Talk:SpaceX Merlin

Move discussion in progress

There is a move discussion in progress on Wikipedia talk:WikiProject Spaceflight which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 11:00, 31 December 2019 (UTC)

Reversion

"Hello, I'm Angus1986. I wanted to let you know that one or more of your recent contributions to SpaceX Merlin have been undone because they did not appear constructive." @Angus1986: Can you provide details of the reversion issue? It was well referenced, factual, and is within scope of the core topic. 67.61.89.32 (talk) 20:39, 16 February 2020 (UTC)

@Angus1986: I have to say that, looking at the changes you reverted, the IP's version seems like an improvement. When you revert without an edit summary, and particularly when you use rollback, the conventionally understood meaning is that you are reverting WP:vandalism. In my opinion, there is no possibility that 67.61.89.32's series of edits can be meaningfully construed as "editing ... deliberately intended to obstruct or defeat the project's purpose. Please take the time to review your revert and consider whether you agree with my assessment. --RexxS (talk) 22:46, 16 February 2020 (UTC)

@Angus1986: Thanks for the reply. I'm sorry, I'm confused - I didn't revert, you did, isn't that true? So what do you mean by taking the time to review "my reversions?" So I did look again - all are factual and well-referenced. EDIT: OK, I get it, that message was from RexxS, not Angus1986. 67.61.89.32 (talk) 22:54, 16 February 2020 (UTC)

Hi 67.61.89.32. Yes, the message was from me and I was addressing Angus1986, in agreement with you. Don't worry about not realising that right away – Wikipedia conventions aren't always intuitive when you're new to them. You'll soon get the hang of it. Cheers --RexxS (talk) 00:03, 17 February 2020 (UTC)

Thanks for the reply, RexxS - how should I proceed? 67.61.89.32 (talk) 00:54, 17 February 2020 (UTC)

With patience. Hopefully Angus1986 will reply here and you can see what objections they had to your initial series of edits. When you have some idea of the issues (if any), you'll be in a much better position to move forward with your editing of the article.

In the meantime, you could improve the article uncontroversially by linking numerous terms to their Wikipedia articles, like benzene, hydrocarbon, pyrolysis, and so on. Just link the first occurrence of any terms that you think a lay reader interested in this topic might want to follow to get a good background understanding. You might also want to have a read of the article RP-1, which would clearly benefit from being expanded using some of the sourcing from this article – after all, the toxic by-products of incomplete combustion of fuel-rich mixtures are an issue for the fuel as much as for any one application using that fuel. Have a think about how you might add a section to that article, and perhaps make a post on Talk:RP-1 raising the idea. Cheers --RexxS (talk) 01:44, 17 February 2020 (UTC)

Thanks for the reply. I will look into those suggestions. I had thought Angus1986 represented Wikipedia, hence my initial language - I assumed Wikipedia objected to those facts. 67.61.89.32 (talk) 03:49, 17 February 2020 (UTC)

Hi everyone, sorry I use recent changes with filters of bad faith, I just noticed now that the editing was constructive, my apologies. I highly recommend you to register on Wikipedia with an account instead of using an IP address. @RexxS I tried "undoing" my rollback but there shows an error, could you help? Thanks. Angus1986 (talk) 06:01, 17 February 2020 (UTC)

@Angus1986: Not to worry: everyone makes mistakes, and I'm glad you have worked it out now. You won't be able to undo rollback now because of some intervening edits, but thanks for trying. I think it best just to let 67.61.89.32 carry on improving the article. They can see from this diff the changes they made previously, and I'm sure they can use copy-paste to resurrect content from there. Cheers --RexxS (talk) 15:52, 17 February 2020 (UTC)

RexxS thank you for managing this and for providing some training which I critically needed. I may be able to provide references into the hydrocarbon pyrolysis literature, which I have studied extensively in my career (e.g., Singer, et al.), so I appreciate the other suggestions. Again, thank you. 67.61.89.32 (talk) 16:22, 17 February 2020 (UTC)

