We are SEDS UCSD, the undergrads that designed, tested, and launched one of the first 3D printed rocket engines. Ask us anything!

What kind of material is the 3D printed engine made out of?

Our rocket thrusters Callan and Vulcan-1 are printed through DMLS (Direct Metal Laser Sintering) in Inconel 718, which is a chromium-nickel alloy. Our first rocket engine, Tri-D, was printed in cobalt chromium.

Was this for a senior design project? Did Nasa sponser you for the cost?

These aren't senior projects. Our group was started in 2012 by a group of friends at UCSD who just really like aerospace and believed they could advance current liquid propulsion technology through 3D printing. Over the years, we've grown into a full-fledged student organization that takes in first through fourth-year undergrads; these members join in on our project teams and learn their skills from older students.

We have NASA support on the Colossus test stand, as well as the Vulcan-1 engine (which actually just returned from NASA's Marshall Space Flight Center where NASA did some post-flight analysis).

Hey, you guys are awesome, go Tritons. Couple of questions I had:

• How much did the entire Vulcan-1 project cost?
• How much do you expect to spend on Triteia?
• What's your view on the future of commercial space ventures, private satellites, affordable space travel, etc?
• Do you plan to commercialize any of your innovations?
• When will Triteia be launch ready?

We estimate that the Vulcan-1 project was about $25,000, not including the sponsored engine.

We expect to spend about $350,000 total on Triteia.

In general, we're pretty excited about these up-and-coming commercial space ventures! We're actually a chapter of a national organization, SEDS USA, which is the Students for the Exploration and Development of Space – which means that most of our members are really excited about this new movement.

We don't have plans to commercialize our projects at the moment, since our focus is on both education and research. Our Colossus test stand is the one that will come closest to commercialization. We'll be seeking clients, but those will be university teams and other student orgs, as part of our mission to drive down the cost of going to space by encouraging innovation. At the moment, we're looking at only asking these groups to fund their own travel and fuel costs.

Triteia is part of the NASA CubeQuest competition, which will select three cubesat entries to fly on its SLS in late 2018. Our current timeline has been documented in accordance with theirs – and if chosen, we will plan for that launch date.

What's the most satisfying/impressive thing you've 3-D printed simply for pleasure? No real scientific applications, just for fun?

One of our favorite things we've 3D printed is a spider that we like to bring to conferences to show the potentials of metal 3D printing!

Here's a picture of it: https://twitter.com/SEDS_UCSD/status/856935028890058752

How did you start learning about building rocket engines?

NASA mentors and lots of library time! Many of us have aerospace or chemistry classes, but most of what we've learned has been through library or online resources – and now, from graduating SEDS members and alumni.

We've been lucky enough to have some NASA mentors who have stuck with us through the years and encouraged our growth. Particularly for our Colossus test stand, our NASA mentors have been invaluable in their guidance with our critical design reviews.

Wow congrats on the launch first!!

What was the biggest challenge for you guys like do you need special permissions and stuff to launch something that big ?

Thanks! The biggest challenge was definitely time – we launched at the FAR site in Mojave, CA, where the winds pick up in the afternoon. We ran into a few snags and were worried we might have to scrub the launch, but we ended up launching anyway despite the winds. Trying to get everything finalized on-site before the afternoon winds was absolutely the biggest challenge.

What other organizations will utilize the test stand? Do they need to trained/is there any monetary cost?

We're hoping to help out other academic and student organizations to promote aerospace and engineering education!

They won't have to provide anyone trained; our team will do all of the testing. As of now, we're estimating that these groups will only have to pay for fuel.

Are you a fan of the Houston Rockets(get it?)?

groan Nice one! (although I think we're bigger fans of the SpaceX Rockets)

This is some cool stuff!

• Whats the advantage to the cube shape on the satellite over the more "traditional" cyllander with wings? How about disadvantages?

• I'm assuming that the choice of chemical fuel in your satellite is a massive cost saver (as compared to solar). How long will the fuel last once the cube is active? How does this compare with the traditional lifetime of a satellite?

And lets get a fun one in here:

• How much of your team enjoys pineapple on pizza?

Thank you! The CubeSat format was designed with packing and deployer space efficiency in mind. The cube shape was chosen because it's much easier to pack multiple cubes on a rocket as opposed to packing cylinders. The cylinder format for larger satellites is designed to fit within the fairing on a cylindrical rocket, and so is the most efficient use of that space.

We chose to design Triteia with a hydrogen peroxide propulsion system (90% concentration) to enable a new mission profile for CubeSats. Current electric/ion drive options would get a cubesat to lunar orbit in weeks to months, while a chemical propulsion system would allow Triteia to reach lunar orbit in a week. The lifespan of our fuel is based on required station keeping. Our astrodynamics team has designed an orbit that is stable for 400 days, after which we would be able to extend the mission lifespan by a few more months.

As for pineapple on pizza, we put it to a vote in our group chat. We're split half and half, and now tensions are rising.

How and when did your organization originate?

Also, as an aspiring accountant, I'm interested in how you manage finances for your projects.

We started in 2012 as a group of friends who wanted to tackle the challenge of using additive manufacturing to create a better liquid rocket engine. The last of that original group graduated just last year and are now working in the industry. We've continued researching and creating 3D printed engines, and as interest in our student org has grown, so have our projects – from the single Tri-D engine project to our multiple current projects and nearly 90 members.

We have a business team that takes care of finances, graphics, and marketing. Like the way we recruit engineering majors for real-world experience, we recruit economics and management science majors to manage our finances. We are mostly funded by sponsorships, so some of it is negotiating those then making sure our parts procurement is within the budget. Our business team has also been working on crowdfunding for our cube satellite project, Triteia, so we can purchase some of the crucial parts!

