Poll

When will full-scale hot-fire testing of Raptor begin?

Component tests - 2017
3 (0.6%)
Component tests - 2018
21 (4.2%)
Integrated tests -  2017
19 (3.8%)
Integrated tests -  2018
237 (47%)
Integrated tests -  2019
181 (35.9%)
Raptor is not physically scaled up
33 (6.5%)
Never
10 (2%)

Total Members Voted: 504


Author Topic: SpaceX Raptor engine (Super Heavy/Starship Propulsion) - General Thread 1  (Read 869800 times)

Offline Rei

  • Full Member
  • ****
  • Posts: 540
  • Iceland
  • Liked: 332
  • Likes Given: 161
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #160 on: 04/13/2017 01:39 pm »
And, it's largely 3-d printed.

The only information I've seen for the 3D printing is 40% of the demonstrator engine by mass, and the notes from Elon's NRO talks that 3D printing doesn't work nearly as well for Raptor as it does for SuperDraco.  They can't just scale it up a little and hit the Print button.
Yup. And 3D printing produces worse strength than forging (for example). And you're limited in your alloy selection.

We should not make the mistake of assuming that all 3d printing technologies are the same. ;) For example, the DMG Mori Lasertec 65:

http://be-nl.dmgmori.com/blob/334060/67241acc5e196393c59bb68002da7c56/pl1uk15-lasertec-65-3d-pdf-data.pdf
http://en.dmgmori.com/blob/120872/cc1b707f03ee3c2b0bfc81d22c3442ca/pl0uk13-lasertec-series-pdf-data.pdf


First off, it's both CNC and printing on the same system, so you can start out with an existing shape and mill elements down, then add onto it.  Secondly, it's laser spraying, not powder bed.  So you don't have to lay down layers across a build, it has a continuous, rapid stream of powder which it melts with a laser as it impacts.  The high speed of the particles means that they also compact as they impact, yielding excellent material properties. The CNC side can mill off all 3d print marks, while the laser can engrave tiny details (holes, etc). The combination of CNC with additive manufacturing means that you can even machine internal areas that normally would be inaccessible. The potential range of materials you can print from is basically unlimited, anything that you can suspend in a dust and which will attach with some combination of impact force and heat. They've validated it with among other things stainless, inconel, bronze, brass, chrome-cobalt-molybdenum alloys, tool steel, stellite, and even tungsten carbide.  Multiple materials printed onto the same part. And part sizes up to half a meter diameter.

We're not talking Makerbots here  ;)

Even if for some reason the quality wasn't right, or you wanted to focus on mass production, you can always use the 3d printer to make molds / die heads / etc for parts. 

It doesn't state, but I wonder if you can "resume" a previous build.  If so, you could take your previously-built engine and tweak its geometry without having to print a new one from scratch (since, again, it can both add and subtract).  Now that would be some fast manufacturing.
« Last Edit: 04/13/2017 01:48 pm by Rei »

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #161 on: 04/13/2017 05:26 pm »
Um, yeah, I know all about those types of additive manufacturing. It is, in fact, my job.

Additive can compete with and exceed /cast/ properties, but forgings are much stronger due to an aligned grain structure. And this is something that simply cannot be done to the same degree with additive approaches.

Again, additively manufactured metal parts are significantly inferior to forged metal parts.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline envy887

  • Senior Member
  • *****
  • Posts: 8144
  • Liked: 6801
  • Likes Given: 2965
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #162 on: 04/13/2017 05:35 pm »
Um, yeah, I know all about those types of additive manufacturing. It is, in fact, my job.

Additive can compete with and exceed /cast/ properties, but forgings are much stronger due to an aligned grain structure. And this is something that simply cannot be done to the same degree with additive approaches.

Again, additively manufactured metal parts are significantly inferior to forged metal parts.

The material as manufactured with additive is inferior to forging, but part properties are a function of both material and geometry. AM allows geometries that are infeasible or completely impossible with forging. So it's possible to make a part with AM that is far superior to a forging serving the same purpose - especially for extremely complex integrated parts, like Raptor appears to use.