Gas Generator

The section SpaceX Merlin#Gas Generator suffers from numerous problems. To wit,

a) It is poorly formatted. There are several instances of excessive citations (one or two is generally sufficient for non-controversial subjects). Also, the extensive use of italics is entirely inappropriate and does not match standard WP style.

b) It is far too long. A simple discussion of the gas generator's pollution characteristics would suffice; there is too much detail.

c) It is potentially original research. While all the claims appear to be factual and well-cited in themselves, the collection of these specific details seems to make it clear that the actual (and unstated) purpose of this section is to detail the degree to which the Merlin motor creates pollution in the atmosphere. While this is an important detail, it's not clear to this editor that this detail is actually appropriate for this encyclopedia. Not because the issue raised is not important, ofc, but rather because, as far as I'm aware, no one is raising this issue. The purpose of this encyclopedia is to inform people of knowledge that has been reported elsewhere, and issues that have been raised elsewhere, not to point out issues that have not been raised by others. This would constitute original research, imo, and that is clearly not allowed.

Despite the obvious amount of effort put into this single long paragraph by User:67.61.89.32, I find it necessary to decimate this section, while reserving the right to question its inclusion in the first place. The edit(s) I have made represent my corrections to the first two of the three issues I raised above; the third is still up for debate, imo. Please do not revert my edits without detailing your intentions here, for others to read. At this point, it appears to me that this entire section is largely an agenda-driven attempt to paint SpaceX as a dangerous polluter. That, ofc, is also not the purpose of WP. If an editor insists on including detail regarding the pollution of the Merlin engine, I feel it would be wise to explain your reasoning here, lest those edits be construed as ideological edit-warring. Eaglizard (talk) 01:12, 14 June 2020 (UTC)

Original research about environmental concerns

After stumbling across this section and doing some digging, it is clear to me that this section is original research. User:67.61.89.32 has identified themselves elsewhere (see [their talk page] and [this talk section on a different article with a link to their personal website]) as a former researcher in the field with a clear agenda with respect to this topic. I have gone for it and deleted the original research content.

I am of course supportive of content within Wikipedia that describes the environmental costs of space launch activity and cites secondary sources -- I was able to find one such secondary source which relates (loosely) to the Merlin engine and added it to the page. Broadly speaking, it seems to me that such content belongs in the SpaceX article or potentially in a new article as I don't see an article about the environmental impact of spaceflight listed in [the spaceflight portal]. In my view, if the editor wishes to include these points in an encyclopedia article on the Merlin engine, they should publish a peer-reviewed article describing the environmental impact of the Merlin engine, obtain secondary (media) coverage of that work, and then wait for other editors to cite the work within the article. Themillofkeytone (talk) 18:10, 18 August 2020 (UTC)

User:Themillofkeytone: The first sentence seems to invoke a "clear agenda" but then claims to act according to an "original research" issue. This seems inappropriate. As a published researcher myself, I can state that this is not original research, this is simply citing many references well-known in the field of hydrocarbon combustion. There can be no agenda in facts presented plainly.

You can't delete something simply because it cites a lot of references, a complete list of references does not constitute research. As far as I know there has been no research on the environmental impacts of the merlin engine. The research remains to be done. This does not constitute original research. 67.61.89.32 (talk) 16:01, 19 August 2020 (UTC)

However, it is still raked with the synthesis materials. In Wikipedia, synthesis materials are similar to the originally researched materials (see WP:SYNTH). --Soumya-8974 ^talk _contribs ^subpages 14:21, 20 August 2020 (UTC)

User:Themillofkeytone: I don't believe there's any synthesis here - just a deep, perhaps overly ambitious, dive into well understood but highly-specialized combustion science.

