US Air Force Says They’re Developing An Open Source Jet Engine; We Say Show Us The Design

November 27, 2019 by Tom Nardi 46 Comments

The economies of scale generally dictate that anything produced in large enough numbers will eventually become cheap. But despite the fact that a few thousand of them are tearing across the sky above our heads at any given moment, turbine jet engines are still expensive to produce compared to other forms of propulsion. The United States Air Force Research Laboratory is hoping to change that by developing their own in-house, open source turbine engine that they believe could reduce costs by as much as 75%.

The Responsive Open Source Engine (ROSE) is designed to be cheap enough that it can be disposable, which has obvious military applications for the Air Force such as small jet-powered drones or even missiles. But even for the pacifists in the audience, it’s hard not to get excited about the idea of a low-cost open source turbine. Obviously an engine this small would have limited use to commercial aviation, but hackers and makers have always been obsessed with small jet engines, and getting one fired up and self-sustaining has traditionally been something of a badge of honor.

Since ROSE has been developed in-house by the Air Force, they have complete ownership of the engine’s intellectual property. This allows them to license the design to manufacturers for actual production rather than buying an existing engine from a single manufacturer and paying whatever their asking price is. The Air Force will be able to shop ROSE around to potential venders and get the best price for fabrication. Depending on how complex the engine is to manufacture, even smaller firms could get in on the action. The hope is that this competition will serve to not only improve the design, but also to keep costs down.

We know what you’re thinking. Where is the design, and what license is it released under? Unfortunately, that aspect of ROSE seems unclear. The engine is still in development so the Air Force isn’t ready to show off the design. But even when it’s complete, we’re fairly skeptical about who will actually have access to it. Open Source is in the name of the project and to live up to that the design needs to be available to the general public. From a purely tactical standpoint keeping the design of a cheap and reliable jet engine away from potential enemy states would seem to be a logical precaution, but is at cross purposes to what Open Source means. Don’t expect to be seeing it on GitHub anytime soon. Nuclear reactors are still fair game, though.

[Thanks to Polymath99 for the tip.]

Solenoid Engine Adds Three “Pistons”

October 28, 2019 by Bryan Cockfield 9 Comments

The earliest piston engines typically had only one cylinder, and at best, produced horsepower measured in single digits. But once you have a working engine, it’s a relatively short step to adding cylinders and increasing the power output. [Emiel] made a similar upgrade to one of his engines recently, upgrading it from one cylinder to four. But this isn’t an internal combustion engine, it gets its power from electric solenoids.

We featured his single-cylinder build about a month ago, and since then he’s been busy with this impressive upgrade. The new engine features four cylinders arranged in a V4 pattern. Of course, this greatly increases the mechanical complexity. To start, he had to machine a crankshaft to connect all four “pistons” to a shared output shaft. He also had to build a set of cams in order to time the firing of the cylinders properly, so they don’t work against one another.

The build is just as polished and impressive as the last, which is saying a lot. [Emiel] has a quality machine shop and built the entire motor from scratch, including winding the solenoids, machining the connecting rods and shafts, and building a very picturesque wooden base for the entire contraption to sit on. It’s definitely worth checking out.

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Drop In Motor Converts Car To EV

October 27, 2019 by Al Williams 42 Comments

With the latest craze of electric vehicles, it might be tempting to take an old project car and convert it from gas to electric. On the surface, it sounds simple, but the reality is there are a number of pitfalls. It would be nice if you could find a drop in engine replacement that was ready to go. According to Swindon Powertrain, you’ll be able to soon.

Based on their existing powertrain that can convert a Mini to EV, the transverse powertrain weighs 70 kg and if it can fit in a Mini, it can probably fit in nearly anything. Specifically, it’s 60 cm wide and 44 cm deep — that means it could fit easily in a roughly two foot box. The height can be as little as 28 cm. The company talks about fitting it on a quad bike or even a loading platform. It can be thought of as sort of an electric “crate engine” — a common term for a ready to install powerplant that, as the name implies, arrives in a crate.

The powertrain with a single-speed transmission, cooling system, and inverter weighs in at 154 pounds and generates up to 110 horsepower. We aren’t sure what the expected battery pack is, but presumably, it will be somewhat flexible.

It’ll be interesting to see how people will integrate these if and when they become available as planned in June of next year. Can you drive a differential? Can you use two or four, each driving a different wheel? Turns out we might just be car designers after all.

If you want to see what they did with a Mini, look at their E Classic which claims an 80 MPH top speed and a range of 125 miles. We’ve looked at conversions before. If a conversion is not your thing, you could try to go Open Source although that project doesn’t seem very active.

A Modular Ecosystem That Evolved Around A Simple Diesel Engine

October 6, 2019 by Roger Cheng 20 Comments

High volume commodity products are a foundation of hacking, we’ve built many projects around popular form factors like NEMA 17 stepper motors, 608 bearings, and 280 DC motors. Their high volume led to lower cost, which further increased popularity, and the cycle repeats. A similar thing happened to a style of single-cylinder diesel engine in China, and [Jalopnik] takes us through an exploration of these “Tuo La Ji” (tractor) machines.

Like many popular standards, circumstances elevated this style of engine to become more popular than its peers. Judging from the pictures, the idea is similar to NEMA 17 in that the core essence is a bolt pattern and an output shaft. Different manufacturers offer various capabilities within this space, and a wild assortment of machinery evolved to take advantage of this class of power source.

