# Definition of axes and angles

The aim of this topic is to explain the commonly used axes for aircraft simulation and aerodynamic analysis.

### Force and moment coefficients

The force and moments acting on the aircraft are commonly defined in terms of dimensionless aerodynamic coefficients. The coefficients are functions of the two aerodynamic angles, the Mach number, the Reynolds number, the control surface deflection, and the aircraft thrust. The thrust generated by the aircraft engines can affect the aerodynamic coefficients.

Other factors that affect the aerodynamic coefficient are geometry changes such as deployment of landing gears, addition of external fuel tanks, ground proximity effect, etc. The definition of the coefficients with respect to the body-fixed coordinate system is:

The Aviumtechnologies Panel Method uses the above definition of the aerodynamic coefficients.

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