# Weight and Balance - PowerPoint

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```					Weight and Balance
2
Lesson Objectives
At the conclusion of this lesson you will…
 Understand why weight and balance is critical
to safety of flight
 Be familiar with the terms associated with
weight and balance
 Be familiar with the methods of calculating
weight and balance
 Understand the effect weight and balance
has on aircraft performance

3
4
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.

5
Weight Terms
 Empty Aircraft
– Standard Empty Weight – weight of a standard
airplane including unusable fuel, full operating
fluids and full oil
– Basic Empty Weight – Standard Empty Weight
plus optional equipment
 Starting Point of Weight and Balance

6
7
Weight Terms
 Fuel
– Usable Fuel – fuel which can be used for flight
planning
– Unusable Fuel – fuel which cannot be use in
flight due to fuel tank design

– 6 lbs per gallon

8
Weight Terms
 Useful Load – total usable fuel,
passengers, and cargo
– Maximum Ramp Weight – Basic Empty Weight = Useful Load

 Payload – passengers and cargo
– What essentially could be revenue generating

9
Weight Terms
– Maximum Ramp Weight
 Maximum allowable mass for ground operations
 Assures ground maneuverability
 Includes fuel for taxi, run-up and start
– Maximum Takeoff Weight
 Maximum allowable mass for initiation of takeoff roll
 Failure to meet weight…
– Maximum Landing Weight
 Maximum allowable mass at touchdown
 Generally limitation of landing gear
– Baggage Compartment Limits
 Could cause structural failure in floor
10
11
Balance Terms
 Weight
– Force that acts straight down to the center of
the Earth
– Not always constant
 Decreases with fuel burn

12
Balance Terms
 Reference Datum
– Reference base for location of components
– Imaginary vertical plane
– Location specified from manufacturer
– Lies on longitudinal axis

– Ex. 78.4 inches from wing leading edge

13
Balance Terms
 Arm
– Distance from the datum measured along the
longitudinal axis
 If located in front of datum, negative
 If located in back of datum, positive

14
Balance Terms
 Moment
– Weight multiplied by its arm
– Tendency of a mass to cause a rotation about
the Center of Gravity
– Force acting at that point

15
Balance Terms
 Center of Gravity (CG)
– Point of a mass through which gravity acts
– Point where aircraft would balance if suspended
– Point where all three axis intercept
– Divide total moment of aircraft by weight of
aircraft

16
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.

17
Basic W&B Math
 Moment = Weight X Arm of All Moments
Sum
 Center of Gravity =   Gross Weight

   Basic Empty Weight
   + Usable Fuel
   =Ramp Weight
   - Fuel used for start, taxi and run-up
   = Takeoff Weight
   - Fuel used for flight
   = Landing Weight

18
Basic W&B Relationships
 Balanced Condition

19
Basic W&B Relationships
 Unbalanced Condition

20
Basic W&B Relationships
 Forces Acting on an Aircraft in Flight
 Center of Gravity
forward of Center of
Pressure
 Downward force
produced at tail to
stabilize interaction
of lift and weight

 www.aero.und.edu/multimedia
21
Basic W&B Relationships
 Center of Gravity Limits

22
   Stall Speed  Increases
   Takeoff and Landing Distance  Increases
   Climb Rate  Reduced
   Cruise Speed  Reduced
   Fuel Consumption  Greater
   Range and Endurance  Reduced
   Stability  Increased

23
Results of a Forward CG
 Longitudinal Stability becomes excessive
– Rotation and Flare are more difficult

 Takeoff Roll  Increased
 Cruise Speed  Decreased
– A greater tail down force must be produced. This is done
aerodynamically, increasing drag.

 Climb Rate  Reduced
 Range and Endurance  Reduced
 Stall Speed  Increased

24
Effects of an Aft CG
Takeoff Roll  Reduced
– Tendency to Over-Rotate
 Cruise Speeds  Increased
– Less tail down force, is less drag
   Climb Rates  Increased
   Fuel Consumption  Decreased
   Range and Endurance  Increased
   Stall Speeds  Reduced
– Recovery hindered due to nose up tendency

25
Weight and Balance
Documentation
POH Section 6
 Section 6 contains…
– Weight and Balance Calculation procedure for
the aircraft
– Basic Empty Weight and Moment of the aircraft
– Changes to the Weight and Balance

27
CENTER FORAEROSPACE SCIENCES
TH
UNIVERSITYOF NOR DAKOTA
WEIGHT AND BALANCE, AND EQUIPMENT LIST REVISION

AIRCRAFT MODEL
N   142 ND
SERIAL NO.
DATE 5-1-94
PA 28-161
2841229
Weight &
AMOUNT

1
DESCRIPTION

Fire Extinguisher
WEIGHT
(LB)

+2.7
ARM
(IN)

