1. Ground School
3.06
Weight
& Balance

2. 3.06 Importance of Weight
Almost every aspect of performance is influenced
by the weight of the aircraft and its contents.
An overweight airplane will has :
longer takeoff run
higher takeoff speed
lower angle and rate of climb
lower cruising speed
shorter range
higher stalling speed
longer landing roll

3. 3.06 Importance of Weight
Loading an airplane too heavy can dangerously decrease its performance, and increase the risk of structural damage.
Airplane manufacturers do extensive testing to establish safe limits for airplane loading. Most common limits are maximum takeoff and landing weights.

4. 3.06 Importance of Balance
Center of gravity (CG) : the imaginary point where the aircraft would balance if suspended
CG is critical to an airplane’s stability and elevator effectiveness.
CG limits are the forward and aft center of gravity locations within which the aircraft must be operated at a given weight.

5. 3.06 Weight And Balance Terms Empty Airplane
Center of Gravity
CG Limits
Reference datum
Arm and Moment

6. 3.06 Weight And Balance Terms
Reference datum : the location from which all horizontal distances are measured for weight and balance purposes
Arm : distance from the datum, measurements aft of the datum are generally positive numbers, while those forward of the datum are generally negative numbers ( Fuselage station ; F.S. is another term for the arm)
Moment : a weight multiplied by an arm

7. 3.06 Aircraft Weight and Balance
10 lbs
5 lbs
1 in.
2 in.
WEIGHT X ARM = MOMENT

8. 3.06 Weight And Balance Terms Empty Airplane
Center of Gravity
CG Limits
Reference datum
Arm and Moment
Basic empty weight
Licensed empty weight
Unusable fuel

9. 3.06 Weight And Balance Terms Empty Airplane
Basic empty weight : weight of airplane + equipment + unusable fuel + full engine oil
Licensed empty weight : weight of airplane + equipment + unusable fuel + full engine oil + undrainable oil
Unusable fuel : small amount of fuel in tanks that cannot be used in flight or drained on ground

10. 3.06 Weight And Balance Terms Loaded Airplane
Ramp Weight
Takeoff Weight
Landing Weight
Total Weight
Payload
Useful Load

11. 3.06 Weight And Balance Terms Loaded Airplane
Ramp Weight : airplane loaded for flight prior to engine start
Takeoff Weight : Ramp Weight – fuel burned during start & runup & taxi
Landing Weight : Takeoff Weight – fuel burned enroute

12. 3.06 Weight And Balance Terms Loaded Airplane
Total Weight : (Gross Wight) weight of airplane and everything carried in it
Payload : weight of only passengers, baggage and cargo
Useful Load : Payload + weight of flight crew and useable fuel

13. 3.06 Methods For Calculating Total Weight And CG
Table
Graph
Computation

14. 3.06 Calculating the position of the CG
5 in.
Ref Line
10 lbs
10 lbs
5 in.
15 in.
W X A = M
10 lbs. X - 5 in = in lbs.
10 lbs. X + 15 in = in lbs.
20 lbs. (W) in lbs.
Average Arm = /20
+ 5 in

15. 3.06 Calculating the position of the CG
10 in.
Reference Line
10 lbs
10 lbs
20 in.
30 in.
W X A = M
10 lbs. X 10 in = in lbs.
10 lbs. X 30 in = in lbs.
20 lbs. (W) in lbs.
Average Arm = /20
+ 20 in

16. 3.06 Calculating the position of the CG on an airplane
Reference Datum
23 in.
10 in. 50 10
100
9 in.
10.18 in.
100 lbs. X 9 in = in lbs
50 lbs. X 10 in = in lbs.
10 lbs. X 23 in = in lbs.
160 lbs. (W) in lbs.
Average Arm = /160
10.18 in

17. 3.06 Calculating the position of the CG on an airplane
Empty Airplane:
Arm: 70 inches
Weight: 1,150 pounds
Pilot:
Arm: 73 inches
Weight: 135 pounds
Weight Arm Moment
Empty Airplane 1,150 pounds X 70 inches = 80,850 pounds - inches
Pilot 135 pounds X 73 inches = 9,855 pounds - inches
Total 1,285 pounds ,355 pounds - inches
Total Moment
Total Weight
= CG Arm
90,355 pounds - inches
1285 pounds
= inches

18. 3.06 Methods For Calculating Total Weight and CG
Computation
Graph
Table

20. 3.06 Methods For Calculating Total Weight and CG
Computation
Table
Graph

21. Add all the amounts to obtain ramp moment.
3.06 Methods For Calculating Total Weight And CG
Fuel
Pilot and Passenger
Baggage
Rear Passenger(s)
Add all the amounts to obtain ramp moment.

22. 3.06 Center Of Gravity Moment Envelope
Ramp Weight
Ramp Moment
Now
what?

23. Divide total moment by total weight to get CG.
3.06 CG Limits
Divide total moment by total weight to get CG.
Ramp Weight
Ramp CG

24. 3.06 Weight Shift Formula
Can be used to calculate the amount of weight that must be moved a specific distance or to determine the distance a specific weight would need to move to bring the CG within approved limits

25. Weight Moved Distance CG Move Weight of A/C Distance Between Arms
3.06 Weight Shift Formula
2600
2500
2400
2300
2200
2100
2000
1900
1800
1700
1600
GROSS WEIGHT MOMENT LIMITS
MOMENT / in. lbs
F33C ACROBATIC
CATEGORY
LIMITS
F33A & F33C
UTILITY CATEGORY
2700
2800
2900
82.1
86.7
3500
3400
3300
3200
3100
3000
WEIGHT - POUNDS
162 Pounds
Weight Moved
Weight of Airplane
Distance CG Moved
Distance Between CG Arms =
162 pounds
2,500 Pounds X
36 inches
162 x 36
2,500
X =
X = 2.3 inches
Weight Moved Distance CG Move
Weight of A/C Distance Between Arms

26. 3.06 Effects of increasing weights
Takeoff Distance
Landing Distance
Climbouts
True Airspeed
Longer distance required
Longer distance required
Angle reduced
Performance reduced
Reduced

27. 3.06 Effects Of Moving CG Aft
Rotation
Flare
Stability
True Airspeed
Too quick
Too quick
Less stable
Faster

29. This could be you.