I've been pondering a lot the last 24 hours trying to understand the actual issue being expressed. When one explains something, one should heavily reference the explanation for interested users, or else create a large page when explaining an arcane subject like thermal oligomerization and condensation-polymerization of hydrocarbons, even though that field is very well understood. (You can even download open-source detailed-combustion-chemistry CFD software like OpenFOAM and run the chemistry of a gas generator on your laptop now. I had considered placing an/some illustrative images in that section - but that much depth seemed out of place, and I suppose might be objected-to despite being common knowledge in the field of combustion.) It is difficult to explain the chemistry and physics in-depth in one short paragraph; and that may be where the issue is - my attempt to do so - but a larger entry seems out of place in a page about rocket motors. Perhaps I should simply state the facts without appeal to any deeper explanation of well-understood chemical processes. That would cut the thing down to, maybe, three sentences (keeping the references for interested readers).

The business of what constitutes a synthesis seems troublesome. For instance, one can say "combustion needs three things, air, heat and fuel." This would seem not to be a synthesis, but a statement of fact. However, it is a false fact; the combustion of acetylene needs only fuel and pressure. So, while guidelines like original research and synthesis may be useful, they can be troublesome in guiding some complex encyclopedic content.

Perhaps a useful conversation would be about the fundamental content of that section? BTW: Are you an editor or are you a Wikipedia representative? I still don't really understand this interface. 67.61.89.32 (talk) 22:57, 20 August 2020 (UTC)

Hi, User:67.61.89.32. I am an editor, just like you. Per WP:NOR, original research "includes any analysis or synthesis of published material that serves to reach or imply a conclusion not stated by the sources." As you said in your edit of 16:01, 19 August 2020, "there has been no research on the environmental impacts of the merlin engine. The research remains to be done." Therefore, the content in the Gas Generator subsection of the article is "analysis or synthesis of published material." My read of the subsection is that it is written to suggest to the reader that the Merlin engine in particular creates potentially toxic combustion by-products. It does so by making reference to tests of an entirely different generator from 1966, and commenting that current environmental assessments don't provide data. The effect is to imply (at least) that dangerous chemicals are released by the Merlin engine in quantities that should give readers pause.

In other words, the subsection "serves to reach or imply a conclusion not stated by the sources." Thus, the subsection as written violates WP:NOR and I removed it.

I am not interested in getting into an edit war with you. That being said, I have not yet been convinced that this material is appropriate for this page. As I mentioned in my original section, I do think that it is within the scope of an encyclopedia to discuss the environmental impacts of spaceflight, and I encourage you to write such an article or add to a more general article. My objection is including general information about the potential environmental harms of gas generators in an article about a specific rocket engine. I actually don't think we are very far away from consensus on this point: you mention that a large entry "seems out of place in a page about rocket motors."

Let me state my objection in the form of questions which could be answered to change my mind: Why is it important to discuss these details of gas generator physics/chemistry on this particular page? What point are you trying to make by phrasing this information in this way?

Themillofkeytone (talk) 21:19, 24 August 2020 (UTC)

Not original research nor synthesis. I'm not sure what you're getting at with the "in particular" comment. This section just considers the gas generator itself. It offers appropriate supportive explanation from a combustion scientist: whenever lox/kerosene are burned together under hot, quite fuel-rich conditions at high pressures, there will be PM2.5 (soot particulates coated with PAH and the other chemicals indicated) being generated. (See references to the combustion literature provided, especially the two excellent summary-images provided.) In particular, fuel-rich lox/kerosene gas generators have been known to do this. (see ref, among others) It's really that simple. The additional references are not synthesis, but a comprehensive sample of the relevant combustion literature (and also plume literature for atmospheric effects) boiled-down to an appropriate size for this article.

It does not need to be written that a tree will burn in a forest fire; nonetheless, I'm not proposing that combustion science is "common knowledge," except among rocket/combustion experts: hence, references. The behavior of such a gas generator is known by early measurements and understood by science since the 1990's. (long after the Apollo era)

An encyclopedic source would be remiss not providing this straightforward information and supportive referenced explanation of details about an important open-cycle gas-generator-based lox/kerosene rocket motor, and this is the page about that motor. Not sure about the comment about "phrasing." 67.61.89.32 (talk) 01:41, 26 August 2020 (UTC)

