Abstract: A ducted fan 20 provides lift to a flying vehicle 10. The ducted fan includes direction control vanes (1, 2, 3, 4) for controlling torques applied to the vehicle, and also includes lift negation vanes (305, 306, 307, 308), which control the available lift. The lift negation vanes are oriented with their longitudinal axes parallel to the forward-aft axis (9) of the vehicle in order to reduce drag at high forward velocities. The thrust negation vanes include fixed (305) and movable (305M) portions, with the movable portions rotatable so as to extend into the duct airflow to cause turbulence. The direction control vanes are airfoils arranged for rotation about their quarter-chord axes (410), which reduces the amount of torque required for rotation of the direction-control vanes. This, in turn, allows stepper motors (924a) to be used to drive the vanes. The effects of forward velocity on the ducted fan also creates effects which tend to pitch the vehicle nose-down.

Abstract: A tank for the depuration of shellfish incorporating an elongated open vessel for retaining sea water and a manifold extending the length of the bottom of the vessel substantially along the longitudinal center axis from one end of the vessel to the other and including a connection at each end thereof for the injection of sea water with a plurality of fill pipes extending from the manifold toward each side of the vessel and each fill pipe including a pattern of holes for the emission of sea water therefrom forming an up-welling pattern to provide a desired turbulence within the vessel and a trough extending around the upper periphery of the vessel for recovering sea water spilling over the upper walls of the vessel such that the injection of sea water through the holes and the recovery of the sea water in the troughs preventing dead spots within the sea water in the vessel.