57.9
MOMENT

+156
Balance -
Equipment List
Revision

E.W.        C.G.       MOMENT

PREVIOUS EMPTY AIRPLANE            1464.4        85.0       124469.5
TOTAL ADDED OR SUBTRACTED
REVISED EMPTY AIRPLANE              +2.7                     +156.0
1467.1        85.0       124625.5
804.9           NAME   Jim Gilstad
CERTIFICA NO.
TE        OGSR092N

28
Weight & Balance -
Equipment List Revision
E.W.         C.G.      MOMENT
PREVIOUS EMPTYAIRPLANE      1464.4        85.0     124469.5
TOTAL ADDED OR SUBTRACTED    +2.7                   +156.0
REVISED EMPTYAIRPLANE      1467.1        85.0     124625.5
CERTIFICA NO.
TE         OGSR092N

29
CENTER FORAEROSPACE SCIENCES
TH
UNIVERSITYOF NOR DAKOTA
WEIGHT AND BALANCE, AND EQUIPMENT LIST REVISION

AIRCRAFT MODEL
N   142 ND
SERIAL NO.
DATE 5-1-94
PA 28-161
2841229
Weight &
AMOUNT

1
DESCRIPTION

Fire Extinguisher
WEIGHT
(LB)

-2.7
ARM
(IN)

57.9
MOMENT

-156
Balance -
Equipment List
SUPERCEDED                                                     Revision
5-1-94

E.W.        C.G.       MOMENT
PREVIOUS EMPTY AIRPLANE            1467.1        84.9       124625.5
TOTAL ADDED OR SUBTRACTED
REVIS ED EMPTYAIRPLANE              -2.7          1          -156.0
1464.4                   124469.5
867.6           NAME   Jim Gilstad
CERTIFICA NO.
TE        OGSR092N
30
Weight and Balance
Calculation
Weight & Balance
Computations
   Weight and balance information
   Weight and balance formulas
   Weight shift formulas
   Weight and balance problem set up

32
Weight & Balance
Computations

Weight Shift Formulas

33
Miscellaneous W&B Solutions
 Weight Shift
Weight to be Moved   = Distance CG Moves
Gross Weight        Distance Weight Moves

 Weight Addition / Deletion
Weight to be Added/Removed      Distance CG Moves
New Aircraft Gross Weight   = Distance Weight Moves

34
Weight & Balance Problem
Set Up
   Computation - - Piper Warrior
   Computation - - Cessna P210
   Graph - - Piper Arrow
   Table - - Beech B33 Debonair

35
Computation Method
 This 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.

36
Computation Method
 Procedure
1. Determine the Basic Empty Weight of the aircraft.
2. Find the moment of each weight to be carried.
3. Add all moments and all weights.
4. Divide the total moment by the total weight. This
number is your Center of Gravity
5. Compare this number to the CG limits for the aircraft.

37
Weight & Balance -
Piper Warrior
For our first
problem, we
use a weight
and balance
form for a
Piper
Warrior.

38
Weight & Balance -
Piper Warrior
Step 1
– find the zero fuel condition

39
Piper Warrior
Weight Arm Moment
(lbs.) (in.) (lbs.-in.)
Basic Empty Weight   1,500         128,850

40
Piper Warrior
Weight    Arm   Moment
(lbs.)    (in.)(lbs.-in.)
Basic Empty Weight         1,500           128,850
Pilot, Front Passengers   340        80.5   27,370
Rear Passengers             340     118.1   40,154

41
Piper Warrior
Weight    Arm   Moment
(lbs.)    (in.)(lbs.-in.)
Basic Empty Weight         1,500           128,850
Pilot, Front Passengers   340        80.5   27,370
Rear Passengers             340     118.1   40,154
Baggage (200 lb. Max)
Zero Fuel Condition       2,180              196,374

42
Weight & Balance -
Piper Warrior
Step 2
– find the ramp condition and takeoff
condition
– determine that it is within limits

43
Piper Warrior
Weight    Arm     Moment
(lbs.)   (in.)   (lbs.-in.)
Zero Fuel Condition         2,180           196,374
Fuel (48 gallons max)         267   95        25,365
Ramp Condition              2,447            221,739
Taxi, start, runup fuel        -7   95          - 665
Takeoff condition         2,440     90.6    221,074

44
45
Weight & Balance -
Piper Warrior
Step 3
– find the landing condition

46
Piper Warrior
Weight Arm         Moment
(lbs.)  (in.)    (lbs.-in.)
Takeoff condition          2,440 90.6        221,074
Cruise fuel (30 gallons)    -180    95.0      -17,100
Landing condition            2,260 90.25      203,974

47
Weight & Balance -
Piper Warrior
Step 4
– confirm that landing weight & C.G. fall
within limits

48
49
Weight & Balance - Cessna
P210

Computation
Method

50
Cessna P210
   BEW: 2,632 lbs. (Moment 109,000)
   Front Seat (170 lbs.)
   Center Seat (160 and 150 lbs)
   Aft Seat (200 and 170 lbs)
   Baggage Area A (150 lbs)
   Baggage Area B (0)

