Talk:Raptor (rocket engine family)

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I've got a possible citation for the Raptor specific impulse, if some guesswork is allowed[edit]

"I realized that a methane-oxygen rocket engine could achieve a specific impulse greater than 380." - Elon Musk

http://money.cnn.com/2013/11/21/leadership/steve-jobs-elon-musk.pr.fortune/index.html

NortySpock (talk) 19:19, 24 November 2013 (UTC)

I'd go ahead and add it to the article, as the current citation does not support the 380 claim at all. N2e (talk) 05:38, 26 November 2013 (UTC)
Musk released a tweet today confirming the 382 s figure as a goal, following first test(s) of Raptor on a test stand. N2e (talk) 11:58, 26 September 2016 (UTC)

There are now (at least) two Raptor rocket engines under development[edit]

With the announcement this month (Jan 2016) that the USAF is going to contract with SpaceX to develop an upper stage Raptor engine (with USD33 million) that will also be methalox and use FFSC combustion cycle, there are now TWO Raptor rocket engines.

So the question is, over time, should this article become the overview article on the Raptor (rocket engine family) or should it become the article to describe only the one (full-size, for MCT, etc.) Raptor engine that SpaceX has been working on since approximately 2013, and began full-scale component testing in 2014-2015? Anyone have any thoughts? Cheers. N2e (talk) 15:51, 18 January 2016 (UTC)

Well, leave it until we know more about the different Raptors, but i think later becoming rocket engine family makes sense. SirKeplan (talk) 03:43, 19 January 2016 (UTC)
I've stubbed out a new article for the partially-USAF-funded prototype engine: Raptor prototype upper-stage engine. So that project can be just summarized in this article—which has been done, it seems—with the detail put in its own article. N2e (talk) 13:36, 28 January 2016 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── In my view, with the substantial additional new info released by Musk in late September, it is no longer clear (to me) if we have necessarily a separate engine for the USAF engine contract, where the US government military was going to pay 1/3 of some subset of development costs for a possible Falcon 9 and Falcon Heavy upper stage engine test on a ground test stand.

Now that Musk has released more data on the Raptor for the ITS launch vehicle, the question is: Do we have any source that clarifies that the two engines are not the same engine? (Before Sep, all we had was that no source indicated that they were one and the same. Now is unclear.) N2e (talk) 17:33, 1 October 2016 (UTC)

First Raptor engine shipped to Texas for testing.[edit]

http://arstechnica.com/science/2016/08/spacex-has-shipped-its-mars-engine-to-texas-for-tests/?comments=1&post=31686107

"SpaceX appears to have taken a significant step forward with the development of a key component of its Mars mission architecture. According to multiple reports, during the Small Satellite Conference Tuesday in Logan, Utah, SpaceX President Gwynne Shotwell said the company has shipped a Raptor engine to its test site in MacGregor, Texas. A spokesman confirmed to Ars that the engine has indeed been moved to Texas for developmental tests."

I think that we should add that information to the article. Cheers..C: Dante 80 (talk) 08:34, 10 August 2016 (UTC)

Raptor on the test stand[edit]

Musk released two photos and tweeted various details of the engine today (via Twitter). I've updated the thrust spec for production engines in the article. Other data is also provided in that series of tweets. Very likely, one of the photos would meet fair use guidelines for use in this article. N2e (talk) 11:57, 26 September 2016 (UTC)

N2e, for the time being, pick one and go with fair use. Since these are closed door tests not open to the public (obviously), there would be no opportunity to otherwise obtain a freely licensed alternative. That said, the moment we're aware of SpaceX officially releasing an image under their CC0 license, we'll take it down. To that end, I've messaged Musk on Twitter to see if those images are intended to be CC0 as well. Maybe I'll hear back, but I'm not holding my breath. Huntster (t @ c) 12:50, 26 September 2016 (UTC)
Someone has added one of those images to the article infobox. Not sure if all the licensing is straight vis a vis Wiki rules; but it's clearly the best image to have for today. Likely will be better non-twitter images released in the context of the speech slated for tomorrow. N2e (talk) 14:27, 26 September 2016 (UTC)
N2e, well this was...unanticipated. Musk affirmed the CC0 licensing rather quickly: https://twitter.com/elonmusk/status/780423473961115649. I'll get to work making sure both images are on Commons and set up properly. I'll post here when finished. Huntster (t @ c) 15:13, 26 September 2016 (UTC)
Okay, images are up: File:Raptor-test-9-25-2016.jpg (already in article) and File:Raptor test firing, 2015-09-25.jpg. Huntster (t @ c) 15:33, 26 September 2016 (UTC)

Comparison table[edit]

It would be nice if the table was sort-able.Doyna Yar (talk) 20:31, 27 September 2016 (UTC)

IAC 2016 talk[edit]

In this talk many details about both the vacuum and SL versions are unveiled. — Preceding unsigned comment added by Leonardorejorge (talkcontribs) 21:07, 27 September 2016 (UTC)

Test stand Raptor size[edit]

