Summary: CG Formulas

Summary of useful formulas for Questions regarding CG

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- Finding CG by mass and moment

Moment = Arm x Mass

CG = Total Moment / Total Mass

! Moments in front of the datum are negative ("-" sign) and those behind datum are positive ("+" sign)

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- Mean Aerodynamic Chord

CG (as %) converting to CG (as distance behind LE) =

1: Divide the number by 100
2: Multiply by the MAC length

CG (as distance behind LE) converting to CG (%MAC) =

1: Divide the number by MAC length
2: Multiply by 100

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- Adding, Removing and moving Mass

1: When Question states that mass is added

Change in Mass / New total mass = Change in CG / Distance mass & Old CG

2: When Question states that mass is removed

Change in Mass / Old total mass = Change in CG / Distance mass & New CG

3: When Question states that mass is moved

Change in Mass / Total mass = Change in CG / Distance moved

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