Failed 3D Printed Part Brings Down Small Plane

Back in March, a small aircraft in the UK lost engine power while coming in for a landing and crashed. The aircraft was a total loss, but thankfully, the pilot suffered only minor injuries. According to the recently released report by the Air Accidents Investigation Branch, we now know a failed 3D printed part is to blame.

The part in question is a plastic air induction elbow — a curved duct that forms part of the engine’s air intake system. The collapsed part you see in the image above had an air filter attached to its front (towards the left in the image), which had detached and fallen off. Heat from the engine caused the part to soften and collapse, which in turn greatly reduced intake airflow, and therefore available power.

Serious injury was avoided, but the aircraft was destroyed.

While the cause of the incident is evident enough, there are still some unknowns regarding the part itself. The fact that it was 3D printed isn’t an issue. Additive manufacturing is used effectively in the aviation industry all the time, and it seems the owner of the aircraft purchased the part at an airshow in the USA with no reason to believe anything was awry. So what happened?

The part in question is normally made from laminated fiberglass and epoxy, with a glass transition of 84° C. Glass transition is the temperature at which a material begins to soften, and is usually far below the material’s actual melting point.

When a part is heated at or beyond its glass transition, it doesn’t melt but is no longer “solid” in the normal sense, and may not even be able to support its own weight. It’s the reason some folks pack parts in powdered salt to support them before annealing.

The printed part the owner purchased and installed was understood to be made from CF-ABS, or ABS with carbon fiber. ABS has a glass transition of around 100° C, which should have been plenty for this application. However, the investigation tested two samples taken from the failed part and measured the glass temperature at 52.8°C and 54.0°C, respectively. That’s a far cry from what was expected, and led to part failure from the heat of the engine.

The actual composition of the part in question has not been confirmed, but it sure seems likely that whatever it was made from, it wasn’t ABS. The Light Aircraft Association (LAA) plans to circulate an alert to inspectors regarding 3D printed parts, and the possibility they aren’t made from what they claim to be.

A Deep Drive Deep Dive Into A Twin-Rotor Motor

Compromise is key to keeping a team humming along. Say one person wants an inrunner electric motor, and the other prefers outrunner. What to do? Well, if you work at [Deep Drive], the compromise position is a dual-rotor setup that they claim can be up to 20% more efficient than standard designs. In a recent video, [Ziroth] provides a deep dive into Deep Drive’s Twin-Rotor Motor. 

This is specifically a radial flux permanent magnet motor, like most used in electric vehicles today — and don’t let talk of inrunners and outrunners fool you, that’s the size of motor we’re talking about here. This has been done before with axial flux motors, but it’s a new concept for team radial. As the names imply, the difference is the direction the magnetic field is orientated: axial flux motors have all the magnetism oriented along the axis, which leads to the short wide profile that inspired the nickname “pancake motors”. For various reasons, you’re more likely to see those on a PCB than in an electric car.

In a radial flux motor, the flux goes out the radius, so the coils and magnets are aligned around the shaft of the motor.  Usually, the coils are held by an iron armature that directs their magnetic flux inwards (or outwards) at the permanent magnets in the rotor, but not here. By deleting the metal armature from their design and putting magnets on both sides of the stator coil, Deep Drive claims to have built a motor that is lighter and provides more torque, while also being more energy-efficient.

Of course you can’t use magnet wire if your coil is self-supporting, so instead they’re using hefty chunks of copper that could moonlight as busbars. In spite of needing magnets on both inner and outer rotors, the company says they require no more rare-earths than their competitors. We’re not sure if that is true for the copper content, though. To make the torque, those windings are beefy.

Still, its inspiring to see engineers continue to innovate in a space that many would have written off as fully-optimized. We look forward to seeing these motors in upcoming electric cars, but more than that, hope they sell a smaller unit for an air compressor so after going on a Deep Drive deep dive we can inflate our rubber raft with their twin rotor motor boater bloater. If it works as well as advertised, we might have to become twin-rotor motor boater bloater gloaters!

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The Engineering That Makes A Road Cat’s Eye Self-Cleaning

Although most people manage to navigate roads without major issues during the day, at night we become very reliant on the remaining navigational clues. The painted marks on the asphalt may not be as obvious in the glare of headlights, not to mention scuffed up and/or covered by snow and hidden by fog. This is where cat’s eyes are a great example of British ingenuity. A common sight in the UK and elsewhere in Europe, they use retroreflectors embedded in the road. Best of all, they are highly durable and self-cleaning, as [Mike Fernie] details in a recent video on these amazing devices.

Invented in the 1930s by [Percy Shaw], cat’s eyes feature a sturdy body that can take the abuse of being driven over by heavy trucks, along with a rubber dome that deforms to both protect the reflectors and wipe them clean using any water that’s pooled in the area below them. They also provide an auditory clue to the driver when they pass the center line, which can be very useful for night-time driving when attention may be slipping.

In the video the cat-squishing cleaning process is demonstrated using an old cat’s eyes unit that seems to have seen at least a few decades to road life, but still works and cleans up like a charm. Different color cat’s eyes are used to indicate different sections of the road, and modern designs include solar-powered LEDs as well as various sensors to monitor road conditions. Despite these innovations, it’s hard to beat the simplicity of [Percy]’s original design.

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Raising A GM EV1 From The Dead

Probably the biggest story in the world of old cars over the past couple of weeks has been the surfacing of a GM EV1 electric car for sale from an auto salvage yard. This was the famous electric car produced in small numbers by the automaker in the 1990s, then only made available for lease before being recalled. The vast majority were controversially crushed with a few units being donated to museums and universities in a non-functional state.

