| 摘要 |
A steering head for use with a casing, the steering head having a generally cylindrical body with a first body end with a lead edge, a second body end with a rear edge, and a body surface extending from the lead edge to the rear edge, an outer tube with an internal side generally facing the body surface, the outer tube extending from the first body end to the second body end, and a steering flap disposed on an external side of the outer tube having a first flap face facing radially inwardly and a second flap face facing radially outwardly. A biased hinge is secured to both the outer tube and the steering flap, the biased hinge being operative to retract the steering flap into a retracted position from an extending position. |
