Monday, May 14, 2012

2.007 Grand Prix

The end of a long semester with 2.007 is finally here! We will have our final race this Sunday at the Albany St. parking garage and we will also be having a drag race in the nearby area. This also marks the end of phase 1 in the development of MelonKart. The project has come a long way from a concept in early February to a fully-realized, functional vehicle ready to race. Here is a general wrapup and assessment of the project in my own opinion, and a list of improvements that I would like to make or things that I wish we would have done differently.

Acceleration and Speed: Exceeds Expectations
MelonKart was much lighter than planned, so the acceleration is significantly more punchy than predicted. I am still amazed with the how fast it feels to drive the go-kart, since it is only using one model airplane motor.

Handling: Acceptable BAD
I would like to accurately model the steering geometry in the future with MATLAB or SolidWorks and refine it to make it more linear in nature. I also would like to add a steering ratio similar to a real car into MelonKart. There was also some manufacturing error in the uprights that severely increased the camber of the front wheels, and I believe that the handling would have a substantial improvement if this was corrected. I flipped MelonKart twice in the competition; steering needs improvement.

Robustness: To be determined, but so far so good
We have accidentally blow several of the fuses in the batteries by accelerating too hard and having the software limit in the motor controller set too high and have suffered no ill effects in the electrical components of the vehicle. We have also hauled the Go-Kart around campus to be filmed for 2.007 and for the DeFlorez Competition (We won a hundred bucks!!), as well as demonstrated it at the MAES extravaganza and MelonKart has held together (even with Radu and Actanner taking it for test rides) so the mechanical components seem to have a certain amount of durability to them. It also did not suffer damage from a few crashes.

The final race video

MelonKart at the DeFlorez Design Competition

Future Improvements

Add a second MelonMotor (if they ever come back in stock on HobbyKing)
Switch to a belt drive that has an auto-tension, or redesign the tensioning system for the chain
Add more structural rigidity to the motor mount and support the motor on both sides
Consider a roll bar?
Weatherproof the system
Increase the ground clearance to not drag on a speed bump


I think I took a lot away from this class. First, I now possess half of a functional MelonKart and an extremely messy design notebook covered in chips and cutting fluid. Beyond these physical takeaways, I really feel more confident as a mechanical engineer. I got to collaborate on a project, go through an entire design process, create a working CAD model, source parts for our design, create a manufacturing plan, build it, troubleshoot, and finally walk away with a working thing. I think that out of everything that an engineer does, the design process is what really stands out to me as a quintessential engineering trait. This project made me feel more like an actual engineer than any pset or test ever has. I really enjoyed the team aspect as well, and feel that the sum of our two ideas on the Go-Kart made it a much better project than either of us would. This project gave me more confidence in working with a higher voltage and a much more powerful system than I have ever worked with before. This class also renewed an interest in building things and applying the knowledge taught in my classes, hopefully resulting in many more successful projects!