3 Lesson Objectives At the conclusion of this lesson you will… Understand why weight and balance is critical to safety of flightBe familiar with the terms associated with weight and balanceBe familiar with the methods of calculating weight and balanceUnderstand the effect weight and balance has on aircraft performance
5 Importance of Weight and Balance Aircraft are designed to be operated within specific Center of Gravity limits.Wings can only produce so much lift. Weight in excess of what the wing is designed to carry is hazardous.Increases in weight also effect the general performance.
6 Weight Terms Empty Aircraft Standard Empty Weight – weight of a standard airplane including unusable fuel, full operating fluids and full oilBasic Empty Weight – Standard Empty Weight plus optional equipmentStarting Point of Weight and Balance
8 Weight TermsFuelUsable Fuel – fuel which can be used for flight planningUnusable Fuel – fuel which cannot be use in flight due to fuel tank design6 lbs per gallon
9 Weight Terms Useful Load – total usable fuel, passengers, and cargo Maximum Ramp Weight – Basic Empty Weight = Useful LoadPayload – passengers and cargoWhat essentially could be revenue generating
10 Weight Terms Loaded Aircraft Maximum Ramp Weight Maximum allowable mass for ground operationsAssures ground maneuverabilityIncludes fuel for taxi, run-up and startMaximum Takeoff WeightMaximum allowable mass for initiation of takeoff rollFailure to meet weight…Maximum Landing WeightMaximum allowable mass at touchdownGenerally limitation of landing gearBaggage Compartment LimitsCould cause structural failure in floor
12 Balance TermsWeightForce that acts straight down to the center of the EarthNot always constantDecreases with fuel burn
13 Balance Terms Reference Datum Reference base for location of componentsImaginary vertical planeLocation specified from manufacturerLies on longitudinal axisEx inches from wing leading edge
14 Balance TermsArmDistance from the datum measured along the longitudinal axisIf located in front of datum, negativeIf located in back of datum, positive
15 Balance Terms Moment Weight multiplied by its arm Tendency of a mass to cause a rotation about the Center of GravityForce acting at that point
16 Balance Terms Center of Gravity (CG) Point of a mass through which gravity actsPoint where aircraft would balance if suspendedPoint where all three axis interceptDivide total moment of aircraft by weight of aircraft
17 Basic W&B Relationships For the next few examples…The seesaw is synonymous with the aircraft.The people are synonymous with the weight of fuel, equipment, passengers, etc…The fulcrum can be thought of as lift, supporting the entire mass.The datum can be considered the nose of the aircraft.
18 Basic W&B Math Moment = Weight X Arm Center of Gravity = Basic Empty Weight+ Payload+ Usable Fuel=Ramp Weight- Fuel used for start, taxi and run-up= Takeoff Weight- Fuel used for flight= Landing WeightSum of All MomentsGross Weight
21 Basic W&B Relationships Forces Acting on an Aircraft in FlightCenter of Gravity forward of Center of PressureDownward force produced at tail to stabilize interaction of lift and weight
22 Basic W&B Relationships Center of Gravity Limits
23 Results of Aircraft Overloading Stall Speed IncreasesTakeoff and Landing Distance IncreasesClimb Rate ReducedCruise Speed ReducedFuel Consumption GreaterRange and Endurance ReducedStability Increased
24 Results of a Forward CG Longitudinal Stability becomes excessive Rotation and Flare are more difficultTakeoff Roll IncreasedCruise Speed DecreasedA greater tail down force must be produced. This is done aerodynamically, increasing drag.Climb Rate ReducedRange and Endurance ReducedStall Speed Increased
25 Effects of an Aft CG Takeoff Roll Reduced Cruise Speeds Increased Tendency to Over-RotateCruise Speeds IncreasedLess tail down force, is less dragClimb Rates IncreasedFuel Consumption DecreasedRange and Endurance IncreasedStall Speeds ReducedRecovery hindered due to nose up tendency
34 Miscellaneous W&B Solutions Weight ShiftWeight to be Moved Distance CG Moves=Gross Weight Distance Weight MovesWeight Addition / DeletionWeight to be Added/Removed Distance CG Moves=New Aircraft Gross Weight Distance Weight Moves
35 Weight & Balance Problem Set Up Computation - - Piper WarriorComputation - - Cessna P210Graph - - Piper ArrowTable - - Beech B33 Debonair
36 Computation MethodThis method uses the basic weight and balance formula to determine center of gravity.This method can be used for most aircraft.Extremely accurate, less arithmetic errors.
37 Computation Method Procedure Determine the Basic Empty Weight of the aircraft.Find the moment of each weight to be carried.Add all moments and all weights.Divide the total moment by the total weight. This number is your Center of GravityCompare this number to the CG limits for the aircraft.
38 Weight & Balance - Piper Warrior For our first problem, we use a weight and balance form for a Piper Warrior.
39 Weight & Balance - Piper Warrior Step 1find the zero fuel condition
40 Piper Warrior Weight Arm Moment (lbs.) (in.) (lbs.-in.) Basic Empty Weight , ,850
41 Piper Warrior Weight Arm Moment (lbs.) (in.) (lbs.-in.) Basic Empty Weight , ,850Pilot, Front Passengers ,370Rear Passengers ,154
42 Piper Warrior Weight Arm Moment (lbs.) (in.) (lbs.-in.) Basic Empty Weight , ,850Pilot, Front Passengers ,370Rear Passengers ,154Baggage (200 lb. Max)Zero Fuel Condition , ,374
43 Weight & Balance - Piper Warrior Step 2find the ramp condition and takeoff conditiondetermine that it is within limits
44 Piper Warrior Weight Arm Moment (lbs.) (in.) (lbs.-in.) Zero Fuel Condition , ,374Fuel (48 gallons max) ,365Ramp Condition , ,739Taxi, start, runup fuelTakeoff condition , ,074
63 Example BEW 2632 109000 Front Seat 150 + 210 Center Seat 190 Aft SeatBaggage A 10Baggage B 25
64 Chart MethodThis method depends on charts provided by the manufacturer to determine the moments.Accuracy of the chart method tends to decrease as the size of the aircraft increases.Accuracy in general is generally within a few hundred pound – inches.The procedure may vary from aircraft to aircraft.
65 Chart Method Procedure (General) Find the charts provided by the manufacturer in Section 6 of the POH. (These may or may not be provided)Correlate the weights to the appropriate chart to determine the moment.Add the moments determined from the charts and correlate them to the CG Limit chart.
77 Weight and Balance Computation Table MethodBeech Debonair
78 Table MethodThis method depends on tables provided by the manufacturer.Moment data is provided for specific weights only.Interpolation will be necessary to determine weights not specifically listed.Accuracy is generally within a few hundred pound – inches.This procedure may vary from aircraft to aircraft.
79 Table Method Procedure Find the tabular data provided in Section 6 of the POH. (These may or may not be provided)Correlate the weight to the appropriate tables to determine the moment.Add the moments determined from the tables and correlate them to the CG Limit chart.
80 Beech B33 Debonair BEW - 1980 lbs. (Moment 1584) Front Seat (Forward 170 lbs. and 200 lbs.)Rear Seat (120 lbs. And 130 lbs)Baggage (50 lbs.)
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