Talk:VTVL

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There was a discussion last month about VTVL, VTHL, etc. terms for Spacecraft and Rockets? on the WikiProject Spaceflight discussion page. Interested editors may want to look at it as part of initiating a more thorough discussion of Aviation-related and Spacecraft-related terms here on THIS talk page. Cheers. N2e (talk) 16:35, 13 January 2011 (UTC)[reply]

I have imported the full discussion to this page (below, in the next Talk page section), as this is really the relevant place to discuss article improvement. I was thinking of trying to summarize the key grafs but want all opinions to be fully and fairly represented. N2e (talk) 16:41, 13 January 2011 (UTC)[reply]

VTVL, VTHL, etc. terms for Spacecraft and Rockets: Should they be kept separate (and cleaned up)? Or merged into the aircraft related term articles? Or what?

There is a poor quality "rocket"-specific article on VTVL, which also briefly mentions VTHL and HTHL. In addition, there are a series of articles that are aircraft-specific (e.g., VTOHL, VTOL; plus see the template bar that is the bottom of each of those articles).

The rocket/spacecraft definitions are unclear. Is the Space Shuttle and the X-37B a VTHL? According to a definition from what source? Or should VTVL be reserved for non-staged craft like the small Lunar Lander Challenge vehicles?

Given the new CCDev phase 2 proposals announced yesterday, at least of couple of which appear to be VTHL spacecraft, I'm thinking it would probably be useful to think about this at a project level soon and see if a consensus might not be reachable as to how to improve the extant articles. What do others think? N2e (talk) 15:23, 14 December 2010 (UTC)[reply]

• I...honestly can't see the slightest difference between 'VTVL' and VTOL, and I've never even heard of VTVL before (yet alone 'VTHL' and 'HTHL'). I, personally, believe VTVL should be a redirect to VTOL, and the others, well VTHL could redirect to VTOHL, and HTHL...well, that's pretty much 'the default' for aerospacecraft and would seem to be at best sometihing for Wiktionary. - The Bushranger _{One ping only} 16:33, 14 December 2010 (UTC)[reply]

• Merge all of the stubs into one article as a table, perhaps, with any larger articles staying as they are? Colds7ream (talk) 14:40, 15 December 2010 (UTC)[reply]

• That would actually make the most sense, I think, yeah. - The Bushranger _{One ping only} 18:04, 15 December 2010 (UTC)[reply]

• I'm with Bushranger; why not merge VTVL (for spacecraft) into VTOL (for aircraft)? The VTOL article already mentions how the term for rockets is VTVL (with a citation needed tag!). Similarly for VTHL -> VTOHL. I don't see why there should be separate rocket specific articles. The template {{Types of take-off and landing}} doesn't specify that it's only for aircraft. Mlm42 (talk) 17:12, 15 December 2010 (UTC)[reply]
  • These has been discussion on this on Talk:VTOL as well. Mlm42 (talk) 17:15, 15 December 2010 (UTC)[reply]
  • By the way, NASA does in fact use the term VTVL (see here). Mlm42 (talk) 17:18, 15 December 2010 (UTC)[reply]

Well, as I said earlier, I think I'd be happy to go with whatever is proved by sources to be both notable and cited. However, in my reading over the years, I do think that the acronyms with the "O" in them (STOL, VTOL, VTOHL, etc.) tend to be used in the aircraft community and aircraft literature, while those without the "O" (VTHL, VTVL, HTHL) tend to be used in the space community. Clearly, there is a large recent, if informal, use in the alt.space (NewSpace) community to use these terms to compare the wide variety of design concepts, and even vehicles in development or in use: VTHL (the new Orbital lifting-body spaceplane proposal for CCDev2 fits here, but so does the X-33, X-37B, and the Space Shuttle); VTVL (e.g. Blue Origin New Shepard, all the Armadillo Aerospace rockets, all of the Masten Space Systems rockets, and the SpaceX plan to equip the Dragon spacecraft with a vertical landing capability in a future version); and HTHL (Reaction Engines Skylon, Rocketplane XP, SpaceShipTwo, etc.)

