1. MASS (WEIGHT) & BALANCE
LECTURE 2
COMPOSITION OF AIRCRAFT WEIGHT
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2. WEIGHT DEFINITION
Weight is the force that results from the acceleration by gravity on the mass of an object.
W = mg
In modern scientific usage, weight and mass are fundamentally different quantities.
Mass is an intrinsic property of matter, whereas weight is a force that results from the action of gravity on matter: it measures how strongly the force of gravity pulls on that matter.
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3. Continue..
However, in most practical everyday situations the word "weight" is used when, strictly, "mass" is meant.
For example, most people would say that an object "weighs one kilogram", even though the kilogram is a unit of mass. weight will give us more stability
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4. Therefore in our discussion later, please KNOW that WEIGHT is a MASS of aircraft.
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5. Continue..
The lift generated by the airfoils of the aircraft must be able to overcome the weight. Why?
Less weight will give us better performance
More weight will give us more stability
Excessive weight will cause the aircraft crash.
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6. TIME TO THINK!! THINK OUT OF THE BOX!
Do you agree with all the facts given??
Give any examples to proves this fact.
You may relate it with anything in your life. Not necessarily related with aviation.
THINK OUT OF THE BOX!
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7. WEIGHT CONTROL
When an aircraft is designed, it is made as light as the required structural strength will allow, and the wings or rotors are designed to support the maximum allowable weight.
Weight is a critical factor for an aircraft.
Excessive weight reduces the efficiency of an aircraft and the safety margin available if an emergency condition should arise.
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8. COMPOSITION OF AIRCRAFT WEIGHT
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9. OVERVIEW All aircraft have a specified maximum mass.
This limit must be respected, whether the aircraft is a micro-light or a Boeing 747 or an Airbus A380.
Attempting to fly an overloaded/overweight aircraft can cause various effects (Performance and stability control)
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10. To ensure aircraft can fly safely, limitation are set by
the design engineer.
Maximum Take-Off Weight (MTOW): The maximum permissible weight to conduct a takeoff.
Maximum Landing Weight (MLW): The maximum permissible weight to conduct a landing.
Maximum Zero Fuel Weight (MZFW): The maximum weight of an aircraft which its structural limits would allow.
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11. Maximum Takeoff Weight (MTOW)
MTOW of an aircraft is the maximum weight at which the pilot of the aircraft is allowed to attempt to take off.
It is the heaviest weight which should be limited in order to ensure the aircraft can fly safely during take-off.
At its MTOW an aircraft complies with all the structural and performance requirements.
The MTOW of an aircraft is fixed.
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12. Continue..
It does not vary with altitude or air temperature or the length of the runway to be used for takeoff or landing.
MTOW is usually specified in units of kilograms or pounds.
What is the difference between kilogram (kg) and pound (lb)??
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13. Maximum Landing Weight (MLW)
The maximum permissible weight to conduct a landing.
What will happen if the aircraft weight during landing is greater than MLW? What is the possibility?
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14. Maximum Zero-Fuel Weight (MZFW)
The Zero Fuel Weight (ZFW) of an airplane is the total weight of the airplane and all its contents, minus the total weight of the fuel on board.
When an airplane is being loaded with crew, passengers, baggage and freight it is most important to ensure that the Zero Fuel Weight does not exceed the Maximum Zero Fuel Weight.
Designers of airplanes can optimize the MTOW and prevent overloading in the fuselage by specifying a MZFW. This is usually done for large airplanes.
Most small airplanes do not have a MZFW specified among their limitations.
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15. Example..
For example, if an airplane is flying at a weight of 5,000 lb and the weight of fuel on board is 500 lb, the Zero Fuel Weight is 4,500 lb.
Some time later, after 100 lb of fuel has been consumed by the engines, the total weight of the airplane is 4,900 lb and the weight of fuel is 400 lb.
What is the Zero Fuel Weight?
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16. All Up Weight (AUW)
The total weight of the aircraft including of all items at any specific time.
During take off All up weight (AUW) must not exceed the Maximum Take Off Weight (MTOW)
For Take-Off: AUW/TOW ≤ MTOW
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17. Continue.. For Landing: AUW/LW ≤ MLW
During landing All up weight (AUW) must not exceed the Maximum Landing Weight (MLW)
For Landing: AUW/LW ≤ MLW
Total ZFW also must not exceed the Maximum Zero Fuel Weight (MZFW). ZFW ≤ MZFW
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18. For Take-Off: AUW/TOW ≤ MTOW For Landing: AUW/LW ≤ MLW
IMPORTANT
For Take-Off: AUW/TOW ≤ MTOW For Landing: AUW/LW ≤ MLW
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19. All Up Weight (AUW) AUW = DOW + PAYLOAD + FUEL
Where, PAYLOAD = Passengers & Cargo FUEL = Flight Fuel + Reserve Fuel DOW = Dry Operating Weight DOW also known as Aircraft Prepared for Service (APS)
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20. Dry Operating Weight (DOW) @ APS
Basic Weight + Crew & Baggage
Basic Weight
It consists of Empty Weight + Basic Equipment Weight.
Empty Weight
Weight of airframe, engines and standard structures.
Basic Equipment Weight
Weight of common installations inside the airplane.
These items are standard: Fuel that cannot be used, Engine oil, oxygen,Miscellaneous equipment, galley structures and fixed inserts. These items are operational: crew and crew baggage, passenger service equipment, catering allowance, potable water, waste tank disinfectant, Items for sale if applicable, emergency equipment.
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21. Payload
The weight of all persons and items of load carried in an aircraft for which a fare or charge is being paid.
PAYLOAD = Passengers + Cargo
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22. Flight Fuel = Fuel Flow × Flight Time
FUEL = Flight Fuel + Reserve Fuel
Flight Fuel = It is the weight of the fuel required for and burnt during a flight.
With the given flight distance and mean airspeed , Flight Fuel can be calculated as follows:
Flight Fuel = Fuel Flow × Flight Time
Where, Flight time= Distance / Mean Airspeed
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23. All Up Weight (AUW)
However, AUW is not same during Take-off and landing. Why?
During TAKE-OFF:
AUW during Take-Off=DOW + PAYLOAD + (Flight Fuel + Reserve Fuel)
During LANDING:
AUW during Landing =DOW + PAYLOAD + Reserve Fuel
Note that, as a flight progresses , flight fuel is consumed and finished.
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24. RELATIONSHOP BETWEEN WEIGHT TERMINOLOGY
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25. Basic Aircraft + Basic Equipment Basic Weight DOW or APS Weight
Crew, Crew Baggage + Equipment
Variable Load
Take-off
Weight
Cargo / Freight
Payload
Passengers
+ Baggage
Disposable load
Fuel
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26. Exercise on Definition of Weight
State true of false. If false, correct it.
Disposable load = usable fuel + payload
Payload = Passenger Load + Cargo Load
Variable Load = Crew load + equipment load
APS Weight = Dry operating Weight (DOW)
APS Weight = AUW – Disposable Load
APS Weight = ZFW – Payload
Basic Weight + Variable Load + Disposable load = AUW
ZFW – Payload = DOW
Basic Weight = Basic equipment weight + Airframe + engine + unusable
fuel.
This course is easy!
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