Electric Jet Engine Uses 3D Printed Compressor, Skips The Turbine Altogether.

March 2, 2022 by Ryan Flowers 52 Comments

Turbojet engines are an incredible piece of 20th century engineering that except for some edge cases, have mostly been replaced by Turbofans. Still, even the most basic early designs were groundbreaking in their time. Material science was applied to make them more reliable, more powerful, and lighter. But all of those incredible advances go completely out the window when you’re [Joel] of [Integza], and you prefer to build your internal combustion engines using repurposed butane canisters and 3d printed parts as you see in the video below the break.

Emoscopes, CC BY-SA 3.0 via Wikimedia Commons

To understand [Integza]’s engine, a quick explanation of Turbojet engines is helpful. Just like any other internal combustion engine, air is compressed, fuel is burned, and the reaction produces work. In a turbojet, a compressor compresses air. Fuel is added in a combustor and ignited, and the expanding exhaust drives a turbine that in turn drives the compressor since both are attached to the same shaft. Exhaust whose energy isn’t spent in turning the turbine is expelled and produces thrust, which propels the engine and the vehicle it’s attached to in the opposite direction. Simple, right? Right! Until the 3d printer comes in.

Sadly for 3d printed parts, they are made of plastic. Last we checked, plastic isn’t metal, and so 3d printing a turbine to give the extremely hot exhaust something turn just isn’t going to work. But what if you just skipped the whole turbine part, and powered the compressor with an electric motor? And instead of using an axial compressor with tons of tiny blades that would likely be impossible to 3d print with enough strength, you went with a sturdy, easy to print centrifugal compressor? Of course, that’s exactly what [Integza] did, or we wouldn’t be talking about it. The results are fantastic, especially considering that the entire machine was built with 3d printing and a home made spot welder.

If you want to build a full jet turbine, we won’t say it’s easy, but you might appreciate this jet turbine whose components include a toilet paper holder as proof that once a technology is understood, it can be built in the worst ways possible and still work. Sort of.

Continue reading “Electric Jet Engine Uses 3D Printed Compressor, Skips The Turbine Altogether.” →

Swap The Laser For A Vortex Cannon And You Have… Lift?

February 28, 2022 by Matthew Carlson 6 Comments

When people are thinking of the future of space travel, an idea that floats around is a spaceship with a giant solar sail pushed along by a massive laser. Inspired by the concept but lacking a giant laser, [Tom Stanton] build a small craft powered by a vortex cannon.

Creating a vortex is hard enough, but creating a vortex with enough oomph to travel a longer distance and push something takes some doing. [Tom] started with some cheap solenoids, but had a few issues. Their interior nozzles were quite small, which restricted airflow. He used four valves all plumbed together to provide the volume of air needed. Additionally, he found that their response time was lacking. They couldn’t quite switch off quickly enough so instead of a puff of air, it pushed out something closer to a stream. To compensate, [Tom] 3d printed and tried a few different sizes of cone nozzles to see if that helped. Unfortunately, it did not. So he combined the nozzle with an expansion chamber that allowed the pressure wave to shorten, then it narrows to speed it up again. This provided a decent vortex.

Next [Tom] turned to his craft. After designing a 3d model, he had a template to cut out some shapes from paper and taped them together to form a light vehicle that can capture the vortex. The initial tests weren’t too promising as the craft twisted and the string that it traveled on had too much friction. Switching to a vertical test showed more promise but trying to generate multiple vortexes rapidly was unsuccessful as the turbulence from the previous rings broke up the newer rings.

So what’s to be learned from this? It seems like he doesn’t have much to show. [Tom] tweaked and iterated his way to a working vortex cannon and has continued to refine his craft. Hopefully, in the future, we’ll see a fully-functional version of this. The lesson is to keep enumerating the possibilities. Like this webcam based posture sensor iterating its way to success. Video after the break.

Continue reading “Swap The Laser For A Vortex Cannon And You Have… Lift?” →

Rotary Valve Engine Gets A Second Chance, Smokes The Competition

February 21, 2022 by Ryan Flowers 42 Comments

It’s a dedicated hacker who has the patience to build an engine from scratch. And it’s a borderline obsessed hacker who does it twice. [Meanwhile In the Garage] is of the second ilk, and in the video below the break, he takes a failed engine design and musters up the oomph to get it running.

The whole build began with an idea for a different kind of intake and exhaust valve. [Meanwhile In the Garage] dreamed up a design that does away with the traditional poppet valve. Instead of valves that open by being pushed away from their seat by a camshaft, this design uses a cylinder that is scooped so that as it rotates, its ports are exposed to either the intake or the exhaust.

Four Stroke Cycle with Poppet valves. Courtesy Wikipedia, CC BY-SA 3.0

During the compression stroke, the valve cylinder becomes part of the combustion chamber, with both ports facing away from the piston. If you read the comments, you’ll find that multiple people have come up with the idea through the years. With his mill, lathe, and know-how, [Meanwhile In the Garage] made it happen. But not without some trouble.

The first iteration resisted all valiant attempts at getting it started. The hour-long video preceding this one ended up in a no-start. Despite his beautiful machine work and a well thought out design, it wasn’t to be. Fire came from the engine either through the exhaust or the carburetor, but it never ran. In this version, several parts have been re-worked and the effect is immediate! The engine fired up nicely and even seems to rev up pretty well. Being a first-generation prototype, it lacks seals and other fancy parts to keep oil out of the combustion chamber. Normal engine oil has been added to the fuel as a precaution as well. The fact that it smokes quite badly isn’t a surprise and only proves that the design will benefit from another iteration. Isn’t that true for most prototypes, though?

