Numerical Investigation of V-Tails and their Interference for commercial Aircraft Configurations

Abstract

For commercial aircraft up to nowadays, only L and T-shaped tails have been widely used for their control and integration simplicity. However, other types of tails such as V-shaped tails have begun to be investigated for their better efficiency while maintaining suitable stability properties. The following thesis analyses the influence of the Vee-tail geometrical parameters on the stability in cruise and high lift. High fidelity computations are performed and the results are compared with a T-tail configuration.

The results show that in cruise, the higher the chord/span ratio or the dihedral of a Vee-tail, the more stable the configuration will be directionally. The longitudinal stability of the aircraft is always assured, apart for very small chord/span ratio Vee-tails. Furthermore, the higher the chord/span ratio or the lower the dihedral of a Vee-tail, the more stable the configuration will be longitudinally. The study also showed that the efficiency of the Vee-tailed configurations could be equal or higher to the one of a T-tailed configuration. In high lift, the most stable Vee-tailed configuration tested in cruise has a similar efficiency to the T-tailed configuration and, for the fight point observed, seems to be at least as stable longitudinally than the T-tailed configuration. Moreover, it was found that the wing wake does not create a separation of the flow around the tail in cruise or in high lift. More globally, the study shows that a Vee-tailed commercial aircraft with a high dihedral and chord/span ratio can be as stable as a T-tailed aircraft without a modification of the fuselage length to integrate the Vee-tail.

In the authors view, further investigations could be done on the Vee-tail airfoil shape as well as on the potential structural variations (inverted Vee or X tails). Moreover, an optimization of the Vee-tail geometric parameters in order to maximize the efficiency can be envisaged