1. Keeping the Shiny Side Up
Weight & Balance
Keeping the Shiny Side Up
Show B-52 Video
Written for the Notre Dame Pilot Initiative
By the Pilots of the University of Notre Dame
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

2. Quote
Balance is beautiful
Miyoko Ohno

3. Roadmap
Terms
Forces
Mathematical Treatment
Graphical Treatment

4. Limitations
An airplane must only be flown within certificated limits of weight and balance to ensure that it remains controllable, performs adequately and is not overstressed. Correct weight and balance means:
Maximum allowable weight is not exceeded; and
Center of gravity (CG) is within a specified range

5. Terms Center of Gravity Center of Lift (Pressure) Basic Empty Weight
Point at which the airplane’s entire weight is assumed to be concentrated
Center of Lift (Pressure)
Point at which the airplane’s entire lift assumed to be concentrated
Basic Empty Weight
Generally, the weight of the airframe, unusable fuel, unusable/full oil, and full hydraulic fluid

6. Forces
The goal in flying any airplane is to always remain in positive control
Knowing how the forces that act on our airplane balance helps us predict how it will fly
AX = BY
Moment arm of A
Moment arm of B X Y A B
Fulcrum

7. Mathematical Treatment
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

8. Practical Exercise
Joe (150) and Jeff (200) want to fly to Cocoa Beach. They decide to take Brady (231) with them for some extra practice with them.
The golden helmets (15) are in the back seat and footballs (35) are in the baggage compartment.
Are we good to go?

9. Weight We want to add up all of the weights in our airplane
Start with BEW
Then we add usable fuel (and oil), passengers, and cargo
FAA standard passenger is 170 lbs
Always ascertain the proper weight of pax and cargo
AVGAS is 6 pounds per gallon
Oil is 7.5 pounds per gallon
Water is 8.35 pounds per gallon

10. Weight Empty Weight 1683 Useable Fuel 350 Front Seats 340 Rear Seats15
Baggage Area 35
Takeoff Weight
2423

11. Balance
The aircraft can only be controlled if it is positively stable.
Maintaining the proper center of gravity assures us that the airplane will be controllable upon liftoff
The Center of Gravity must be forward of the Center of Lift (Pressure) in order to achieve positive dynamic stability

12. Loading Chart

13. Balance Empty Weight 1,683 39.7 66,815 Useable Fuel 350 48.0 16,800
Front Seats
340
37.0
12,580
Rear Seats 15
73.0
1,095
Baggage Area 35 95
3,325
Takeoff Weight (lbs)
2,423
Total Moment (lb-in)
100,615
C.G (in)
41.53
“WAM” Weight x Arm = Moment
Total Moment / Total Weight = C.G

14. Graphical Treatment C-182
“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

15. 63+12.5+12+2+3+1 = 93.5 lb-in Cessna 182 W&B Front 340 Fuel 260
Rear 25
Baggage 25
Hat Shelf 2
Note to include basic empty weight as well

17. Center of Gravity Envelope
Very similar to previous slide, x axis is inches instead of pound-inches

18. Stability & Control Center of Gravity concerns:
Unable to compensate with elevator in pitch axis
Weight and Balance becomes critical – stalls & landing
Too much weight in the front of the airplane will cause it to pitch downward
Too much weight in rear of aircraft will cause aircraft to pitch upward

19. Tricks of the Trade
Flying with a rear CG is more efficient but decreases stability
Flying with a forward CG decreases performance and makes flaring for landing more difficult, yet makes for a quick stall recovery
Flying over gross weight may overstress the airplane and cause it to self-destruct

20. Conclusions
It is very easy to make an airplane unflyable by misloading it.
When you fly outside of tolerance, you become a test pilot.
Understanding weight and balance will allow you to maximize performance and understand poor performance

21. Say Intentions
One Passenger, No baggage, Full Fuel, Calm Winds, No Ceiling, PIC-25 hours
Go for it
Three Passengers, Full Fuel, Golf Clubs for 4 (10 each), Scattered T-storms, PIC-500 hours
Calculations bring you right to max GW and a rear CG
Go for it with that experience
Second scenario again (Passengers are his grandmother, girlfriend, and the bosses 3 year old daughter), PIC-50 hours, 5 hours in an Archer
No go, passengers are not easy to deal with, pilot has little experience in type, and the airplane will be difficult to control in turbulence

22. Salmon 30 Salmon