Offline RonM

  • Senior Member
  • *****
  • Posts: 3340
  • Atlanta, Georgia USA
  • Liked: 2231
  • Likes Given: 1584
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #163 on: 04/13/2017 05:44 pm »
As the old saying goes, use the right tool for the job.

Online matthewkantar

  • Senior Member
  • *****
  • Posts: 2075
  • Liked: 2506
  • Likes Given: 2211
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #164 on: 04/13/2017 06:07 pm »
Um, yeah, I know all about those types of additive manufacturing. It is, in fact, my job.

Additive can compete with and exceed /cast/ properties, but forgings are much stronger due to an aligned grain structure. And this is something that simply cannot be done to the same degree with additive approaches.

Again, additively manufactured metal parts are significantly inferior to forged metal parts.

The material as manufactured with additive is inferior to forging, but part properties are a function of both material and geometry. AM allows geometries that are infeasible or completely impossible with forging. So it's possible to make a part with AM that is far superior to a forging serving the same purpose - especially for extremely complex integrated parts, like Raptor appears to use.

I think a more salient comparison is between casting and AM. You can cast just about anything, but the cost/difficulty really shoots up when casting more complex parts. I think AM and casting produce parts with similar properties these days, though the state of the art is a rapidly moving target for AM.

Matthew

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #165 on: 04/13/2017 06:14 pm »
Yeah, for small cast parts, additive is a big threat. Strength can be greater for additive. Really expensive, but not a problem for low part count runs.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Rei

  • Full Member
  • ****
  • Posts: 540
  • Iceland
  • Liked: 332
  • Likes Given: 161
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #166 on: 04/17/2017 09:12 am »
Additive can compete with and exceed /cast/ properties, but forgings are much stronger due to an aligned grain structure. And this is something that simply cannot be done to the same degree with additive approaches.

Again, additively manufactured metal parts are significantly inferior to forged metal parts.

https://link.springer.com/article/10.1007%2Fs00170-011-3423-2?LI=true

Quote
Tensile mechanical properties of selective laser-melted Hastelloy® X alloy in as-deposited condition and after hot isostatic pressing (HIP) have been studied at ambient and elevated temperatures. Room temperature four-point bending and tension–tension fatigue properties have also been investigated in as-deposited condition and after HIP. The yield strength of the as-deposited selective laser-melted Hastelloy® X specimen is higher than the heat-treated (hot forged) samples. The ultimate strength is also higher than that of the hot forged samples while the elongation property is lower. This can be attributed to its ultrafine microstructure caused by rapid solidification, which is characteristic of the selective laser melting process. It is also found that the mechanical properties (tensile and fatigue) do not vary with samples built in different bed locations.


Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #167 on: 04/17/2017 03:41 pm »
Additive can compete with and exceed /cast/ properties, but forgings are much stronger due to an aligned grain structure. And this is something that simply cannot be done to the same degree with additive approaches.

Again, additively manufactured metal parts are significantly inferior to forged metal parts.

https://link.springer.com/article/10.1007%2Fs00170-011-3423-2?LI=true

Quote
Tensile mechanical properties of selective laser-melted Hastelloy® X alloy in as-deposited condition and after hot isostatic pressing (HIP) have been studied at ambient and elevated temperatures. Room temperature four-point bending and tension–tension fatigue properties have also been investigated in as-deposited condition and after HIP. The yield strength of the as-deposited selective laser-melted Hastelloy® X specimen is higher than the heat-treated (hot forged) samples. The ultimate strength is also higher than that of the hot forged samples while the elongation property is lower. This can be attributed to its ultrafine microstructure caused by rapid solidification, which is characteristic of the selective laser melting process. It is also found that the mechanical properties (tensile and fatigue) do not vary with samples built in different bed locations.
What's the ultimate tensile strength in MPa of this printed sample?