Consider the sentence "The United Nations' stated objective is to maintain international peace and security, but since its creation there have been 160 wars throughout the world." In this sentence, both parts may be reliably sourced, but they have been combined to imply that the UN has failed to maintain world peace. If no reliable source has combined the material in this way, it is original research. Do you understand? --Soumya-8974 ^talk _contribs ^subpages 09:45, 26 August 2020 (UTC)

Also, this is not an article about the RP-1/LOX rocket engines in general. This article is about the Merlin engine. If you want to write anything about the RP-1/LOX rocket engines in general, go to rocket engine. --Soumya-8974 ^talk _contribs ^subpages 09:48, 26 August 2020 (UTC)

Hi 67.61.89.32. I am a little stuck here. I have provided a detailed justification as to why the content in this section violates WP:NOR, and in your responses you have agreed with me that there hasn't actually been any research on the environmental impacts of the Merlin engine -- thus this content, synthesized in this way, must be original research. To be clear, given that you have identified yourself as a scientist, the bar for "original research" is different on Wikipedia than it is in academia, and it might be good to familiarize yourself with the policy that I am relying on for my views here.

Again, I have no problem with a discussion of the environmental impacts of rocket engines -- and I even don't have a problem with some discussion of the idea that the environmental impacts are yet unknown. However, the content has only one sentence which could conceivably be relevant on this page ("During free-flight of the Falcon launch vehicle in the lower troposphere, the extremely hot main-engine exhaust and substantial partial pressure of atmospheric oxygen are observed to ignite and burn off the gas generator exhaust.") and even that assertion is unsourced. If you want to write about the environmental impacts of the Falcon launch vehicle, find some reliable secondary sources on the issue, and include them on the Falcon page. If you want to provide some information about the environmental impacts of gas generators, contribute to the gas generator page. As Soumya-8974 wrote, if you want to write about the environmental impacts of rocket engines in general, do so on rocket engine. What I don't see here is well-sourced material about the impacts of this engine in particular. I can't find any secondary sources talking about the environmental impacts of the Merlin engine.

Given that I don't see an attempt to engage in discussion about a path forward, per WP:BRD, I am removing the original research once again. Themillofkeytone (talk) 18:28, 26 August 2020 (UTC)

Again, this is direct-referenced information, not a synthesis nor original research - it is directly relevant to the merlin engine. I've cited all the relevant sources necessary while trying not to extend beyond the scope of the page - that is, to discuss these types of engines in general (although there are no other engines of this type currently in use except Delta II) You seem to be interested mainly in keeping this information from being referenced to the relevant engine, namely, the merlin. In particular, you always remove the most important parts - the information about chemistry. This suggests bad faith or an agenda of some sort. Any path forward would include this fundamental information. Since your only agenda seems to be to delete everything related to the chemistry, I'm guessing this might be a sentence-by-sentence thing as the only possible path forward. 67.61.89.32 (talk) 20:01, 29 August 2020 (UTC)

Hi 67.61.89.32. I don't see a response to the points that I have raised -- including my suggestions to move more general statements about gas generators to other pages. As such, I do not feel as though I am being engaged in good faith. I am going to engage dispute resolution resources to see if we can find a path here. In the interests of engaging as best as I can with that process, and for the record here, I am happy to flesh out some of my thoughts on this content.

"During tests of that engine (ca. 1966), Rocketdyne showed that open-cycle RP-1 gas generators of this type yield 20 - 200 pounds of class-1 carcinogens, such as benzene and butadiene, per ton of RP-1 fuel."

This is about a different gas generator from 50+ years ago. There is no direct link to the gas generator used in the Merlin engine. The implication I read is that because they share a design history, the Merlin must also produce the same carcinogens as the F-1.

"Note that by the current date, the thermal-cracking/condensation-polymerization chemistry of fuel-rich aliphatic hydrocarbon combustion has been well-understood for decades."

As a follow-on to the previous sentence, this seems to be saying "something bad is happening, and the perpetrators should know they are doing something bad."

"Due to their toxicity, these combustion products are now legally regulated within the US, providing community and worker health protections which did not exist during the Apollo era."

