An Analytical Study of the Longitudinal Dynamics of a Tilt-Wing Vtol

Abstract

Introduct ion 13 Analysis 23 Assumptions Non-dimensionalizat ion 25 Equations of motion 26 Evaluation of stability derivatives Static derivatives Dynamic derivatives Evaluation of coefficients to stability quartic Characteristic equation in hovering Calculation of roots to the quartic and cubic equations for various flight configurations Approximate factorization of quartic Discussion Variation of quartic roots with tilt angle Effect of physical parameters Conclus ions Recommendations for further study 90 References Page A. Inflow ratio and induced velocity derivatives 137 B. Values of parameters and assumed lift-curve slope for Vertol 76 139 C. Determination of value for K from experimental data 141 D. Calculated values for all parameters 153 4 LIST OF FIGURES Page 1. Sketch showing velocity vectors at wing and definition of various angles 2. Forces acting on aircraft 95 3. Center of gravity movement with wing tilt 4. Graph of Z and 70as function of Lw 5. Charts of R and derivatives 6. Charts of () and derivatives 106 7, Forces acting at flapping hinge 113 8. Sketch showing velocity change at rotor due to pitching 114 9. Sketch defining velocity vectors and angles at tail 113 10. Aircraft in steady pull-up 115 11. Charts of trim conditions L16 12. Variation of roots of characteristic equation with wing tilt angle 122 13. Comparison of exact roots with approximations 123

Design and wind tunnel tests of a tiltwing UAV

“…Further analysis was done by Mckinney [5] on tiltwing configurations regarding their performance and control aspects. Especially the horizontal control during hovering and transition, which was also analyzed by [6][7][8], proved difficult. Extensive modeling was done during the design of the described tiltwing to include these effects and ensure a stable transition.…”