Flexible aircraft flight dynamics and loads model identification from flight test data in unsteady conditions

A. Jurisson*, Bart Eussen, C.C. de Visser, R. De Breuker

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientific

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Abstract

This paper presents a method for identifying flight dynamics models for aircraft that includes effects from the flexible structure and the effects from unsteady aerodynamics. In the time domain, the unsteady aerodynamic effects are often modelled using aerodynamic lag states. The proposed method involves first determining the poles that govern the dynamics for these lag states from flight data. This is followed by reconstructing the time signal histories for these lag states so that they can then be used as part of the model fitting procedure. Flight tests were conducted using a scaled Diana2 glider unmanned aerial vehicle (UAV) in order to collect experimental data for modelling. To be able to measure the response of the aircraft and its structure, the glider was instrumented with a wide range of sensors including accelerometers, gyroscopes and strain gauges placed across the aircraft structure. During the flight, various excitation manoeuvres were conducted by the pilot while the aircraft responses were collected. From these measurements, a full flight dynamics model consisting of both lateral and longitudinal dynamics was then identified. Additionally, a model predicting the tail and wing root loads was also identified. First, a rigid aircraft model was fitted that was then extended with states corresponding to the flexible modes and aerodynamic lags. Comparison between the rigid and extended model showed that the addition of structural modes and aerodynamic lag states to the identified models can lead up to 30% improvement in predicting aircraft responses. In conclusion, the method developed and presented in this paper is able to identify flight dynamics models from flight data that more accurately capture the dynamics of flexible aircraft by including effects from the flexible structure and unsteady aerodynamics.
Original languageEnglish
Title of host publicationAeroelasticity & Structural Dynamics in a Fast Changing World 17 – 21 June 2024, The Hague, The Netherlands
Number of pages19
Publication statusPublished - 2024
EventInternational Forum on Aeroelasticity and Structural Dynamics - Den Haag, Netherlands
Duration: 17 Jun 202421 Jun 2024
Conference number: 20

Conference

ConferenceInternational Forum on Aeroelasticity and Structural Dynamics
Abbreviated titleIFASD 2024
Country/TerritoryNetherlands
CityDen Haag
Period17/06/2421/06/24

Keywords

  • system identification
  • flight testing
  • unsteady aerodynamics
  • flight dynamics
  • aeroelasticity

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