51
102

52
Zero Fuel Condition
Item         Weight    Arm       Moment
BEW            2632               109000
Front Seat       170       37        6290
Center Seat      310       71        22010
Aft Seat        370       102       37740
Baggage A        150       138       20700
Zero-Fuel        3632     53.89     195740

53
Ramp Condition
 Add 64 gallons of fuel
Item        Weight        Arm     Moment
Zero-Fuel      3632         53.89   195740
Fuel         384           43      16512
Ramp Weight    4016         52.85   212252

54
Takeoff Condition
 Run-up minus 16 lbs of fuel
Item         Weight      Arm     Moment
Ramp Weight     4016       52.85   212252
Run-up         -16        43      -688
Takeoff        4000       52.89   211564

55
56
57
Shift a Passenger
 Move the 200 pound passenger from the aft
seat to the front seat.

 Equation
– Weight Moved   Distance CG Moves
– Total Weight   Distance between CG Location

58
– Weight Moved   Distance CG Moves
– Total Weight   Distance between CG Location

 200 lbs           ???????????????????
 4000 lbs          (102-37) 65’

 (65 x 200)/4000
 13000/4000 = 3.25

 52.89 – 3.25 = 49.64

59
60
Fuel Burn
 2.5 hour flight at 20 gallons per hour
Item       Weight          Arm       Moment
Takeoff      4000           49.64     198560
Fuel Burn   (2.5 x 20 x 6)    43       -12900
-300
Landing        3700          50.18         185660

61
62
Example
   BEW           2632        109000
   Front Seat    150 + 210
   Center Seat   190
   Aft Seat      150 + 190
   Baggage A     10
   Baggage B     25

63
Chart Method
 This 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.

64
Chart Method
 Procedure (General)
1. Find the charts provided by the manufacturer
in Section 6 of the POH. (These may or may
not be provided)
2. Correlate the weights to the appropriate chart
to determine the moment.
3. Add the moments determined from the charts
and correlate them to the CG Limit chart.

65
Weight & Balance -
Piper Arrow

 Graph Method

66
PA28-R-201 ARROW
   BEW - 1774.2 lbs. (moment 147,695.8)
   Pilot and Front Passenger - 370 lbs.
   Rear passenger - 210 lbs.
   Baggage - 100 lbs.

67
68
 Moment
–   BEW - 147,695.8
–   Front Seat - 30,000
–   Back Seat - 25,000
–   Baggage - 14,200
Item            Weight      Arm     Moment
BEW              1774.2              147695.8
Front Pas.          370                 30000

Rear Pas.            210                25000
Baggage              100                14200
Zero Fuel           2454.2     88.38   216895.8

69
 Fuel (72 gallon maximum)
– 50 gallons
 300 lbs.
 Moment
– 29000

70
Item        Weight   Arm     Moment
Zero Fuel     2454.2   88.38   216895.8
Fuel         300              29000
Ramp Weight   2754.2           245895.8
Run-up         -8              -1000
Takeoff      2746.2   89.17   244895.8

71
72
 Fuel used in flight
– 3 hours at 11.6 gallons per hour
 34.8 gallons
– 208.8 lbs.
– Moment - 20,000

73
Item     Weight   Arm     Moment
Takeoff   2746.2   89.17   244895.8
Fuel     -208.8            -20000
Landing   2537.4   88.63   224895.8

74
75
Problem!
   BEW         1774        147695
   Front Pax   400
   Rear Pax    150
   Fuel        200

76
Weight and Balance
Computation
Table Method

Beech Debonair
Table Method
 This 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.

78
Table Method
 Procedure
1. Find the tabular data provided in Section 6 of
the POH. (These may or may not be provided)
2. Correlate the weight to the appropriate tables
to determine the moment.
3. Add the moments determined from the tables
and correlate them to the CG Limit chart.

79
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.)

80
81
82
83
Calculations
Item      Weight   Arm    Moment
BEW        1980            1584
Front Pax    370             314
Rear Pax     250             295
Baggage       50              70
Zero Fuel    2650            2263

84
85
 Fuel (64 gallons maximum)
– 60 gallons
 360 lbs.

86
Ramp Condition
Item           Weight   Arm     Moment
Zero Fuel         2650             2263
Fuel             360             270
Ramp Weight       3010             2533
Run-up          -10              -8
Takeoff Weight    3000             2525

87
88
Fuel Burn
 3 hour flight (14.7 gallons per hour)
 44.1 gallons
– 264 lbs.

89
Landing Condition
Item          Weight    Arm      Moment
Takeoff Weight     3000               2525
Fuel flight       264               198
Landing         2736               2327
Weight

90
91
Problem!!
   BEW 1980 lbs. (Moment 1584)
   Front Pax (Aft) 190 And 160
   Rear Pax        150
   Baggage         200

 30 gallons of fuel

92

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 views: 454 posted: 11/29/2011 language: English pages: 92