...if you can 3D print a rocket engine?

Ever Wonder? / September 28, 2022

...if you can 3D print a rocket engine?

Image
 Nate Perkins, mechanical design engineer on the RS-25 engine nozzles
Image attribution
Courtesy of Aerojet Rocketdyne

NASA is planning to launch a massive new rocket as part of the Artemis I mission to fly around the moon. Earlier this year, we talked to engineers Nate Perkins and Doug Bradley from Aerojet-Rocketdyne about the engines for that rocket. Although the rocket is new, NASA is reusing the same RS-25 engines that once powered the Space Shuttle. (In fact, two of the engines on Artemis I actually flew on Endeavour!) But since the rocket for Artemis won’t be reusable like the Shuttle, its engines will have to be replaced for future missions. The engineers at Aerojet-Rocketdyne have gotten pretty creative coming up with efficient, cost-effective ways to build new engines…

Ever wonder if you can 3D print a rocket engine?

In this short, Nate tells us how he is using 3D printing to build the RS-25 engines more cheaply and quickly than during the past Shuttle Program. Here’s more of our conversation with Nate.

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Transcript

Perry Roth-Johnson (00:06):

Hello, this is Ever Wonder? from the California Science Center. I'm Perry Roth-Johnson. NASA is planning to launch a massive new rocket as part of the Artemis I mission to fly around the moon. Earlier this year, we talked to engineers Nate Perkins and Doug Bradley from Aerojet Rocketdyne about the engines for that rocket. Although the rocket is new, NASA is reusing the same RS-25 engines that once powered the space shuttle. In fact, two of the engines on Artemis I actually flew on Endeavour. But since the rocket for Artemis won't be reusable like the shuttle, its engines will have to be replaced for future missions. The engineers at Aerojet Rocketdyne have gotten pretty creative coming up with efficient cost effective ways to build new engines. Ever wonder if you can 3D print a rocket engine in this short Nate tells us how he is using 3D printing to build the RS-25 engines more cheaply and quickly than during the past shuttle program. Here's more of our conversation with Nate.

Perry Roth-Johnson (01:11):

So Nate, uh, maybe this is a good segway to you, like can you just describe what your specific role on Artemis I is?

Nate Perkins (01:18):

So technically I'm a combustion devices design engineer. That's just the group in the company that, that focuses on things like nozzles and main combustion chambers. And as far as hardware goes, you know, the, the RS-25 engine really, it consists of, you know, the nozzle, which is attached to the main combustion chamber, uh, which is where everything's igniting and the hot gas is getting pushed out into the nozzle. And then there's the turbo machinery and the, um, the power head all all up top. So from a combustion devices design engineer, you're either working on, you know, the power head up top, um, which has all the turbo pumps and things, or you're working on the main combustion chamber of the nozzle. So the nozzle is what I work on, and that's the big part of the, of the rocket. It's really the only part you can see when it's launched and when it's, um, you know, assembled into the vehicle. It's the big bell portion, you know, it's the size of a, of a minivan hanging out the back. You know, when I started the company almost five years ago now, um, we were still doing a lot of initial drawing releases for a lot of the, the new design essentially. So yes, we're using this heritage design, but we're having to make this this engine, which is now gonna be an expendable engine much more affordably and by leveraging new manufacturing technologies and 3D printing and…

Perry Roth-Johnson (02:31):

3D printing!?

Nate Perkins (02:32):

Yeah. 3D printing, uh, metallics.

Perry Roth-Johnson (02:34):

Tell me more about that.

Nate Perkins (02:35):

Yeah, so, you know, it's, it's a powder bed method. So you imagine just having metallic powder, uh, in a, in a chamber, and then, uh, a laser just moves around and, um, does it layer by layer by layer by layer. You know, some of these prints can take, uh, you know, weeks.

Perry Roth-Johnson (02:51):

Wow.

