AN ANALYTICAL STUDY OF FACTORS INFLUENCING THE LONGITUDINAL STABILITY OF TILT-WING VTOL AIRCRAFT
PRINCETON UNIV NJ DEPT OF AEROSPACE AND MECHANICAL SCIENCES
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An analytical method for predicting the stability characteristics of tilt-wing VTOL aircraft in the transition speed range is presented. Sample calculations based on an assumed tilt-wing VTOL transport configuration of the XC-142A class with double slotted flaps are given. Particular emphasis is placed on the sensitivity of the results to various assumptions made in the analysis. The contributions of the various aircraft components and the aerodynamic interactions of the components to the stability derivatives are discussed, as well as the changes in the characteristic modes of motion of the vehicle that result from variations in the stability derivatives. The trim conditions of the vehicle are shown to be quite sensitive to the prediction of the flap characteristics. A limited comparison of the calculated results with experimental data obtained from a dynamic model of the XC-142A, which is somewhat dissimilar from the assumed configuration, is presented. This comparison indicates that the trends of the stability derivatives are correctly predicted. The agreement between theory and experiment is good in hovering however, as the wing incidence is reduced, the difference between theory and experiment becomes quite large.
- Transport Aircraft