PURPOSE: To prevent supporting load from being added to a wing portion by unifying the outer wings extending from a fixed wing centerpiece in one together with engine pods, making them tiltable, while supporting a through tubular spar rotatably on the fixed wing centerpiece in parallel with a transverse axis of aircract as the support of the outer wings integrally forming the engine pods in one each.

CONSTITUTION: Outer wings 4 are rotatably supported by a fixed wing centerpiece 2 and set up in a through tubular spar 5 acting as a supporter. Therefore, supporting load at the fixed wing centerpiece 2 is substantially reduced. In addition, since there is no need of complete helicopter rotor head control, control over a rotor of the engine pods 3 becomes simplified.