In context, this sentence says "these bad chemicals might have been OK back then, but they are not OK now." That is relevant if it had been established that the Merlin was producing these same chemicals. As you agree above, the research to back this point up has not yet been done.

"During free-flight of the Falcon launch vehicle in the lower troposphere, the extremely hot main-engine exhaust and substantial partial pressure of atmospheric oxygen are observed to ignite and burn off the gas generator exhaust. However, during the test-stand and launch-stand (pre-lift-off) water deluges, as well as in-flight at altitudes above the mid-stratosphere, this post-combustion is extinguished, and these chemicals, tars, and soot are released to the atmospheric and space environments."

The sources for these sentences do not refer to either the Falcon launch vehicle nor the Merlin engine in particular, with one potential exception (the environmental assessment of 27 September 2007) which is unlinked and has an editorial note indicating synthesis.

"Rocket engine thrust chemistry models and mechanisms exclude large toxic molecules such as benzene and butadiene, and SpaceX Environmental Assessments provide no data on this important chemistry for environment, community, and worker protection."

Who decides that this is "important chemistry?" We have not established that the chemistry is occurring in this engine -- instead, we must assume that this chemistry is happening in this way and at this scale because of tests of a different gas generator for a different engine more than 50 years ago. We have not cited secondary sources that identify this potential omission as a concern. Stringing together a chain of logic in this way reads to me as synthesis.

Taken together, the chain of logic reads to me to be something like: "This gas generator of this old engine produced output which we now know to be potentially harmful. The gas generator used in this engine shares some design features with this old one. SpaceX should know that this harm is possible. They haven't done anything to prove that the harm isn't occurring. Therefore, communities and workers are threatened and should be worried about the Merlin engine." If this argument were made in a reliable secondary source, I would be happy to have it included here. If components of this discussion were included in more general pages, I would be happy to see them. But I don't see a way to include this specific chain of logic without violating WP:NOR and WP:NPOV.

I'm not interested in engaging in an edit war, so I will leave the content as is pending dispute resolution. Themillofkeytone (talk) 22:40, 29 August 2020 (UTC)

It looks like original research to me, so I removed it and invite 67.61.89.32 to explain to me why he believes that it isn't original research --Guy Macon (talk) 00:08, 30 August 2020 (UTC)

Again, you can't just delete information you don't like from an encyclopedia, even by bending the rules. It seems clear that this isn’t coming from a random editor who stumbled across this Wiki page, as initially claimed in this round of protests. The introductory criticism on this section included ad hominem, and falsely cited "original research." Failing that, "synthesis" and "unrelated information" were cited, which are also false. The first sentence clearly lays out the referenced core fact. Subsequent sentences lay out key, related facts/references which aid understanding of the relevant underlying chemistry, as it's been understood for the last few decades. The environmental assessment reports are public record and are also directly related to the merlin engine. You can’t bend rules to serve an agenda of removing information you don’t like (as our current government does https://climate.law.columbia.edu/Silencing-Science-Tracker). Also, if you don't understand the science, don't presume to edit it. 67.61.89.32 (talk) 16:34, 5 September 2020 (UTC)

Don't abbreviate "Wikipedia" as "Wiki"! There are other wikis out there – Wikipedia is just one of them.

See WP:CITE for better understanding about referencing Wikipedia. Given the interest you've expressed by your edits in this article, have you considered joining WikiProject Rocketry? WikiProject Rocketry is a group of editors dedicated to improving the overall quality of Wikipedia's rocketry-related content. If you would like to join, register your account and add your name to the list of participants. Thanks! --Soumya-8974 ^talk _contribs ^subpages 06:41, 8 September 2020 (UTC)

Wikipedia:Administrators' noticeboard/IncidentArchive1046#67.61.89.32.

Wikipedia:Administrators' noticeboard/Incidents#67.61.89.32 again.

