3D Printed Swirl Rocket Injector Turns Up The Heat

Conceptually speaking, a liquid propellant rocket engine is actually a very simple piece of hardware. All you need to do is spray your fuel and oxidizer into the combustion chamber at the proper ratio, add a spark, and with a carefully designed nozzle you’re off to the races. Or the Moon, as the case may be. It’s just that doing it in the real-world and keeping the whole thing from exploding for long enough to do some useful work is another story entirely.

Taking the process one step at a time, [Luke Walters] has been working on a 3D printed injector that tackles the first half of the problem. After nearly a dozen different prototypes, he’s come up with a printable injector design that atomizes the fuel and combines it with pressurized air at a suitable ratio for combustion. As you can see in the video at the break, it’s certainly capable of generating some impressive fireballs.

A cloud of highly atomized alcohol from the injector.

The internal passages of the injector have been designed in such a way that fuel (91% isopropyl alcohol) and air are spinning in opposite directions when they meet. This promotes more complete mixing, which in turn leads to a more efficient burn. Originally developed in the 1930s, so-called “swirl injectors” of this type were one of the key technological advancements made by Germany’s V-2 rocket program. Some ideas never go out of style.

Since the injector only touches the fuel and air prior to ignition, it doesn’t need to be particularly heat resistant. To be on the safe side [Luke] has printed the part in PETG at 100% infill, but in reality the flame front is far enough away that temperature isn’t much of a concern. That said, he does hope to eventually fit these injectors into some kind of combustion chamber, which is where things will start getting toasty.

To be clear this is not a rocket engine, and it produces no appreciable thrust. Turning a big flame into a useful means of propulsion is where things get tricky, almost as though it’s rocket science or something. But that doesn’t mean it can’t be done by suitably ambitious hackers.

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Hackaday Links: March 1, 2020

Talk about buried treasure: archeologists in Germany have – literally – unearthed a pristine Soviet spy radio, buried for decades outside of Cologne. While searching for artifacts from a Roman empire settlement, the archeologists found a pit containing the Soviet R-394KM transceiver, built in 1987 and apparently buried shortly thereafter without ever being used. It was found close to a path in the woods and not far from several sites of interest to Cold War-era spies. Curiously, the controls on the radio are labeled not in Cyrillic characters, but in the Latin alphabet, suggesting the radio was to be used by a native German speaker. The area in which it was found is destined to be an open-cast lignite mine, which makes us think that other Cold War artifacts may have fallen victim to the gore-covered blades of Bagger 288.

Good news for Betelgeuse fans, bad news for aficionados of cataclysmic cosmic explosions: it looks like the red giant in Orion isn’t going to explode anytime soon. Betelgeuse has been dimming steadily and rapidly since October of 2019; as a variable star such behavior is expected, but the magnitude of its decline was seen by some astronomers as a sign that the star was reaching the point in its evolution where it would go supernova. Alas, Betelgeuse started to brighten again right on schedule, suggesting that the star is not quite ready to give up the ghost. We’d have loved to witness a star so bright it rivals the full moon, but given the times we live in, perhaps it’s best not to have such a harbinger of doom appear.

If you plan to be in the Seattle area as the winter turns to spring, you might want to check out the Vintage Computer Fair Pacific Northwest. We visited back during the show’s first year and had a good time, and the Living Computers: Museum + Labs, where the event is held, is not to be missed. The Museum of Flight is supposed to be excellent as well, and not far away.

Mozilla announced this week that Firefox would turn on DNS over HTTPS (DoH) by default in the United States. DoH encrypts the DNS requests that are needed to translate a domain name to an IP address, which normally travel in clear text and are therefore easily observed. Easily readable DNS transactions are also key to content blockers, which has raised the hackles of regulators and legislators over the plan, who are singing the usual “think of the children” song. That DoH would make user data collection and ad-tracking harder probably has nothing to do with their protests.

And finally, sad news from California as daredevil and amateur rocketeer “Mad” Mike Hughes has been killed in a crash of his homemade rocket. The steam-powered rocket was to be a follow-up to an earlier, mostly successful flight to about 1,900 feet (580 m), and supposed to reach about 5,000 feet (1.5 km) at apogee. But in an eerily similar repeat of the mishap that nearly killed Evel Knievel during his Snake River Canyon jump in 1974, Mike’s parachute deployed almost as soon as his rocket left the launch rails. The chute introduced considerable drag before being torn off the rocket by the exhaust plume. The rocket continued in a ballistic arc to a considerable altitude, but without a chute Mike’s fate was sealed. Search for the video at your own peril, as it’s pretty disturbing. We never appreciated Mike’s self-professed Flat Earth views, but we did like his style. We suppose, though, that such an ending was more likely than not.