I'm distrustful when actual figures are not given in the summary.
« Last Edit: 04/17/2017 06:17 pm by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online acsawdey

https://link.springer.com/article/10.1007%2Fs00170-011-3423-2?LI=true

Quote
Tensile mechanical properties of selective laser-melted Hastelloy® X alloy in as-deposited condition and after hot isostatic pressing (HIP) have been studied at ambient and elevated temperatures. Room temperature four-point bending and tension–tension fatigue properties have also been investigated in as-deposited condition and after HIP. The yield strength of the as-deposited selective laser-melted Hastelloy® X specimen is higher than the heat-treated (hot forged) samples. The ultimate strength is also higher than that of the hot forged samples while the elongation property is lower. This can be attributed to its ultrafine microstructure caused by rapid solidification, which is characteristic of the selective laser melting process. It is also found that the mechanical properties (tensile and fatigue) do not vary with samples built in different bed locations.

I think this still does not address at all the comparison to a conventionally manufactured part that starts with a forged blank. Seems to me the summary calling the HIP treated part "hot forged" is confusing things.

Offline JamesH65

  • Full Member
  • ****
  • Posts: 1559
  • Liked: 1739
  • Likes Given: 10
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #169 on: 04/18/2017 12:00 pm »
Surely comparing the different process strengths is mostly irrelevant - just use the one that is strong enough? And if its AM, then fill yer boots?


Offline meekGee

  • Senior Member
  • *****
  • Posts: 14158
  • N. California
  • Liked: 14046
  • Likes Given: 1392
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #170 on: 04/18/2017 01:31 pm »
Surely comparing the different process strengths is mostly irrelevant - just use the one that is strong enough? And if its AM, then fill yer boots?
Anything can be strong enough if you make it beefier...

Saving mass is not the only consideration, but it's right up there at the top of the list.
ABCD - Always Be Counting Down

Offline Rei

  • Full Member
  • ****
  • Posts: 540
  • Iceland
  • Liked: 332
  • Likes Given: 161
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #171 on: 04/18/2017 03:17 pm »
Additive can compete with and exceed /cast/ properties, but forgings are much stronger due to an aligned grain structure. And this is something that simply cannot be done to the same degree with additive approaches.

Again, additively manufactured metal parts are significantly inferior to forged metal parts.

https://link.springer.com/article/10.1007%2Fs00170-011-3423-2?LI=true

Quote
Tensile mechanical properties of selective laser-melted Hastelloy® X alloy in as-deposited condition and after hot isostatic pressing (HIP) have been studied at ambient and elevated temperatures. Room temperature four-point bending and tension–tension fatigue properties have also been investigated in as-deposited condition and after HIP. The yield strength of the as-deposited selective laser-melted Hastelloy® X specimen is higher than the heat-treated (hot forged) samples. The ultimate strength is also higher than that of the hot forged samples while the elongation property is lower. This can be attributed to its ultrafine microstructure caused by rapid solidification, which is characteristic of the selective laser melting process. It is also found that the mechanical properties (tensile and fatigue) do not vary with samples built in different bed locations.
What's the ultimate tensile strength in MPa of this printed sample?

I'm distrustful when actual figures are not given in the summary.

You could read more than the summary if you wanted, it's not an incredibly long paper  ;)  923-937 MPa, depending on where on the sample they tested.

Quote from: acsawdey
Seems to me the summary calling the HIP treated part "hot forged" is confusing things.

There's actually an additional category in there: SLM, SLM + HIP, and hot forged / no SLM.  SLM has the strongest UTS, followed by SLM + HIP (838-845 MPa), followed by hot forged (767 MPa). The images of the microstructure in figure 5 are telling; it makes very fine, very regular dendrites surrounded by precipitates, with the dendrites oriented in the building direction. After HIP the dendrites coarsen and become more irregular, while in the purely hot forged version, the microstructure is coarse grains.
 
HIP did however improve the fatigue life by removing cracks, decreasing porosity, eliminating embedded unmelted powder, etc. But it comes at a cost of tensile strength.
« Last Edit: 04/18/2017 03:24 pm by Rei »

Online acsawdey

You could read more than the summary if you wanted, it's not an incredibly long paper  ;)  923-937 MPa, depending on where on the sample they tested.

