Since our initial launch about a month ago, we have been busy testing the prototype. Through a sophisticated testing program, we have characterized relationships between velocity, drag and power consumption. We expect these results to scale well to our final craft.
To find the relationship between power consumption and speed, we measured the current drawn by the motor with a current sensor. Timing the boat over an interval of known length, we were able to relate the current to the speed of the boat.
Additionally, we need to know how drag force relates to velocity when designing our Trans-Atlantic vessel. To find this relationship, we used a block and tackle setup with calibrated weights to exert various constant known forces on the boat. By measuring the terminal velocity, we determined the generalized drag curve for the hull.
From theory, we expect both current draw and drag force to be proportional to velocity squared. As seen in the graph above, this behaviour was seen from the experimental data.
Looking forward, we will use these findings to decide on the parameters for our final craft concept. Stay tuned for updates on this design concept later this week!