抄録
Static hovering characteristics of an ACV with annular nozzle above the rough ground were studied experimentally. The rough ground was simulated in such a way that straight wooden bars having rectangular cross sections, d in width, were placed regularly on a smooth board at equal intervals of d. The lift force variation was mess ured by moving the center of the bottom of an ACV through a half wave length of the roughness at the constant hovering height.
The results obtained by these experiments were as follows;
(I) The lift augmentation ratio of an ACV over the rough ground is roughly proportional to the nozzle length ratio lj/lj, where lj is the total nozzle length and lj is the nozzle length above convex portions of the roughness.
(II) When the ratio d/D is sufficiently small, changes of augmentation ratio are small and the mean value of this ratio shows similar tendency to that obtained by adding effective height above the smooth ground.
