Fail of the Week: Power Wheels Racing Series

[ITMAN496] and his local HAM radio group entered the Power Wheels Racing Series with great intentions, a feeling of unlimited power, and the universal spirit of procrastination all hackers share.

It wasn’t the first time his group had worked together on something a little different, such as a robot that can deploy an antenna by climbing poles. However, this one had a time limit and they ended up trying to fit it all in the week before the race.

They had a pretty good design. [ITMAN496] had modeled the entire frame in SketchUp and even did physics simulations to get the steering just right. However, the best laid plans of mice and men often don’t fully take into account just how hard it is to get the motor drivers they bought working.

In the end, what they really needed was time to test. The setscrews couldn’t hold the motor on the shaft, the electronics needed debugging, and one of the belts was too long. The design was solid, but without time to percussively maintain the last bugs out of the system, it just wasn’t going to run.

[ITMAN496] is taking this lesson properly; he’s already planning for next year’s run, but this time he’ll have time to test. We must commend him — the build under these time constraints was still impressive. Even more so that he took the time to document everything while it was happening, and to share the story of shortfall after the fact. We’re always on the hunt for documented fails (the best way to really learn something).

[Harrison Krix’s] Marriott Chariot

Atlanta’s Mini Maker Faire had plenty of booths to keep visitors busy, but the largest spectacle by far was the racetrack smack-dab in the middle, and you’d be hard pressed to find a more eye-catching contender than [Harrison Krix’s] vehicle: the Marriott Chariot.

If [Krix’s] name looks familiar, that’s because he’s the master artisan behind Volpin Props, and is responsible for such favorites as the Futurama Holophonor replica and the Daft Punk helmet. (Actually, he made the other one, too).

The Chariot is yet another competitor in the Power Racing Series, an event that keeps popping up here on Hackaday. [Krix] drew inspiration from this Jeep build we featured earlier in the summer, and went to work sourcing an old plastic body to get started. The frame is 16 gauge square tubing, with a custom motor mount machined from 3/16 steel. After welding the chassis together, [Krix] chopped up a small bicycle to snag its head tube and headset bearings. A pair of sealed lead acid batteries fit horizontally in the frame, providing a slightly lower center of gravity.

[Krix] has a keen eye for precision and his build journal shows each step of his meticulous process. But, you ask, why “Marriott Chariot?” and why does the car look like someone threw up a kaleidoscope? Read on beyond the break, dear reader, to learn the Chariot’s origin and to see a video of it winding around the track.

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Even More Power Wheels Racers

With the Power Wheels Racing series wrapping up for the year, the teams are winding down and writing up their build and rebuild logs for their cars. In previous years, the kids from MIT, a.k.a. MITERS, have brought small electric cars to the races, but nothing like this. It’s a true Power Wheels, or at least the plastic shell, an alternator, a huge battery pack, and a completely custom drivetrain.

[Dane], [Ben], [Rob], [Mike], and [Ciaran] started their build with an alternator that was salvaged from [Charles]’ Chibi-Mikuvan, added a motor from a CDROM drive for a sensor, and basked in the glory of what this cart would become. The frame was crafted from 1″ square tube, a custom disc brake machined, and a 10S2P battery pack built.

The alternator the team used for a motor had a rather small shaft, and there were no readily available gearboxes. The team opted to build their own with helical gears milled on the MITERS Bridgeport mill. That in itself is worth of a Hackaday post. Just check out this video.

With the build held together with duct tape a baling wire, the team headed out to the races in Detroit. Testing the racer before getting to Detroit would have been a good idea. During the endurance race, a set of 10″ rear tires were torn apart in just four laps, impressively bad, until you realize the smaller pink tires that were also from Harbor Freight fared even worse.

After a few races, the MITERS team figured out the weaknesses of their car and managed to get everything working perfectly for the race at Maker Faire NY.

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The Chibi-Mikuvan, or a Power Wheels with a Ford Fusion Battery

At all the big Maker Faires, the Power Racing Series makes an appearance, turning old Power Wheels into race cars that whip around the track at dozens of miles an hour. [Charles] is somewhat famous in the scene – there’s even a clause in the official rules named after him – so of course anything he brings to race day will be amazing. It was. It used a battery pack from a Ford Fusion plugin hybrid, a custom body, and a water cooling unit from a dead Mac G5.

A few months ago, we saw [Charles] tear into the battery pack he picked up for $300. This is the kind of equipment that will kill you before you know you’ve made a mistake, but [Charles] was able to take the pack apart and make a few battery packs – 28.8v and 16Ah – enough to get him around the track a few times.

The chassis for the Chibi-Mikuvan was built from steel, and the bodywork was built from machined pink foam, fiberglassed, and finished using a few tips [Charles] gleaned from [Burt Rutan]’s book, Moldless Composite Sandwich Aircraft Construction. The motor? That’s an enormous brushless motor meant for a 1/5th scale RC boat. The transmission is from an angle grinder, and the electronics are a work of art.

The result? A nearly perfect Power Wheels racer that has a curb weight of 110 pounds and tops out at 25 mph. It handles well, too: in the videos below, it overtakes the entire field of hacky racers in the Power Wheels Racing competition at Maker Faire NYC, and afterwards still had enough juice to tear around the faire.

Continue reading “The Chibi-Mikuvan, or a Power Wheels with a Ford Fusion Battery”