Milestone 4

Optimization

Fig. 1. Motor-battery optimization calculations.

The boat is currently designed with three motors and seven batteries. Calculations were done to examine the weight, thrust force, and required amp hours (Ah) for the boat to complete the five-mile race as fast as possible. 

From the analysis shown in Figure 1, the required amp hours and weight associated with a three-motor and seven batteries setup is not optimal for the race. The reason is that getting the thrust force from the three motors requires adding 10% in weight to the boat, ultimately slowing down the boat.

Figure 1 shows that the optimal setup for our boat is to use two motors with five batteries, as this optimizes the weight with the thrust force. Based on the calculations above, this should allow our boat to complete the five-mile course in under 22 minutes.

Fig. 2. Removal of motor.

Fig. 3. Removal of water jet.

To accomplish the optimization of the boat, the middle motor was removed, as shown in Figure 2. Subsequently, the water jet was removed as well to help reduce the overall weight shown in Figure 3.

From the previous leak test, it was determined that the best way to seal the stern was to replace the rear end of the boat with a new piece of foam.  

Delivery

Fig. 4. Fully assembled boat (top view) 

Fig. 5. Fully assembled boat (front view) 

Figure 4 and 5 shows our fully assembled boat utilizing the PixHawk system with two BLDC Motors and five Liperior batteries. Currently an external battery pack is being used to power the PixHawk system. This will be fixed later once the power module for the PixHawk arrives.

Further changes may be made to better optimize the boat down the line, such as reducing the hull weight and positioning components in better locations.

Management

Management of this project was divided into sub-teams to utilize skills where appropriate as well as reduce the load on individual teammates. However, in practice, individuals on sub-teams that chose not to care about this project ultimately created more work for those who cared. The team meet routinely to provide updates on each task they were given and report any new task that need to be done. 

The task were broken down as follows:

The optimization shown above was supposed to have more weight reduced than only system components. However, due to a lack of participation from some Mechanical Engineers tasked with this weight reduction, the optimization of the weight was reduced to only system components. 

While we were able to make significant progress on our boat, there are few task that are left for next years team. These task include deciding to switch to a propeller system, reducing the hull weight, and research into light-weight energy-dense batteries.

Figure 6 shows a breakdown of the project timeline of what was done over the year.

ASNE_PEP.pdf

Fig. 6. Project timeline