Retrotechtacular: The Fell Locomotive

January 3, 2024 by Jenny List 20 Comments

If you were to visit a railway almost anywhere in the world, you would find that unless it was in some way running heritage trains, the locomotives would bear a similarity to each other. Electric traction is the norm, whether it comes from a trackside supply or from a diesel generator. In the middle of the last century, as the industry moved away from steam traction though, this was far from a certainty. Without much in the way of power electronics, it was a challenge to reliably and efficiently control a large traction motor, so there were competing traction schemes using mechanical gearboxes or hydraulic drives. One of these is the subject of an archive film released by the oil company Shell, and it’s a fascinating journey into a technology that might have been.

A model of a gearbox, in black and white. — The Fell differential gearbox.

All diesel locomotive designs struggle with the problem of transmitting the huge torque required to start a fully loaded train at low speeds, and because of the huge force required, it’s impossible to design a locomotive-sized conventional gearbox to do the job in the way it might be managed on a truck. Electric and hydraulic drives exploit the beneficial torque characteristics of electric and hydraulic motors, but the mechanical gearbox isn’t quite done for. The subject of the video is British Rail number 10100, otherwise commonly known as the Fell locomotive, and it was a one-off prototype that took to the rails at the start of the 1950s designed to test a very novel gearbox design.

At the heart of the Fell gearbox is a set of differential gears the same as you’d find in the axle of a car, and in the locomotive they are used to combine the output of more than one engine. The loco had four smaller-than-normal diesel traction motors that could be combined, but even then, it wasn’t done. To achieve variable torque, they employed superchargers driven by a set of even-smaller diesel engines, resulting in an ungainly multi-engined beast but with the desired characteristics for both starting heavy trains and for moving them at high speed. Continue reading “Retrotechtacular: The Fell Locomotive” →

Developing An App For Reduced-Gravity Flying

January 1, 2024 by Tom Nardi 19 Comments

You’ve likely heard of the “vomit comet” — an rather graphic nickname for the aircraft used to provide short bursts of near-weightlessness by flying along a parabolic trajectory. They’re used to train astronauts, perform zero-g experiments, and famously let director Ron Howard create the realistic spaceflight scenes for Apollo 13. But you might be surprised to find that, outside of the padding that lines their interior for when the occupants inevitably bump into the walls or ceiling, they aren’t quite as specialized as you might think.

In fact, you can achieve a similar result in a small private aircraft — assuming you’ve got the proper touch on the controls. Which is why [Chaz] has been working on an Android app that assists pilots in finding that sweet spot.

With his software running, the pilot first puts the plane into a climb, and then noses over and attempts to keep the indicator on the phone’s display green for as long as possible. It’s not easy, but in the video after the break you can see they’re able to pull it off for long enough to get things floating around the cockpit.

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Paddling Help From Electric-Assisted Kayak

December 31, 2023 by Bryan Cockfield 15 Comments

Electric-assisted bicycles, or ebikes, are fundamentally changing the way people get around cities and towns. What were once sweaty, hilly, or difficult rides have quickly turned into a low-impact and inexpensive ways around town without foregoing all of the benefits of exercise. [Braden] hoped to expand this idea to the open waters and is building what he calls the ebike of kayaking, using the principles of electric-assisted bicycles to build a kayak that helps you get where you’re paddling without removing you completely from the experience.

The core of the project is a brushless DC motor originally intended a hydrofoil which is capable of providing 11 pounds (about 5 kg) of thrust. [Braden] has integrated it into a 3D-printed fin which attaches to the bottom of his inflatable kayak. The design of the fin took a few iterations to get right, but with a working motor and fin combination he set about tuning the system’s PID controller in a tub before taking it out to the open water. With just himself, the battery, and the motor controller in the kayak he’s getting about 14 miles of range with plenty of charge left in the battery after the trips.

[Braden]’s plans for developing this project further will eventually include a machine learning algorithm to detect when the rider is paddling and assist them, rather than simply being a throttle-operated motor as it exists currently. On a bicycle, strapping a sensor to the pedals is pretty straightforward, but we expect detecting paddling to be a bit more of a challenge. There are even more details about this build on his personal project blog. We’re looking forward to seeing the next version of the project but if you really need to see more boat hacks in the meantime be sure to check out [saveitforparts]’s boat which foregoes sails in favor of solar panels.

