e l e r a t i o n F o r c e
A e r o d y n a m i c D r a g + F r i c t i o n D r a gA e r o d y n a m i c D r a g
F r i c t i o n D r a g
Figure 12
The thrust available/thrust required curve is used not only has to tool to see how much this is needed
by an aircraft to maintain level, constant velocity flight but it can also tell the theoretical maximum
velocity of which the aircraft can go. The point where the two curves intersect is the point of
maximum velocity as this is the point where the thrust available from the engines match the thrust
required to overcome drag. At the maximum take-off weight and at sea-level conditions, the aircraft
has a maximum velocity of 100 metres per second, equivalent to approximately 200 knots. The point
where the maximum endurance of an aircraft can be found from the minimum point on the thrust
required curve, this relates to a velocity of 58 ms-1. This point is where the drag on the aircraft is at a
minimum and the engines are required to do the minimum amount of work in order to keep the
aircraft aloft and therefore will burn the lowest amount of fuel. However the aircraft's velocity is very
slow in comparison to the maximum velocity that can be achieved, and the aircraft will not be able to
fly as far as could be possible. The point where the tangent to the thrust required curve passes through
the origin of the graph is the point where the maximum range of the aircraft is theoretical possible.
4 0 6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 0 1 8 0 2 0 0 2 2 0- 1
- 0 . 5
0
0 . 5
1
1 . 5
2
2 . 5
3
3 . 5
4x 1 0
4
V e l o c i t y m / s
Thru
st N
T h r u s t A v a i l a b l e a n d T h r u s t R e q u i r e d c u r v e f o r A l t i t u d e o f 0 m .
T h r u s t A v a i l a b l e
T h r u s t R e q u i r e d
Take-Off Distances
Figure 13
This performance graph shows the effect of changes in mass and altitude to the ground run distance
for the take-off phase of the flight. As the aircraft's mass increases either due to an increase in payload
or fuel, the aircraft's ground run distance will increase. Firstly, with the increase in mass, the aircraft
will be slower to accelerate proved by Newton's 2nd Law and secondly, the aircraft will have to attain
a higher lift-off speed due to the increased stall speed. At MTOM, the aircraft will take nearly 3 times
longer than the aircraft at a typical wet operating mass. The increasing altitude of the runway also has
an effect on the take-off performance, the reason for the degrading performance with the increase in
altitude is primarily due to the fact that as the altitude increases the density of the air will decrease. As
the aircraft's lift is directly proportional to the density of the air, the aircraft will have to obtain a
greater speed in order for the same amount of lift required for lift-off. In the event of a short runway
5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 00
1 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
7 0 0
M a s s ( k g )
Tak
e-O
ff G
roun
d D
ista
nce
(met
res)
T a k e - O f f G r o u n d D i s t a n c e v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
at a high altitude, the aircraft may have to have a restricted take-off mass in order to get out of the
airfield and then land at a lower altitude airfield to take on the required fuel.
Figure 14
This is the distance from the minimum distance from the runway threshold to the aircraft passing the
screen height of 35 feet or 10.67metres. As the aircraft has the transition and the initial climb in the
calculation and therefore the distance will be larger, however the same trend of increasing distance
with increasing mass and altitude still applies. Taking the simple case where the runway is going to be
at sea level, the aircraft, even at MOTM will still be able to climb and reach the screen height in under
350 metres.
5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 01 0 0
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
7 0 0
8 0 0
M a s s ( k g )
Tak
e-O
ff D
ista
nce
Req
uire
d (m
etre
s)
T a k e - O f f D i s t a n c e R e q u i r e d v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Landing Distances
Figure 15
This graph shows the variation of the minimum ground run in the landing phase of the landing phase.
The landing mass of the aircraft is taken as the take-off mass minus the fuel burned during the flight.
As the aircraft's weight increases, the landing ground run increases due to the fact that the aircraft will
have to obtain a higher touchdown speed and hence the aircraft will take longer, and further, to stop.
With the increase in the altitiude, the density of the air reduces and the touchdown, and stall, velocity
will increase once again and distances increases. This is the absolute minimum ground run distance
with the spoilers being applied on touchdown and the maximum braking force being applied by the
brakes giving a frictional co-efficient of 0.4. If the aircraft is operated from runways in which there is
extra distance, the brakes can be used less, both to increase passenger comfort in the ground run phase
and also to increase the life of the brakes by using them less and enabling less maintenance costs.
4 0 0 0 4 5 0 0 5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 04 0
6 0
8 0
1 0 0
1 2 0
1 4 0
1 6 0
1 8 0
2 0 0
2 2 0
L a n d i n g M a s s ( k g )
Land
ing
Gro
und
Dis
tanc
e (m
etre
s)
L a n d i n g G r o u n d D i s t a n c e v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Figure 16
This graph shows the total minimal landing distance with the maximum braking force being applied
and the spoilers activated on touchdown. This is the distance from the screen height of 50 feet to the
stop point of the aircraft, this is the distance to show the total landing distance that is required by the
aircraft on a runway and will be the determining factor in the choice of airfields that the aircraft will
be able to operate out of and, if required, the maximum allowable landing weight. From studying the
previous figures and the next figure, it appears that the landing distance is the limiting factor on the
aircraft and it will be the determining distance for the aircraft operations.
