030 aırcraft performance
031 MASS AND BALANCE
Lesson Objectives
At the conclusion of this lesson you will…
⚫Understand why weight and balance is critical to safety
of flight
⚫Be familiar with the terms associated with weight and
balance
⚫Be familiar with the methods of calculating weight and
balance
⚫Understand the effect weight and balance has on aircraft
performance
MASS is the amount of an item inside a
body.
This is expressed in kilograms or pounds
depending on the system used.
FaXA=FbXB
Weight Terms
� Empty Aircraft
� Standard Empty Weight – weight of a standard airplane including
unusable fuel, full operating fluids and full oil
� Basic Empty Weight – Standard Empty Weight plus optional
equipment
� Starting Point of Weight and Balance
>
>
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Fire extinguishers
Pyrotechnics
Emergency oxygen equipment
Supplementary electronic equipment
BEM
Weight Terms
� Useful Load – total usable fuel, passengers, and cargo
� Payload – passengers and cargo
� What essentially could be revenue generating
Traffic Load
Variable Load
Dry Operating Mass (DOM)
� Is the total mass of the aeroplane ready for a specific type of operation
excluding all usable fuel and traffic load. The mass includes items such as:
� 1. Crew and crew baggage
� 2. Catering and removable passenger service equipment
� 3. Potable water and lavatory chemicals
� 4. Food and beverages
� BEM + Variable Load =Dry Operating Mass
STRUCTURAL LIMITATIONS
� MaxIMum Structural TaxI Mass(MSTM)
Is the structural lImItatIon on the mass of the aeroplane at the
commencement of taxI.
� MaxIMum Structural Take-Off Mass(MSTOM) The maxIMum
permISSIBLE total aeroplane mass at the start of the take-off run.
Maximum Structural Landing
Mass(MSLM) - The maximum
permissible total aeroplane mass on
landing under normal
circumstances.
Maximum Zero Fuel Mass (MZFM) The maximum permissible mass of an
aeroplane with no usable fuel.
CALCULATIONS
+ BasIc Empty WeIght
+ VarIable Load
+ TraffIc Load
+ Usable Fuel
� =Ramp WeIght
� - Fuel used for start, taxI and run-up
� = Take-off WeIght
� - Fuel used for flIght
� = LandIng WeIght
WeIght Terms
� Fuel
� Usable Fuel – fuel whIch can be used for flIght plannIng
� Unusable Fuel – fuel whIch cannot be use In flIght due to fuel tank
desIgn
Fuel DefInItIons
� Block Fuel (bulk fuel or ramp fuel)
� Start,Run up,and TaxI Fuel
� Take off Fuel
� TrIp Fuel
� LandIng Fuel
-ContIngency Fuel
-Reserve Fuel
-ALTERNATE FUEL
-EXTRA FUEL
Usable Fuel
� LandIng Fuel + TrIp Fuel = Take-Off Fuel
� Take-Off Fuel + Start and TaxI Fuel = Ramp Fuel
� OperatIng Mass (OM) -Is the DOM plus fuel but wIthout traffIc
load.
� From DOM, the aIrcraft can be brought up to OM by loadIng
the Take-Off Fuel (TOF) but none of the passengers, baggage,
ballast, and cargo.
� DOM+TOF =OM
� BEM + VL + TOF = OM
Zero Fuel Mass (ZFM)
�
Is DOM plus traffIc load but excludIng fuel. From DOM, the
aIrcraft can be brought up to ZFM by loadIng all of the
passengers, baggage, ballast, and cargo but none of the fuel.
� DOM + TraffIc Load = ZFM
� BEM + VL + TraffIc Load =ZFM
CG
LOCATION
CalculatIng The BEM CG
LONGITUDINAL STABILITY CG
POSITION IN FLIGHT
1-FUEL CONSUMPTION
2-FLAP EXTENSION/RETRACTION
3-GEAR
EXTENSION/RETRACTION
4-CARGO MOVEMENT
FUEL CONSUMPTION
FLAPS EXTENSION/RETRACTION
LANDING GEAR DESIGN
CARGO
CG LocatIon
MSTOM
MZFM+TAKE-OFF FUEL=TOM
MSLM+TRIP FUEL =TOM
THREE CG POINTS THAT MUST BE CALCULATED
� Take off Mass(TOM)
� LandIng Mass(LM)
� Zero Fuel Mass(ZFM)
Stability
Stability
Stability is the tendency of an object (airplane) to
return to its state of equilibrium once disturbed from
it. There are two kinds of stability: static and dynamic.
