3D printing a rocket engine

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.

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How to convert an internal combustion engine to run from steam power

We had no idea that what’s needed to convert an internal combustion engine to steam power is actually rather trivial. [David Nash] shows us how it’s done by performing the alterations on the engine of a string trimmer. These are the tools used to cut down vegetation around obstacles in your yard. The source of the engine doesn’t really matter as long as it’s a 2-cycle motor.

This engine had one spark plug which is threaded into the top of the block. [David] removed this and attached his replacement hardware. For now he’s using compressed air for development, but will connected the final version to a boiler.

There are only a couple of important parts between the engine and the boiler. There’s an in-line oil reservoir to help combat the corrosive nature of the steam. There is also a check valve. In the video after the break [David] shows the hunk of a ball-point pen that he uses to actuate the check valve. It’s really just a spacer that the piston pushes up to open the valve. This will be replaced with a metal rod in the final version.

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Firing rocket engines in the wrong direction — this is only a test

LVL1 has a new rocketeering group. This rocket engine testing platform is the first project to come out of the fledgling club. The purpose of the tool is to gather empirical data from model rocket engines. Having reliable numbers on thrust over time will allow the team to get their designs right before the physical build even starts.

The rig uses a pine base, with a PVC frame, threaded bolts, and a PVC cuff for mounting the engine in place. It is set to fire up in the air, directing the thrust down onto a scale. The flex sensor in the scale is monitored by an Arduino, and should be able to hold up to the 5000 pounds grams of thrust max which this type of engines can put out. The data is pushed via USB to a laptop computer where it is stored in a spreadsheet.

Calibration would be an issue here. But as long as they’re always using the same strain sensor the numbers will be accurate enough relative to each other.

LVL1 has a rocketeers group, is not working on ICBMs.

We’re very familiar with the Louisville Hackerspace LVL1 here at Hackaday. From their GLaDOS-inspired sentient overlord, an evil box to filter the Internet, and a friggin’ moat, LVL1 is the closest we’ve got to a mad scientist heard cackling from a wind-swept castle on a stormy night. It turns out they also have a rocketry program. Now we’re just waiting for confirmation of their subterranean complex of missile silos.

The rocketery-oriented part of LVL1 spawned from a University of Louisville’s group. The goal of the group is to compete in the NASA University Student Launch Initiative, dedicated to competing against other teams to launch a scientific payload to 1 mile AGL. At the competition last May, the team placed 5th out of 42 teams and won the award for best website. We can’t wait to see what they come up with next year.

Even though the team is out of school for the summer, they’re still cooking up a few rocketry hacks. They’ve built a test stand to measure the thrust of off-the-shelf motors, kitbashed a few Estes Baby Berthas (very awesome and very easy if you have a laser cutter), and are starting a pulse jet project.

We’re assuming the LVL1 Rocketeers group is just a front for their yet to be unveiled moon-based “laser” project, but you can check out a few videos from the ULSI competition after the break.

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Test firing the largest amateur-built liquid fuel rocket engine

Last April, we caught wind of a very impressive rocket engine being built by Copenhagen Suborbitals. That engine was on the test pad this weekend, and the video is incredible (skip to 20:30 for the actual test). The Copenhagen Suborbitals team pulled off a successful test firing of their 65 kilo Newton alcohol and liquid Oxygen-fueled rocket.

When last we saw the TM65 engine, it was sitting on the design floor of the Copenhagen Suborbitals workspace. The plan was to fire the engine using alcohol fuel and LOX pressurized by Helium, but that plan was changed to use Nitrogen as the pressurant. The static test was an immensely successful demonstration of the engine, but unfortunately the chamber pressure (and therefore thrust) was a little low meaning the team will be moving back to Helium for the next test.

Thanks to the very successful test of the TM65, Copenhagen Suborbitals may be launching their HEAT booster later this year possibly carrying their new space capsule. Even if it’s only a crash test dummy that will make the ride into space, we can’t wait for the video of the flight.

Check out a few more (abridged) videos of the TM65 test firing after the break.

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Melting beer cans and building engines

What do you do if you’ve got a fully equipped machine shop and you’re tired of taking old beer cans to the recycler? If you’re like [Brock], you’ll probably end up melting those cans down to build an engine.

After gathering 50 pounds of beer cans and melting them down into ingots of various sizes, [Brock] and company had a lot of aluminum and nothing to build. Eventually, someone got the idea to build an internal combustion engine out of these beer can ingots.

So far, the beer can engine crew has built two engines from these beer can ingots. The four-stroke engine started off as a 5-inch aluminum cube, bored and milled into something resembling an engine block. When [Brock] and the beer can engine team completed their four-stroke masterpiece, they had a water-cooled engine displacing 150cc with a single 2″ bore piston. The two-stroke engine is a much simpler affair with a 1 inch bore displacing 19cc.

Even though there’s no information at all covering the pottery kiln foundry used to melt the beer cans into ingots, it’s an amazing piece of work building and engine from the ground up.

You can check out a few videos of both engines after the break.

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Watch a rocket engine test live this afternoon

If you want to see something awesome this afternoon, watch SpaceX’s live broadcast of an engine test today at 3:00 pm EDT/12:00 pm PDT/7:00 pm GMT. You’ll see nine Merlin rocket engines power up to full thrust during a test for the upcoming launch of a Dragon space capsule to the ISS.

This is just a static test - hopefully the nine Merlin engines won’t go anywhere. To get an idea of the power behind these engines this is a test of just  Merlin engine being fired at the SpaceX open house in Texas a year or so ago. Today, nine engines will be fired at once.

Check out the videos after the break to see just how awesome the Falcon 9 is going to be.

via boingboing

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