Weight and Balance
Also known as: W&B, center of gravity, CG analysis
Weight and balance analysis is the process of determining the total weight of an aircraft and the location of its center of gravity (CG) throughout its operational envelope. Essential for aircraft safety and performance, weight and balance ensures that the CG remains within allowable limits (forward and aft) to maintain stable flight and controllability. Regulatory certification requires comprehensive weight and balance documentation for every aircraft configuration.
Key highlights
- Simple arithmetic; weight and balance is straightforward calculation; easily automated and verified.
- Physically intuitive; everyone understands the concept of balance and center of gravity.
- High impact; incorrect weight and balance directly affects aircraft handling, stability, and safety.
- Documented standard; FAA and EASA provide detailed guidance (ACs, certification specs) for weight and balance.
Intuition
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How it works
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When to use it
Perform weight and balance analysis for every aircraft design, manufacture, and operational change. Mandatory before first flight and after any significant modification. Repeat for each configuration change (different cargo load, fuel plan, or equipment installation). Regulatory requirement for certification (FAA, EASA, etc.).
Strengths & limitations
- Simple arithmetic; weight and balance is straightforward calculation; easily automated and verified.
- Physically intuitive; everyone understands the concept of balance and center of gravity.
- High impact; incorrect weight and balance directly affects aircraft handling, stability, and safety.
- Documented standard; FAA and EASA provide detailed guidance (ACs, certification specs) for weight and balance.
- Static analysis; assumes the aircraft is stationary; does not account for fuel sloshing or dynamic load transfer during maneuvers.
- Component discretization; requires detailed knowledge of component weights and positions; estimation errors propagate.
- Configuration specificity; each payload/fuel configuration must be analyzed separately; large number of configurations needed for comprehensive envelope.
- Ignores aerodynamic pressure center; structural balance (CG) differs from aerodynamic center; separate analysis needed for trim.
Common pitfalls
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Applications
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Frequently asked
What is the MAC (Mean Aerodynamic Chord) and why is it used?
The MAC is the average chord length of the wing; CG location is often expressed as a percentage of MAC from the leading edge (% MAC). This normalizes CG location independent of wing size, making it easier to compare different aircraft and identify stability margins.
What are typical CG limits (forward and aft)?
For a general aviation aircraft, forward CG limit is often ~23% MAC and aft limit ~30% MAC (typical ranges vary by aircraft). Forward limit ensures pitch control authority; aft limit prevents departure from controlled flight. Limits are derived from aerodynamic analysis (pitch control trim) and stability requirements.
How does fuel burn affect weight and balance in flight?
As fuel is consumed, both total weight decreases and CG location shifts (depending on tank geometry). As aircraft burns fuel from wing tanks before center tank, CG may move aft. Pilots and engineers must account for CG shift during flight and ensure it remains in envelope throughout descent and landing.
What is an empty weight and tare weight?
Empty weight is the aircraft's weight without crew, fuel, or payload; used as baseline for W&B analysis. Tare weight includes fixed equipment and liquids (hydraulic fluid, coolant) but excludes fuel and payloads. Tare weight is more realistic for actual operational conditions.
Sources
- 1.Federal Aviation Administration (2017). Airplane Weight and Balance Control. Advisory Circular AC 23-8B-1C.
- 2.Raymer, D. P. (1992). Aircraft Design: A Conceptual Approach (2nd ed.). American Institute of Aeronautics and Astronautics.
- 3.Nicolai, L. M., & Carichner, G. E. (2010). Fundamentals of Aircraft and Airship Design, Volume 1: Aircraft Design (Rev. ed.). American Institute of Aeronautics and Astronautics.
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Cite this page
ScholarGate. (2026, June 3). Weight and Balance. ScholarGate. https://scholargate.app/aerospace/weight-and-balance