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# READ - PowerPoint PPT Presentation

READ. GLEIM CHAPTER 5 (5.7-5.9) 17 QUESTIONS JEP CHAPTER 8 SECTION B (8-29 TO 8-47) PHAK CHAPTER 9 ASA Chapter 8-1 through 8-20. Private Pilot Ground School Weight & Balance Class #5. Content of Lesson. Terms used in weight and balance calculations.

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Presentation Transcript
• GLEIM CHAPTER 5 (5.7-5.9)

17 QUESTIONS

• JEP CHAPTER 8 SECTION B (8-29 TO 8-47)
• PHAK CHAPTER 9
• ASA Chapter 8-1 through 8-20
Content of Lesson
• Terms used in weight and balance calculations.
• Effects of weight and the distribution of weight
• Various Manufacturers display of weight and balance info and use of
• B-19 weight and balance computations sample and actual problems
Weight and Balance Terminology
• Reference Datum- imaginary vertical plane from which all horizontal distances are measured for balance purposes
Weight and Balance Terminology
• Standard Empty Weight - the weight of a standard airplane including unusable fuel, full operating fluids and full oil.
• Basic empty weight - Standard empty weight plus optional equipment
Weight and Balance Terminology
• Max ramp weight - max weight of aircraft for taxi operations (it includes start taxi and run-up fuel)
• Max takeoff weight - max weight approved for the start of the takeoff run
• Max landing weight - max weight approved for the landing touchdown
Weight and Balance Terminology
• Useful load - Difference between take off weight and basic empty weight
• Payload - Weight of the occupants, cargo and baggage
• Zero fuel weight - weight exclusive of usable fuel useful for calculations when fuel is a variable
Weight and Balance Terminology
• Tare - Weight of chocks, blocks, stands ect used when weighing an aircraft
• Arm - the horizontal distance from the reference datum
• Moment - the force exerted by a weight using an arm usually measured in in/lbs or foot/lbs
• Station- a designated location on the fuselage measured from the reference datum
Weight and Balance Terminology
• Center of Gravity - The point at which an airplane would balance if suspended from that point
• C. G. Arm (center of gravity)- The arm obtained by adding the airplane’s individual moments and dividing the sum by the total weight
Weight and Balance Terminology
• C. G. Limits - The extreme center of gravity location within which the airplane must be operated at a given weight.
• Useable Fuel - Fuel available for flight planning
Weight and Balance Terminology
• Unusable Fuel - Fuel remaining after a runout test.
• Falcrum - Support point
Principles of Weight and Balance
• Weight x Arm = Moment
• Arm = Moment/Weight
• Weight=Moment/Arm
Determining Gross Weight & Center of Gravity
• Three ways
• Computation method,
• Tabular method, and
• Graphical method
Tabular method (p136)
• Like B-19, uses tables to quickly determine arm and moment.
Graphical method (p136)
• Also used for B-19 to determine gross weight moment limits (6-12)
• Easy way to determine if aircraft is in the envelope.
High gross weights
• Increased fuel consumption
• Overheating in climb
High gross weights
• It is a violation of FARs to exceed gross weight limits
LLF
• Limit load factors normal 3.8 -1.52 utility 4.4 -1.76 aerobatic 6.0 -3.0
High gross weights
• Baggage floor may have limits on weight for structural reasons
• Stability may be effected to the negative if overloaded
High gross weights
• The higher the gross weight the higher the stall speed
• Less reserve angle of attack
Safety
• Manufacturer set limits for controllability and maneuverability
• Certification procedures demand a certain amount of oscillations before dampening out this determines where the aft cg is located
Forward CG gives:
• Higher stall speed,
• Higher elevator control forces (critical in takeoff and landing phase),
• Slower cruise, (higher angle of attack need more tail down force.)
• More overall stability,
• Longer takeoff and landing distance,
Aft C of G
• With an aft cg recovery from a stall spin harder or impossible.
• Lower stall speed
• Less elevator control forces in T.O. landing
• Faster cruise, (Lower angle of attack need less tail down force.)
• Less overall stability, Less takeoff and landing distance
Lateral Balance
• Lateral unbalance usually a result of unbalanced fuel load will cause additional lift and drag on heavy side
Weights
• Oil weighs 7.5 lbs. per gallon. Since oil is usually measured in quarts, each quart weights 1 7/8 pounds.
• The average weight for passengers is approx. 170 lbs.
• Aviation fuel (Avgas)weighs 6 lbs. Per gallon
• 2 gallons of fuel = 12 lbs.
Problem #1.
• Determine the CG of these three objects
• Weight A=100 lbs Arm 50
• Weight B=100 lbs Arm 90
• Weight C=200 lbs Arm 150
• What is the CG
• =110
Problem #2
• Basic Empty Weight = 1340
• Arm=37
• Front seats=140 lbs Pilot and 115 pound passenger, Moment=8,925
• Rear seat =212 lbs passenger and 97 pound passenger. Arm 72
• Useable Fuel=40 Gallons, Arm 48
• Baggage 50 lbs. Moment 4,600
• To stay in envelope CG limits=+35.6 to +43.2. What is the CG? Is the aircraft in the envelope?
• CG=44.1
• No the aircraft is not in the envelope.
• Can we fly the aircraft?
• No, not legal
• One possible solution would be to trade places between the 212 pound rear-seat occupant and the 115 pound occupant. Using a weight shift equation we can see how far the CG will move.
Weight Shift Equation
• By manipulating the formula we find that CG=(Weight shifted X Distance it is shifted)/Total Weight
Weight Shift Equation
• Weight to be shifted is equal to what?
• (212lbs-115lbs)
• Distance it is shifted is equal to what?
• (72 inches-35inches)
Weight Shift Equation
• Total Weight = What?
• 2,194
• (212-115)X(72-35)/2,194=
• 97X37/2,194=
• 1.6 inches
• This makes the new CG 42.5 within limits
B-19 PROBLEM
• BB2
• PILOT 190 LBS ARM 109
• FRONT PASSENGER 180 LBS ARM 108
• BACK SEAT 15 LBS
• FUEL 40 GALLONS
• FLIGHT 1.5 HOURS
• GPH 7.8
• START RUNUP TAXI 1 GALLON