US$ 39.95 to read a 7-page paper? No thanks. But thank you for giving us a few numbers.

Online acsawdey

Here's another paper you can grab a pdf of, it references the one Rei linked.

http://www.gruppofrattura.it/ocs/index.php/ICF/icf13/paper/view/11306/10685

Shows the properties are strongly anisotropic with respect to the build direction.

Offline DanielW

  • Full Member
  • ****
  • Posts: 628
  • L-22
  • Liked: 577
  • Likes Given: 85
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #174 on: 04/18/2017 05:09 pm »
Surely comparing the different process strengths is mostly irrelevant - just use the one that is strong enough? And if its AM, then fill yer boots?
Anything can be strong enough if you make it beefier...

Saving mass is not the only consideration, but it's right up there at the top of the list.

This is not true. There will always be important properties involved in "strength" that don't scale with "beefy" This is especially true for anythings that requires cooling.

Offline Lar

  • Fan boy at large
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13463
  • Saw Gemini live on TV
  • A large LEGO storage facility ... in Michigan
  • Liked: 11864
  • Likes Given: 11086
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #175 on: 04/19/2017 01:49 am »
This is a fascinating discussion. Can we draw any conclusions? How likely is it that AM state of the art will advance fast enough to rival forging by the time Raptor goes into serial production?  And even if not, SpaceX optimizes for cost. In this case, weight has a big leverage, presumably, but does that change the answer at all? 

Not sure if there's a better thread but maybe?
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Rei

  • Full Member
  • ****
  • Posts: 540
  • Iceland
  • Liked: 332
  • Likes Given: 161
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #176 on: 04/19/2017 12:30 pm »
You could read more than the summary if you wanted, it's not an incredibly long paper  ;)  923-937 MPa, depending on where on the sample they tested.

US$ 39.95 to read a 7-page paper? No thanks. But thank you for giving us a few numbers.

If you don't have a subscription and can't get to a place that does, there's always sci-hub  ;)

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25240
  • Likes Given: 12115
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #177 on: 04/19/2017 01:18 pm »
I read the article. AM parts get higher strength than regular parts, but if you cold forge (cold draw) the metal, you get 1100MPa ultimate strength, which is a good 20% stronger than the figure they use in the paper (780MPa, I think?). Heat aging the metal also helps a lot.

So I feel vindicated. The right kind of forging definitely produces a much stronger part than a mere AM part, even if you HIP the AM part.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Rei

  • Full Member
  • ****
  • Posts: 540
  • Iceland
  • Liked: 332
  • Likes Given: 161
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #178 on: 04/19/2017 07:58 pm »
I read the article. AM parts get higher strength than regular parts, but if you cold forge (cold draw) the metal, you get 1100MPa ultimate strength, which is a good 20% stronger than the figure they use in the paper (780MPa, I think?). Heat aging the metal also helps a lot.

So I feel vindicated. The right kind of forging definitely produces a much stronger part than a mere AM part, even if you HIP the AM part.

Reference to that 1100 MPa figure just from cold rolling, if you would. I've been checking a variety of references for Hastelloy X and the only ones that show figures that high are from tempering.  And you can temper 3d prints, just like you can temper forged products.
« Last Edit: 04/19/2017 09:41 pm by Rei »

Offline Navier–Stokes

  • Full Member
  • ***
  • Posts: 367
  • Liked: 720
  • Likes Given: 6766
Re: ITS Propulsion – The evolution of the SpaceX Raptor engine
« Reply #179 on: 04/21/2017 11:44 pm »
New job posting for a Raptor Test Specialist at McGregor:
Quote
Responsibilities:
*    Work with design engineers to develop and document test procedures
*    50% hands on working with hardware, 50% control systems/operation work
*    Perform tests according to procedure
*    Design fixtures and adaptors needed to perform tests
« Last Edit: 04/21/2017 11:47 pm by Navier–Stokes »

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1