# 12.3: General equations of motion

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The physic-mathematical model governing the movement of the aircraft in the atmosphere are the so-called general equations of motion: three equations of translation and three equations of rotation. The fundamental simplifying hypothesis is:

##### Theorem 12.2 6-DOF model

The aircraft is considered as a rigid solid with six degrees of freedom, i.e., all dynamic effects associated to elastic deformations, to degrees of freedom of articulated subsystems (flaps, ailerons, etc.), or to the kinetic momentum of rotating subsystems (fans, compressors, etc ), are neglected.

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