TS ISO 1151-3

TS ISO 1151-3 is a terminology standard for flight dynamics that addresses derivatives of forces, moments and related coefficients. It provides a common conceptual framework for describing how aerodynamic and other load quantities change with independent variables, using the language of partial derivatives.

Why these derivatives matter in flight dynamics

In general technical use, force and moment derivatives are central to stability and control analysis because they express sensitivity: how lift, drag, side force, rolling moment, pitching moment, yawing moment, and their coefficients respond to changes in conditions such as speed, angle of attack, sideslip, or control-surface deflection. These relationships are often linearised around a reference condition so that small perturbations can be analysed with practical engineering methods. This part of ISO 1151 focuses on the naming and symbolisation of those derivative quantities rather than on prescribing a complete aerodynamic model.

What the scope does and does not cover

• It is restricted to first-order terms.
• Higher-order terms would require additional definitions.
• The aircraft is assumed to be rigid in the base formulation.
• Most definitions can also be applied to a flexible aircraft in general technical context.
• The standard covers derivatives of forces, moments and other quantities that characterise such forces and moments.