Hacking Toy RC Cars With The HackRF One

April 30, 2022 by Ryan Flowers 3 Comments

The origin story for many who’d call themselves a member of the hacker community usually starts with taking things apart as a child just to see how they worked. For [Radoslav], that trend doesn’t seem to have slowed down, and he’s continued taking toys apart. Although since it’s his daughters little radio controlled car, he stuck to a non-destructive teardown. The result? He’s able to control the car with his laptop through a HackRF One SDR transceiver as shown in the video below the break.

[Radoslav] is no stranger to reverse engineering embedded devices, IoT gadgets, and probably more. So he started with what information was publicly available about the radio control interface in use. Many electronic devices sold in the US must be certified by the FCC (Federal Communications Commission) and prominently display their ID number, and this toy was no exception. The FCC database gave [Radoslav] enough information to know that the communication protocol is modulated with GFSK, a type of Frequency Shift Keying.

He fired up his favorite radio signal analysis tool and and got to work on the protocol itself. Along the way he found that communication between the car and controller is bidirectional but also very easy to get around. The result is that he can drive the car around with his laptop- definitely a cool hack, but for this one, the journey was surely the goal, not the destination.

If hacking on RC cars really gets your wheels turning, you might like this little RC car that can drive on the ceiling. Or if you’re feeling a bit hungry, check out how you can use the HackRF to nab a table at your local restaurant.

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RC Car Test Tether Takes Car Testing To New Lengths

April 5, 2022 by Ryan Flowers 8 Comments

It’s fascinating to see what happens when a creative hacker is given a set of constraints to work within. [rctestflight] found themselves in a very specific set of circumstances: Free RC cars from sponsors, and no real purpose for them. Instead of just taking them apart to see what made them tick (itself the past time of many a beginning hacker), [rctestflight] decided to let the RC cars disassemble themselves, destructively, on their way to 100,000 (scale) RC Car Miles, tallying up the distance (and the carnage) in the end as you see in the video below the break.

Re-using a jig and test track (his backyard) from another test, [rctestflight] set up solar powered tether that could power any of the vehicles under test. The vehicles were modified as needed to drive along the circular track on a tether, and once stability was achieved, the cars were set on their own to either drive 100,000 scale miles or die trying.

Seeing as how [rctestflight] hales from the Pacific NorthWet of the United States near Seattle, the endurance test turned out to be not just a test of distance. Among the factors evaluated were how well each vehicle could withstand the mud, grime, and yes, even earthworms, that awaited them.

After each vehicle failed beyond the point of a quick fix, they were all torn down. Where each manufacturer cut corners could clearly be seen, and the weaknesses and strengths of each vehicle were pretty interesting. Plus, there’s a pretty great (awful) uh… rendition… of an iconic 80’s song. Twice. And of course the final conclusion: Exactly how many miles did each vehicle go before catastrophic failure? Check the video for results.

Regular readers will know that [rctestflight] is somewhat of a Hackaday regular, with plentiful great hacks such as this drone boat that sails the high seas of Lake Washington.

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Ground Effect Aerodynamics On An RC Car

December 21, 2021 by Lewin Day 3 Comments

Ground effect aerodynamics will return to Formula 1 in a big way in the 2022 season, hopefully washing away the bad taste left in fan’s mouths after the recent controversial season decider. [Engineering After Hours] has experimented with F1 aerodynamics on RC cars before, and decided that it was time to try and implement a proper ground-effect design himself.

The aim of ground effect aerodynamics is to create a constriction for airflow between the bottom of the car and the ground underneath. This constriction accelerates the flow beneath the car, and as per Bernoulli’s principle, causes a corresponding pressure drop, sucking the car down onto the track. Viscosity also plays a role; from the car’s perspective, the road beneath the vehicle is moving backwards at some speed, pulling on the fluid thanks to the boundary layer on the ground itself. This further helps increase the strength of the effect.

A vacuum-formed undertray complete with side skirts was installed on the RC car in order to generate ground effect downforce. A quick test with a leaf blower indicates the system works, and that the side skirts are a key component.

Lateral acceleration was significantly improved by around 20% in testing with the ground effects installed, though [Engineering After Hours] admits that without a wind tunnel, the results aren’t the most scientific. However, with the undertray being relatively lightweight, we suspect the aero elements are likely providing plenty of benefit without too much of a negative effect on acceleration or handling.

Check out some of the other aero experiments [Engineering After Hours] has undertaken, too. Video after the break. Continue reading “Ground Effect Aerodynamics On An RC Car” →

Building An Aluminum RC Truck From Scratch

September 5, 2021 by Adam Fabio 14 Comments

These days you can get just about any kind of radio controlled vehicle as a ready-to-run model. Cars, trucks, excavators, you name it. Open the box, charge the batteries, and you’re ready to roll. Even with all these modern conveniences, there is still a special breed of modelers who create their own models using only a few off-the-shelf parts.

