NASA Technical Reports Server (NASA) · 1973 · 45 citations · 0 references
EngineeringAerospace EngineeringSystems EngineeringAerodynamicsFlight DynamicsFlight MechanicsAircraft ControlAircraft StabilityManeuvering FlightModel IdentifiabilityStability DerivativesSystem IdentificationAircraft Stability AnalysisAircraft Stability DerivativesControl Derivative AnalysisControl DerivativesFlight Dynamics ModelingFlight Test Estimation Of Stability DerivativesParameter IdentificationSystem Identification Of Stability Derivatives
The study discusses the various challenges encountered in aircraft stability and control derivative identification. The paper develops a maximum‑likelihood method for extracting aircraft stability and control derivatives from flight‑test data. The method employs maximum‑likelihood estimation, incorporates a priori weighting, parameter fixing, and constrained values to address identifiability, and designs optimal inputs for linear systems by maximizing output sensitivity to unknown parameters. The method successfully processes both linear and nonlinear data, handles process noise, and was applied to HL‑10 and M2/F3 flight tests to extract derivatives amid wind gusts, with further examples and a detailed C‑8 simulation confirming its effectiveness.
A new method of extracting aircraft stability and control derivatives from flight test data is developed based on the maximum likelihood cirterion. It is shown that this new method is capable of processing data from both linear and nonlinear models, both with and without process noise and includes output error and equation error methods as special cases. The first application of this method to flight test data is reported for lateral maneuvers of the HL-10 and M2/F3 lifting bodies, including the extraction of stability and control derivatives in the presence of wind gusts. All the problems encountered in this identification study are discussed. Several different methods (including a priori weighting, parameter fixing and constrained parameter values) for dealing with identifiability and uniqueness problems are introduced and the results given. The method for the design of optimal inputs for identifying the parameters of linear dynamic systems is also given. The criterion used for the optimization is the sensitivity of the system output to the unknown parameters. Several simple examples are first given and then the results of an extensive stability and control dervative identification simulation for a C-8 aircraft are detailed.