Nate Perkins (02:53):

You know, very, very long prints. But when you're able to take a component that historically would've been, I don't know, a dozen, two dozen, three dozen piece parts that were manually welded together, and all those welds have to be inspected and you can then print that into a net shape part where we say net shape part, maybe there's a little bit of machining and some other things that have to be done and, and clearly, uh, new and specialized inspections to inspect those kind of parts. Um, but you're able to reduce cost tremendously, uh, because, and, and schedule, even if it takes, you know, a week or longer to print apart. Sure. Um, it's hugely different than machining all the individual parts and modeling them all together. So that's a big part of our, our new redesign effort is leveraging those kind of technologies and, and, uh, leveraging all the lessons learned from, from the space shuttle program. Um, you know, certain manufacturing steps that were either very expensive or particularly difficult. And really looking at all of those things, identifying key areas, uh, for improvement and then, uh, executing on those to, to make this engine, uh, a lot more affordably.

Perry Roth-Johnson (04:00):

Okay. I gotta ask you more questions about 3D printing cause I'm just obsessed with this stuff. Um, I have...

Nate Perkins (04:06):

Me too.

Perry Roth-Johnson (04:06):

...a crummy little printer in my, in my living room.

Nate Perkins (04:09):

I have a printer in my garage as well.

Perry Roth-Johnson (04:11):

Yeah. Where, where is the 3D printing happening? Um, to, to my naive eye, when I look at a engine, I hope you don't take this the wrong way. I see the pretty bell shape, you know, the nozzle that you were talking about, uh, Nate. And then there's this rats nest of, of, of pipes and pumps and, and things on top. So are you 3D printing things on that rats nest, or, or are you 3D printing the bell shaped nozzle?

Nate Perkins (04:32):

So really there's, um, there's several steps to the way you approach this. First you have to identify if it makes sense for a part to be 3D printed because there's absolutely parts that are either size constrained, maybe it's just too large and, and you know, it's, uh, exceeds the capability of certain printers and, and things. Um, and then there's parts that just maybe they're so simple that they're really easy to manufacture with, with, uh, you know, more standard machining processes. And then those aren't gonna be really good candidates either. You know, just roughly speaking, you're looking for slightly smaller components. So, you know, think of like bear hug size, you know, baseball, beach ball, you know that kind of envelope size components. Those are, those are good candidates for the current capabilities of 3D printing, at least during using some of those powder bed methods. So you're looking for components that have, uh, a reasonable amount of complexity. Things that maybe have historically been really difficult to machine, or you're looking for components that previously had a whole lot of welds that maybe you want to eliminate those welds. And what you're essentially doing when you're 3D printing in that way with metals is you're creating one giant weld, essentially, Right. With all the material. I mean, you're, you're just melting all the material together. Um, so those are some of the thought processes that go into figuring out what components are good for 3D printing. So some things like bracketry, uh, can make sense depending on how complex they are. Um, some smaller components like that. Uh, but there's, there's definitely some much more complex components that we have that, uh, that make sense for, for 3D printing. But things like ducks, not so much. Um, like you're saying the rats nest of, uh, of line routing and stuff, those things are pretty standard. You know, machine stock, uh, that you can get tube stock and all that stuff is, is much more typical and easy to, to make with standard manufacturing. So you wouldn't look into 3D printing stuff like

Perry Roth-Johnson (06:28):

That's our show, and thanks for listening until next time keep wondering. Ever Wonder? from the California Science Center is produced by me, Perry Roth-Johnson, along with Jennifer Aguirre, Liz Roth-Johnson is our editor. Theme music provided by Michael Nickolas and Pond5. We'll drop new episodes every other Wednesday. If you're a fan of the show, be sure to subscribe and leave us a rating or review on Apple Podcasts. It really helps other people discover our show. Have a question you've been wondering about? Send an email or voice recording to everwonder@californiasciencecenter.org, to tell us what you'd like to hear in future episodes.