At the end of the day, Wikipedia ought to reflect whatever is descriptively verifiable, and not be force-fit to use whatever language we might prescriptively prefer. I don't know for sure just yet what that language is, but my sense tells me that there will be a distinction between the terms used by the two communities, and that it will be a distinction with a difference. Cheers. N2e (talk) 18:16, 15 December 2010 (UTC)[reply]

I completely agree that it should be explained that the aircraft and space terms are different. Absolutely, since this is backed up by reliable sources, and seems readily verifiable. This distinction should definitely be made within the article. That said, I don't think it's worth having two separate articles for such similar concepts. It would be like having two separate articles: Astronaut and Cosmonaut. Two groups of people have different names for the same concept, but we should only have one article. Mlm42 (talk) 18:49, 15 December 2010 (UTC)[reply]

I agree with Mlm42: only a single article is justified to clarify all the various concepts, both aircraft and spacecraft/rockets. Probably could modify the existing VTVL article to become this newly-scoped, more comprehensive article. However, since the aircraft community clearly has an existing set of articles on the various concepts, the ones I looked at all look rather aircraft-centric (e.g., STOL, VTOL, VTOHL, etc. -- see the template at the bottom of any of those articles to get the full set of A/C extant articles), I think each subsection of the aircraft section of the more comprehensive article would need to link/point to the fuller details. But I don't think it necessary to create separate spacecraft-centric articles on VTVL, VTHL, HTHL, etc. N2e (talk) 05:45, 16 December 2010 (UTC)[reply]

I think the content of this article should be split into the relevant aircraft-related articles. An overview of the different types of takeoff and landing types would be appropriate for the articles Rocket or Spacecraft, and should probably be added to new sections there. Mlm42 (talk) 17:33, 13 January 2011 (UTC)[reply]

I've started a discussion here on the VTOL talk page regarding a merge. Please add comments there. I'm not sure why this article has recently been extended to include concepts other than VTVL; based on the above discussion, they should probably go in the relevant aircraft-related articles. Mlm42 (talk) 17:29, 13 January 2011 (UTC)[reply]

My thinking is that it would be difficult to impose the more common rocket-related terminology (VTVL, VTHL, HTHL, etc.) on the aircraft wikicommunity, where they have an extensively-developed set of separate articles using distinctly different acronyms (VTOL, STOL, HTOL, etc.) that have a long history in aviation related literature. Thus, I oppose the merge.

But as I said in the previous discussion, I definitely agree with your concept that only a single article is justified to clarify all the various concepts, both aircraft and spacecraft/rockets. We could indeed probably modify the existing VTVL article (this article) to become a newly-scoped, more comprehensive article, and it would likely then need to be renamed as well to adequately describe the space-side terminology (VTVL, VTHL, HTHL, etc.). However, we aren't working in a vacuum here, and since the aircraft community clearly has an existing full set of articles on the various concepts, the ones I looked at all look rather aircraft-centric (e.g., STOL, VTOL, VTOHL, etc. -- see the template at the bottom of any of those articles to get the full set of aviation-centric extant articles), I think each subsection of the aircraft section of the new more comprehensive article would need to link/point to the fuller details. But I don't think it necessary to create separate spacecraft-centric articles on VTVL, VTHL, HTHL, etc. N2e (talk) 18:06, 13 January 2011 (UTC)[reply]

I don't think you should think of it as rocket-people "imposing" on aircraft-people. All that would be required is in the first line of the VTOL article say something like "also called VTVL, in rocket-related contexts". Again, you opposing this merge is analogous to someone opposing the merge of cosmonaut into astronaut. I understand that different people use different terms, but a single concept should be in a single article.

I also don't think we need an entire article to clarify the various concepts.. why not explain this in the article Rocket or Spacecraft? It really doesn't seem like the situation is so complicated that it should have it's own article.

And can we move this discussion to the VTOL talk page, as I requested above? Mlm42 (talk) 18:20, 13 January 2011 (UTC)[reply]

I would be happy to respond on that page; but much of your substantive comment exists only on this page. Let me know which you prefer. I want to write my response to your comment on the same page in which your comment exists. I'll try to get back to this and check on it in another day or so. Cheers. N2e (talk) 06:13, 14 January 2011 (UTC)[reply]

And by the way, I agree with some of what you've presented, and think we can definitely come up with something workable if we keep at it. N2e (talk) 06:15, 14 January 2011 (UTC)[reply]

I guess I don't understand what's wrong with a merge of this VTVL article into VTOL. Several editors in the above discussion appear to support this move; your main objection, N2e, appears to be that you think aircraft-editors won't like it? Mlm42 (talk) 06:33, 14 January 2011 (UTC)[reply]

I was meaning for you to let me know which article Talk page you wanted to continue the discussion on. But I believe that what I wrote was not very clear. Sorry for the confusion. Looks like you are fine with continuing the discusion staying here, no?