4 0 0 0 4 5 0 0 5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 03 0 0
4 0 0
5 0 0
6 0 0
7 0 0
8 0 0
9 0 0
L a n d i n g M a s s ( k g )
Land
ing
Dis
tanc
e R
equi
red
(met
res)
L a n d i n g D i s t a n c e R e q u i r e d v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Figure 17
This is the figure that shows the different distances that are limiting the aircraft's operation on an
airfield at sea level. As is show the landing distance is the longest and therefore the landing distance
will be used to find the minimal runway distance that can be used for an aircraft at a specific mass.
This graph is given as the aircraft performance distances at a sea level density of 1.225kgm-3. The
short field landing is done with using a 60 degree flap setting, the difference between the short field
landing and the standard landing distance is very small due to the fact that there is only a very small
increase in the lift co-efficient and hence the velocities during the landing will be very similar and
also there is an increase in drag but does not have a large difference in the retarding force during the
decelleration and hence there does not appear to be much change in the distances.
4 0 0 0 4 5 0 0 5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 01 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
M a s s ( k g )
Dis
tanc
e (m
)R u n w a y D i s t a n c e v s M a s s
T O D R
L D R
A S D RL D R - S h o r t F i e l d
A S D R - S h o r t F i e l d
Aircraft Velocities
Figure 18
This graph shows the point where the maximum avialable thrust equal the thrust required. This is the
maximum level flight velocity and will give the maximum cruise speed, this flight speed will be very
inefficient in terms of fuel being burnt, however the aircraft will get to the destitation quickest. Since
this aircraft is designed for the commercial market, the direct operating costs will be very important
and therefore the operators will want to operate the aircraft at the highest miles per fuel used.
Although this speed will give the aircraft the lowest fuel burn for the flight, however the flight will
take longer and therefore other costs such as maintenance and crew costs will be higher and therefore
may not be the most cost efficient speed to operate the aircraft.
5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 01 9 5
2 0 0
2 0 5
2 1 0
2 1 5
2 2 0
2 2 5
2 3 0
2 3 5
2 4 0
M a s s ( k g )
Max
imum
Vel
ocity
(kn
ots)
M a x i m u m V e l o c i t y v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Figure 19
The stall velocity is the minimal flight velocity with the wing operating at the maximum lift co-
efficient and no high lift devices being deployed. The stall speed is given by V s= 2mg S C Lmax
,
therefore as the mass of the aircraft increases, the stall speed will increase due to the fact that the
weight of the aircraft must be equal to the lift generated in order to maintain the level flight. As the
density decreases with the increase of altitude, the stall speed will increase. At the MTOM, in sea
level conditions, the stall velocity of the aircraft is found to be 78 knots with increasing to 119 knots
TAS at 8000 feet.
5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 06 0
7 0
8 0
9 0
1 0 0
1 1 0
1 2 0
M a s s ( k g )
Sta
ll V
eloc
ity (
knot
s)S t a l l V e l o c i t i y v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Figure 20
This is the speed, commonly refered to as Vr, which the aircraft will rotate and begin the transition arc
during the take-off phase. It is given as 1.1 times the stall speed of the aircraft and this will give the
aircraft sufficient speed in which to get airborne.
5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 06 0
7 0
8 0
9 0
1 0 0
1 1 0
1 2 0
1 3 0
1 4 0
M a s s ( k g )
Rot
ate
Vel
ocity
(kn
ots)
R o t a t e V e l o c i t i y v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Figure 21
This is the flight speed for the initial climb just after the transition arc, and is refered to the V2 speed.
With the flight speed given as 1.2 times the stall speed, this will give the aircraft extra lift in order to
allow the aircraft to produce a safe initial climb.
5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 0 7 5 0 0 8 0 0 07 0
8 0
9 0
1 0 0
1 1 0
1 2 0
1 3 0
1 4 0
1 5 0
M a s s ( k g )
Clim
b V
eloc
ity (
knot
s)C l i m b V e l o c i t y v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
Figure 22
The approach speed is generally given as 1.3 times the stall speed for a steady approach in a constant
wind. The aircraft will have an approach speed of 75 knots at a landing weight of 7000kgs, a typical
landing mass for the aircraft carrying a full payload, and as low as 58knots for the minimal operating
mass. If the aircraft is flying in gusts an addition of 5 knots is added in order to be able to keep the
approach safe. If the wind dies down by 10 knots without warning, the aircraft's velocity may become
very slow and close to the stall if the additional speed is not added.
4 0 0 0 4 5 0 0 5 0 0 0 5 5 0 0 6 0 0 0 6 5 0 0 7 0 0 05 0
6 0
7 0
8 0
9 0
1 0 0
1 1 0
1 2 0
L a n d i n g M a s s ( k g )
App
roac
h V
eloc
ity (
knot
s)A p p r o a c h V e l o c i t y v s M a s s
0 f e e t1 0 0 0 f e e t
2 0 0 0 f e e t
3 0 0 0 f e e t
4 0 0 0 f e e t5 0 0 0 f e e t
6 0 0 0 f e e t
7 0 0 0 f e e t8 0 0 0 f e e t
