“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

Weight & BalanceWeight & BalanceWeight & BalanceWeight & BalanceKeeping the Shiny Side UpKeeping the Shiny Side Up

Written for the Notre Dame Pilot Initiative By the Pilots of the University of Notre Dame

Written for the Notre Dame Pilot Initiative By the Pilots of the University of Notre Dame

RoadmapRoadmapRoadmapRoadmap

TermsForcesMathematical TreatmentGraphical Treatment

TermsForcesMathematical TreatmentGraphical Treatment

LimitationsLimitationsLimitationsLimitations

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; andCenter of gravity (CG) is within a

specified range

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; andCenter of gravity (CG) is within a

specified range

TermsTermsTermsTerms

Center of Gravity 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

Center of Gravity 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

ForcesForcesForcesForcesThe goal in flying any airplane is to

always remain in positive controlKnowing how the forces that act on

our airplane balance helps us predict how it will fly

AX = BY

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

A B

Fulcrum

Moment arm of A Moment arm of BX Y

“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

Mathematical TreatmentMathematical TreatmentMathematical TreatmentMathematical Treatment

Practical ExercisePractical ExercisePractical ExercisePractical 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?

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?

WeightWeightWeightWeightWe want to add up all of the weights in our

airplane Start with BEW Then we add usable fuel (and oil), passengers,

and cargoFAA standard passenger is 170 lbs

Always ascertain the proper weight of pax and cargo

AVGAS is 6 pounds per gallonOil is 7.5 pounds per gallonWater is 8.35 pounds per gallon

We want to add up all of the weights in our airplane Start with BEW Then we add usable fuel (and oil), passengers,

and cargoFAA standard passenger is 170 lbs

Always ascertain the proper weight of pax and cargo

AVGAS is 6 pounds per gallonOil is 7.5 pounds per gallonWater is 8.35 pounds per gallon

WeightWeightWeightWeight

Empty Weight 1683

Useable Fuel 350

Front Seats 340

Rear Seats 15

Baggage Area 35

Takeoff Weight 2423

BalanceBalanceBalanceBalance

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

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

Loading ChartLoading ChartLoading ChartLoading Chart

BalanceBalanceBalanceBalance

“WAM” Weight x Arm = Moment

Empty Weight 1,6831,683 39.739.7 66,81566,815

Useable Fuel 350 48.048.0 16,800

Front Seats 340 37.037.0 12,580

Rear Seats 15 73.073.0 1,095

Baggage Area 35 9595 3,325

Takeoff Weight (lbs) 2,423

Total Moment (lb-in) 100,615

C.G (in) 41.5341.53

Total Moment / Total Weight = C.G

“Teaching the Science, Inspiring the Art, Producing Aviation Candidates!”

Graphical TreatmentGraphical TreatmentGraphical TreatmentGraphical Treatment

63+12.5+12+2+3+1 = 93.5 lb-in

Center of Gravity EnvelopeCenter of Gravity EnvelopeCenter of Gravity EnvelopeCenter of Gravity Envelope

Stability & ControlStability & ControlStability & ControlStability & Control

Center of Gravity concerns: Unable to compensate with

elevator in pitch axis Weight and Balance

becomes critical – stalls & landing

Center of Gravity concerns: Unable to compensate with

elevator in pitch axis Weight and Balance

becomes critical – stalls & landing

Tricks of the TradeTricks of the TradeTricks of the TradeTricks 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

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

ConclusionsConclusionsConclusionsConclusions

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

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

Say IntentionsSay IntentionsSay IntentionsSay IntentionsOne 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

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

Salmon 30 SalmonSalmon 30 SalmonSalmon 30 SalmonSalmon 30 Salmon