Submersibles

Submersibles are vehicles designed to go beneath the surface of a liquid. Traditionally, this liquid is water. However, submersible vehicles could potentially be used to monitor other liquids, such as fermentation tanks at breweries, mixing tanks at chemical plants, and ping into raw sewage tanks. Other than ping into a vat of beer, I'm sure you can see how using drones is preferable to ping in yourself.

We won't be attempting to create a submersible in this book. However, the techniques employed are very similar to the subject matter of this book. Submersibles should only be attempted by highly experienced drone designers, as they'll have to contend with reduced ability to utilize GPS, reduced radio transmission distance, and highly reduced visibility in water (or other liquids). Therefore, technologies such as forward looking infrared (FLIR), signal repeaters, and collision avoidance (via SONAR) should be considered. However, as you can see from the following image, the similarities between underwater drones and fixed-wing aerial drones (airplanes) are fairly obvious:

The similarities between the Navy's "Ocean Glider" submersible drone and the original X-1 airplane (the airplane which first broke the sound-barrier) are rather astounding.