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Building a rocket engine from scratch

blog.ablspacesystems.com

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Re: Building a rocket engine from scratch

#11

Post by numpad0 »

FredPret wrote: post #3
datadrivenangel wrote: post #2

"At one point, I received a well-deserved earful from our machinist about how tightly spaced the turbine blades were. The program was taking nearly a month to run and required tiny end mills that broke often. We performed a turbine blade count study to see if we could use fewer blades with more space between them. It turned out the performance impact of running fewer blades was minimal, so we cut the number down, all…

And also the value of a completely obsessed engineer. If the mech eng designing the parts is also the type to build things in his spare time, this type of machining problem would stand out right away. Of course, not everything can ever be anticipated, so tight feedback loops are fantastic when you can get them.

I'd agree with this take more. It's just cheaper and faster to just know whys and plan ahead than waiting for failures, if you could.

I've been tinkering with 3D printers long enough that I've trivially halved print times after seeing long print time predictions. Lots of my brackets and parts fits together on first try and needs no supports. Rapid turnaround did help in _acquiring_ those skills, but now I could just waterfall little projects and tight looping is not that important.

Re: Building a rocket engine from scratch

#12

Post by avmich »

Awesome story, thanks!

It seems the design choices are rather conservative, which is entirely justified by the "from scratch" part for the first engine. I'm sure subsequent designs will be more bold and adventurous.

Keep up great work!

Re: Building a rocket engine from scratch

#14

Post by avmich »

AndriyKunitsyn wrote: post #4

Nice read. The fact that it is possible to 3d print metal parts that withstand temperatures and pressures of a rocket engine is so exciting. How expensive is it?

Paul Breed, from Unreasonable Rocket team - https://x.com/unrocket - mentioned, a decade or so ago, that he printed some aluminum engines for regenerative cooling by hydrogen peroxide for ~$1000 . Another story from http://rocketmoonlighting.blogspot.com/2010/ is about a small engine cooled with nitrous oxide - and manufactured entirely on personal money, also quite some time ago. I think these numbers are still indicative of the current prices.

Re: Building a rocket engine from scratch

#15

Post by psunavy03 »

FredPret wrote: post #3
datadrivenangel wrote: post #2

"At one point, I received a well-deserved earful from our machinist about how tightly spaced the turbine blades were. The program was taking nearly a month to run and required tiny end mills that broke often. We performed a turbine blade count study to see if we could use fewer blades with more space between them. It turned out the performance impact of running fewer blades was minimal, so we cut the number down, all…

And also the value of a completely obsessed engineer. If the mech eng designing the parts is also the type to build things in his spare time, this type of machining problem would stand out right away. Of course, not everything can ever be anticipated, so tight feedback loops are fantastic when you can get them.

Valuing "completely obsessed" employees is a great way to build a company with toxic burnout culture. Some people want lives outside of work and are still good at their jobs.

Re: Building a rocket engine from scratch

#16

Post by quartesixte »

psunavy03 wrote: post #15
FredPret wrote: post #3

Earlier quoted context omitted.

And also the value of a completely obsessed engineer. If the mech eng designing the parts is also the type to build things in his spare time, this type of machining problem would stand out right away. Of course, not everything can ever be anticipated, so tight feedback loops are fantastic when you can get them.

Valuing "completely obsessed" employees is a great way to build a company with toxic burnout culture. Some people want lives outside of work and are still good at their jobs.

Or some people are so good at their jobs that even while being completely obsessed, they still have great work-life balance.

I interact with a lot of people like the author in the article from this industry. And while yes, their worklife balance skews "work", they all have interesting hobbies and find time to hang out with friends, go on adventures, and live a pretty full life.

Unless you're on the Starship team at SpaceX. Truly, hats off to y'all at Boca Chica some intense hours you are pulling there.

Re: Building a rocket engine from scratch

#17

Post by quartesixte »

avmich wrote: post #14
AndriyKunitsyn wrote: post #4

Nice read. The fact that it is possible to 3d print metal parts that withstand temperatures and pressures of a rocket engine is so exciting. How expensive is it?

Paul Breed, from Unreasonable Rocket team - https://x.com/unrocket - mentioned, a decade or so ago, that he printed some aluminum engines for regenerative cooling by hydrogen peroxide for ~$1000 . Another story from http://rocketmoonlighting.blogspot.com/2010/ is about a small engine cooled with nitrous oxide - and manufactured entirely on personal money, also quite some time ago. I think these numbers are still indi…

Aluminum is magnitudes cheaper than Inconel. And since volume is cubic, and pricing mostly on based on powder weight, you are about an order of magnitude or two off for the size of engine ABL is producing here.

Re: Building a rocket engine from scratch

#18

Post by avmich »

quartesixte wrote: post #17
avmich wrote: post #14

Earlier quoted context omitted.

Paul Breed, from Unreasonable Rocket team - https://x.com/unrocket - mentioned, a decade or so ago, that he printed some aluminum engines for regenerative cooling by hydrogen peroxide for ~$1000 . Another story from http://rocketmoonlighting.blogspot.com/2010/ is about a small engine cooled with nitrous oxide - and manufactured entirely on personal money, also quite some time ago. I think these numbers are still indi…

Aluminum is magnitudes cheaper than Inconel. And since volume is cubic, and pricing mostly on based on powder weight, you are about an order of magnitude or two off for the size of engine ABL is producing here.

That's correct, but it's still interesting that you have that opportunity to shave - slash? - costs here.

And also the other engine mentioned isn't an aluminum one.

Re: Building a rocket engine from scratch

#19

Post by guynamedloren »

psunavy03 wrote: post #15
FredPret wrote: post #3

Earlier quoted context omitted.

And also the value of a completely obsessed engineer. If the mech eng designing the parts is also the type to build things in his spare time, this type of machining problem would stand out right away. Of course, not everything can ever be anticipated, so tight feedback loops are fantastic when you can get them.

Valuing "completely obsessed" employees is a great way to build a company with toxic burnout culture. Some people want lives outside of work and are still good at their jobs.

This may surprise you, but it's possible to be completely obsessed with your work (while you're working!), while also maintaining a work-life balance.

Re: Building a rocket engine from scratch

#20

Post by numpad0 »

spxneo wrote: post #8
AndriyKunitsyn wrote: post #4

Nice read. The fact that it is possible to 3d print metal parts that withstand temperatures and pressures of a rocket engine is so exciting. How expensive is it?

side question to this: where can i design stuff involving metal parts (presumably in CAD tools) and have it printed en masse? With PCBs? ex) car components

You can draw up mechanical components in Autodesk Fusion, OnShape, SOLIDWORKS for Makers, or FreeCAD, and send STEP or STL to PCBWay or JLCPCB in China for manufacturing(note that export restrictions may apply if it's literal rockets or otherwise dual-use/controlled in nature).

PCB mounting outlines can be exported from above 3D CAD and imported to EDA tools such as Altium and KiCAD; KiCAD is fine unless you're doing DRAM or PCIe. Same PCBWay and JLCPCB takes your design, and optionally assemble PCB with parts for you.

That should take you to first 2-3 working units at ~$500 and up to few dozen beta units with zero initial cost and much inflated unit costs, and I guess beyond that involves significant human resourcing and networking problems outside of PoC hardware scope.

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