On the substantive point, you said

I don't think you should think of it as rocket-people "imposing" on aircraft-people. All that would be required is in the first line of the VTOL article say something like "also called VTVL, in rocket-related contexts".

I agree with the basic idea you've expressed here. A single article for the concept would be best, in a perfect world. But Wikipedia is an emergent world. Several of the aviation-centric articles have extensive, and quite long, histories and would necessarily overwhelm the brief info that hase been wiki-written to date on the rocket/spacecraft-related technologies and terms.

So how might we get there? I'm still thinking a merge of this article, as is, into VTOL is not a good move. However, if some group of interested editors were to improve/write a decent paragraph or two, a "stub" so to speak, on each of the four rocket/spacecraft-related terms, and then some editor were to insert that "section" into the existing aircraft-terminology-titled articles, with your suggested text in the beginning of the lede ("also called VTVL, in rocket-related contexts"), and maybe add a {{sectstub}} tag to the section to encourage rocket-related examples and elaboration to occur emergent. Now even all that doesn't quite get it. We would also need to, eventually, create top-level sections in each article for ==Aviation== (or Aircraft) and ==Spacecraft== (or Rocket, or ???), and then demote all of the extensive existing aviation-related section headings to ===Heading=== rather than ==Heading==. If we accomplished all of this, without a revolt from the existing aviation-centric articles editors who care, etc., then I think we would have a good solution. And then, of course, we would need to ensure the four VTVL/HTHL/VTHL/HTVL terms all have redirect pages that get them to the correct section of the (wrongly named) articles. Absent some way of getting to the end state, I don't yet want to see this article removed (which it would be, via a merge). Anyway, I think it is doable if we were to begin to make a few of these steps, and guide it over time. In the process of doing all four terms in this way, we would eliminate the need for this article and it could be deleted (or alternatively, we could just fold in the VTVL stuff last, via a merge). What do you think about any of these ideas? N2e (talk) 07:29, 14 January 2011 (UTC)[reply]

You outline a good plan; as the anon pointed out below, the only aircraft-related articles are VTOL and the tiny stub VTOHL, so I doubt there would be many people complaining if we were to expand them.. there isn't really a corresponding aircraft article for HTHL or HTVL; I think this content could easily be put into the Spacecraft#Reusable vessels section. Of course I don't think we should redirect the VTVL article until its content is diffused elsewhere. I think the Spacecraft article could do with an overhaul anyway. Mlm42 (talk) 16:31, 14 January 2011 (UTC)[reply]

The issue of having an article to "explain the differences" is a separate issue, and should be kept separate.. this is the talk page of the article VTVL, and I don't think this article should exist separate from VTOL. Adding content relating to concepts not related to VTVL is confusing the matter (hence the confusion of the anon below). If you think there should be an article to explain the differences between the different acronyms, this article is not the place for it. I have suggested either the article rocket or spacecraft as possible alternatives. Mlm42 (talk) 06:33, 14 January 2011 (UTC)[reply]

I didn't set up this confusing article to be named one thing and then have a little bit of poorly-done stuff on other terms as well. That is how I found it when I discovered it three weeks ago. But until we get an approach in place to more comprehensively deal with all four rocket/spacecraft-related terms, then I'm just not quite ready to "disappear" the entire subject, such as it is, with a single merge. Hope that explanation is helpful to forward progress. N2e (talk) 07:29, 14 January 2011 (UTC)[reply]

mergers? huh?[edit]

I'm not sure I'm understanding the proposals. (1) Is it to merge all the rocketry articles into one article? or (2) To merge each rocketry concept into its equivalent aircraft concept? (3) To merge all aircraft concepts into one article, and all spacecraft concepts into another? (4) Merge all rocketry and aircraft concepts into one grand article?