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An RC Tank Chassis That’s Not Messing About

December 26, 2023 by Jenny List 3 Comments

It’s not uncommon to see a tracked robot build on these pages, but it’s fair to say that many of them are somewhat on the small side. That was where [iforce2d] started, but the idea of making a more capable version just wouldn’t go away. Thus, he’s come back and made what looks to be a very promising, fully capable outdoor RC tank chassis, one that, within reason, we think should eventually be able to go anywhere.

For plenty of power, he’s using a pair of hoverboard motors with a chain reduction drive and in turn, a couple of shafts to the tracks. The chassis is a TIG-welded aluminium affair, while the tracks are an early incarnation with machined MDF drive wheels and a homemade tread. The suspension is a work of machined-aluminium art, though, and while there are teething troubles as he takes it for a spin, we can see plenty of potential as its deficiencies are ironed out. Take a look at it in the video below the break.

If large-size R/C tanks are your thing, we have another for you to look at.

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Digital Bike Horn Will Play Custom Sounds, Please Be Tasteful

December 23, 2023 by Lewin Day 19 Comments

When you’re out riding your bike, a horn can be a useful warning device to other road users and pedestrians alike. It can also be a source of fun and amusement, or annoyance, depending on the sounds it makes and how you use it. For the ultimate flexibility, you might like this digital bicycle horn that offers customizable sounds, as developed by [gokux].

The build has attractive two-tone components, consisting of a button pad for playing four sounds, and a sound module with a 3 watt speaker and battery pack. A Seeed Studio XIAO SAMD21 is the heart of the operation, with the microcontroller paired with a DFPlayer Mini which handles sound duties. When one of the four buttons is pressed, the microcontroller loads the relevant sound off an SD card, and plays it out over the speaker. For power, the build uses a lithium rechargeable battery with a healthy 1200 mAh capacity, which can be readily recharged thanks to a TP4056 charger module with a USB-C port.

It’s a nifty little build, and we love the Metal Gear Solid sounds. Though, we do wonder just how audible that 3 watt speaker is. If it proves inadequate, you could always step up to a much larger driver paired with a hefty audio amp if you so desire.

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Old Prius Gets Upgraded Batteries

December 18, 2023 by Bryan Cockfield 24 Comments

So many of the batteries made today are lithium batteries of some sort, from mobile phones, laptops, and drones to electric cars and grid storage solutions. But this technology is relatively new; even as late as the 90s and early 00s the only widely-available batteries for things like power tools or the new hybrid vehicles coming on the market were nickel-metal hydride (NiMH). While it was good for the time, they don’t hold up to all of the advantages lithium has. There’s still plenty of hybrid vehicles on the road using these batteries, so if you’re driving an older Prius and want to give it a modern refresh, there’s a quick option to swap your old batteries.

Despite lithium technology being available for several decades, the switch to lithium for the Toyota Prius wasn’t instant, with many variants still using NiMH batteries as late as the 2020s largely because the NiMH batteries are less expensive and less maintenance-intensive than lithium batteries are. As these batteries lose capacity, the cars are still driveable but the advantages of the hybrid drivetrain won’t be as accessible anymore. The upgrade, from a company called Project Lithium, replaces these batteries with modern lithium technology that can improve the efficiency and performance of these cars even above their original capabilities since lithium batteries have more power density.

With the Toyota Prius being among the most reliable vehicles on the road thanks to the electric motor in the hybrid drivetrain taking a lot of stress off of the internal combustion engine, it’s often worth upgrading these old batteries to modern ones to squeeze every last mile from these workhorses as possible. With many of the replacement processes being almost as simple as lifting out an old battery and placing a new one in, it can be a no-brainer if that’s the only issue with the vehicle otherwise. This is also true of all-electric vehicles as well, although the process to replace the battery can be a little more involved.

Thanks to [JohnU] for the tip!

Hubless E-Bike Is Nostalgic

December 16, 2023 by Al Williams 12 Comments

[Chris Makes Stuff] is an aptly named channel. His recent video shows how he took a kid’s electric motorcycle toy and built a “penny farthing” bicycle. You might not know the bike by that name, but when you see it in the video below, you’ll recognize it. These Victorian-era bikes used a single large wheel before chain drives on a bike became a thing.

Of course, the big part of this — literally and figuratively — is the giant front wheel. There’s a second video showing how it was built in layers using wood.

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