Keep An Eye On Your Air-Cooled Engine

October 23, 2025 by Bryan Cockfield 23 Comments

There was a time, long ago, when passenger vehicles used to be much simpler than they are today. There were many downsides of this era, safety chief among them, but there were some perks as well. They were in general cheaper to own and maintain, and plenty could be worked on with simple tools. There’s perhaps no easier car to work on than an air-cooled Volkswagen, either, but for all its simplicity there are a number of modern features owners add to help them with these antiques. [Pegor] has created his own custom engine head temperature monitor for these vehicles.

As one could imagine with an air-cooled engine, keeping an eye on the engine temperature is critical to ensuring their longevity but the original designs omitted this feature. There are some off-the-shelf aftermarket solutions but this custom version has a few extra features that others don’t. It’s based on a ATMega32u4 microcontroller and will work with any K-type thermocouple, and thanks to its open nature can use a wide array of displays. [Pegor] chose one to blend in with the rest of the instrumentation on this classic VW. The largest issue that needed to be sorted out was around grounding, but a DC-DC converter created an isolated power supply for the microcontroller, allowing the thermocouple to be bonded to the grounded engine without disrupting operation of the microcontroller.

The finished product looks excellent and does indeed blend in to the dashboard more than the off-the-shelf temperature monitor that was in use before. The only thing that is planned for future versions is a way to automatically dim the display when the headlights are on, as [Pegor] finds it a little bright at night. We also enjoy seeing anything that helps these antiques stay on the road more reliably as their modern descendants don’t have any of the charm or engineering of these classics.

Was The Napier Nomad The Most Complex Aero Engine Ever Made?

October 18, 2025 by Dave Rowntree 11 Comments

From 1945 to 1955, a British aeronautical company called Napier & Son produced not just one but two versions of an intricate hybrid piston engine, which they named the Napier Nomad. The post-World War II era saw the development of several fascinating (and highly complex) piston-powered aeronautical engines alongside the emerging gas turbine engine designs. During this period, gas turbines were inefficient, unreliable, and primarily used for military applications. The (then) British Ministry of Supply commissioned the design and creation of a more fuel-efficient piston engine for aeronautical purposes, both military and civil, aiming to achieve gas turbine-like power while maintaining piston engine efficiency. Quite the challenge!

The specification aimed for 6000 hp and optimal fuel efficiency for long-range use. Napier knew gas turbines were limited by maximum operating temperature, constrained by available materials, which increased fuel consumption and reduced range. Piston engines operated at higher peak temperatures. They considered combining both principles to create a superior design, a concept suggested by aeronautical engineer Sir Harry Ricardo, who had consulted for Napier on other projects. Their complex solution was to build a gas turbine with a two-stroke diesel engine as the combustion chamber, merging the benefits of both.

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Keep That Engine Running, With A Gassifier

October 15, 2025 by Jenny List 53 Comments

Every now and then in histories of the 20th’s century’s earlier years, you will see pictures of cars and commercial vehicles equipped with bulky drums, contraptions to make their fuel from waste wood. These are portable gas generators known as gasifiers, and to show how they work there’s [Greenhill Forge] with a build video.

A gasifier on a vintage tractor. Per Larssons Museum, CC BY 2.5.

When you burn a piece of wood, you expect to see flame. But what you are looking at in that flame are the gaseous products of the wood breaking down under the heat of combustion. The gasifier carefully regulates a burn to avoid that final flame, with the flammable gasses instead being drawn off for use as fuel.

The chemistry is straightforward enough, with exothermic combustion producing heat, water vapour, and carbon dioxide, before a further endothermic reduction stage produces carbon monoxide and hydrogen. He’s running his system from charcoal which is close to pure carbon presumably to avoid dealing with tar, and at this stage he’s not adding any steam, so we’re a little mystified as to where the hydrogen comes from unless there is enough water vapour in the air.

His retort is fabricated from sheets steel, and is followed by a cyclone and a filter drum to remove particulates from the gas. It relies on a forced air draft from a fan or a small internal combustion engine, and we’re surprised both how quickly it ignites and how relatively low a temperature the output gas settles at. The engine runs with a surprisingly simple gas mixer in place of a carburetor, and seems to be quite smooth in operation.

This is one of those devices that has fascinated us for a long time, and we’re grateful for the chance to see it up close. The video is below the break, and we’re promised a series of follow-ups as the design is refined.

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PLA Gears Fail To Fail In 3D Printed Bicycle Drivetrain

October 10, 2025 by Tyler August 33 Comments

Anyone who has ever snapped a chain or a crank knows how much torque a bicycle’s power train has to absorb on a daily basis; it’s really more than one might naively expect. For that reason, [Well Done Tips]’s idea of 3D printing a gear chain from PLA did not seem like the most promising of hacks to us.

Contrary to expectations, though, it actually worked; at the end of the video (at about 13:25), he’s on camera going 20 km/h, which while not speedy, is faster than we thought the fixed gearing would hold up. The gears themselves, as you can see, are simple spurs, and were modeled in Fusion360 using a handy auto-magical gear tool. The idler gears are held in place by a steel bar he welded to the frame, and are rolling on good old-fashioned skateboard bearings–two each. (Steel ones, not 3D printed bearings.) The healthy width of the spur gears probably goes a long way to explaining how this contraption is able to survive the test ride.