Home-grown engines aren’t a new thing at Hackaday, and one of This Author’s favorite jet turbines used a toilet paper holder. Yes, really. Thanks to [Keith] for the Tip!

Continue reading “Rotary Valve Engine Gets A Second Chance, Smokes The Competition” →

There’s A Wrinkle In This 3D Printed Wankel

February 10, 2022 by Matthew Carlson 10 Comments

Rotary engines such as the Wankel have strange shapes that can be difficult to machine (as evidenced by the specialized production machines and patents in the 70s), which means it lends itself well to be 3D printed. The downside is that the tolerances, like most engines, are pretty tight, and it is difficult for a printer to match them. Not to be dissuaded, [3DprintedLife] designed and built a 3D printed liquid piston rotary engine. The liquid piston engine is not a Wankel and is more akin to an inside-out Wankel. The seals are on the housing, not the rotor itself, and there are three “chambers” instead of two.

The first of many iterations didn’t run. There was too much friction, but there were some positive signs as pressure was trapped in a chamber and released as it turned. The iterations continued, impressively not using any o-rings to seal, but instead sanding each part down using a 1-2-3 block as a flat reference, within 25 microns of the design. Despite his care and attention to detail, it still couldn’t self-sustain. He theorizes that it could be due to the resin being softer than other materials he has used in the past. Not to be left empty-handed, he built a dynamo to test his new engine out. It was a load cell and an encoder to measure speed and force. His encoder had trouble keeping up, so he ordered some optical limit switches.

This engine is a follow-on to an earlier 3D printed air-powered Wankel rotary engine, and we’re looking forward to part two of the liquid piston series. Video after the break.

Continue reading “There’s A Wrinkle In This 3D Printed Wankel” →

How Can 335 Horses Weigh 63 Pounds?

February 9, 2022 by Al Williams 110 Comments

Koenigsegg, the Swedish car company, has a history of unusual engineering. The latest innovation is an electric motor developed for its Gemera hybrid vehicle. The relatively tiny motor weighs 63 pounds and develops 335 horsepower and 443 lb-ft of torque. Dubbed the Quark, the motor uses both radial and axial flux designs to achieve these impressive numbers.

There is a catch, of course. Like most EV motors, those numbers are not sustainable. The company claims the motor can output peak power for 20 seconds and then drops to 134 horsepower/184 lb-ft of torque. The Gemera can supplement, of course, with its internal combustion engine — a 3 cylinder design.

Continue reading “How Can 335 Horses Weigh 63 Pounds?” →

The Air Multiplier Fan Principle, Applied To A Jet Engine

January 28, 2022 by Jenny List 26 Comments

Many readers will be familiar with the Dyson Air Multiplier, an ingenious bladeless fan design in which a compressor pushes jets of air from the inside edge of a large ring. This fast-moving air draws the surrounding air through the ring, giving the effect of a large conventional fan without any visible moving parts and in a small package. It’s left to [Integza] to take this idea and see it as the compressor for a jet engine, and though the prototype you see in the video below is fragile and prone to melting, it shows some promise.

His design copies the layout of a Dyson with the compressor underneath the ring, with a gas injector and igniter immediately above it. The burning gas-air mixture passes through the jets and draws the extra air through the ring, eventually forming a roaring jet engine flame exhaust behind it. Unfortunately the choice of 3D print for the prototype leads to very short run times before melting, but it’s possible to see it working during that brief window. Future work will involve a non-combustible construction, but his early efforts were unsatisfactory.

It’s clear that he hasn’t created the equivalent of a conventional turbojet. Since it appears that its operation happens when the flame has passed into the center of the ring, it has more in common with a ramjet that gains its required air velocity with the help of extra energy from an external compressor. Whether he’s created an interesting toy or a useful idea remains to be answered, but it’s certainly an entertaining video to watch.

Meanwhile, this isn’t the first project we’ve seen inspired by the Air Multiplier.

Continue reading “The Air Multiplier Fan Principle, Applied To A Jet Engine” →

Running Methanol RC Engines On Gasoline

January 22, 2022 by Lewin Day 33 Comments

Methanol is a popular fuel for small engines used in radio-controlled models, but comes at a higher price than gasoline. It’s also harder to source and can be a mite corrosive, too. Gasoline comes with some benefits, but running it in a methanol engine usually requires some mods. [David] and [Bert] worked together to build a mixture controller for just this purpose.

The controller uses a solenoid to control the flow of gasoline to a conventional methanol-tuned carburetor for a small RC engine, allowing it to be accurately tuned to run gasoline well across the whole RPM range. Having gone through many revisions, all documented in a big forum thread, the latest version uses a Seeduino Xiao controller and a BMP280 pressure and temperature sensor for determining the right fuel/air mixture for the conditions. A small OLED screen can optionally be fitted to help with configuration of the mixture controller.

The system has worked well in testing, with [David] and [Bert] reporting that they have “converted engines as small as 0.3 CID up to large radials with this system.” It’s a promising tool that could be handy to have in the RC modeller’s arsenal.

These tiny engines have other applications too; they can make for one crazy power drill, that’s for sure!