Flutter Characteristics of a Morphing Flight Vehicle with Varying Inboard and Outboard Folding Angles

  • Received : 2013.02.27
  • Accepted : 2013.04.16
  • Published : 2013.06.30


Morphing aircraft capable of varying their wing form can operate efficiently at various flight conditions. However, radical morphing of the aircraft leads to increased structural complexities, resulting in occurrence of dynamic instabilities such as flutter, which can lead to catastrophic events. Therefore, it is of utmost importance to investigate and understand the changes in flutter characteristics of morphing wings, to ensure uncompromised safety and maximum reliability. In this paper, a study on the flutter characteristics of the folding wing type morphing concept is conducted, to examine the effect of changes in folding angles on the flutter speed and flutter frequency. The subsonic aerodynamic theory Doublet Lattice Method (DLM) and p-k method are used, to perform the flutter analysis in MSC.NASTRAN. The present baseline flutter characteristics correspond well with the results from previous study. Furthermore, enhancement of the flutter characteristics of an aluminum folding wing is proposed, by varying the outboard wing folding angle independently of the inboard wing folding angle. It is clearly found that the flutter characteristics are strongly influenced by changes in the inboard/outboard folding angles, and significant improvement in the flutter characteristics of a folding wing can be achieved, by varying its outboard wing folding angle.


Doublet Lattice Method;Flutter Analysis;Folding Wing Concept;Morphing Wing;p-k Method


  1. Canfield, B., and Westfall, J., "Distributed actuation system for a flexible in-plane Morphing wing, Advanced Course on Morphing Aircraft, Mechanisms and Systems", Lisbon, Portugal, November 2008.
  2. Baugher, J., Grumman F-14A Tomcat: Joe Baugher's Encyclopedia of American Military Aircraft, February 2000.
  3. Withington, T., B-1B Lancer Units in Combat (Osprey Combat Aircraft 60), Osprey Publishing, London, 2006.
  4. Pace, S., "Triplesonic Twosome", Wings, Volume 18, No. 1, February 1988.
  5. Lazos, B. S., "Biologically inspired Fixed-Wing Configuration Studies", Journal of Aircraft, Vol.42, No.5, September-October 2005.
  6. Wlezien, R. W., Horner, G. C., McGowan, A. R., Padula, S. L., Scott, M. A., Silcox, R. J., and Simpson, J. O., "The Aircraft Morphing Program", 39th AIAA/ASME/ASCE/ASC Structures, Structural Dynamics, and Materials Conference, Long Beach, CA, April 1998.
  7. Terrence, A. W., "Morphing Aircraft Technology -New Shapes for Aircraft Design", Purdue University, October 2006.
  8. Michael, W. K., "A Historical Overview of Flight Flutter Testing", NASA Technical Memorandum 4720, October 1995.
  9. Zhao, Y., and Hu, H., "Parameterized aeroelastic modeling and flutter analysis for a folding wing", Journal of Sound and Vibration, 2012. DOI:10.1016/j.jsv.2011.08.028
  10. Matthew, P. S., Brian, S., Franklin, E. E., and Geoffrey, J. F., "Vibration and flutter characteristics of a folding wing", Morphing Aircraft Structures: Research in ARFL/RB, 2008.
  11. Albano, E., and Rodden, W. P., 1969, "A doublet lattice method for calculating lift distribution on oscillating wings in subsonic flows", AIAA Journal, Vol. 7, No. 2, pp. 279-285.
  12. Hodges, D. H., and Pierce, G. A., Introduction to Structural Dynamics and Aeroelasticity, Cambridge University Press, New York, 2002.


Supported by : KARI (Korea Aerospace Research Institute)