--Guy Macon (talk) 04:26, 12 September 2020 (UTC)

Second stage configurations

@Ergzay I just needed a help. Since the data for second stages is not collected like me by any other website as far as I know, so for SpaceX Merlin#Second stage configurations, we don't have a single website in handy to cite my graph. The only reference is to cite all SpaceX livestreams that is a very bad idea, so will just citing https://www.spacex.com/launches/ work? ‍—🪦NΛSΛ B1058 (TALK) 05:24, 26 March 2024 (UTC)

I don't have a good idea. In my opinion it doesn't belong on Wikipedia as it's a pointless statistic that doesn't really matter. It's also nigh impossible to source and in my opinion counts as WP:OR. The text of the article doesn't even talk about short bell vehicles. Nor does it talk about the difference between what a "long coast kit" and a "medium coast kit" are. I only put a citation needed tag on it because some people really want that table on wikipedia for some reason. If you can't find a source for it, then delete it. Note that sourcing SpaceX streams directly doesn't count as that's a primary source and you can't use primary sources generally on wikipedia. See WP:PRIMARY Ergzay (talk) 09:55, 26 March 2024 (UTC)

Everyday Astronaut has told us about short bell vehicles and we have talked on then in SpaceX Merlin#Merlin 1D Vacuum improvements and variants and for medium coast kit i just remembered, there's a line written, "Based on mission requirements, they are Medium Coast & Long Coast kits, i.e., depending on the number of helium bottles for pressurization, added batteries for power and other hardware to make sure that the fuel and stages systems operate as long as needed." ‍—🪦NΛSΛ B1058 (TALK) 14:08, 26 March 2024 (UTC)

For example from WP:PRIMARY.

A primary source may be used on Wikipedia only to make straightforward, descriptive statements of facts that can be verified by any educated person with access to the primary source but without further, specialized knowledge. For example, an article about a musician may cite discographies and track listings published by the record label, and an article about a novel may cite passages to describe the plot, but any interpretation needs a secondary source.

Any smart editor should, without any knowledge of SpaceX or rocketry, be able to verify the information in that table from SpaceX's streams in order to use that as a source. I'm pretty sure that is not possible as not even I, with plenty of knowledge about SpaceX and rocketry, know the difference between a "long coast kit" and a "medium coast kit" and I'm pretty sure most people wouldn't be able to tell what a "coast kit" is. Ergzay (talk) 10:05, 26 March 2024 (UTC)

Long and medium coast kit varies just that after medium coast kit was launched, it was said if grey band is seen on 2nd stage,

1) Mission that requires less than 6 hours of 2nd stage operations (counting coast phases) - medium coast phase

1) Mission that requires more than 6 hours of 2nd stage operations (counting coast phases) - long coast phase

Difference is just the batteries and things required to avoid fuel sloge,etc is more in long wrt medium coast phase. In my opinion, sometimes I feel to merge them as if they are different one may oppose and ask, "Hey if it's as such, recently SpaceX started ditching 2nd stage engine bell stiffener ring, call it a different 2nd stage then!" ‍—🪦NΛSΛ B1058 (TALK) 14:00, 26 March 2024 (UTC)

(Just told the difference in my reply to your 1st comment in this discussion. ‍—🪦NΛSΛ B1058 (TALK) 14:10, 26 March 2024 (UTC)

@RIP B1058 You're missing my point. The fact that you can describe to me what the difference is is completely irrelevant. I'm not the one that needs to know. Any random editor is the one that needs to know in order to verify the information. Ergzay (talk) 16:29, 26 March 2024 (UTC)

Again. Please read WP:OR and WP:PRIMARY. Ergzay (talk) 16:30, 26 March 2024 (UTC)

So Everyday Astronaut's insider view perspective and direct connection to elon/spacex and others such points listed on WP:PRIMARY designate him as primary source? Just confirming what I am realizing is right or still wrong ‍—🪦NΛSΛ B1058 (TALK) 18:02, 26 March 2024 (UTC)

Oh you meant the point 3 in wp:primary that you said explicitly here! ‍—🪦NΛSΛ B1058 (TALK) 18:06, 26 March 2024 (UTC)