Ch 7 - Datum, Moments And Determining CofG

Question 1

Forces in a Steady Flight

Answer 1

Thrust = Drag

Lift = Weight (+ Downforce)

Always a compromise between range of CofG and manoeuvrability

Question 2

Moment

Answer 2

The tendency of a force to rotate an object around an axis.

Moment = Force x Distance

• Moments are generated because forces don’t originate from the same point
• Aircraft moves around CofG
• To not pitch, the sum of all of the moments must equal 0

Question 3

CofG Arm Position Equation

Answer 3

CofG Arm = Total Moments / Total Mass

Question 4

Aircraft CG

Answer 4

Will change during flight as fuel is burnt

CofG must stay between fwd and aft limits for the entire flight

Question 5

CofG Envelope Rules

Answer 5

All points from the load sheet have to be within the envelope

Points should plot a straight line as the only difference between them should be the fuel burn