Dear Huntster (t @ c), the Raptor in the test stand is a scaled down version and next week an article will be discussing its thrust and turbomachinery power. Let's not keep this edit war, please. – Baldusi (talk) 15:23, 30 September 2016 (UTC)

Baldusi, this is not edit warring. The "scaled down" thing was not sourced, and I've seen no evidence of it being such. I'm not doubting you, and if an article comes out next week supporting that, I'm all for it. Huntster (t @ c) 02:14, 1 October 2016 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────It appears that different sources are reporting different things on this, even in news stories written some days after the Musk reveal. I've updated the article to reflect this uncertainty on the size of the engine. Cheers. N2e (talk) 13:36, 12 October 2016 (UTC)

The NSF article was pretty clear: they first talk about the 2014 prototype that was tested in Stennis, then they move on to the full-scale version tested on a dedicated stand in McGregor. I have updated the text accordingly. Self-reverted after reading it again; still unclear. — JFG talk 15:03, 6 November 2016 (UTC)

Real versions?[edit]

The section on putative Raptor versions strikes me as contradicting the sources. First of all, the naming "ER40", "ER50" etc. is nowhere to be found, so we should strike it as WP:OR, and second I can only find sources mentioning TWO versions: the sea-level and vacuum versions, differing only by their nozzle. This is the same situation as with Merlin 1D and Vacuum, which are considered ONE engine. Hence my suggestions:

  • Revert the page name to Raptor (rocket engine), not "family"
  • List only the two official versions and don't assign them arbitrary names
  • Mention the prototype variants (e.g. the scaled-down model tested in 2014 or the 150-ratio nozzle potentially used to test the vacuum version on Earth) within the discussion of the engine development or under the corresponding production version

Looking forward to your input before proceeding. — JFG talk 15:25, 6 November 2016 (UTC)

Yeah, let's get some eyes on this. I believe that some source that User:Baldusi pointed me at showed that there was a exp ratio 40 engine for sea-level Earth use on the ITS launch vehicle and a very similar-but-slightly-different ER nozzle for the second stage spaceship and tanker since the optimizing condition was landing on Mars (very low pressure, with atmospheric lower than Earth) plus maneuvering etc. use in the lower-pressure higher-altitude atmosphere of Earth (or Mars); even though both spacecraft would briefly be used during the final landing burn at (near-sea-level, higher pressure) Earth landings, but that the ER=50 nozzle would perform better (Isp) and be "tough enough" to handle the back pressures etc. of landing on a flat surface (whereas the ER=40) engines are used only over an open flame trench where the back pressure is considerably less. Baldusi, R U there?
As for whatever descriptive terms are used, since the expansion ratios are the differing factor, and this is a technical article, they can be described non-technically as "sea level nozzle" and "vacuum nozzle", but listing the exp. ratio in the descriptor seems a fine and perfectly encyclopedic way to describe them. Just as long as we don't say, in wikiprose, that "SpaceX calls them the "ER40" model etc. In other words, we are writing prose for an encyclopedia, and lots of such prose is descriptive, rather than pure quotations of source material, and as such, we could, in fact, use the descriptive characteristic that is unique to describe the several different engine versions: expansion ratio 40, expansion ratio 50, expansion ratio 200, or ER40, ER50, ER200. At least, that is my take.
But, yes, if we can't find a WP:V source for the ER50 engine, then that part would go, and only what is in decent sources would be used here. N2e (talk) 17:00, 6 November 2016 (UTC)
Not sure where User:Baldusi has been; we all get busy with our non-WP life. But I think it is worth making the point that, based on current sourced information, it seems rather clear that Raptor is an engine class name for a number of different models of large methalox rocket engines. Nothing in the reliable sources indicates it is merely a single engine. N2e (talk) 15:14, 27 November 2016 (UTC)
Yes, I'm sorry that I haven't been around but my line of works and family life sometimes leave no material time to contribute here. I don't think that I pointed out the ER40 sources, I did for the isp figures. But from all the speculation and calculations that I've seen around, I only see inconsistencies. For example by measuring the presented graph, which were supposedly based on engineering models, you get different ER and diameters for first and second stage atmospheric optimized Raptors. Also, they are just now getting empirical result on a sub-scale demonstrator.
So, I'm pretty sure that Raptor should be considered for now as a moving target, and more of a project. This is normal for SpaceX, as if you try to get the specs on Merlin 1 you'll go from an ablative design with less thank 95klf to a 170klf regen engine. Even the Merlin 1D has changed its specs at least three times. So I would simple try to reflect the inconsistency of avaialable analysis, the culture of constant optimization and the early stage of development. I'm sorry but SpaceX is very jealous of its propulsion information and I couldn't get more than what's publicly available. Baldusi (talk) 15:41, 27 November 2016 (UTC)
Thanks for getting over here with a comment Baldusi. So with no reliable source for teh ER50 expansion ratio engines for the two spacecraft, I've removed that statement from the article prose. And when some years of ground tests are complete, and early flights, SPaceX will undoubtedly be updating all of these specification, specs that are only, as of now, based on CAD models of engines using CFT models for all of the low-atmospheric pressure specs.N2e (talk) 00:48, 30 November 2016 (UTC)