[Joe Barnard] made a solid propellant rocket motor, and as one does in such situations, he put it through its paces on the test stand. The video below is not about the test, nor is it about the motor’s construction. Rather, it’s a deconstruction of the remains of the motor in order to better understand its design, and it’s pretty interesting stuff.
Somewhere along the way, [Joe], aka “BPS.Space” on YouTube, transitioned from enthusiastic model rocketeer to full-fledged missile-man, and in the process stepped up his motor game considerably. The motor that goes under the knife — or rather, the bandsaw — in this video is his “Simplex V2,” a completely DIY build of [Joe]’s design. For scale, the casing is made from a 6″ (15 cm) diameter piece of aluminum tubing over a meter in length, with a machined aluminum forward closure and a composite nozzle assembly. This is a pretty serious piece of engineering.
The closure and the nozzle are the focus of the video, which makes sense since that’s where most of the action takes place. To understand what happened during the test, [Joe] lopped them off and cut them roughly in half longitudinally. The nozzle throat, which was machined from a slug of graphite, fared remarkably well during the test, accumulating only a little slag from the propellant, a combination of powdered aluminum, ammonium perchlorate, and HTBP resin. The lower part of the nozzle, made from phenolic-impregnated linen, did pretty well too, building up a pyrolyzed layer that acted much like a space capsule’s ablative heat shield would. The forward closure, whose sole job is to contain the inferno and direct the exhaust anywhere but up, took more of a beating but stood up to the challenge. Especially interesting was the state of the O-rings and the way that the igniter interfaced with the closure.
Post mortems like these are valuable teaching tools, and while it must be heartbreaking to destroy something you put so much work into, you can’t improve what you can’t measure. Hats off to [Joe] for the peek inside his world. Continue reading “A Look Inside A DIY Rocket Motor”→
Model rocketry has always taken cues from what’s happening in the world of full-scale rockets, with amateur rocketeers doing their best to incorporate the technologies and methods into their creations. That’s not always an easy proposition, though, as this three-year effort to nail a SpaceX-style vertical landing aptly shows.
First of all, hats off to high schooler [Aryan Kapoor] from JRD Propulsion for his tenacity with this project. He started in 2021 with none of the basic skills needed to pull off something like this, but it seems like he quickly learned the ropes. His development program was comprehensive, with static test vehicles, a low-altitude hopper, and extensive testing of the key technology: thrust-vector control. His rocket uses two solid-propellant motors stacked on top of each other, one for ascent and one for descent and landing. They both live in a 3D printed gimbal mount with two servos that give the stack plus and minus seven degrees of thrust vectoring in two dimensions, which is controlled by a custom flight computer with a barometric altimeter and an inertial measurement unit. The landing gear is also clever, using rubber bands to absorb landing forces and syringes as dampers.
The video below shows the first successful test flight and landing. Being a low-altitude flight, everything happens very quickly, which probably made programming a challenge. It looked like the landing engine wasn’t going to fire as the rocket came down significantly off-plumb, but when it finally did light up the rocket straightened and nailed the landing. [Aryan] explains the major bump after the first touchdown as caused by the ascent engine failing to eject; the landing gear and the flight controller handled the extra landing mass with aplomb.
All in all, very nice work from [Aryan], and we’re keen to see this one progress.
Reaching orbit around Earth is an incredibly difficult feat. It’s a common misconception that getting into orbit just involves getting very high above the ground — the real trick is going sideways very, very fast. Thus far, the most viable way we’ve found to do this is with big, complicated multi-stage rockets that shed bits of themselves as they roar out of the atmosphere.
Single-stage-to-orbit (SSTO) launch vehicles represent a revolutionary step in space travel. They promise a simpler, more cost-effective way to reach orbit compared to traditional multi-stage rockets. Today, we’ll explore the incredible potential offered by SSTO vehicles, and why building a practical example is all but impossible with our current technology.
A Balancing Act
The SSTO concept doesn’t describe any one single spacecraft design. Instead, it refers to any spacecraft that’s capable of achieving orbit using a single, unified propulsion system and without jettisoning any part of the vehicle.
The Saturn V shed multiple stages on its way up to orbit. That way, less fuel was needed to propel the final stage up to orbital velocity. Credit: NASA
Today’s orbital rockets shed stages as they expend fuel. There’s one major reason for this, and it’s referred to as the tyranny of the rocket equation. Fundamentally, a spacecraft needs to reach a certain velocity to attain orbit. Reaching that velocity from zero — i.e. when the rocket is sitting on the launchpad — requires a change in velocity, or delta-V. The rocket equation can be used to figure out how much fuel is required for a certain delta-V, and thus a desired orbit.