A Cheap And Easy GoPro Mount For Model Rocketry

Launching model rockets is fun, but the real meat of the hobby lies in what you do next. Some choose to instrument their rockets or carry other advanced payloads. [seamster] likes to film his flights, and built a nosecone camera package to do so. 

A GoPro is the camera of choice for [seamster]’s missions, with its action cam design making it easy to fire off with a single press of a button. To mount it on the rocket, the nosecone was designed in several sections. The top and bottom pieces are 3D printed, which are matched with a clear plastic cylinder cut from a soda bottle. Inside the cylinder, the GoPro and altimeter hardware are held in place with foam blocks, cut to shape from old floor mats. The rocket’s parachute is attached to the top of the nose cone, which allows the camera to hang in the correct orientation on both the ascent and descent phases of the flight. Check out the high-flying videos created with this setup after the break.

It’s a simple design that [seamster] was able to whip up in Tinkercad in just a few hours, and one that’s easily replicable by the average maker at home. Getting your feet wet with filming your flights has never been easier – we’ve certainly come a long way from shooting on film in the 1970s.

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Liquid Methane Rocket Is Set To Soar

Solid rockets are a fun way to get started in rocketry. Brewing up a batch of rocket candy is something achievable even in the home lab, and anyone can give it a go with the right materials. Building a flight-capable liquid-fuelled rocket engine is another thing entirely, but the Purdue Space Program is up to the task.

The result of their hard work is Boomie Zoomie, a rocket which stands 15ft tall and weighs 130lbs. With peak thrust of 800 lbs, it’s got plenty of grunt to help get things off the ground. It’s fuelled by liquid methane, a first for a university-built rocket. The craft is constructed out of 6″ aluminium pipe sections, which were a best-case trade-off between weight, cost, and machinability. Special care was taken during the design process to make things modular, to both allow for future design revisions and ease of field prep. This allows different parts of the team to work independently, streamlining the process of preparing the rocket for launch.

Aiming to compete in the FAR MARS liquid rocket competition, the rocket has undergone two successful hotfires. The team estimates that the first launch should happen in the next few months. Preparations are continuing on the launch trailer and ancilliary support equipment to get things up and running. The aim is to reach a lofty altitude of 45,000 feet.

For those interested in a career in rocketry, Purdue may just be the place to be, with over 300 members in its space program. We’ve seen other top-notch collegiate rocket programs, too – such as this Boston University effort that aims to reach space. Video after the break.

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Student-Built Rocket Engine Packs A Punch

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.

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An (Almost) Free Apollo-Era Rocket

According to recent news reports, NASA’s Marshall Space Flight Center in Huntsville Alabama wants to give away a piece of history — an engineering test article of a Saturn I Block I booster. The catch? You’ll need to pay to haul it off, which will cost about $250,000. According to C|Net, the offer appears to be for museums and schools, but it’s likely that price tag would probably scare most private buyers off anyway.

On the other hand, if you are a museum, library, school, or university, you can score cheap or free NASA stuff using their GSAXcess portal. In general, you do have to pay shipping. For example, a flexible thermal blanket from the shuttle costs $37.28. A heat tile runs about $25.

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Mary Sherman Morgan, Rocket Fuel Mixologist

In the fall of 1957, it seemed as though the United States’ space program would never get off the ground. The USSR had launched Sputnik in October, and this cemented their place in history as the first nation in space. If that weren’t bad enough, they put Sputnik 2 into orbit a month later.

By Christmas, things looked even worse. The US had twice tried to launch Navy-designed Vanguard rockets, and both were spectacular failures. It was time to use their ace in the hole: the Redstone rocket, a direct descendant of the V-2s designed during WWII. The only problem was the propellant. It would never get the payload into orbit as-is.

The US Army awarded a contract to North American Aviation (NAA) to find a propellant that would do the job. But there was a catch: it was too late to make any changes to the engine’s design, so they had to work with big limitations. Oh, and the Army needed it two days before yesterday.

The Army sent a Colonel to NAA to deliver the contract, and to personally insist that they put their very best man on the job. And they did. What the Army didn’t count on was that NAA’s best man was actually a woman with no college degree.

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