Transportation Hacks

1497 Articles

Will The Lilium Jet Work? A Deep-Dive Into The Physics Behind EVTOL Aircraft

June 22, 2023 by 26 Comments

The Lilium Jet is a proposed eVTOL (electric Vertical Take Off and Landing) aircraft that the German company Lilium GmbH has claimed it will bring to the market ‘soon’, which would made it the first eVTOL aircraft in the world to enter into commercial service. As anyone who has any experience with VTOL knows, it’s a tricky subject to engineer, let alone when you want to do it fully electric. In a deep-dive video on the Lilium Jet and eVTOL in general, [John Lou] goes through the physics behind VTOL take-off, landing and flight, as well as range and general performance.

It is clear that Lilium’s presented aircraft concept has many issues, some of which are due to new and unproven technologies, while others seem to be founded in over-promising and likely under-delivering. With Lilium having signed a number of contracts to deliver the first Pioneer Edition Lilium Jets and commercial service promised by 2025, it’s hard to ignore that the first full prototype of the 7-seater Lilium Jet is supposed to fly this year.

Although as [John] points out in the video, eVTOL is not an impossible concept, it is important to remain realistic about what is physically possible, and not seek to push the boundaries. When the UK introduced its first mass-produced VTOL jet in the form of the Harrier, it too faced an uncomfortable time as bugs got ironed out. As these eVTOL aircraft would be carrying real human passengers, it’s a good place to realize that although you can pick a fight with physics, you will never come out on the winning side.

Hopefully Lilium realizes this too, and these sleek, battery-powered aircraft will truly take to the skies in a few years.

Continue reading “Will The Lilium Jet Work? A Deep-Dive Into The Physics Behind EVTOL Aircraft” →

Is This The World’s Largest Dot Matrix Printer?

June 22, 2023 by 27 Comments

[RyderCalmDown] was watching a road painting vehicle lay down fresh stripes on the road one day and started thinking about the mechanism that lets it paint stripes in such a precise way. Effectively the system that paints the interspersed lines acts as a dot matrix printer that can only print at a single frequency. With enough of these systems on the same vehicle, and a little bit more fine control of when the solenoids activate and deactivate, [RyderCalmDown] decided to build this device on the back of his truck which can paint words on a roadway as he drives by. (Video, embedded below.)

Of course, he’s not using actual paint for this one; that might be prohibitively expensive and likely violate a few laws. Instead he’s using a water-based system which only leaves temporary lettering on the pavement. To accomplish this he’s rigged up a series of solenoids attached to a hitch-mounted cargo rack. A pump delivers water to each of the solenoids, and a series of relays wired to a Raspberry Pi controls the precise timing needed to make sure the device can print readable letters in much the same way a dot matrix printer works. There’s an algorithm running that converts the inputted text to the pattern needed for the dot matrix, and after a little bit of troubleshooting it’s ready for print.

Even though the printer works fairly well, [RyderCalmDown] had a problem thinking of things to write out on the roadways using this system, but it’s an impressive build based around a unique idea nonetheless. Dot matrix printers, despite being mostly obsolete, have a somewhat vintage aesthetic that plenty of people still find desirable and recreate them in plenty of other ways as well, like this 3D printer that was modified to produce dot matrix artwork.

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How To Land A Model Rocket Vertically

June 21, 2023 by 20 Comments

Perhaps most readers will remember when they saw the first SpaceX demonstration of a rocket stage landing vertically on the pad under control. It’s something of a shock to be reminded that their first suborbital demonstration “hops” were around a decade ago, and how quickly what was once so special has become commonplace. We’re now in the era of the more complex model rockets having the same capability, with [BPS.space] managing it last year, and now [TTS Aerospace] sharing a video showing how they achieved the same feat.

The basics of the system revolve around a directed rocket nozzle, but to make it work is a lot more complex than simply hooking up a flight controller and calling it good. The steps in arriving at a landable rocket are examined, with plenty of failures shown along the way. Even the legs are more complex than they might appear, having to combine lightness, ease of unfurling under the power of elastic, and enough strength and give to survive a rough landing.

Those of us from countries where model rocketry is a highly licensed activity can only look on in envy at these projects, and we look forward to seeing where this avenue leads next. We covered the [BPS.space] rocket last year, should you be interested.

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A Ride-On Picnic Table For Those Idylic Summer Evenings

June 12, 2023 by 12 Comments

For most outsiders the Netherlands is a country of picturesque cities, windmills, tulips, and maybe those famous coffee shops. Head away from the coast though and you enter the country’s rural hinterland, farming country with lush green fields, dairy cattle, and farm lads doing what they do best, which is hacking old machinery to do crazy things under those wide skies. [Plodno] are based on a farm somewhere in the eastern Netherlands, and the latest of these lads’ creations is a motorised picnic table (Dutch language, you’ll need YouTube translated subtitles).

