“teaching the science, inspiring the art, producing aviation candidates!” weight & balance...
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“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
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
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
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