MASS (WEIGHT) & BALANCE

LECTURE 2COMPOSITION OF AIRCRAFT WEIGHTMASS (WEIGHT) & BALANCE1MBC 3204 - SIR ARIFF AMCWEIGHT DEFINITIONWeight 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.

2MBC 3204 - SIR ARIFF AMCContinue..MBC 3204 - SIR ARIFF AMC3However, 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 stabilityMBC 3204 - SIR ARIFF AMC4Therefore in our discussion later, please KNOW that WEIGHTis a MASS of aircraft.Continue..MBC 3204 - SIR ARIFF AMC5The 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.

TIME TO THINK!!MBC 3204 - SIR ARIFF AMC6Do 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!

WEIGHT CONTROLMBC 3204 - SIR ARIFF AMC7When 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.MBC 3204 - SIR ARIFF AMC8COMPOSITION OFAIRCRAFT WEIGHTOVERVIEWMBC 3204 - SIR ARIFF AMC9All 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)

MBC 3204 - SIR ARIFF AMC10To 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.

MBC 3204 - SIR ARIFF AMC11Maximum 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.

Continue..MBC 3204 - SIR ARIFF AMC12It 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)??

Maximum Landing Weight (MLW)MBC 3204 - SIR ARIFF AMC13The maximum permissible weight to conduct a landing.

What will happen if the aircraft weight during landing is greater than MLW? What is the possibility?

MBC 3204 - SIR ARIFF AMC14The 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.

Maximum Zero-Fuel Weight (MZFW)Example..MBC 3204 - SIR ARIFF AMC15For 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?

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

16MBC 3204 - SIR ARIFF AMC16Continue..MBC 3204 - SIR ARIFF AMC17During 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

IMPORTANTMBC 3204 - SIR ARIFF AMC18For Take-Off: AUW/TOW MTOW

For Landing: AUW/LW MLWAll Up Weight (AUW)Where,PAYLOAD = Passengers & CargoFUEL = Flight Fuel + Reserve FuelDOW = Dry Operating Weight

DOW also known as Aircraft Prepared for Service (APS)

AUW = DOW + PAYLOAD + FUEL19MBC 3204 - SIR ARIFF AMCDry Operating Weight (DOW) @ APSBasic Weight + Crew & Baggage

Basic WeightIt consists of Empty Weight + Basic Equipment Weight.

Empty WeightWeight of airframe, engines and standard structures.

Basic Equipment WeightWeight of common installations inside the airplane.

20MBC 3204 - SIR ARIFF AMCThese 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.20PayloadThe weight of all persons and items of load carried in an aircraft for which a fare or charge is being paid.

PAYLOAD = Passengers + Cargo

21MBC 3204 - SIR ARIFF AMCMBC 3204 - SIR ARIFF AMC22FuelFUEL = 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 AirspeedAll 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.

23MBC 3204 - SIR ARIFF AMCMBC 3204 - SIR ARIFF AMC24RELATIONSHOP BETWEEN WEIGHT TERMINOLOGYMBC 3204 - SIR ARIFF AMC25Basic Aircraft + Basic EquipmentCrew, Crew Baggage + EquipmentCargo / FreightPassengers+ BaggageFuelBasicWeightPayloadVariable LoadDOW or APS WeightDisposable loadTake-off WeightMBC 3204 - SIR ARIFF AMC26Exercise on Definition of Weight

State true of false. If false, correct it.Disposable load = usable fuel + payloadPayload = Passenger Load + Cargo LoadVariable Load = Crew load + equipment loadAPS Weight = Dry operating Weight (DOW)APS Weight = AUW Disposable LoadAPS Weight = ZFW PayloadBasic Weight + Variable Load + Disposable load = AUWZFW Payload = DOWBasic Weight = Basic equipment weight + Airframe + engine + unusable fuel.This course is easy!