Initially the ballast engine was modeled after a previous build for an open source underwater glider (https://hackaday.io/project/20458-osug-open-source-underwater-glider). The syringe design was low cost and elegant however we quickly discovered that the syringes would bind and it did have a very low pressure rating despite upgrading the drive motor from a Nema-17 to a Nema-23. For this reason the ballast design was reformatted to use a High pressure pump combined with a reservoir. This would allow for the glider to reach greater depths and therefore become more energy efficient.

The following figure was a test of just the new pump design.

This design included two solenoid valves rated for 100PSI, a control board, and arduino uno and a diaphragm pump rated to approximately 30meters of seawater with a lifting bag as a bladder.



Choosing the pump was difficult as finding a pump that fit the power requirements (12V), the tube diameter (4inches) and had the power capable of pumping out water at depth proved to be quite a challenge and is a driving factor in potentially shifting to a 6inch tube for the 2nd version.

Once implemented into the glider the new ballast engine design preformed very well. The glider will need to be ballasted but this engine design should be able to descend to 15 to 20 meters.

In this image the wings have not been attached and the altimeter is hanging loose as the nosecone is also off for testing purposes.