Motor Orientations and Propeller Designs: Week 5

Now that the Sea Perch is assembled using all the standard parts, the next step is to optimize propulsion and maneuverability. Our first step was to adjust motor orientation. The two factors that are affected most by changes in motor orientation are the Sea Perch's turn radius and upward/downward movement. The propeller are capable of spinning in forward and reverse directions, but because of their shape, propellers provide more thrust in one direction than the other. The direction that provides more thrust will be referred to as the forward direction.
The vertical movement motor was originally mounted with the propeller's forward direction aiming down. We decided to reverse this for two reasons. The way the Sea Perch was constructed, it's average density was slightly greater than that of water, so it had the tendency to sink slowly. With the forward direction aimed up, the Sea Perch was able to overcome this tendency more efficiently than before. Also, in the original orientation, The propeller itself was located on the top of the Sea Perch, above the motor. When the Sea Perch would ascend to the surface of the water, this propeller would emerge from the water and splash around as it would spin on above the water. This caused instability and minor loss of control. The new motor orientation avoids this issue altogether.
The two side mounted motors are used to control the submarine through turns. Through first-hand testing, we determined that the when the motors were farther apart, the Sea Perch had a smaller turn radius. To implement this advantage into our design, we positioned the motors on the outside of the chassis, as opposed to the inside where the were originally. This added about 3 more inches of space between the two propellers (distance motor shaft to motor shaft), and should give the Sea Perch a smaller turn radius.
Our next approach to improving the Sea Perch is to increase the propulsion the motors are able to exert. To accomplish this, we will be using the 3D printer to manufacture new propellers. We are currently in the process of designing propellers in Pro ENGINEER. We are basing the designs off of research done on propellers and propulsion to come up with designs that maximize propulsion delivered by the propellers.

Brian Bucci
Daniel Stenger
Justin Goebel
James Esser
Tim Kaack