[Rini Anita] is exactly that rare breed, creating this aluminum RC truck from scratch. The truck itself is a cab-over — short for Cab Over Engine (COE), a style seen making local deliveries worldwide. He starts with the ladder frame chassis, which is constructed using an extruded aluminum channel. This is the same material you’d normally use for the door tracks in retail store display cases. The electronics and standard RC fare: a receiver, electronic speed control, and a servo for steering. Batteries are recycled lithium cells. The main gearbox and drive axle look to be sourced from another RC vehicle, while leaf springs and suspension components are all custom built.

The truck’s body is a great example hand forming metal. First, a wooden form was created. Sections for the windows and door panels were carved out. Sheet aluminum was then bent over the wood form. Carefully placed hammer blows bend the metal into the carved sections – leaving the imprints of doors, windows, and other panel lines.

Throughout this build, we’re amazed by [Rini]’s skills, and the fact that the entire job was done with basic tools. A grinder, an old drill press, and a rivet gun are the go-to tools; no welder or 3D printer to be found. This puts a project like this well within the means of just about any hacker — though it may take some time to hone your skills! For his next truck, maybe [Rini] can add a self driving option!

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Fan Lets RC Car Drive On The Ceiling

September 4, 2021 by Lewin Day 7 Comments

Downforce is a major part of modern motorsport, keeping cars glued to the track at high speeds. However, for small radio control cars, adding a fan for a little suction can achieve even greater feats, as demonstrated by this build by [DD ElectroTech].

The build began as a simple two-motor, skid-steer RC car build with a fan for suction. Controlled by a smartphone app, a cheap Arduino board with an HC-05 Bluetooth module ran the show. However, when this was all assembled, the car was too heavy to climb walls or stick to the ceiling.

Thus, a weight-saving plan was in order. Wheels were swapped out for lighter 3D printed parts. The electronics saw significant re-engineering, too, with the multiple separate modules all condensed down into one single custom PCB. After a few other tweaks, the new lighter car was able to easily drive on the ceiling and even climb walls, albeit with some difficulty.

It’s a fun little build and a good demonstration of how easy it is to whip up cool projects with modern electronics and 3D printed parts. We’ve seen other printed fan car builds before, too, but did you know the concept was first trialed in real-world motorsport competition? Video after the break.

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A Cold Gas Thruster On An RC Car

August 15, 2021 by Lewin Day 12 Comments

Tesla have boldly claimed that one day they’ll ship a Roadster complete with a cold-gas thruster for truly ridiculous acceleration. Whether or not that ever comes to pass remains to be seen, but [Engineering After Hours] decided to try out the technology on an RC car instead.

The thruster uses a pair of disposable CO2 canisters to deliver 1770 g of thrust via a converging-diverging nozzle. Actuated by servos and a simple valve, the system dumps the high-pressure CO2 to help accelerate the car up to speed. Paired with sticky tires and a powerful brushless motor, the plan was to try and beat Tesla’s claimed 1.1 second 0-60mph acceleration figure for the thruster-boosted roadster.

Unfortunately, the high center of gravity of the RC car led to stability issues, largely due to the mounting of the thruster itself. Additionally, the high weight of the car – around 4.3kg – meant that at best, the thruster would only add 0.5g to the vehicle’s acceleration.

While the car didn’t net a quick 0-60 time, it’s still neat to see a cold gas thruster on an RC car. It may not have been a Tesla-beater like some earlier projects, but it was cool all the same. Video after the break.

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RC Car Gets Fan-Assisted Downforce To Slay Tesla’s 0-60 Times

May 23, 2021 by Lewin Day 26 Comments

Tesla have claimed that their upcoming new Roadster will post a sub-2 second 0-60mph time. While it’s backed up by little more than a shiny website at this stage, [Engineering After Hours] took the number as a target to beat with his RC fan car build. (Video, embedded below.)

We’ve seen an earlier prototype of this build before, with the first version generating enough downforce to successfully drive upside down. The new build has several modifications to maximise its lateral acceleration capabilities. The new build drives all four wheels, which are fitted with sticky tyres coated in traction compound for maximum grip. The main drive motor, along with the fan and skirt assemblies, are all mounted in the center of the car now to properly balance the aero loads across the axles and provide a stable weight distribution for fast launches.

The results are impressive, with the car posting a 0-60mph time of just 1.825 seconds. There’s likely still time left on the table, too, once the car can be tuned to launch harder off the line. We’d love to see a racing series of fan-equipped RC cars hit the track, too, given the amount of grip available with such hardware.

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