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Back at it: Power Racing at Maker Faire part two

Now that I’ve had time to recover from Maker Faire Bay Area, I think it’s about time for an update on the Power Racing series.  We had a blast hanging out with everyone there and showing off the Power Racing car.  I presented the car on both Friday and Sunday on the Make: Electronics stage to a full audience.  Thanks to everyone who came out to learn about the build!  Unfortunately, the vehicle experienced some troubles in shipping and we weren’t actually able to race.  We were still able to enjoy the Power Racing series though, and we learned a lot from the other teams competing there.  After the races were over, I even got to drive one of the winning cars!

After the experience of driving one of the cars and fraternizing with the other teams I knew I had to build another car, which would need to be beyond awesome.  I decided the new vehicle would be designed fully in 3D CAD tools, would probably completely obliterate the budget of $500, and would have a power to weight ratio in the same ballpark as some of the leading electric sedans like the Tesla Model S.

Where would I start?  I've clearly learned a lot from the first Power Racing build, but I’m still an electrical engineer and I’ve never modeled anything in a 3D mechanical modeling tool.  I downloaded an open source tool called FreeCAD and started working through tutorials.  At the same time, I searched for the perfect electric motor to power the vehicle.  For this build, I decided to spare no expense.  I found a big brushless DC (BLDC) motor that would put out 5kW continuous and 10kW peak (~13.5hp). 

The motor cost $500, so at this point I had already spent my entire budget on a single part.  Even more crazy is that the race limits vehicles to only 1.4kW.  Why would I pick a motor this powerful and this expensive for a race with these power and budget limitations?  Because this thing is going to be awesome, that’s why.  In addition to budget and power requirements, the race has a special rule called the “I ain’t even mad” clause.  It reads as follows:

“If you are going to break one of our rules, we encourage you to go… above and beyond the call of duty. We don’t want cheap and sneaky exploits. We want clever [builds] that will make great stories. Want to make a 6-wheel power wheel? Awesome. DRS inspired Must-Go-Faster button? Sweet, can’t wait to see it. So if you feel like taking things too seriously, we want you to build something so blissfully impressive, so Adrian Neweyesque clever, or downright SpeedyCop crazy that your rule infraction gets an “I’m not even mad, actually I’m impressed” reaction from our judges.”

I think using this motor qualifies, don’t you?

After I had picked out the motor I started modeling the components.  It started out slow as I learned how the tools worked.  For instance, here’s one of my original models of the motor and its bushing:

As I modeled more and more, my skills quickly progressed!  I shortly had a rough sketch of what I wanted the rolling chassis to look like:

Around this time, parts orders started rolling in.  Once I had received everything needed to build the chassis, I mocked up the wheels and axles to get a first look at what the car might look like:

On the whole, I think the model resembles the actual parts well.  At this point it was time to begin fabrication, but I think we’ll save that story for another day.

My goal is to have the car completed and ready to race in time for the Power Racing Series at Maker Faire New York on September 26th and 27th at the New York Hall of Science, so save the date and be sure to come see us race!

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