Festo presented during the Hannover Fair, Hannover, Germany the first fish with pneunatice drive with the name “Airacuda”.

Airacuda
The Airacuda glides gracefully and silently through the water. The construction of the remote-controlled, pneumatically driven fish closely follows the lines and motions of its biological precursor. The watertight head houses the electronics and pneumatics which control the S-shaped motion of its tail fin, supplied by two fluidic muscles. Steering is facilitated by two additional muscles.

The fin itself contains an alternating tension/compression flank connected to a rib structure. When a flank is pressurised, the geometric structure arches against the acting force. What might sound complicated is actually a simple principle which enables a fish to utilize the full power of its fin stroke in water. The structure is called the “Fin Ray Effect” and is used in two ways: firstly, as a passive component of the tail fin and secondly as an active structure in the body. The diagonals in the structure are shortened alternately with the aid of fluidic muscles.

Fin drives have numerous advantages over conventional propellers. All in all, a greater proportion of the motion is converted into thrust. In contrast to conventional drives used in water, the fish does not need a rigid drive unit.

The fluidic muscle is a Festo innovation. Its properties are similar to those of a real muscle – and yet it is operated with compressed air. The initial force of this artificial muscle is extremely high and its dynamics resemble those of the human muscle. With its low weight, high flexibility and wide variety of uses, it is ideally suited to bionic applications.