A group of students at Boston University recently made a successful test of a powerful rocket engine intended for 100km suborbital flights. Known as the Iron Lotus (although made out of mild steel rather than iron), this test allowed them to perfect the timing and perfect their engine design (also posted to Reddit) which they hope will eventually make them the first collegiate group to send a rocket to space.
Unlike solid rocket fuel designs, this engine is powered by liquid fuel which comes with a ton of challenges to overcome. It is a pressure-fed engine design which involves a pressurized unreactive gas forcing the propellants, in this case isopropanol and N2O, into the combustion chamber. The team used this design to produce 2,553 lb*ft of thrust during this test, which seems to be enough to make this a class P rocket motor. For scale, the highest class in use by amateurs is class S. Their test used mild steel rather than stainless to keep the costs down, but they plan to use a more durable material in the final product.
The Boston University Rocket Propulsion Group is an interesting student organization to keep an eye on. By any stretch of the imagination they are well on their way to getting their rocket design to fly into space. Be sure to check out their other projects as well, and if you’re into amateur rocketry in general there are a lot of interesting things you can do even with class A motors.
Continue reading “Student-Built Rocket Engine Packs A Punch”
Copenhagen Suborbitals just launched their latest amateur liquid fuel rocket. Why? Because they want to strap someone to a bigger amateur liquid fuel rocket and launch them into space.
We’ve covered them before, but it’s been a while. While they make a big deal of being amateurs, they are the least amateurish amateurs we’ve come across. We’ll forgive a lot as long as they keep making great videos about their projects. Or posting great pictures of the internals of their rockets.
The Nexø I rocket they recently launched claims to be the first guided, amateur, liquid-fueled rocket. There is a nice post on the guidance system. It was launched from a custom built barge off the shore of Denmark, which allows them to escape quite a few legal hurdles around the launch. The rocket flew beautifully. That is, it went only away from the ground; no other directions. Also, it didn’t explode, which is a lot to expect from even the biggest players in the field.
Copenhagen Suborbitals continues to do amazing work. Hopefully their next rocket will be even more impressive… for amateurs, that is.
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”
Robert’s Rocket Project has been going on for a long time. It has been around so long that you can go all the way back to posts from 2001, where he talks about getting his first digital camera! The site is dedicated to his pursuit of liquid fueled rocket engine building. It’s a great project log and he has finally come to the point where he will be testing his first flight vehicle soon.
His latest project is a 250lbf regeneratively cooled engine. It uses kerosene as the fuel, and liquid oxygen as the oxidizer. The neat thing is he utilizes the temperature change of the liquid oxygen expanding to cool the chamber and nozzle before being burned. This allows for a very efficient and powerful combustion of the fuel. He has some videos of testing it on his site, we just wonder why he doesn’t host them on YouTube or something…
Anyhow, there’s more than enough info on his site to try and recreate some of his experiments, but perhaps you should start here instead: How to Design, Build and Test Small Liquid-Fuel Rocket Engines.
[Graham] over at FUBAR labs took it upon himself to build a rocket engine. This isn’t a simple solid-fuel motor, though: [Graham] went all out and built a liquid-fueled engine that is ignited with a spark plug.
The build started off with a very small ‘igniter’ engine meant to shoot sparks into a larger engine. This engine is fueled with ethanol and air – not the best fuel for a rocket engine by a long shot but save and cheap enough to do a few serious experiments with.
To test out this small engine, [Graham] made a test platform out of aluminum extrusion to remotely control the fuel and oxidizer valves. The valves are controlled by an Arduino and XBee for remote operation and a telemetry downlink for measuring the fluid flow into the engine.
After he had some experience with pressure, plumbing, valves, and engines, [Graham] upgraded his fuel and oxidizer to gaseous oxygen and ethanol. With proper safety protocol in place, [Graham] was able to a series of three 3-second burns less than a minute apart as well as a single burn lasting nearly 5 seconds.
Even though [Graham] eschewed the usual stainless steel construction of rocket engines (his engine is milled out of aluminum), he demonstrated it is possible to build a real liquid-fueled rocket engine at home.
Most any rocket engine you’d find on a spacecraft – save for solid or hybrid rockets – use an engine system that’s fairly complex. Because of the intense heat, the fuel is circulated around the chamber before ignition giving a motor its regeneratively cooled nomenclature. This arrangement leads to a few complicated welding and machining processes, but surprisingly these obstacles can be overcome by simply printing a rocket engine on a 3D printer.
The current engine is quite small, but still fueled just like any other proper rocket engine that makes it into Earth orbit. The fuel is propane, the oxidizer is NO2, and the entire device is ignited with an automotive spark plug. Of course this was an expensive proposition; a motor with 12 pounds of thrust cost somewhere in the range of four figures.
Printing a rocket engine has a few advantages over traditional manufacturing techniques. [Rocket Moonlighting] explains that traditional techniques (mills, lathes and other heavy equipment) are bound by labor, material, and time. The costs of printing a rocket engine are only bound by the volume of the finished piece, meaning the most expensive engine per unit of thrust is the one that will fit in your pocket; scaling up means more efficiency for less cost.
There are a few videos up after the break showing the engine in action at full throttle, a few start and restart tests, and a test that involved throttling the engine. It’s an extremely impressive piece of kit, and hopefully [Rocket Moonlighting] will release the CAD source so we can make our own.
EDIT: [RM] tells me his engine cost less than $2000 to make. If just 10 people wanted their own engine from a ‘group buy,’ the price would drop by more than half. If you’d like your own 3D printed rocket engine, you might do well to drop [Rocket Moonlighting] a line.
Continue reading “3D Printing A Rocket Engine”
While we’re reluctant to say it for fear of being misinterpreted, the new liquid fuel rocket engine being built by Copenhagen Suborbitals is one of the most impressive, daring, and nearly the sexiest machine we’ve ever seen. Although the engine hasn’t been fired yet, [Peter Madsen], Chief launch vehicle designer at Copenhagen Suborbitals, gives an amazing 18-minute-long rundown of the function of each and every tank and tube of the TM65 in this video.
When the TM65 engine begins its firing sequence, valves attached to tanks of alcohol and liquid Oxygen are opened. The Oxygen pours directly into an injector manifold that atomizes the liquid in the combustion chamber, while the alcohol makes a much longer trip down to the engine bell, flowing between the double wall of the chamber and nozzle for cooling. Once the alcohol and Oxygen in the combustion chamber ignite, two gigantic tanks of Helium are opened and the gas is forced down to a heat exchanger at the end of the nozzle, increasing the temperature and pressure of the Helium. The Helium is then routed to the tanks, pressurizing them and forcing fuel and oxidizer into the combustion chamber at 40 liters per second. This entire process happens in only eight seconds; after that, the rocket attached to the TM65 will be on its way upward.
We’re not going to say the TM65 is the best engine ever seen on Hackaday; we’ll leave you to decide that. We can’t wait for the video of the test fire to hit the Internet, though.