Finding an old car isn’t really a Hackaday story in itself, but now it’s landed in [The Questionable Garage]. It’s being subjected to a teardown as a prelude to its restoration, offering a unique opportunity to look at the state of the art in 1990s electric automotive technology.

The special thing about this car is that by a murky chain of events it ended up as an abandoned vehicle. GM’s legal net covers the rest of the surviving cars, but buying this car as an abandoned vehicle gives the owner legal title over it and frees him from their restrictions. The video is long, but well worth a watch as we see pieces of automotive tech never before shown in public. As we understand it the intention is to bring it to life using parts from GM’s contemporary S10 electric pickup truck — itself a rare vehicle — so we learn quite a bit about those machines too.

Along the way they find an EV1 charger hiding among a stock of pickup chargers, take us through the vehicle electronics, and find some galvanic corrosion in the car’s structure due to water ingress. The windscreen has a huge hole, which they cover with a plastic wrap in order to 3D scan so they can create a replacement.

This car will undoubtedly become a star of the automotive show circuit due to its unique status, so there will be plenty of chances to look at it from the outside in future. Seeing it this close up in parts though is as unique an opportunity as the car itself. We’ve certainly seen far more crusty conventional cars restored to the road, but without the challenge of zero parts availability and no donor cars. Keep an eye out as they bring it closer to the road.

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Ride On With FOSS And GoldenCheetah

If you exclude certain companies like Peloton, the world of cycling technology is surprisingly open. It’s not perfect by any means, but there are enough open or open-ish standards for many different pieces of technology from different brands to interoperate with each other, from sensors and bike computers and even indoor trainers to some extent. This has also made it possible for open source software to exist in this realm as well, and the GoldenCheetah project has jumped in for all of us who value FOSS and also like to ride various bicycles from time to time.

GoldenCheetah focuses on gathering data from power meters, allowing cyclists to record their rides and save them in order to keep track of their training performance over time. It works well with sensors that use the ANT+ protocol, and once it has that data it can provide advanced analytics such as power curves, critical power modeling, and detailed charts for power, heart rate, and cadence. It can display and record live indoor-training data, and in some situations it can even run interval workouts, although not every indoor trainer is supported. There are no social features, subscriptions, or cloud requirements which can be refreshing in the modern world, but is a bit of a downside if you’re used to riding with your friends in something like Zwift.

All in all, though, it’s an impressive bit of software that encourages at least one realm of consumer electronics to stay more open, especially if those using bike sensors, computers, and trainers pick ones that are more open and avoid those that are proprietary, even if they don’t plan to use GoldenCheetah exclusively. And if you were wondering about the ANT+ protocol mentioned earlier, it’s actually used for many more things that just intra-bike wireless communications.

bikes are shown raised from the floor from the garage opener lift

Raise Bikes To The Heavens With Humble Garage Door Opener

Biking can be an incredibly rewarding hobby, but what do you do with all of your expensive pieces of metal and composite when you aren’t hitting the trails? They take up space that you could use for more bikes! [Chaz] figured there had to be a better way and discovered the unlikely solution of the humble garage opener.

Garage doors are made to lift high with moderate weight, exactly what one would expect from a bike lift. If you have high ceilings in your garage or wherever else you store your bikes there can’t be much easier than pushing a button to get your bike out of the way.

To assemble the unusual bike rack, [Chaz] mounted the motor to the wall with a few scraps of wood, and built a wooden platform that rides along the rail. This additional board allows you to use a traditional bike wheel rack to gently raise the bike. While initially [Chaz] had some questionable results, this was quickly resolved with removing the rotational elements of the mount and allowing a slight slant in the bike.

While not everyone may need to raise their bikes to the heavens, this type of simple hacking is always rewarding to see come together. If you want to see how some more bike specific tech works, check out the insides of this expensive bike seat!

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Has Steampunk Delivered The Hoverboard?

The hoverboard, one of the teen crazes of the last decade, is both a marvel of technology and a source of hacker parts that have appeared in so many projects on these pages. It contains an accelerometer or similar, along with a microcontroller and a pair of motor controllers to drive its in-wheel motors. That recipe is open to interpretation of course and we’ve seen a few in our time, but perhaps not quite like this steampunk design from [Skrubis]. It claims a hoverboard design with no modern electronics, only relays, mercury switches, and neon bulbs.

The idea is that it’s a hoverboard from 1884 using parts available in that era, hence there’s talk of telegraph relays and galvanomic piles. The write-up is presented in steampunk-style language which if we’re honest makes our brain hurt, but the premise is intriguing enough to persevere. As far as we can see it uses a pair of relays and a transformer to make an oscillator, from which can be derived the drive for a 3-phase motor. This drive is sent to the motors by further relays operating under the influence of mercury tilt switches.

There are a full set of hardware designs once you wade past the language, but as yet it has no evidence of a prototype. We admit we kinda want it to work because the idea is preposterous enough to be cool if it ran, but we’d be lying if we said we didn’t harbor some doubts. Perhaps you our readers can deliver a verdict, after all presenting you with entertainment is what it’s all about. If a working prototype surfaces we’ll definitely be featuring it, after all it would be cool as heck.

Oddly this isn’t the first non-computerized balance transport we’ve seen.

Featured image: Simakovarik, CC BY-SA 4.0.