It Isn’t Rocket Science — Wait, Maybe It Is

We don’t know why, but for some reason, the more dangerous something is, the more hacker appeal it seems to have. We like to deal with high temperatures, high voltages, dangerous chemicals, and powerful lasers. So [Tech Ingredient’s] recent video about homemade rocket motors certainly caught our attention. You may need a little commitment, though. The first video (yes, there isn’t just one) is over an hour long.

Turns out, [Tech] doesn’t actually want to use the rockets for propulsion. He needed a source of highly-ionized high-velocity plasma to try to get more power from his magnetohydrodynamic project. Whatever you want to use it for, these are serious-sized motors. [Tech] claims that his design is both powerful and easy to build. He also has a “secret” rocket fuel that he shares. What is it? We won’t spoil the video for you, but it is a sweet surprise.

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SpaceX Starship Replica Attempts The Bellyflop

SpaceX are perhaps most well known for their vertically-landing reusable rocket technology. The latest such effort is the Starship, which recently underwent a fiery test in the last month to attempt a bellyflop maneuver. [Nicholas Rehm] wanted to attempt a similar flight profile in the local park, and set to building an RC Starship of his own.

The build is like a few we’ve seen before, in which electric power is used to propel a rocket-like craft straight upwards using propellers and active stabilization. In this case, there’s a pair of twin motors with counter-rotating propellers which can pivot to direct their thrust, as well as four external control surfaces. These are all under the command of [Nicholas]’s custom flight controller.

Upon testing the rig, [Nicholas] was able to execute a smooth ascent, followed by a bellyflop, before a smooth return to vertical flight and descent. Landing vertically on the grass was out of the question, due to the rough surface, but we imagine it would be doable with the right landing gear attached.

While flight without wings in this manner isn’t particularly efficient, it’s great to see what can be achieved with smart use of control systems engineering to keep a craft stable. We look forward to seeing [Nicholas]’s next attempts, too. Video after the break.

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SLA 3D Printed Vortex Cooled Rocket Engine

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.

Robust Water-Rocket Launcher Gets The Engineering Just Right

Normally when we run across a project that claims to be overengineered, we admit that we get a little excited. Such projects always hold the potential for entertainingly over-the-top designs, materials, and methods. In this case, though, we’ll respectfully disagree with [Zach Hipps] assessment of his remote-controlled soda bottle rocket launcher as “overengineered”. To us, it seems just right.

That’s not to take away from anything accomplished with this build. Indeed, we’re mighty impressed by the completeness of the build, which was intended to create a station for charging and launching air-powered water rockets. The process started with a prototype, built mainly from 3D-printed parts but with a fair selection of workshop scraps to hold it together. This allowed [Zach] to test the geometry of the parts, operation of the mechanism, and how it interfaced with the flange on the necks of 2-liter soda bottles.

Honestly, the prototype was pretty good by itself and is probably where many of us would have stopped, but [Zach] kept going. He turned most of the printed parts into machined aluminum and Delrin, making for a very robust pneumatically operated stand. We’ve got to say the force with which the jaws close around the bottle flange is a bit scary — looks like it could easily clip off a wayward finger. But if he manages to avoid that fate, such a hearty rig should keep [Zach] flying for a long time. Perhaps it could even launch a two-stage water rocket?

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Rocket Plane Build Aims For High Speed Flight

[James Whomsley] likes flying, and likes flying fast. After reaching a speed of 114 miles an hour with an RC plane, he wanted to go further and break that record. To do so, he looked towards rocket power, and started a new build.

The design consists of a combination of 3D printed parts, laser-cut plywood bulkheads, and foamboard flight surfaces, with a few carbon fiber stiffeners thrown in here and there. For this early prototype, power is solely from hobby rocket motors, providing thrust for 1.6 seconds, meaning flight times are necessarily short. The craft is launched from an aluminium profile rail thanks to a 3D printed sliding guide pin.

Initial tests with two rocket motors were promising, leading to a second trial with a full six motors fitted. The thrust line was a little low, however, and a major pitch-up just after launch meant the plane only reached around 62 miles an hour. [James] still has a ways to go to beat his previous record, so intends to explore adding ducted fan propulsion to get the plane in the air before using the rockets as a speed booster in steady flight.

Of course, if you can’t lay your hands on rocket engines, you could always consider spinning up your own. (Or ditch the engine entirely.) Video after the break.

