Unsteady aerodynamics analysis and modelling of a Slingsby Firefly aircraft: Detached-Eddy Simulation model and flight test validation

A. F. Neves, N. J. Lawson, C. J. Bennett, B. Khanal, R. I. Hoff

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
40 Downloads (Pure)


This paper presents unsteady stall characteristics of a Slingsby T67M260 Firefly light aircraft from both a computational fluid dynamics (CFD) half model and flight tests. Initial results from the steady CFD, based on a RANS k−ω SST turbulence model, established the critical angle of attack of the stall to be αstall=16, with a maximum lift coefficient of CLmax=1.2. Comparisons with straight and level flight test data were comparable up to α=12 – 14, with the increasing deviation at higher α attributed to the effect of the propeller slipstream under these flight conditions. The RANS CFD model was then extended to an unsteady Detached-Eddy Simulation (DES) model for three angles of attack at pre-stall and stall condition (α=14, 16, 18), with analysis of the vortex shedding frequency. Further comparisons were then made with flight test data taken using on-board accelerometers and wing tuft surface flow visualization, at a stalled condition at equivalent α. These unsteady CFD data established a dominant shedding frequency ranging from 11.7 Hz – 8.74 Hz with increasing α and a Strouhal number based on wing chord of St = 0.11, which when compared to flight test accelerometer spectra matched within 2.9% of the measured frequency.

Original languageEnglish
Article number106179
JournalAerospace Science and Technology
Early online date7 Sep 2020
Publication statusPublished - Nov 2020

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Aerospace Science and Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Aerospace Science and Technology, 106, (2020) DOI: 10.1016/j.ast.2020.106179

© 2020, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/


  • Buffet frequency
  • CFD
  • Detached-Eddy Simulation
  • Flight test
  • Stall
  • Strouhal number

ASJC Scopus subject areas

  • Aerospace Engineering


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