What Is Flight Dynamics?

It is the science that studies the movement law and overall performance of the aircraft in the air. All moving bodies that pass through a fluid medium or a vacuum are collectively referred to as an aircraft. It mainly includes spacecraft, aircraft, projectiles, and underwater weapons. The study of the law of projectiles and arrows is called external ballistics, and the study of the laws of aircraft movements is called aircraft flight dynamics. However, from the perspective of mechanics, they all belong to the typical flight dynamics category. The purpose of studying flight dynamics is to provide a theoretical basis for the development and use of aircraft in terms of basic principles and performance analysis skills.

Flight performance

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The purpose of aircraft flight dynamics research is to provide theoretical basis for aircraft design, use and performance. The research methods of flight dynamics can be divided into theoretical research and experimental research. Its theoretical basis includes aerodynamics, theoretical physics (rigid body mechanics), structural mechanics, elastic mechanics, and automatic control theory; the main tools for theoretical research are applied mathematics and computers; the main problem studied by aircraft flight dynamics is aircraft flight Performance and stability and maneuverability (ie the dynamic characteristics of the aircraft). Among them, flight performance mainly studies the laws of aircraft movement as particles under known external forces, such as flight speed, flight altitude, range, take-off, landing, and maneuvering. The stability and maneuverability of aircraft are mainly studied as particle systems ( (Rigid or elastomer) aircraft's ability to maintain and change flight status, that is, to study the aircraft's motion characteristics under external disturbance and control. The starting point for studying the flight dynamics of an aircraft is the equation of motion of the aircraft, which is a basic description of the laws of motion of the aircraft. The premise of establishing the equation of motion is to define parameters that characterize the state of motion of the aircraft, such as the space of the aircraft, in a coordinate system in a certain sense. Position, attitude, flight speed, and angular velocity. ^[2]

Aircraft flight dynamics is a branch of mechanics, and its task is to establish a model describing the aircraft motion dynamics (or mathematics) and analyze the stability and maneuverability of the designed aircraft on this basis. Generally, the following aspects should be considered in aircraft dynamics modeling:

(1) The dynamic model of the aircraft body. According to the different requirements of the research problem, the aircraft body can be regarded as a particle, a rigid body or an elastic body.

(2) The kinematics model of the aircraft, according to the requirements of the research question, can choose different coordinate axis systems to describe the aircraft's spatial position, azimuth and the relationship between them.

(3) A mathematical description of the aerodynamic forces and moments acting on the aircraft during flight.

(4) A description of the engine forces and moments acting on the aircraft during its flight. ^[3]