Bladder Mechanism
The bladder mechanism is the component that controls the altitude of the HoverFish. The design process is less complicated than the tail mechanism. The design just has to consider the compatibility with the 3mm carbon fibre rod and the weight of the battery holder. If there is too much weight, the torque required to swing the mechanism may be more than what the servo can handle, which lead to the servo being fried.
Bladder platform
Taking the concept from the tail mechanism, we have two parallel structure that holds the servo vertically. Moreover, we can simplify the platform to a straight line to reduce the complexity and the weight of the bladder platform.
Battery holder
Since we are using the battery as our weight for the bladder mechanism, we have to come up with a secure way to mount the battery to the carbon fibre rod. Even though enough tape does the trick, it prevents us from replacing the battery over and over again.
The 1st iteration of the battery holder can hold the battery and the DC/DC boost. The component can be super-glued securely to the carbon fibre rod. However, we need blu tack to secure the DC/DC boost to the battery holder, and the entire 3d printed component is too heavy. In our 2nd iteration, we make sure that the weight of the entire component is minimised and we no longer use blue tack or any adhesive to mount the DC/DC boost.