3D printing is an incredible tool for prototyping and development, but the properties of the materials can be a limiting factor for functional parts. [Sam Rogers] and colleagues at [AX Technologies] have been testing and developing a small liquid-fueled rocket engine and successfully used vortex cooling to protect a resin 3D printed combustion chamber. (Video, embedded below.)
Vortex cooling works by injecting oxygen into the combustion chamber tangentially, just inside the nozzle of the engine, which creates a cooling, swirling vortex boundary layer along the chamber wall. The oxygen moves to the front end of the combustion chamber where it mixes with the fuel and ignites in the center. This does not protect the nozzle itself, which only lasts a few seconds before becoming unusable. However, thanks to the modular design of the test engine, only the small nozzle section had to be reprinted for every test. While this part could be manufactured using a metal 3D printer, the costs are still very high, especially at this experimental stage. The clear resin parts also allow the combustion observed and more accurate conclusions to be drawn from every test.
This engine intended to be used as a torch igniter for a much larger rocket engine. Fuel is injected into the front of the combustion chamber, where a spark plug is located to ignite the oxygen-fuel mixture. The flow of the oxygen and fuel is controlled by two servo-operated valves connected to a microcontroller, which is mounted with the engine on linear rails. This allows the test engine to move freely, and push against a load cell to measure thrust. The spark is created before the valves are opened to prevent a delayed ignition, which can blow up the engine, and getting the valve sequence and timing correct is critical. Many iterations and destroyed parts later, the [AX Technologies] team achieved successful ignition, with a clear supersonic Mach diamond pattern in the exhaust.
This is just one more example of 3D printing and cheap electronics allowing impressive progress on a limited budget. Another example is [Joe Barnard]’s progress in getting a model rocket to land itself with a solid fuel engine. Companies and organisations have been using 3D printed components in rocket engines for a few years now, and we’ve even seen an open source version.
On January 21st, 2018 at 1:43 GMT, Rocket Lab’s Electron rocket lifted off from New Zealand’s Mahia Peninsula. Roughly eight minutes later ground control received confirmation that the vehicle entered into a good orbit, followed shortly by the successful deployment of the payload. On only their second attempt, Rocket Lab had become the latest private company to put a payload into orbit. An impressive accomplishment, but even more so when you realize that the Electron is like no other rocket that’s ever flown before.
Not that you could tell from the outside. If anything, the external appearance of the Electron might be called boring. Perhaps even derivative, if you’re feeling less generous. It has the same fin-less blunted cylinder shape of most modern rockets, a wholly sensible (if visually unexciting) design. The vehicle’s nine first stage engines would have been noteworthy 15 years ago, but today only serve to draw comparisons with SpaceX’s wildly successful Falcon 9.
But while the Electron’s outward appearance is about as unassuming as they come, under that jet-black outer skin is some of the most revolutionary rocket technology seen since the V-2 first proved practical liquid fueled rockets were possible. As impressive as its been watching SpaceX teach a rocket to fly backwards and land on its tail, their core technology is still largely the same as what took humanity to the Moon in the 1960’s.
Vehicles that fundimentally change the established rules of spaceflight are, as you might expect, fairly rare. They often have a tendency to go up in a ball of flames; figuratively if not always literally. Now that the Electron has reached space and delivered its first payload, there’s no longer a question if the technology is viable or not. But whether anyone but Rocket Lab will embrace all the changes introduced with Electron may end up getting decided by the free market.
Continue reading “Smaller And Smarter: The Electron Rocket Takes Flight”
A liquid-fuel rocket engine is just about the hardest thing anyone could ever build. There are considerations for thermodynamics, machining, electronics, material science, and software just to have something that won’t blow up on the test rig. The data to build a liquid engine isn’t easy to find, either: a lot of helpful info is classified or locked up in one of [Elon]’s file cabinets.
[Graham] over at Fubar Labs in New Jersey is working to change this. He’s developing an open source, 3D printed, liquid fuel rocket engine. Right now, it’s not going to fly, but that’s not the point: the first step towards developing a successful rocket is to develop a successful engine, and [Graham] is hard at work making this a reality.
This engine, powered by gaseous oxygen and ethanol, is designed for 3D printing. It’s actually a great use of the technology; SpaceX and NASA have produced 3D printed engine parts using DMLS printers, but [Graham] is using the much cheaper (and available at Shapeways) metal SLS printers to produce his engine. Rocket engines are extremely hard to manufacture with traditional methods, making 3D printing the perfect process for building a rocket engine.
So far, [Graham] has printed the engine, injector, and igniter, all for the purpose of shoving oxygen and ethanol into the combustion chamber, lighting it, and marveling at the Mach cones. You can see a video of that below, but there’s also a few incredible resources on GitHub, the Fubar Labs wiki, and a bunch of pictures and test results here.
Continue reading “Open Source, 3D Printed Rocket Engines”