The “Impossible” Tech Behind SpaceX’s New Engine

Followers of the Church of Elon will no doubt already be aware of SpaceX’s latest technical triumph: the test firing of the first full-scale Raptor engine. Of course, it was hardly a secret. As he often does, Elon has been “leaking” behind the scenes information, pictures, and even video of the event on his Twitter account. Combined with the relative transparency of SpaceX to begin with, this gives us an exceptionally clear look at how literal rocket science is performed at the Hawthorne, California based company.

This openness has been a key part of SpaceX’s popularity on the Internet (that, and the big rockets), but its been especially illuminating in regards to the Raptor. The technology behind this next generation engine, known as “full-flow staged combustion” has for decades been considered all but impossible by the traditional aerospace players. Despite extensive research into the technology by the Soviet Union and the United States, no engine utilizing this complex combustion system has even been flown. Yet, just six years after Elon announced SpaceX was designing the Raptor, they’ve completed their first flight-ready engine.

The full-flow staged combustion engine is often considered the “Holy Grail” of rocketry, as it promises to extract the most possible energy from its liquid propellants. In a field where every ounce is important, being able to squeeze even a few percent more thrust out of the vehicle is worth fighting for. Especially if, like SpaceX, you’re planning on putting these new full-flow engines into the world’s largest operational booster rocket and spacecraft.

But what makes full-flow staged combustion more efficient, and why has it been so difficult to build an engine that utilizes it? To understand that, we’ll need to first take a closer look at more traditional rocket engines, and the design paradigms which have defined them since the very beginning.

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Electrifying a Honda NC50 Express

[Quasse] bought a 1978 Honda NC50 Express moped with the intention of fixing it up and riding it, only to find that the engine was beyond repair. So, they did what any self-respecting hacker would do: tear out the motor and replace it with an electric one. It’s still a work in progress, but they have got it up and running by replacing the engine with a Turnigy SK3 6374 motor, a 192KV motor that [Quasse] calculated should be able to drive the moped at just over 30 miles per hour. Given that this was the top speed that the NC50 could manage on gas power, that’s plenty fast.

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Radio Control Buggy Gets V10 Power

Amongst the more difficult machining tasks in the world are those involved in the production of internal combustion engines. Thanks to the Internet, it’s now possible to watch detailed videos of master craftsmen assembling tiny desktop V8 and V12 engines in home workshops with barely a CNC in sight. However, up until now, most of these builds have been left on the test stand to bark and wail away. No longer – [Keith] has decided that needs to change.

We’ve seen [Keith]’s work before – particularly, his 125cc V10 build, featuring fuel injection, dual overhead cams, and even a supercharger. With several micro engines under his belt now, it was time to put them to work – the V10 is getting a new home in a 1/3rd scale RC buggy.

We’re not sure [Keith] has heard the phrase “off the shelf” – even the suspension dampers on this build are custom machined. Currently up to part 5, the chassis is coming together and there are plans for a hybrid powertrain, too. Carbon fiber and anodized parts are in abundance – this build is truly a work of art.

We can’t wait to see this V10 monster tearing up the dirt – It’s an ambitious build, but if anyone can pull it off, it’s [Keith]. Video after the break.

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3D-Printing Wankel Engine from Mazda’s Beloved “Rotary Rocket”

Although there was briefly a company called Rotary Rocket, the term is much better known as a nickname for the Mazda RX-7 — one of the few cars that used a Wankel, or rotary, engine. If you ever wondered how these worked, why not print a model? That’s what [Engineering Explained] did. They printed a 1/3 scale model and made a video explaining and demonstrating its operation. The model itself was from Thingiverse, created by [EricThePoolBoy].

One thing we really liked about the model was the use of lights to show the different stages of combustion. Cool air intake is a blue light, hot air is red, and so on. It really helps visualize what’s happening. You can watch the video below.

If you haven’t seen a Wankel before, it is a clever design. It has very few moving parts and offers very smooth power transfer and high power to weight ratio. The downside, though, is that the engine deliberately burns oil to lubricate and seal, so it is difficult to meet emission standards and requires a lot of oil. The fuel efficiency of current designs is not very good either, especially since manufacturers will often trade fuel efficiency for better emissions.