Cool stuff, guys! When I was an undergrad at CU Boulder, I was part of a team that used a similar laser sintering technique to make the first recorded 3D printed solid rocket fuel. Have you guys ever dabbled in printing nozzles for SRBs? It would be awesome to be able to print an entire propulsion system. That's where this type of technology needs to go!

That's really cool, /u/do_you_even_lurk! We haven't dabbled in that; we're still pretty focused on just liquid engines and injector plates. Printing an entire propulsion system would be neat!

Honestly, printing a nozzle would be a cake walk compared to a full liquid engine. Pretty much the only consideration would be the expansion ratio. Have you done any fatigue/cycle analysis on your printed engine vs. a traditionally manufactured engine? That research could be an undergrad research project on its own, but I'm curious if you've looked at it. Longevity and reliability is a big concern pushing into the future of space technologies.

We've done fatigue/cycle analysis with just our printed engines and they undergo fatigue/cycle analysis by going through repeated cold flows and water flow analysis.

And for sure – we're definitely looking into reliability and reusability with our technology. We recovered the engine in one piece after the launch and just received it back from Marshall Space Flight Center where NASA did some post-flight analysis and testing on it.

That is so cool! I love this whole project. Do you have plans to carry the project forward, either yourselves or handing it off to a new group of students?

We're focusing on this technology as a club, but it manifests itself in different variations and projects – a 3D printed thruster for our cubesat's chemical propulsion system, or a rocket engine test stand that will support liquid rocket engine innovation in academic groups across the west coast. Our goal at the moment is to remain true to the idea of making getting to space cheaper and easier, especially through additive manufacturing/3D printing, and our hope is that every new class of SEDS members will keep that mission in mind when deciding what new projects our group will take on. And as we have in the past, each new class of students will help with the current projects (as we have graduating seniors), but will be the future of the club and will be instrumental in determining our future research and engineering.

Hi,
do you own the printer or do you outsource the printing?
What printer do you use?
Any thoughts on 3D printed hybrid rocket engines? (printed part as fuel)

Hi! We don't own a printer, nor do we have access to a metal 3D printer on campus. Our sponsors, GPI Prototype (Vulcan) and MTI (Triteia) print iterations at their locations, then send them to us so we can test them. As for thoughts on hybrid rocket engines, we're putting the question out to some our team – we'll update when we get some answers!

What are the pros/cons of 3D printing these kinds of parts? How much more efficient is it than not using 3D printing technologies? Thank you!

There are tons of pros to 3D printing engines! Traditional manufacturing methods are more expensive, time-intensive, and are more prone to mistakes.

Benefits of 3D printing engines:

• we can make more precise, intricate designs that would be nearly impossible with traditional manufacturing (especially with our injector plates)

• it's quicker – setting up a printer and leaving it to get to work is easier than recruiting an entire team to manufacture it, and it only takes about a week (for our Vulcan engine, 10 inches).

• it's cheaper – compared to the time and manpower needed for traditional rocket engines, our 3D printed ones are much cheaper – less that $100,000 for Vulcan, and less than $50,000 for Callan, our cube sat thruster.

Because of 3D printing, we've been able to turn our time and energy to other things, like playing with potential injector plate patterns, developing new projects, and making our other subsystems the best they can be!

Do you think ordering TapX's popcorn chicken is a questionable decision?

If you want to order it, we'll support you all the way!

Did you play with Estes model rockets as a kid?

A fair number of our members did play with model rockets, but we're not sure if they were Estes.

What is everyone's career goals?

A lot of us are looking to work at space companies, like SpaceX or Virgin Galactic, or at places like NASA. Some of us are looking to go into similar industries, like robotics or AI, or even create start-ups.

What is the best spec / fun thing about the radio you are using to communicate with the CubeSat?

We're using a SWIFT XTS Tethers radio. We like that it's modular, so we can add different band cards and change radio frequency easily, as well as its full software library and extensive documentation, so integrating it into our satellite system has been really easy. The Tethers team has also been incredibly supportive of our Triteia project and our group!

What awards and trophies did you get?

We have a number from SpaceVision, which is put on by SEDS USA and is the largest student-run space conference in the country. In recent years, we've won Best Chapter and Best Technical Project out of the chapters attending.

How often are you all on Reddit and what are your favorite subreddit?

Not too often – we're usually either in class or working on our projects! When we do get a chance, /r/rocketry and /r/SpaceX are fun ones.

When do you think NASA will finally have the replacement for the space shuttle ready and in use?

You would have to direct that question to NASA!

Have you all been to any NASA facilities for tours or special treatment?

We try to arrange for our members to go on pre-professional tours of aerospace facilities as much as we can! It's a great way to keep ourselves excited about the industry and keep up with all the cool projects NASA and space companies are working on.

What is everyone's majors?

We have all sorts – from mechanical/aerospace/structural engineers, to computer science, to physics, to economics!

Do you think you can have an animal astronaut on board your next rocket? Maybe like a mouse, or rat?

We're pretty inclined to leave the living cargo to the big aerospace players at the moment.

Did you all the see AMA with the https://www.reddit.com/r/IAmA/comments/67i3mz/i_am_emily_calandrelli_an_mit_engineer_whos_an/?utm_content=title&utm_medium=hot&utm_source=reddit&utm_name=IAmA

MIT Aerospace engineer?

Indeed we did – we're fans!

Do you have YouTube videos of your rockets?

We do! Here's our YouTube channel: https://www.youtube.com/channel/UC3R26P3mDxS6l-2qgVIdLGw

First off, this sounds really fun. Second, how does one join SEDS?

It's one of the best experiences we've ever had! SEDS UCSD accepts applications from current UCSD students during our recruitment periods. We post all information about recruitment events and application deadlines on our Facebook page, so be sure to keep up with us there!