RC Test Flight Goes Self-Driving to See if R/C Cars Can Hit 100,000 Scale Miles on a Buried Wire

Four years after Daniel Riley first lashed remote-control crawlers to a backyard tether and asked whether any of them could rack up 100,000 scale miles, he ran the experiment again. This time the cars steered themselves. In the original 2022 test, a spinning line kept every vehicle on a circle, which also loaded one side of the drivetrain harder than the other and turned wear into a lopsided argument. For the Self Driving Edition, Riley laid a perimeter wire through his yard, borrowed the sensing idea from robot lawn mowers, and taught an Arduino to twitch a steering servo whenever a coil on the bumper drifted off the signal.

Later, he combined all of this into a package called Trail Tracer. A cheap crawler and an expensive crawler spent months crawling the same nasty track, grinding to a halt on their charge strips as rain, mud, rats, snow, and ice each tried to put an end to the runs. The competitors were an Exceed RC Mad Watt 10, a $169 top-of-the-line crawler with metal U-joints and a main gear that was a little too exposed for comfort, and a Stirlingkit YK6101, a $769 1/10-scale 6×6 with a top-notch all-metal chassis, portal axles, lockable diffs, a two-speed gearbox, and a 750-size brushed motor.

Riley was sure to keep the YK in low range, however, to prevent it from outrunning the wire. Building the track was its own mini-project. Wire segments were rewired (after the rats had bitten them to pieces, they had to be re-soldered and reburied). Then there were the turns, a nasty downhill run, and a swampy low place that caused the cars to oscillate all over the track, all of which required hours of controller tuning to perfect. To top it all off, the charge contacts were constantly sparking until he switched to a bench supply. Then there was his faithful lap timer, a spring-loaded board that recorded each pass. He also installed an FPV camera so he could watch from inside when the weather got bad.

Cheap hardware folded first. After the bolt in one of its gears had a bit too little thread and fell loose from its lock nut (fortunately not scored, so it wasn’t a death sentence), the Mad Watt’s open spur gear simply chewed itself bald on all the grit. Riley finally drove about 75 miles on that chassis, which is equivalent to 750 scale miles at 1/10 scale. The drivetrain ultimately failed. He changed gears and deemed it ordinary maintenance, which is quite generous if you’ve ever had a toy with its teeth sticking out in the mud.

The YK6101, on the other hand, simply kept trucking. By the fall, it had completed several thousand laps and a staggering 356 miles in the real world (or 3,560 scale miles, to give you a better sense) and was only beginning to show signs of wear in the form of extra steering slop and a bit of a wobble sliding down the hill when the controller was turned up to the utmost. The soft tires even broke through a few inches of ice. Of course, frozen ground helped for a time, but the thaw converted the track into soup, forcing Riley to dump a load of gravel, dirt, and concrete powder into the ruts to keep them from eating the axles.

Not a single car reached 100,000 scale miles. That’s a milestone equivalent to 10,000 real-world miles of crawling on a toy truck size, which would imply years of continuous use even if everything kept together, which it didn’t, but what the sequel actually proved was far more interesting. A tethered circle of wire is essentially a devious torture device. A wire-guided self-charging loop that is much more in line with how real vehicles live, as both sides of the drivetrain are worn down, the steering is constantly stressed, water and dirt find their way in through every small gap, and the only thing holding it together is whatever you’ve managed to reinforce the metal with.

Exposed gears wear out. Sealed gears, good steel shafts, and a chassis that can be easily disassembled into a plethora of spare parts make for a winning combination. Riley continues to manage the YK with a skeleton workforce, selling Trail Tracer devices so others can go lay a wire in their own garden, and the 100,000-mile mark remains, effectively a running joke that may become old news if someone simply refuses to give up. For now the interesting result is the gap. Seven hundred fifty scale miles on the bargain crawler. More than three thousand and counting on the 6×6. Same yard, same weather, same buried wire, and a very loud lesson about what you get when you pay for the metal.