The problem is that the mass of fuel required scales exponentially with delta-V. If you want to go faster, you need more fuel. But then you need even more fuel again to carry the weight of that fuel, and so on. Plus, all that fuel needs a tank and structure to hold it, which makes things more difficult again.
Work out the maths of a potential SSTO design, and the required fuel to reach orbit ends up taking up almost all of the launch vehicle’s weight. There’s precious mass left over for the vehicle’s own structure, let alone any useful payload. This all comes down to the “mass fraction” of the rocket. A SSTO powered by even our most efficient chemical rocket engines would require that the vast majority of its mass be dedicated to propellants, with its structure and payload being tiny in comparison. Much of that is due to Earth’s nature. Our planet has a strong gravitational pull, and the minimum orbital velocity is quite high at about 7.4 kilometers per second or so.
Stage Fright
Historically, we’ve cheated the rocket equation through smart engineering. The trick with staged rockets is simple. They shed structure as the fuel burns away. There’s no need to keep hauling empty fuel tanks into orbit. By dropping empty tanks during flight, the remaining fuel on the rocket has to accelerate a smaller mass, and thus less fuel is required to get the final rocket and payload into its intended orbit.
The Space Shuttle sheds its boosters and external fuel tank on its way up to orbit, too. Credit: NASA
So far, staged rockets have been the only way for humanity to reach orbit. Saturn V had five stages, more modern rockets tend to have two or three. Even the Space Shuttle was a staged design: it shed its two booster rockets when they were empty, and did the same with its external liquid fuel tank.
But while staged launch vehicles can get the job done, it’s a wasteful way to fly. Imagine if every commercial flight required you to throw away three quarters of the airplane. While we’re learning to reuse discarded parts of orbital rockets, it’s still a difficult and costly exercise.
The core benefit of a SSTO launch vehicle would be its efficiency. By eliminating the need to discard stages during ascent, SSTO vehicles would reduce launch costs, streamline operations, and potentially increase the frequency of space missions.
Pushing the Envelope
It’s currently believed that building a SSTO vehicle using conventional chemical rocket technology is marginally possible. You’d need efficient rocket engines burning the right fuel, and a light rocket with almost no payload, but theoretically it could be done.
Ideally, though, you’d want a single-stage launch vehicle that could actually reach orbit with some useful payload. Be that a satellite, human astronauts, or some kind of science package. To date there have been several projects and proposals for SSTO launch vehicles, none of which have succeeded so far.
Lockheed explored a spaceplane concept called VentureStar, but it never came to fruition. Credit: NASA
One notable design was the proposed Skylon spacecraft from British company Reaction Engines Limited. Skylon was intended to operate as a reusable spaceplane fueled by hydrogen. It would take off from a runway, using wings to generate lift to help it to ascend to 85,000 feet. This improves fuel efficiency versus just pointing the launch vehicle straight up and fighting gravity with pure thrust alone. Plus, it would burn oxygen from the atmosphere on its way to that altitude, negating the need to carry heavy supplies of oxygen onboard.
Once at the appropriate altitude, it would switch to internal liquid oxygen tanks for the final acceleration phase up to orbital velocity. The design stretches back decades, to the earlier British HOTOL spaceplane project. Work continues on the proposed SABRE engine (Syngergetic Air-Breathing Rocket Engine) that would theoretically propel Skylon, though no concrete plans to build the spaceplane itself exist.
The hope was that efficient aerospike rocket engines would let the VentureStar reach orbit in a single stage.
Lockheed Martin also had the VentureStar spaceplane concept, which used an innovative “aerospike” rocket engine that maintained excellent efficiency across a wide altitude range. The company even built a scaled-down test craft called the X-33 to explore the ideas behind it. However, the program saw its funding slashed in the early 2000s, and development was halted.
McDonnell Douglas also had a crack at the idea in the early 1990s. The DC-X, also known as the Delta Clipper, was a prototype vertical takeoff and landing vehicle. At just 12 meters high and 4.1 meters in diameter, it was a one-third scale prototype for exploring SSTO-related technologies
It would take off vertically like a traditional rocket, and return to Earth nose-first before landing on its tail. The hope was that the combination of single-stage operation and this mission profile would provide extremely quick turnaround times for repeat launches, which was seen as a boon for potential military applications. While its technologies showed some promise, the project was eventually discontinued when a test vehicle caught fire after NASA took over the project.
McDonnell Douglas explored SSTO technologies with the Delta Clipper. Credit: Public domain
Ultimately, a viable SSTO launch vehicle that can carry a payload will likely be very different from the rockets we use today. Relying on wings to generate lift could help save fuel, and relying on air in the atmosphere would slash the weight of oxidizer that would have to be carried onboard.
