Breaking Land Speed Records With An RC Car

July 19, 2023 by Lewin Day 23 Comments

Building and running a land speed record car is an expensive business that requires incredibly wealthy benefactors. Doing it on a smaller scale with a radio control car is still pricy, but more within the reach of the individual. [ProjectAir] has been working on just that, and recently set out to break records with a car of his own design.

The car runs a Jetcat 220 engine capable of delivering 220 newtons of thrust, built into a custom aluminium chassis with streamlined bodywork. Early runs saw it reach 112 km/h, but the goal was to push it beyond 150 km/h to break the standing Guinness World Record.

With an RC event running on a local runway, [ProjectAir] had the venue and opportunity to make an attempt. It was tough going, with the car throwing off its nosecose in one run, while rough weather brought further struggles. Strong crosswinds played a role in a violent crash on the car’s fastest pass, which ripped the car apart and destroyed the engine. However, in the end, it had done enough to secure a record at over 152 km/h, even if its later faster efforts didn’t officially count.

It’s clear that the car has come a long way since [ProjectAir’s] initial efforts in 2022, and we can’t wait to see where the project goes next. Video after the break.

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Toyota Makes Grand Promises On Battery Tech

July 10, 2023 by Bryan Cockfield 125 Comments

Toyota is going through a bit of a Kodak moment right now, being that like the film giant they absolutely blundered the adoption of a revolutionary technology. In Kodak’s case it was the adoption of the digital camera which they nearly completely ignored; Toyota is now becoming similarly infamous for refusing to take part in the electric car boom, instead placing all of their faith in hybrid drivetrains and hydrogen fuel cell technologies. Whether or not Toyota can wake up in time to avoid a complete Kodak-style collapse remains to be seen, but they have been making some amazing claims about battery technology that is at least raising some eyebrows. Continue reading “Toyota Makes Grand Promises On Battery Tech” →

Improved Hydrogen Fuel Cells Are Groovy

July 7, 2023 by Al Williams 13 Comments

According to [Charles Q. Choi], a new study indicates that grooves in the hydrogen fuel cells used to power vehicles can improve their performance by up to 50%. Fuel cells are like batteries because they use chemical reactions to create electricity. Where they are different is that a battery reacts a certain amount of material, and then it is done unless you recharge it somehow. A fuel cell will use as much fuel as you give it. That allows it to continue creating electricity until the fuel runs out.

Common hydrogen fuel cells use a proton exchange membrane — a polymer membrane that conducts protons to separate the fuel and the oxidizer. You can think of it as an electrolyte. Common fuel cells use an electrode design that hasn’t changed in decades. The new research has catalyst ridges separated by empty grooves. This enhances oxygen flow and proton transport.

Conventional electrodes use an ion-conducting polymer and a platinum catalyst. Adding more polymer improves proton transport but inhibits oxygen flow. The grooved design allows for dense polymer on the ridges but allows oxygen to flow in the grooves. In technical terms, the proton transport resistance goes down, and there is little change in the oxygen transport resistance.

The grooves are between one and two nanometers wide, so don’t pull out your CNC mill. The researchers admit they had the idea for this some time ago, but it has taken several years to figure out how to fabricate the special electrodes.

A man in a dark shirt stands at a podium in front of a projector screen with the text "50% OF US CAR TRIPS" in white above yellow text saying "1 HUMAN < 3 MILES". The screen is flanked by decor saying "Supercon" in white on a black background.

Supercon 2022: Bradley Gawthrop Wants You To Join The PEV Revolution

July 3, 2023 by Navarre Bartz 70 Comments

During the 20th Century, much of the western world decided that motor vehicles were the only desirable form of transportation. We built our cities to accommodate cars through parking, stop lights, and any number of other infrastructure investments so that you could go get milk and bread in style. In the US, 50% of automobile trips are less than three miles and have only one occupant. [Bradley Gawthrop] asked if there might be a more efficient way to do all this? Enter the Personal Electric Vehicle (PEV).

What Are PEVs?

PEVs are a nascent part of the transportation mix that fall under the wider umbrella of “micromobility,” including scooters, bikes, skateboards, and the like. The key differentiator here is that they are at least partially electrically-driven. [Gawthrop] walks us through several of the different types during his Supercon 2022 talk, but since they are all small, electric powered devices for transporting one or two people, they can trace their lineage back to the infamous Segway Human Transporter.

Using an electric motor or two connected to a controller and batteries, the overall system complexity for any of these devices is quite low and ripe for the hacking. Given the right tools and safety precautions, anyone should be able to crack a PEV open and repair or tinker with it. As with many things in life, the real story is more complicated.