This is farm hacking at its best, with a scrap FIAT hatchback donating its running gear to a welded tubular frame, with a chain drive to a small single-cylinder engine. There’s no suspension save for the air in the tyres, the steering column is vertical, and the brake is a single inboard disk on the rear axle. Perhaps it’s fortunate that the intended beating heart, a Kawasaki motorycle engine, was misfiring, as it would have been truly lethal with that much power. We’re not too convinced at the legality of taking such a contraption on the public road in the Netherlands, but they seem to get away with it. Take a look at the build in the video below the break.

Here at Hackaday we like a good hacky farm build, even though sometimes they’re not so well-assembled.

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High Voltage Ion Engines Take Trip On The High Seas

June 12, 2023 by 21 Comments

Over the last several months, we’ve been enjoying a front-row seat as [Jay Bowles] of Plasma Channel has been developing and perfecting his design for a high voltage multi-stage ionic thruster. With each installment, the unit has become smaller, lighter, and more powerful. Which is important, as the ultimate goal is to power an RC aircraft with them.

There’s still plenty of work to be done before [Jay] will be able to take his creation skyward, but he’s making all the right moves. As a step towards his goal, he recently teamed up with [RcTestFlight] to attach a pair of his thrusters — which have again been further tweaked and refined since we last saw them — to a custom catamaran hull. The result is a futuristic craft that skims across the water with no moving parts and no noise…if you don’t count the occasional stray arc from the 40,000 volts screaming through its experimental thrusters, anyway. Continue reading “High Voltage Ion Engines Take Trip On The High Seas” →

A Peek Inside A 747 Fuel Gauge

June 11, 2023 by 28 Comments

It isn’t that often that we civilians get the chance to closely examine the fantastic internals that make up the modern marvels of avionic engineering. Luckily for us, [Glen] got his hands on a 747 fuel gauge and tore it down for our benefit. Not only does he tear it down, but he also builds a controller to display values.

Unlike your typical automotive fuel gauge that reports the distance from the top of the tank to the fuel level, this gauge reports the number of pounds of fuel. The fact that the indicator pictured above can go all the way to 95,000 pounds of fuel hits home the sheer scale of the fuel tanks on a 747 compared to your Volvo. Of course, where this gets interesting is the teardown with the metal sleeve removed. A 400 HZ AC servo motor moves the pointer and counter through the gearing with the help of a feedback potentiometer. The resistance tolerance is only 3%, as there are adjustment knobs on the back. But the linearity spec is only 0.06%, putting this part in a different grade from most pots.

One of the indicators was in worse shape than the others, so [Glen] got to work tapping into the internals of the gauge to drive the motor directly. A custom AC power supply repurposed from another project provided power, and a Raspberry Pi Pico was the PID controller. For [Glen], it isn’t all roses. Unfortunately, a noisy spot around 22,500 prevents accurate placement around there.

The code is up on GitHub, and we love having a gauge on the desk to show whatever value we like. If you are curious about more 747 instruments, this retro control unit might interest you.

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The Yamato 1, a sleek grey ship that looks vaguely like a computer mouse or Star Trek shuttlecraft. It has an enclosed cockpit up front with black windows and blue trim. It is sitting on land in front of a red tower at a museum in Tokyo.

Navy Program PUMPs Up Hopes For Magnetic Propulsion

June 5, 2023 by 43 Comments

The “caterpillar drive” in The Hunt for Red October allowed the sub to travel virtually undetected through the ocean, but real examples of magnetohydrodynamic drives (MHDs) are rare. The US Navy’s recently announced Principles of Undersea Magnetohydrodynamic Pumps (PUMP) intends to jump-start the technology for a new era.

Dating back to the 1960s, research on MHDs has been stymied by lower efficiencies when compared with driving a propeller from the same power source. In 1992 the Japanese Yamato-1 prototype, pictured at the top of the page, was able to hit a blistering 6.6 knots (that’s 12 kph or 7.4 mph for you landlubbers) with a 4 Tesla liquid helium-cooled MHD. Recent advances courtesy of fusion research have resulted in magnets capable of generating fields up to 20 Telsa, which should provide a considerable performance boost.

The new PUMP program will endeavor to find solutions for more robust electrode materials that can survive the high currents, magnetic fields, and seawater in a marine environment. If successful, ships using the technology would be both sneakier and more environmentally friendly. While you just missed the Proposers Day, there is more information about getting involved in the project here.