However, it’s not as simple as just penning a spaceplane with an air-breathing engine and calling it done. No air breathing engine that exists can reach orbital velocity, so such a craft would need an additional rocket engine too, adding weight. Plus, it’s worth noting a reusable launch vehicle would also still require plenty of heat shielding to survive reentry. One could potentially build a non-reusable single-stage to orbit vehicle that simply stays in space, of course, but that would negate many of the tantalizing benefits of the whole concept.
Single-stage-to-orbit vehicles hold the promise of transforming how we access space by simplifying the architecture of launch vehicles and potentially reducing costs. While there are formidable technical hurdles to overcome, the ongoing advances in aerospace technology provide hope that SSTO could become a practical reality in the future. As technology marches forward in materials, rocketry, and aerospace engineering in general, the dream of a single-stage path to orbit remains a tantalizing future goal.
What’s the most thrilling part of rocketry? Well, the liftoff, naturally. But what about the sweet anticipation in those tense moments leading up to liftoff? In other words, the countdown. Where did it come from?
Far from being simply a dramatic device, the countdown clock serves a definite purpose — it lets the technicians and the astronauts synchronize their actions during the launch sequence. But where did the countdown — those famed ten seconds of here we go! that seem to mark the point of no return — come from? Doesn’t it all seem a little theatrical for scientists?
It may surprise you to learn that neither technicians nor astronauts conceived of the countdown. In their book, “Lunar Landings and Rocket Fever: Rediscovering Woman in the Moon”, media scholars Tom Gunning and Katharina Loew reveal that a little-known Fritz Lang movie called Woman In the Moon both “predicted the future of rocketry” and “played an effective role in its early development”.
We’re still in the early days of generatively-designed objects, but when combined with the capabilities of 3D printing, we’re already seeing some interesting results. One example is this new copper aerospike engine. [via Fabbaloo]
A collaboration between startups Hyperganic (generative AI CAD) and AMCM (additive manufacturing), this 800 mm long aerospike engine may be the most complicated 3D print yet. It continues the exciting work being done with 3D printing for aerospace applications. The complicated geometries of rocket nozzles of any type let additive manufacturing really shine, so the combination of generative algorithms and 3D printed nozzles could result in some big leaps in coming years.
Aerospikes are interesting as their geometry isn’t pressure dependent like more typical bell-shaped rocket nozzles meaning you only need one engine for your entire flight profile instead of the traditional switching mid-flight. A linear aerospike engine was one of the main selling points for the cancelled VentureStar Space Shuttle replacement.
This isn’t the only generative design headed to space, and we’ve covered a few projects if you’re interested in building your own 3D printed rocket nozzles or aerospike engines. Just make sure you get clearance from your local aviation regulator before your project goes to space!
Hackaday has been around long enough to see incredible changes in what’s possible at the hobbyist level. The tools, techniques, and materials available today border on science-fiction compared to what the average individual had access to even just a decade ago. On a day to day basis, that’s manifested itself as increasingly elaborate electronic projects that in many cases bear little resemblance to the cobbled together gadgets which graced these pages in the early 2000s.
Kip Daugirdas
But these gains aren’t limited to our normal niche — hobbyists of all walks have been pushing their respective envelopes. Take for example the successful launch of MESOS, a homebuilt reusable multi-stage rocket, to the very edge of the Kármán line. It was designed and built by amateur rocket enthusiast Kip Daugirdas over the course of several years, and if all goes to plan, will take flight once again this summer with improved hardware that just might help it cross the internationally recognized 100 kilometer boundary that marks the edge of space.
We were fortunate enough to have Kip stop by the Hack Chat this week to talk all things rocketry, and the result was a predictably lively conversation. Many in our community have a fascination with spaceflight, and even though MESOS might not technically have made it that far yet (there’s some debate depending on who’s definition you want to use), it’s certainly close enough to get our imaginations running wild.
Started by graduate students from the California Institute of Technology in the late 1930s, the Jet Propulsion Laboratory (JPL) was instrumental in the development of early rocket technology in the United States. After being tasked by the Army to analyze the German V2 in 1943, the JPL team expanded from focusing purely on propulsion systems to study and improve upon the myriad of technologies required for spaceflight. Officially part of NASA since December of 1958, JPL’s cutting edge research continues to be integral to the human and robotic exploration of space.
For longtime friend of Hackaday Ara “Arko” Kourchians, getting a job JPL as a Robotics Electrical Engineer was a dream come true. Which probably explains why he applied more than a dozen times before finally getting the call to join the team. He stopped by the Hack Chat back in August of 2019 to talk about what it’s like to be part of such an iconic organization, reminisce about some of his favorite projects, and reflect on the lessons he’s learned along the way.
