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What percentage of the Mac line is best for CG placement?
Most airfoils have an aerodynamic center located around 25% – 33% of the mean aerodynamic chord (MAC) from the leading edge, so 25% is often used as a reference point on our models. Locating the CG at 25% is a safe bet for a maiden flight. Remember, it’s always better to have a nose heavy plane than a tail heavy one.
Why must the CG be in the CG range?
The Balance point (Centre of Gravity – CG) is very important during flight because of its effect on the stability and performance of the aircraft. It must remain within carefully defined limits at all stages of flight. The structural strength of the aircraft also limits the maximum weight the aircraft can safely carry.
How is CG calculated on Mac?
To find the center of gravity, we divide the total moment by the total mass: 193,193 / 2,055 = 94.01 inches behind the datum plane. In larger aircraft, weight and balance is often expressed as a percentage of mean aerodynamic chord, or MAC. For example, assume the leading edge of the MAC is 62 inches aft of the datum.
What happens if a plane is tail heavy?
In a tail heavy plane, as it looses lift and approaches stall speed, the tail will drop — the worst possible thing that could happen! You’ll loose airspeed and it will rapildy move into a full stall.
Why is CG optimum position at 25% Mac?
I have read a320’s optimum CG position is 25% MAC. But, the aerodynamic center is also at 25% of chord. So since CG and aerodynamic center at the same position, there would be no moment arm of lift, so what will be the use of tail plane?
When to use the term optimum CG position?
Typically the term “optimum CG position” is used not for a range but for a given CG position that optimizes whatever you wish to optimize. Usually for transport category aircraft it’s used to refer to the target zero fuel weight CG that produces the best fuel economy.
How is the Mac related to the center of gravity?
The MAC is the chord drawn through the geographic center of the plan area of the wing. The relative positions of the CG and the aerodynamic center of lift of the wing have critical effects on the flight characteristics of the aircraft.
How is the CG related to the aerodynamic center of lift?
The relative positions of the CG and the aerodynamic center of lift of the wing have critical effects on the flight characteristics of the aircraft. Consequently, relating the CG location to the chord of the wing is convenient from a design and operations standpoint.