If you’d like to read more about the Wankel, check out our earlier post (and the 165 comments attached). We also looked at — or rather through — another Wankel earlier this year.

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Building The World’s Smallest Jet Turbine By Hand

There are very few machines as complex to build as a turbojet engine. The turbine blades on a commercial airliner are grown from a single crystal of metal. The engineering tolerances are crazy, and everything spins really, really fast. All of these problems aren’t a concern for [Igor], who’s building what will probably end up being the world’s smallest turbojet engine. He’s doing it in his home shop, and a lot of the work is being done by hand. We don’t know the Russian translation for ‘hold my beer’, but [Igor] certainly does.

The design of this turbojet — as far as we can tell — is a centrifugal flow turbine, or something that’s not terribly different than the projects we’ve seen that turn the turbocharger from a diesel engine into a jet. The innovation here is using a lathe to machine the compressor stages by mounting an end mill to the headstock and the compressor blank on the cross slide, in a rotary table. It’s weird, but you really can’t argue with something that looks like it’ll work.

[Igor] has made a name for himself by creating some crazy contraptions. The most impressive, by far, is a gigantic remote controlled plane, powered by a handmade jet engine. This is an enormous fiberglass plane with a homebrew engine that spins at 90,000 RPM and doesn’t fly apart. That’s impressive by any measure.

[Igor] is posting a lot of his build process on YouTube and Instagram, including heat treating the compressor stages with a blowtorch. This is an amazing project, and even if this tiny turbine will be able to self-sustain, that’s an amazing accomplishment. You can check out a few more videos from [Igor] below.

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GE’s Engine to Reignite Civil Supersonic Flight

On October 24th, 2003 the last Concorde touched down at Filton Airport in England, and since then commercial air travel has been stuck moving slower than the speed of sound. There were a number of reasons for retiring the Concorde, from the rising cost of fuel to bad publicity following a crash in 2000 which claimed the lives of all passengers and crew aboard. Flying on Concorde was also exceptionally expensive and only practical on certain routes, as concerns about sonic booms over land meant it had to remain subsonic unless it was flying over the ocean.

The failure of the Concorde has kept manufacturers and the civil aviation industry from investing in a new supersonic aircraft for fifteen years now. It’s a rare example of commercial technology going “backwards”; the latest and greatest airliners built today can’t achieve even half the Concorde’s top speed of 1,354 MPH (2,179 km/h). In an era where speed and performance is an obsession, commercial air travel simply hasn’t kept up with the pace of the world around it. There’s a fortune to be made for anyone who can figure out a way to offer supersonic flight for passengers and cargo without falling into the same traps that ended the Concorde program.

With the announcement that they’ve completed the initial design of their new Affinity engine, General Electric is looking to answer that call. Combining GE’s experience developing high performance fighter jet engines with the latest efficiency improvements from their civilian engines, Affinity is the first new supersonic engine designed for the civil aviation market in fifty five years. It’s not slated to fly before 2023, and likely won’t see commercial use for a few years after that, but this is an important first step in getting air travel to catch up with the rest of our modern lives.

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Out Of Batteries For Your Torch? Just Use A Mini Nitro Engine

We can certainly relate to an incomplete project sowing the seed for a better one, and that’s just what happened in [JohnnyQ90]’s latest video. He initially set out to create an air compressor powered by a nitro engine, and partially succeeded – air was compressed, but not nearly enough to be useful.

Instead, he changed tack and decided to use the 1 cc engine to make a small electric generator. [JohnnyQ90] is, of course, no stranger to the nitro engine, having previously brought us the micro chainsaw conversion, and nitro powered rotary tool. This time round, the build is a conceptually simple task: connect an engine to a DC motor and you’re done. But physically implementing it in an elegant way is a different story, and this is always where [JohnnyQ90] shines; we never get tired of watching him produce precision parts on the lathe. A fuel tank is made from a modified Zippo can and, courtesy of a CNC milled fan and 3D printed shroud, the motor air cools itself.

Towards the end of the video, [JohnnyQ90] plays with the throttle a little, causing the bulb connected to the generator to brighten accordingly. It might be fun to control the throttle with a servo and try to regulate the voltage on the output under different load conditions.

We love novel ways of creating electricity; previously we’ve written about how to generate power from a coke can, as well as this 120 W thermoelectric generator (TEG) setup.

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