• Static stability is the initial tendency of an object to
move toward or away from its original equilibrium
position.
• Dynamic stability is the position with respect to time,
or motion of an object after a disturbance.
Static Stability
Positive Static Stability
If an object has an initial tendency toward its original equilibrium
position after a disturbance, it is said to possess positive static
stability.
Static Stability
Negative Static Stability
Is the initial tendency to continue moving away from equilibrium
following a disturbance.
Static Stability
Neutral Static Stability
Is the initial tendency to accept the displacement position as a new
equilibrium.
Static Stability
Positive-Neutral-Negative
Dynamic Stability
Positive Dynamic Stability
After it is released, it will roll back to the bottom and up the other side.
It will roll back and forth, oscillating less and less about the equilibrium
position until it finally came to rest at the bottom of the bowl. It
possesses positive dynamic stability.
Dynamic Stability
Neutral Dynamic Stability
If the ball oscillates about the equilibrium position and the oscillations
never dampen out, it possesses neutral dynamic stability.
Dynamic Stability
Negative Dynamic Stability
If, somehow, the ball did not slow down, but continued to climb to a
higher and higher position with each oscillation, it would never return
to its original equilibrium position, depicts negative dynamic stability.
Maneuverability
The quality of an airplane that permits it to be maneuvered easily and
to withstand the stresses imposed by maneuvers. It is governed by
the airplane’s weight, inertia, size and location of flight controls,
structural strength, and powerplant. It too is an airplane design
characteristic.
Controllability
The capability of an airplane to respond to the pilot’s control,
especially with regard to flightpath and attitude. It is the quality of
the airplane’s response to the pilot’s control application when
maneuvering the airplane, regardless of its stability characteristics.
Flight Controls and
Effectiveness
As the CG moves toward the fwd lImIt
� StabIlIty
� ControllabIlIty
� ClImb
� TrIm Drag (deflectIon of the elevator)
� WIng LoadIng Increase
� Stall Speed
� Range and Endurance
� LandIng Speed
As the CG moves toward the AFT lImIt
� StabIlIty
� ControllabIlIty
� ClImb
� TrIm Drag
� WIng LoadIng decrease
� Stall Speed SpIn
� Range and Endurance
� LandIng Speed
EFFECT OF OVERLOADING
� • If MaxImum Take-off Mass (MTOM) Is exceeded
�
take-off run
�
clImb performance
�
aIrspeed
�
stall speed
�
fuel consumptIon.
�
range.
�
landIng speed &landIng run.
�
Heavy brakIng, damaged tyres.
CG ENVELOPE
AIRCRAFT
PERFORMANCE
FUnDAMENTAL POF
DYNAMIC PRESSURE
AEROPLANE SPEEDS
IAS
CAS
EAS
TAS
GS
MACH NUMBER
LIFT
Lift increases when
Extending flaps,slats,slots
Pulling the sticks,Increasing Aoa
Increasing thrust
TOTAL DRAG
EFFECT OF MASS
THE EFFECT OF FLAP
STEADY CLIMBING FLIGHT
STEADY DESCENDING FLIGHT
THE GLIDE
AEROPLANE PERFORMANCE CLASSES
98
STAGES OF FLIGHT
� Four stages of flIGhts are consIdered.
1. Take-off
2. ClImb and CruIse
3. Descent
4. LandIng
99
TAKE OFF
100
TAKE OFF
The Take-Off Performance of the
aeroplane needs to be compared to
the runway and surroundIng obstacles In
the exIstIng condItIons prIor to actually
takIng off.
Take-off
101
Brake
relase
point
Rotatio
n point
Ground Roll (Take-off Roll)
Airborne
Section (Initial
Climb)
The Take-off stage flight is defined as being
from the brake relase point until the aircraft
reaches a specified height. (screen height).
102
Take-off
� Take off or Ground Roll : From brake release untIl LIft-off (VLO)
� InItIal ClImb: From lIft off untIl the screen heIght.
TODR: The distance from
brake release until the
screen height
VLO
BRP
Take-off Roll
TODR – Take-off
Distance Required
Initial Climb
Take-off (Dıstance Avaılable)
103
TORA: The length of runway declared avaIlable and suItable for the
ground run of an aeroplane.
STOPWAY: A defIned obstacle free rectangular area on the ground at
the end of TORA the same wIdth as the assocIated runway prepared
as a suItable area In whIch an aeroplane can be stopped In the case
of an abandoned take-off.
CLEARWAY: A defIned rectangular area on the ground or water under
the control of the approprIate authorIty, selected or prepared as a
suItable area over whIch an aeroplane may make a portIon of Its InItIal
clImb to a specIfIed heIght. The clearway Is beyond TORA In the
dIrectIon of the extended centre lIne.
