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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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  1. 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

  2. Private Pilot Ground School Weight & Balance Class #5

  3. 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

  4. Weight and Balance Terminology • Reference Datum- imaginary vertical plane from which all horizontal distances are measured for balance purposes

  5. Different Datum Locations

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. Weight and Balance Terminology • Unusable Fuel - Fuel remaining after a runout test. • Falcrum - Support point

  13. Principles of Weight and Balance • Weight x Arm = Moment • Arm = Moment/Weight • Weight=Moment/Arm

  14. WAM

  15. A balanced teeter-totter

  16. - ARMS

  17. Determining Gross Weight & Center of Gravity • Three ways • Computation method, • Tabular method, and • Graphical method

  18. Computation method (p135)

  19. Tabular method (p136) • Like B-19, uses tables to quickly determine arm and moment.

  20. Graphical method (p136) • Also used for B-19 to determine gross weight moment limits (6-12) • Loading graphs commonly found in cessna POH’s • Easy way to determine if aircraft is in the envelope.

  21. Graphical method (p136)

  22. High gross weights

  23. High gross weights • Added wear on engine • Increased fuel consumption • Overheating in climb

  24. High gross weights • It is a violation of FARs to exceed gross weight limits

  25. LLF • Limit load factors normal 3.8 -1.52 utility 4.4 -1.76 aerobatic 6.0 -3.0

  26. High gross weights • Over loading may accelerate metallic fatigue failures • Baggage floor may have limits on weight for structural reasons • Stability may be effected to the negative if overloaded

  27. High gross weights • The higher the gross weight the higher the stall speed • Less reserve angle of attack • Load distribution

  28. 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

  29. 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,

  30. 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

  31. Lateral Balance • Lateral unbalance usually a result of unbalanced fuel load will cause additional lift and drag on heavy side

  32. STANDARD WEIGHTS

  33. 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.

  34. 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

  35. 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?

  36. Problem #2 Answer • 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.

  37. Weight Shift Equation • By manipulating the formula we find that CG=(Weight shifted X Distance it is shifted)/Total Weight

  38. Weight Shift Equation • Weight to be shifted is equal to what? • (212lbs-115lbs) • Distance it is shifted is equal to what? • (72 inches-35inches)

  39. 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

  40. 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

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