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Blow Dryers And Metal Shears: Hacks Of Early Falcon 9 Flights

Orbiting over our heads right now are two human beings who flew to the International Space Station in a SpaceX Crew Dragon vehicle on top of a Falcon 9. The majority of coverage focused on the years since human spaceflight last launched from Florida, but [Eric Berger] at Ars Technica reminds us it also makes for a grand ten-year celebration of the SpaceX workhorse rocket by sharing some stories from its early days.

Falcon 9 is a huge presence in the global space launch industry today, but ten years ago the future of a young aerospace company was far from certain. The recent uneventful launch is the result of many lessons learned in those ad-hoc days. Some early Falcon 9 flights were successful because the team decided some very unconventional hacks were worth the risk that paid off. A bit of water intrusion? Dry it out with a blow dryer and seal it back up. Small tear in a rocket nozzle? Send in someone to trim a few inches with shears (while the rocket was standing vertical on the launchpad).

Industry veterans appalled at “a cowboy attitude” pounced on every SpaceX failure with “I told you so.” But the disregard for convention is intentional, documented in many places like this old Wired piece from 2012. Existing enshrined aerospace conventions meant the “how” was preserved but the “why” was reduced to “we’ve always done it this way” rarely re-evaluated in light of advancements. Plus the risk-averse industry preferred staying with flight-proven designs, setting up a Catch-22 blocking innovation. SpaceX decided to go a different way, rapidly evolving the Falcon 9 and launching at a high cadence. Learning from all the failures along the way gave them their own set of “why” to back up their “how” growing far beyond blow dryers and metal shears. We’re happy to see the fail-learn-improve cycle at the heart of so many hacker projects have proven effective to send two astronauts to the space station and likely beyond.

[Photo: SpaceX Crew Demo-2 on the launch pad]

Hackaday Links: April 19, 2020

While the COVID-19 pandemic at least seems to be on a downward track, the dystopian aspects of the response to the disease appear to be on the rise. As if there weren’t enough busybodies and bluenoses shaming their neighbors for real or imagined quarantine violations on social media, now we have the rise of social-distancing enforcement drones. These have been in use in hot zones around the world, of course, but have only recently arrived in the US. From New Jersey to Florida, drones are buzzing about in search of people not cowering in fear in their homes and blaring messages about how they face fines and arrest for seeking a little fresh air and sunshine. We’re all in favor of minimizing contact with potentially infected people, but it seems like these methods might be taking things a bit too far.

If you somehow find yourself with some spare time and want to increase your knowledge, or at least expand your virtual library, Springer Publishing has some exciting news for you. The journal and textbook publisher has made over 400 ebook titles available for free download. We had a quick scan over the list, and while the books run the gamut from social sciences to astrophysics, there are plenty of titles that are right in the wheelhouse of most Hackaday readers. There are books on power electronics, semiconductor physics, and artificial intelligence, as well as tons more. They all seem to be recent titles, so the information isn’t likely to be too dated. Give the list a once-over and happy downloading.

Out of all the people on this planet, the three with the least chance of being infected with SARS-CoV-2 blasted off from Kazakhstan this week on Soyuz MS-16 to meet up with the ISS. The long-quarantined crew of Anatoly Ivanishin, Ivan Vagner, and Chris Cassidy swapped places with the Expedition 62 crew, who returned to Earth safely in the Soyuz MS-15 vehicle. It’s a strange new world they return to, and we wish them and their ISS colleagues all the best. What struck us most about this mission, though, was some apparently surreptitiously obtained footage of the launch from a remarkably dangerous position. We saw some analysis of the footage, and based on the sound delay the camera was perhaps as close as 150 meters to the launchpad. It’s hard to say if the astronauts or the camera operator was braver.

And finally, because neatness counts, we got this great tip on making your breadboard jumpers perfectly straight. There’s something satisfying about breadboard circuits where the jumpers are straight and exactly the length the need to be, and John Martin’s method is so simple you can’t help but use it. He just rolls the stripped jumpers between his bench and something flat; he uses a Post-it note pad but just about anything will do. The result is satisfyingly straight jumpers, ready to be bent and inserted. We bet this method could be modified to work with the stiffer wire normally used in circuit sculptures like those of Mohit Bhoite; he went into some depth about his methods during his Supercon talk last year, and it’s worth watching if you haven’t seen it yet.