TODA: TORA + Length of Clearway or 1.5 x TORA
Take-off (Dıstance Avaılable)
104
107
Factors affectıng Take-off
(Mass)
MASS Increases
� Increase InertIa, reducIng
acceleratIon
� Increase wheel load,
reducIng acceleratIon
Increase Take-off dIstance
� Increase Take-off speed
10% increasing mass
20% increase
take-off distance
Also reduces initial climb angle
108
Factors Effectıng Take-off (DensIty)
� DensIty decreases
� Reduced thrust and therefore accelAratIon
� Increases TAS of Take-off
� Reduces InItIal clImb angle
HIGH, HOT and HUMID condItIons DECREASE AIrcraft Performance
Factors Effectıng Take-off (Wınd)
110
The affect of either a headwind or a tailwind
can be quite marked on the take-off distance.
� HeadwInd
Reduces ground speed for a given
IAS and increase initial climb
angle.
DECREASES TAKE-OFF DISTANCE
Factors Effectıng Take-off (WInd)
111
� TaIl WInd
Increase the ground speed for
gIven IAS and reduce the InItIal
clImb angle.
INCREASE THE TAKE-OFF DISTANCE
Factors Effectıng Durıng Take-Off (Slope)
112
The slope of a runway affects the take-off dIstance:
Downslope The downslope wIll assIst In the accelAratIon
process and thus decrease the take-off dIstance.
Upslope The upslope wIll counter the acceleratIng force and
wIll cause an Increase In the take-off dIstance.
For every 1% slope the take-off dIstance
affected by 5% or factor of 1.05
RUN WAY SLOPE
115
Factors Effectıng Take-Off (Surface)
� Grass runways, Increase the wheel drag
and Increase the take-off dIstance
� Water, snow and slush surface, Increase
wheel drag and create spray drag
(precIpItatIon drag) whIch wIll Increase
the take off dIstance.
� Water, Ice and slush contamInated
runways decrease the wheel frIctIon.
� ContamInated runways may also lead to
engIne faIlure, dIrectIonal control
dIffIcultIes are structural damage.
116
Factors Effectıng Take-Off (Weather)
� Heavy raIn, can Increase drag and decrease
lIft
� WIndshear Is rapId change In wInd speed /
dIrectIon. ThIs may cause performance loss.
WIND SHEAR
Factors Effectıng Take-Off (Flap Settıngs)
118
Small Flap angles decrease take-off dIstance and
decrease the clImb angle.
CLIMB
BasIc AerodynamIcs
� An aIrcraft possesses a steady clImb capabIlIty by convertIng
propulsIve energy In excess of that requIred to maIntaIn steady level
flIght Into potentIal energy.
� An aIrcraft can eIther be clImbed steeply at a low aIrspeed, or be
clImbed at a hIgher aIrspeed at a shallower angle.
BasIc AerodynamIcs
MaxImum ANgle of ClImb (Vx)
If the aIrspeed Is too low or too hIgh, all of the power or thrust
avaIlable wIll be needed to overcome the drag, thus reducIng an
aIrcraft's clImb capabIlIty to zero.
MaxImum Angle of ClImb. - ThIs Is achIeved when an aIrcraft gaIns
the most altItude In the shortest horIzontal dIstance covered, I.e.
best gradIent. ThIs occurs when It Is
flown at a relatIvely low aIrspeed, and gIves good ground obstacle
clearance.
MaxImum Rate of ClImb (Vy)
MaxImum Rate of ClIMb
ThIs Is achIeved when an aIrcraft gaIns the most altItude In the
shortest tIme.
ThIs occurs when It Is flown at a small angle of clImb and
hIgh aIrspeed.
a
Forces IN a StraIght Steady ClImb
With increasing angles of climb the amount of lift
required steadily decreases, whilst the thrust requirement
increases.
ClImb Speed
The clImb can be defINed by usIng the followIng two speeds:
Vx -The maxImum gradIent of clImb speed.
Vy - The maxImum rate of clImb speed.
Factors AffectIng ClImb Performance
The clImb performance wIll be affected
by certaIn varIables:
WeIght
Any change In aeroplane weIght wIll
affect:
✔The clImb gradIent
✔The rate of clImb
✔The drag
Both the climb gradient and rate of climb speeds decrease as the weight increases.
With an increase in weight more induced drag is produced. This will move the power required curve upwards. Because the power available stays the same this
means that there is a reduction excess power which accordingly decreases the climb performance.
