DEFINITION:

The research in open-loop stability uses analytical and experimental techniques to study the aircraft’s natural motion around the centre of gravity, resulting from the external forces and moments acting on the aircraft, without interference from a pilot or autopilot. In the analysis it is determined if in a certain flight condition all forces and moments are in equilibrium. Subsequently, an aircraft is considered to be open-loop stable if, after a small disturbance from an equilibrium flight condition, the aircraft has a natural tendency to return to the original condition, without interference from a pilot or autopilot.

(Source: ACARE Domain 501)

SUBDOMAINS:

1. System identification – from empirical / analytical model parameter estimation, wind tunnel tests and flight tests.
2. Mathematical modelling – equations of motion, aerodynamics, mass properties and geometry, taking into account modelling errors and uncertainties).
3. Analytical analysis of stability and stability margins – including a sensitivity analysis to determine the most influential physical parameters.
4. Flight Tests – experimental analysis of stability and natural motion of the aircraft, including model validation, definition of suitable test manoeuvres, instrumentation.