As [Gawthrop] notes, many a hacker has said, “I wish I’d been able to be involved in X before…” where X equals some technology like home automation and it’s before it got creepy or dystopian in some manner. He exhorts us that the time to be in on the ground floor with PEVs is now. Continue reading “Supercon 2022: Bradley Gawthrop Wants You To Join The PEV Revolution” →

The toroidal propeller's details in the CAD software. (Credit: rctestflight))

Testing Futuristic Propeller Designs With A 3D Printer And A Solar-Powered Boat

July 2, 2023 by Maya Posch 21 Comments

The toroidal boat propeller pair installed. (Credit: rctestflight)

As boring as propeller designs may seem to the average person, occasionally there’s a bit of a dust-up in the media about a ‘new’ design that promises at least a few percent improvement in performance, decreased noise profile, or any combination of such claims. Naturally, if you’re [Daniel Riley] of RCTestFlight, then you have to 3D print a few of them, and make a video covering a handful. Most famous of these is probably the toroidal propeller that made waves a while ago, mostly in the field of flying drones, but commercial toroidal boat props exist too.

Test results of the different boat propeller designs. (Credit: rctestflight)

Interestingly, the 2-blade FDM-printed propeller ended up performing the best, while the bi-blade design (with two sets of blades positioned one after the other) performed worse — but better than the toroidal design. Here the last two designs were professionally printed in nylon, rather than printed at home in a standard FDM printer with all of the surface sanding and treatment required. Even so, the surface treatment did not seem to noticeably affect the results in further testing.

Hints at the root cause of the problem came from the bubble tests. In a bubble test, air is blown in front of the spinning propeller to visualize the flow of the water. This revealed some stalling on the bi-blade and the toroidal design too, which would explain some of the performance loss. Going back between the CAD model and the design in the patent by Sharrow Marine didn’t provide any obvious hints.

Considering that this latter company claims a performance uplift over regular boat propellers, the next steps for [Daniel] would appear to involve some careful navigating between fluid dynamic modeling and claims made in glossy marketing material to figure out exactly how close someone at home with a 3D printer and some spare time can get to those claimed numbers.

(Heading image: The toroidal propeller’s details in the CAD software. (Credit: rctestflight) )

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A CVT For Every Application

July 1, 2023 by Jenny List 36 Comments

When the subject of CVTs or continuously variable transmissions comes up, the chances are that most readers will think of the various motor vehicles they’ve appeared in. Whether it’s a DAF, a Ford, a FIAT, or a Chevrolet, most major manufacturers have tried one at some point or another with greater or lesser success. The automotive ones inevitably use a variation on a V-belt or metal band between variable separation conical pulleys, but this is by no means the only CVT configuration. Serial tinkerer [Robert Murray-Smith] takes an in-depth look at the subject as part of his ongoing fascination with wind turbines.

What caught our eye about this video isn’t so much the final 3D-printed design he selects for his experiments, but the history and his look at the different CVT designs which have appeared over the years. We see the V-belts, as well as the various cone configurations, the disk transmissions, the hydrostatic ones, and even magnetic versions. His transmission uses two cones with a rubber coating, with of all things a movable golf ball between them. We’re guessing it will appear somewhere in his future videos, so watch out for it.

Meanwhile, this isn’t the first time we’ve seen a CVT, [James Bruton] used a hemisphere to make one on a robot.

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Hydroplaning Boat Skims Over Water

June 29, 2023 by Lewin Day 3 Comments

Regular hulled boats are all well and good for rowing and all, but if you wanna go fast, you’ve gotta cut your draft. [RCLifeOn] built a hydroplane design that skims on the very surface of the water, and thus travels very quickly as a result.

The build came about as [RCLifeOn] has an upcoming race which he wishes to win with speed and finesse. To that end, he 3D printed an RC hydroplane, using spray paint and spackle to waterproof the parts. It’s a trimaran design, with the large central hull connected to two pontoons via carbon fiber rods. Propulsion is via a triple-motor fan setup on the rear of the boat.

The outer motors were initially used to steer the boat via variable thrust, which comes with zero drag penalty compared to a conventional rudder. However, they proved ineffective, and a servo driven rudder was used instead. Eventually, all three motors were reconfigured for forward thrust.

The boat worked well when it was able to get up to speed and hydroplane over the surface of the water. However, it was difficult to film, as even the weight of a GoPro was enough to keep it stuck on the water’s surface. Instead [RCLifeOn] used his electric surfboard as a chase rig to film the boat — a neat trick itself. Continue reading “Hydroplaning Boat Skims Over Water” →