Fig. 13. Force components and body velocities of single flies flying freely in a stationary (left) and rotating (500° s^–1, right) random-dot flight arena. (A,F) Flight paths of the two animals lasting 2.4 s each. Horizontal (B,G), vertical (C,H), centripetal (D,I) and total (E,J) forces (black, left scale) and velocities (red, right scale), measured from the fly's body motion inside the arena and calculated from the equations given in the text, respectively. Total velocity is the vector sum of horizontal, vertical and turning velocity. Grey dots indicate saccades in which turning velocity exceeds 1000° s^–1 angular speed. Red cross, centre of flight arena.