It starts with a set of wheels and handlebars to create a walk-behind farm tractor, something pretty common around the world. But this particular ecosystem grew far beyond that to many other applications, including full sized trucks with off-road capability that would embarrass most of the genteel SUVs cruising our roads today. They may not be fast, but they only needed to be faster and have longer endurance than beasts of burden to be effective as “a horseless horse”.

Due to factors such as poor crash safety, absence of diesel emission controls, and affordability of more powerful (and faster!) vehicles, these machines are a dying breed. But that won’t change the fact there was a fantastic amount of mechanical hacking ingenuity that had sprung up around this versatile engine building simple and effective machines. Their creativity drew from the same well that fed into these Indonesian Vespas.

Photo by [Brian Holsclaw] CC BY-ND 2.0

Indonesian Jungle Vespas

October 4, 2019 by Sharon Lin 10 Comments

Typically, we associate Vespas with Italians, riding their posh scooters midday under the heat of the Mediterranean sun. In one community, however, the riders and vehicles are pretty different – and by that we mean a whole lot different. Think Mad Max: Fury Road meets The Jungle Book.

The first Vespa arrived in Indonesia in the 1960s when the vehicles were rewarded to Indonesian peacekeepers returning from a mission in Africa. While many of the Vespas on the archipelago maintain the same classic style, some riders have modified theirs into entirely new conceptions.

Indonesian photographer [Muhammad Fadli] captures these riders on their Vespa sampah (“garbage Vespa”) and Vespa gembel (“Vespa drifter”), as they are known by locals. The unique design of the riders is partially attributed to their emergence in the early 2000s coinciding with the fall of the Soeharto authoritarian regime. The newfound freedom and self expression, as well as the relaxed law enforcement, contributed to the development of new types of modified vehicles on the road.

While the scooters are widespread, there isn’t any known count of extreme Vespas in the country. Most of the Vespas are not meant for riding, but rather to show off their physical form. While some are made from cheap steel frames and tires, others are adorned with road scraps and symbols. Anything from buffalo skeletons to machine gun rounds are used to accentuate the design of the scooters, many of which have a punk or metal vibe.

Within the community, there are annual extreme Vespa gatherings, which can draw thousands of riders from all over Indonesia. From frames made of bamboo to frames made of garbage, stalls that collect recyclables to add to their vehicles, and riders from all walks of life, there’s no apparent limit to the builders’ creativity.

[Thanks edmonkey for the tip!]

Build Your Own Solenoid Engine

September 25, 2019 by Bryan Cockfield 13 Comments

A solenoid engine is a curiosity of the electrical world. By all measures, using electricity to rotate something can be done almost any other way with greater efficiency and less hassle. But there’s just something riveting about watching a solenoid engine work. If you want to build one of your own and see for yourself, [Emiel] aka [The Practical Engineer] has a great how-to.

For this build though he used a few tools that some of us may not have on hand, such as a lathe and a drill press. The lathe was used to make the plastic spool to hold the wire, and also to help wind the wire onto the spool itself rather than doing it by hand. He also milled the wood mounts and metal bearings as well, and the quality of the work really shows through in the final product. The final touch is the transistor which controls power flow to the engine.

If you don’t have all of the machine tools [Emiel] used it’s not impossible to find substitute parts if you want to build your own. It’s an impressive display piece, or possibly even functional if you want your build to have a certain steampunk aesthetic (without the steam). You can even add more pistons to your build if you need extra power.

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3D Printing May Be The Key To Practical Scramjets

September 3, 2019 by Tom Nardi 32 Comments

The first scramjet, an airbreathing jet engine capable of pushing an aircraft beyond Mach 5, was successfully flown in the early 1990s. But while pretty much any other technology you could imagine has progressed by leaps and bounds in the nearly 30 years that have passed, the state-of-the-art in hypersonic scramjets hasn’t moved much. We still don’t have practical hypersonic aircraft, military or otherwise, and any missiles that travel at those sort of speeds are rocket powered.

This is somewhat surprising since, at least on paper, the operating principle of the scramjet is simplicity itself. Air rushing into the engine is compressed by the geometry of the inlet, fuel is added, the mixture is ignited, and the resulting flow of expanded gases leaves the engine faster than it entered. There aren’t even any moving parts inside of a scramjet, it’s little more than a carefully shaped tube with fuel injectors and ignitors in it.

Unfortunately, pulling it off in practice is quite a bit harder. Part of the problem is that a scramjet doesn’t actually start working until the air entering the engine’s inlet is moving at around Mach 4, which makes testing them difficult and expensive. It’s possible to do it in a specially designed wind tunnel, but practically speaking, it ends up being easier to mount the engine to the front of a conventional rocket and get it up to speed that way. The downside is that such flights are one-way tickets, and end with the test article crashing into the ocean once it runs out of fuel.

But the bigger problem is that the core concept is deceptively simple. It’s easy to say you’ll just squirt some jet fuel into the stream of compressed air and light it up, but when that air is moving at thousands of miles per hour, keeping it burning is no small feat. Because of this, the operation of a scramjet has often been likened to trying to light a match in a hurricane; the challenge isn’t in the task, but in the environment you’re trying to perform it in.

Now, both Aerojet Rocketdyne and Northrop Grumman think they may have found the solution: additive manufacturing. By 3D printing their scramjet engines, they can not only iterate through design revisions faster, but produce them far cheaper than they’ve been able to in the past. Even more importantly, it enables complex internal engine geometries that would have been more difficult to produce via traditional manufacturing.

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