The drive gear at the wheel is steel-reinforced by part of the donor bike’s cassette, as [Well Done Tips] recognized that the shallow splines on the freewheel hub were not exactly an ideal fit for PLA. He does complain of a squeaking noise during the test ride, and we can’t help but wonder if switching to helical gears might help with that. That or perhaps a bit of lubricant, as he’s currently riding the gears dry. (Given that he, too, expected them to break the moment his foot hit the pedal, we can’t hardly blame him not wanting to bother with grease.)

We’ve seen studies suggesting PLA might not be the best choice of plastic for this application; if this wasn’t just a fun hack for a YouTube video, we’d expect nylon would be his best bet. Even then, it’d still be a hack, not a reliable form of transportation. Good thing this isn’t reliable-transportation-a-day!

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Building A Diwheel To Add More Tank Controls To Your Commute

October 7, 2025 by Maya Posch 19 Comments

It’s often said that one should not reinvent the wheel, but that doesn’t mean that you cannot change how the use of said wheel should be interpreted. After initially taking the rather zany concept of a monowheel for a literal ride, [Sam Barker] decided to shift gears, did a ‘what if’ and slapped a second monowheel next to the first one to create his diwheel vehicle. Using much thicker steel for the wheels and overall much more robust construction than for his monowheel, the welding could commence.

It should be said here that the concept of a diwheel, or dicycle, isn’t entirely new, but the monowheel – distinct from a unicycle – is much older, with known builds at least as far back as the 19th century. Confusing, self-balancing platforms like Segways are also referred to as ‘dicycles’, while a diwheel seems to refer specifically to what [Sam] built here. That said, diwheels are naturally stable even without gyroscopic action, which is definitely a big advantage.

The inner frame for [Sam]’s diwheel is built out of steel too, making it both very robust and very heavy. High-tech features include suspension for that smooth ride, and SLS 3D-printed nylon rollers between the inner frame and the wheels. After some mucking about with a DIY ‘lathe’ to work around some measurement errors, a lot more welding and some questionable assembly practices, everything came together in the end.

This is just phase one, however, as [Sam] will not be installing pedals like it’s an old-school monowheel. Instead it’ll have electrical drive, which should make it a bit less terrifying than the Ford Ka-based diwheel we featured in 2018, but rather close to the electric diwheel called EDWARD which we featured back in 2011. We hope to see part two of this build soon, in which [Sam] will hopefully take this beast for its first ride.

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The WindRunner unloading a blade, image Radia.

Giant Airplane Goes Long On Specialization

October 3, 2025 by Tyler August 63 Comments

While not everyone agrees on the installation of wind turbines in their proverbial back yards, one thing not up for debate is that there is a drive to build them bigger, and bigger. Big turbines means big blades, and big blades need to be transported… somehow. If air freight is going to stay relevant to the industry, we’re gonna need a bigger airplane.

A startup called Radia has a plan for that plane, and it is a doosie. The “WindRunner” would clock in at a massive 108 meters (354 feet) long, but with a wingspan of just 80 m (262 ft). That’s very, very long, but it might not be the largest airplane, depending how you measure it. Comparing to the 88 m wingspan for the late, lamented An-225 Mriya, you can expect a lower payload capacity, but heavy payloads aren’t the point here. Wind turbine blades really aren’t that heavy. They’re big, or they can be — the WindRunner is designed to fit a single 105 m blade within its long fuselage, or a pair of 90 m blades.

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A forest green kei truck sits in an actual forest. In its bed is a dark grey box with a small window, wood trim, and a solar panel tilted on its roof. The headlights are on, hinting at the onset of twilight. You have a sudden urge to go glamping now.

Kei Truck Becomes Tiny RV

October 2, 2025 by Navarre Bartz 16 Comments

Tent camping lets you explore places on foot you could never reach another way, but sometimes you want to camp with a bit more luxury. [Levi Kelly] decided to see how small you could make an RV. [via Autopian]

While we won’t argue one way or another on his claim to world’s smallest, as that likely depends on your definition of an RV, starting with a kei truck certainly puts you in a more compact format than something built on a bus chassis. With four wheel drive and a small footprint, this could be better for overlanding than the Rivian bed camper we featured recently.

The 21 sq. ft. (1.95 m²) camper portion itself is framed in 2 x 2s (38 x 38 mm) to save weight and uses foam board insulation. A working faucet uses a pump to draw drinking water from a 5 gallon (19L) refillable jug and empties into a 7 gallon (26L) grey water tank. A solar panel on the roof charges the battery that drives the pump, ventilation fan, and can also be used to run other devices like a hot plate for cooking.

A teeny tiny wood stove can be used for heat, although [Kelly] is using a different fuel source to reduce unpredictability from a wood fire in such a small space. A faucet-mounted sprayer can be routed to the outside of the camper to create a makeshift shower and is run from the sink water system. There’s even a small cabinet above the foot area of the bed to house a portable toilet and a bubble window to observe your surroundings while you do your business.

We’ve seen some even smaller campers, like this vintage-inspired bike camper, or this more streamlined version. If you want the most efficient RV ever then check out this solar-powered one.

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