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In many instances, the weight and balance of the aircraft will be changed by the addition or removal of weight. When this happens, a new CG must be calculated and checked against the limitations to see if the location is acceptable. This type of weight and balance problem is commonly encountered when the aircraft burns fuel in flight, thereby reducing the weight located at the fuel tanks. Most small aircraft are designed with the fuel tanks positioned close to the CG; therefore, the consumption of fuel does not affect the CG to any great extent.

The addition or removal of cargo presents a CG change problem that must be calculated before flight. The problem may always be solved by calculations involving total moments. A typical problem may involve the calculation of a new CG for an aircraft which, when loaded and ready for flight, receives some additional cargo or passengers just before departure time.

In the previous examples, the CG is either added or subtracted from the old CG. Deciding which to accomplish is best handled by mentally calculating which way the CG will shift for the particular weight change. If the CG is shifting aft, the CG is added to the old CG; if the CG is shifting forward, the CG is subtracted from the old CG.

Determining Loaded Weight and CG (Part Five) – Weight Shifting

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0savesSave When weight is shifted from one location to another, the total weight of the aircraft is unchanged. The total moments, however, do change in relation and proportion to the direction and distance the weight is moved. When weight is moved forward, the total moments decrease; when weight is moved aft, total moments increase. The [...]

Determining Loaded Weight and CG (Part Four) – Computations

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0savesSave Computations With a Negative Arm Figure 9-10 is a sample of weight and balance computation using an airplane with a negative arm. It is important to remember that a positive times a negative equals a negative, and a negative would be subtracted from the total moments. Computations With Zero Fuel Weight Figure 9-11 is [...]

Determining Loaded Weight and CG (Part Two) Graph Method

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0savesSave Another method for determining the loaded weight and CG is the use of graphs provided by the manufacturers. To simplify calculations, the moment may sometimes be divided by 100, 1,000, or 10,000. [Figures 9-6, 9-7, and 9-8] Front seat occupants………………………………340 pounds Rear seat occupants ………………………………..300 pounds Fuel ………………………………………………………..40 gallons Baggage area 1 ………………………………………..20 pounds [...]

Determining Loaded Weight and CG (Part One) Computational Method

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0savesSave The following is an example of the computational method involving the application of basic math functions. Aircraft Allowances: Maximum gross weight…………………. 3,400 pounds CG range……………………………………… 78–86 inches Given: Weight of front seat occupants…………. 340 pounds Weight of rear seat occupants………….. 350 pounds Fuel………………………………………………….. 75 gallons Weight of baggage in area 1………………..80 pounds 1. List [...]

Principles of Weight and Balance Computations

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0savesSave It might be advantageous at this point to review and discuss some of the basic principles of weight and balance determination. The following method of computation can be applied to any object or vehicle for which weight and balance information is essential. By determining the weight of the empty aircraft and adding the weight [...]

Lift and Basic Aerodynamics

Aircraft Structure

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0savesSave Four forces act upon an aircraft in relation to straight-and-level, unaccelerated flight. These forces are thrust, lift, weight, and drag. [Figure 2-1] Thrust is the forward force produced by the powerplant/propeller. It opposes or overcomes the force of drag. As a general rule, it is said to act parallel to the longitudinal axis. This [...]

Management of Weight and Balance Control

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0savesSave Title 14 of the Code of Federal Regulations (14 CFR) section 23.23 requires establishment of the ranges of weights and CGs within which an aircraft may be operated safely. The manufacturer provides this information, which is included in the approved AFM, TCDS, or aircraft specifications. While there are no specified requirements for a pilot [...]

Balance, Stability, and Center of Gravity

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0savesSave Balance refers to the location of the CG of an aircraft, and is important to stability and safety in flight. The CG is a point at which the aircraft would balance if it were suspended at that point. The primary concern in balancing an aircraft is the fore and aft location of the CG [...]