Handling Human Waste In The Sky

Have you ever wondered what goes into making it possible to use the restroom at 30,000 feet (10,000 m)? [Jason Torchinsky] at the Autopian recently gave us an interesting look at the history of the loftiest of loos.

The first airline toilets were little more than buckets behind a curtain, but eventually the joys of indoor plumbing took to the skies. Several interim solutions like relief tubes that sent waste out into the wild blue yonder or simple chemical toilets that held waste like a flying porta-potty predated actual flush toilets, however. Then, in the 1980s, commercial aircraft started getting vacuum-driven toilets that reduce the amount of water needed, and thus the weight of the system.

These vacuum-assisted aircraft toilets have PTFE-lined bowls that are rinsed with blue cleaning fluid that helps everything flow down the drain when you flush. The waste and fluid goes into a central waste tank that is emptied into a “honey truck” while at the airport. While “blue ice” falling from the sky happens on occasion, it is rare that the waste tanks leak and drop frozen excrement from the sky, which is a lot better than when the lavatory was a funnel and tube.

The longest ever flight used a much simpler toilet, and given the aerospace industry’s love of 3D printing, maybe a 3D printed toilet is what’s coming to an airplane lavatory near you?

A baby blue hatchback with red accents drives down a road with blurry trees and a blue sky in the background.

Hyundai Paywalls Brake Pad Changes

Changing the pads on your car’s brakes is a pretty straightforward and inexpensive process on most vehicles. However, many modern vehicles having electronic parking brakes giving manufacturers a new avenue to paywall simple DIY repairs.

Most EVs will rarely, if ever, need to replace their mechanical brake pads as in most driving situations the car will be predominantly relying on regenerative braking to slow down. A hot hatch like the Ioniq 5N, however, might go through brakes a lot faster if it spends a lot of time at the track, which is what happened with Reddit user [SoultronicPear].

Much to their chagrin, despite buying the required $60/wk subscription to the National Automotive Service Task Force (NASTF) and the $2,000 interface tool, [SoultronicPear]’s account was suspended because it was not intended for use for anyone but “service professionals.” Not exactly a Right-to-Repair friendly move on Hyundai’s part. After trying a number of different third party tools, they finally found a Harbor Freight T7 bidirectional scan tool was able to issue the parking brake retract command to perform the pad swap, albeit not without throwing some error codes in the process.

Electrification of vehicles should simplify repairs, but manufacturers are using it to do the opposite. Perhaps they should read our Minimal Motoring Manifesto? There is a glimmer of hope in the promises of Slate and Telo, but we’ll have to see if they make it to production first.

What Do You Call An Ekranoplan With An Outboard Motor?

If there’s one thing [rctestflight] likes, it’s… probably radio controlled test flights. If there are two things [rctestflights] likes, the second one is probably ground-effect vehicles, AKA Ekranoplans. Tired of having them flip over and crash, he’s trying an an innovative solution: stick a planing hull on it.

Ekranoplans have a stability problem because the center-of-pressure isn’t static: as the wing gets closer to the ground, the high pressure cushion of air that creates the ground effect tends to put more lift rearwards. The net effect of that is to torque the vehicle nose-down, which is kind of a self-limiting problem at a fraction of a wingspan’s altitude. The opposite problem is more concerning: the higher the ekranoplan gets, the more it wants to nose up, and there’s nothing to stop it. That leads to the vehicle flipping over. Continue reading “What Do You Call An Ekranoplan With An Outboard Motor?”

BART Display

Real-Time BART In A Box Smaller Than Your Coffee Mug

Ever get to the train station on time, find your platform, and then stare at the board showing your train is 20 minutes late? Bay Area Rapid Transit (BART) may run like clockwork most days, but a heads-up before you leave the house is always nice. That’s exactly what [filbot] built: a real-time arrival display that looks like it was stolen from the platform itself.

The mini replica nails the official vibe — distinctive red text glowing inside a sheet-metal-style enclosure. The case is 3D printed, painted, and dressed up with tiny stickers to match the real deal. For that signature red glow, [filbot] chose a 20×4 character OLED. Since the display wants 5 V logic, a tiny level-shifter sits alongside an ESP32-C6 that runs the show. A lightweight middleware API [filbot] wrote simplifies grabbing just the data he needs from the official BART API and pushes it to the little screen.

