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Steady flight, unaccelerated flight, or equilibrium flight is a special case in flight dynamics where the aircraft's linear and angular velocity are constant in a body-fixed reference frame. Basic aircraft maneuvers such as level flight, climbs and descents, and coordinated turns can be modeled as steady flight maneuvers. Typical aircraft flight consists of a series of steady flight maneuvers connected by brief, accelerated transitions. Because of this, primary applications of steady flight models include aircraft design, assessment of aircraft performance, flight planning, and using steady flight states as the equilibrium conditions around which flight dynamics equations are expanded. ==Reference Frames== Steady flight analysis uses three different reference frames to express the forces and moments acting on the aircraft. They are defined as: * Earth frame (assumed inertial) * * Origin - arbitrary, fixed relative to the surface of the Earth * * ''xE'' axis - positive in the direction of north * * ''yE'' axis - positive in the direction of east * * ''zE'' axis - positive towards the center of the Earth * Body frame * * Origin - airplane center of gravity * * ''xb'' (longitudinal) axis - positive out the nose of the aircraft in the plane of symmetry of the aircraft * * ''zb'' (vertical) axis - perpendicular to the ''xb'' axis, in the plane of symmetry of the aircraft, positive below the aircraft * * ''yb'' (lateral) axis - perpendicular to the ''xb'',''zb''-plane, positive determined by the right-hand rule (generally, positive out the right wing) * Wind frame * * Origin - airplane center of gravity * * ''xw'' axis - positive in the direction of the velocity vector of the aircraft relative to the air * * ''zw'' axis - perpendicular to the ''xw'' axis, in the plane of symmetry of the aircraft, positive below the aircraft * * ''yw'' axis - perpendicular to the ''xw'',''zw''-plane, positive determined by the right hand rule (generally, positive to the right) The Euler angles linking these reference frames are: * Earth frame to body frame: yaw angle ''ψ'', pitch angle ''θ'', and roll angle ''φ'' * Earth frame to wind frame: heading angle ''σ'', flight-path angle ''γ'', and bank angle ''μ'' * Wind frame to body frame: angle of sideslip ''β'', angle of attack ''α'' (in this transformation, the angle analogous to ''φ'' and ''μ'' is always zero) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Steady flight」の詳細全文を読む スポンサード リンク
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