Factors AffectIng CLImb Performance
WInd
HeadwInd - Increases the effectIve clImb angle
TaIlwInd -
Decreases the effectIve clImb angle
Factors AffectIng ClImb Performance
ConfIguratIons
Flaps - Use of the flaps Increases both lIft and drag. Any lIft Increase
does not Influence the clImb; an Increase In drag reduces the clImb
performance.
The advantage of usIng flap Is the reductIon In the stallIng speed.
LandIng Gear - The clImb gradIent decreases when the landIng gear Is
In the down posItIon.
Factors AffectIng ClImb
Performance
CeIlIng
� As an aeroplane clImbs eventually the gradIent and the rate of clImb decrease to
zero. ThIs Is known as the absolute ceIlIng.
� ThIs wIll Increase wIth decreasIng aeroplane mass.
� ThIs Is not a practIcal altItude for the aeroplane to use so most flIght manuals offer
an aeroplane servIce ceIlIng.
✔ Absolute CeIlIng - The pressure altItude where the rate of clImb Is zero.
(The maxImum heIght AMSL at whIch an aIrcraft can maIntaIn level flIght under
standart atmospherIc condItIons)
✔ ServIce CeIlIng - The pressure altItude where the rate of clImb Is a defIned value:
(The hIghest altItude at wHIch an aIrcraft can maIntaIn a steady rate of clImb of 100
fpm)
GENERAL PERFORMANCE
CRUISE
Forces In the CruIse
For constant speed level flIght In the cruIse the forces shown In the
dIagram below must equalIse.
L
T
D
W
Lift – Weight : causes large pitch down
moment
Endurance / Range
Endurance - The tIMe that an aeroplane can fly on a set amount of fuel.
Range - The dIstance that an aeroplane can fly on a set amount of fuel.
SpecIfIc Range for Jet Aeroplanes
Fuel flow In a turbojet Is SFC multIplIed by thrust requIred, the specIfIc range
equatIon:
SpecIfIc Range = (TAS) / (SFC x Thrust RequIred)
For a jet aeroplane Thrust equals Drag and for a propeller aeroplane the power
avaIlable must equal the power requIred.
In real terms the SR depends upon the engIne effIcIency and the aIrframe
effIcIency.
JET
PISTON PROPELLER
Factors AffectIng Range (WIND)
MaxImum range speed Is affected by the change
In groundspeed and the dIstance flown.
HEADWIND
✔Headwind - A higher maximum range speed is
required. Thus the ground distance travelled will
be less.
AILWIND
✔Tailwind - A lower
maximum range speed
is required. The ground
distance travelled will
be more.
Factors AffectIng Range (WEIGHT)
� Increased weIght Increases the drag and
power.
� The greater the thrust the greater the fuel
flow requIred whIch wIll decrease the SR.
WEIGHT OR MASS
WIND
� DOES NOT AFFECT ENDURANCE
� BECAUSE THE HORIZONTAL POSITION OF THE AEROPLANE IS
IRRELEVANT FOR ENDURANCE
GENERAL PERFORMANCE
DESCENT
StraIght Steady Descent (DIve)
Steady GlIde
GRAPHS
The Effect of the LIft/Drag RatIo on
GlIde Performance
The Effect of the LIft/Drag RatIo on GlIde
Performance
the mInImum drag speed produces the best glIde performance, flIght
at any other speed wIll reduce the lIft/drag ratIo, and consequently
Increase the angle of glIde.
ThIs wIll reduce the aIrcraft's glIde performance, and reduce the
overall glIde dIstance.
The Effect of a Steady WInd on GlIdE
Performance
SUMMARY
The followIng poInts summarIse the glIde:
⮚ Increased weIght Increases the forward speed of the aeroplane. The lIft and drag are consequently
Increased and so the lIft/drag ratIo remaIns constant. Thus:
✔ The glIde angle remaIns constant.
✔ The aeroplane wIll descend at a hIgher speed whIch Increases the rate of descent.
⮚ If the aeroplane descends at a constant IAS
✔ Both the gradIent and pItch angle are constant
GENERAL PERFORMANCE
LANDING
LANDING
Airborne Section
Touch down
point
Landing Roll
Landing Distance
Required
VREF
Class B/C Aeroplane VREF ≥ 1.3 VSO
Force DurINg LandIng
WeIght / LIft
⮚ LIft wIll need to be reduced to zero
⮚ The weIght of the aeroplane can be balanced by ground through the wheels
⮚ LIft can be destroyed by usIng the flIght and ground spoIlers
Speeds