We love how much effort went into shrinking a full-size transit sign into a desk-friendly package that only shows the info you actually care about. If you’re looking for more of an overview, we’re quite fond of PCB metro maps as well.

The Cardboard Airplane Saga Continues

History is full of engineers making (or attempting to make) things out of the wrong stuff, from massive wooden aircraft to boats made of ice and sawdust. [PeterSripol] is attempting to make an ultralight aircraft out of a rather wrong material: cardboard. In the previous installment of the project, a pair of wings was fabricated. In this installment, the wings find their home on an equally mostly cardboard fuselage, complete with rudder and elevator. 

The fuselage construction amounts to little more than a cardboard box in the shape of an RC airplane. Doublers provide additional strength in critical areas, and fillets provide a modicum of additional strength around seams. To support the weight of the pilot, a piece of corrugated cardboard is corrugated again, with an additional piece making up the floor. With the addition of a couple of side windows for comfort and visibility, the fuselage is completed, but additional components need to be added.

Continue reading “The Cardboard Airplane Saga Continues”

What Has 5,000 Batteries And Floats?

While it sounds like the start of a joke, Australian shipmaker Incat Tasmania isn’t kidding around about electric ships. Hull 096 has started charging, although it has only 85% of the over 5,000 lithium-ion batteries it will have when complete. The ship has a 40 megawatt-hour storage system with 12 banks of batteries, each consisting of 418 modules for a total of 5,016 cells. [Vannessa Bates Ramierz] breaks it down in a recent post over on IEEE Spectrum. You can get an eyeful of the beast in the official launch video, below. The Incat Tasmania channel also has other videos about the ship.

The batteries use no racks to save weight. Good thing since they already weigh in at 250 tonnes. Of course, cooling is a problem, too. Each module has a fan, and special techniques prevent one hot cell from spreading. Charging in Australia comes from a grid running 100% renewable energy. When the ship enters service as a ferry between Argentina and Uruguay, a 40-minute charge will be different. Currently, Uruguay has about 92% of its power from renewable sources. Argentina still uses mostly natural gas, but 42% of its electricity is sourced from renewable generation.

The ship is 130 meters (426 feet) long, mostly aluminum, and has a reported capacity of 2,100 people and 225 vehicles per trip. Ferry service is perfect for electric ships — the distance is short, and it’s easy to schedule time to charge. Like all electric vehicles, though, the batteries won’t stay at full capacity for long. Typical ship design calls for a 20-year service life, and it’s not uncommon for a vessel to remain in service for 30 or even 40 years. But experts expect the batteries on the ferry will need to be replaced every 5 to 10 years.

While electric ferries may become common, we don’t expect to see electric cargo ships plying the ocean soon. Diesel is hard to beat for compact storage and high energy density. There are a few examples of cargo ships using electric, though. Of course, that doesn’t mean you can’t build your own electric watercraft.

Continue reading “What Has 5,000 Batteries And Floats?”

Rocket Roll Control, The Old Fashioned Way

The vast majority of model rockets go vaguely up and float vaguely downwards without a lot of control. However, [newaysfactory] built a few rockets that were altogether more precise in their flight, thanks to his efforts to master active roll control.

[newaysfactory] started this work a long time ago, well before Arduinos, ESP32s, and other highly capable microcontroller platforms were on the market. In an era when you had to very much roll your own gear from the ground up, he whipped up a rocket control system based around a Microchip PIC18F2553. He paired it with a L3G4200D gyro, an MPXH6115A barometer, and an MMA2202KEG accelerometer, chosen for its ability to provide useful readings under high G acceleration. He then explains how these sensor outputs were knitted together to keep a rocket flying straight and true under active control.

[newaysfactory] didn’t just master roll control for small rockets; he ended up leveraging this work into a real career working on fully-fledged autopilot systems. Sometimes your personal projects can take your career in interesting directions.

Continue reading “Rocket Roll Control, The Old Fashioned Way”