1. Professor, Dept. of Aerospace Vehicles, Polytechnic Univ. of Madrid, 28040 Madrid, Spain (corresponding author).
2. M.Sc. Student, Aerospace Vehicle Design, Cranfield Univ., College Rd., Cranfield, Bedfordshire MK43 0AL, UK.
3. Spain Local Team Leader, Structural Dynamics and Aeroelasticity Department, AIRBUS Defence and Space, Paseo John Lennon s/n, 28906 Getafe, Madrid, Spain.