If it is (4) or (3), I definitely oppose since several of the aircraft articles are quite big. In any case, HTHL equivalent in aircraft is covered by alot of articles (CATOBAR, STOL. STOBAR, CTOL, etc) all of which have alot of background material to build out their own subarticles and subsubarticles. This also applies to VTOL, S/VTOL, STOVL, and even VTOSL (autogyros with spinup capability do this mode). 65.93.14.196 (talk) 22:25, 13 January 2011 (UTC)[reply]

The proposal, as the merge tags indicate, is what you call (2). In fact, I've only proposed a merge for the one case VTVL -> VTOL. Unfortunately the VTVL article currently has a much more content than it should; this is probably why you were confused. Mlm42 (talk) 01:01, 14 January 2011 (UTC)[reply]

As an aside, it would seem I've failed at trying to keep this discussion on the VTOL talk page.. oh well. Mlm42 (talk) 01:03, 14 January 2011 (UTC)[reply]

I understood the merge tag, but the discussion in the several sections above detail what appears to be different things, hence my confusion. 65.93.14.196 (talk) 06:44, 14 January 2011 (UTC)[reply]

So do you support the merge suggested by the tags, then? Mlm42 (talk) 06:52, 14 January 2011 (UTC)[reply]

Though the concepts covered here, VTVL is VTOL, HTHL is HTOL, VTHL is VTOHL, but HTVL isn't covered by any single aircraft article... No one wrote a HTOVL article. And HTOL is currently a dab page to all the various HTOL articles, as we don't have a single article for that one either. It certainly isn't CTOL, since there's nothing conventional about a rocket taking off sideways and landing that way. A CTL for rockets would be taking off vertically and crashing back down vertically. 65.93.14.196 (talk) 06:48, 14 January 2011 (UTC)[reply]

The merge discussion above appears not to have developed a consensus. But there was some agreement amongst (at least) two editors about a process that might work for improvement, essentially by adding spaceflight-related terminology and prose to the existing aviation-centric article set. Here is a recapitulation of the main ideas of that proposal:

Given that Wikipedia is an emergent world and several of the aviation-centric articles have extensive, and quite long, histories and would necessarily overwhelm any brief info that has been wiki-written to date on the rocket/spacecraft-related technologies and terms, how might we get started on improvement?

N2e Proposal: If some group of interested editors were to work together to

1. improve/write a decent paragraph or two—a "stub" or "sandbox draft" so to speak—on each of the four rocket/spacecraft-related terms (VTVL, VTHL, HTHL, and HTVL). and then some editor were to
2. insert that "section" into the existing aircraft-terminology-titled articles, while adding Mlm42's suggested text in the beginning of the lede ("also called xTyL, in rocket-related contexts"), and then maybe
3. add a {{sectstub}} tag to the rocket/spacecraft-related section in each of the (overwhelmingly aviation centric articles) to encourage rocket-related examples and elaboration to occur over time;
4. ensure appropriate redirs are created/adjusted for VTVL, VTHL, HTHL and HTVL–they could redirect directly to the section of the aviation-named article via something like, for example for VTVL, #REDIRECT [[VTOL#VTVL]]. Finally, if we wanted to, we might go one step further:

(this next item should be left for later on, and not done too quickly: I'm thinking a few weeks or a month later. Moreover, it need not be a part of the main mutual effort at all, and could be left to the natural evolutionary change of the articles over time.)

5. The first four steps don't quite get us to an even-ground article set that clearly explicates both the aviation- and spaceflight-related terms in a minimum set of articles for the various sorts of takeoff-and-landing vehicles: the articles would still have a large number of level-2 section headings for the aviation-related material and the spaceflight term would have only one. We might therefore also want to, over time, create top-level sections in each article for ==Aviation== (or Aircraft) and ==Spacecraft== (or Rocket, or Spaceflight, or ???), and then demote all of the extensive existing aviation-related section headings to ===Heading=== rather than ==Heading==.

In my view, if we accomplished the first four steps, without a revolt from the existing aviation-centric articles editors who care, etc., then I think we would have a good solution. Mlm42 seemed to agree with the conceptual approach when I first outlined it a month ago in the midst of the merge discussion.

My question is, are there any others willing to help with this mini-project and devote a few hours of edit work to it? If so, I'm in. If not, I think I'll just let the idea age until such time as any fellow-interest emerges. Cheers. N2e (talk) 18:17, 4 February 2011 (UTC)[reply]

Let's just be clear.. VTOL and VTVL are really the only articles that currently have any content. HTOL is a disambiguation page, without an article about "Horizontal takeoff and landing"; VTOHL is a stub, and won't be damaged by being expanded - in particular if someone were to add in stuff about rockets. So I'm not sure which articles you are calling "overwhelmingly aviation centric"? It's just VTOL, right?

I did not look at each of the aviation possibilities; I was just aware of the template at the bottom of many of the aviation pages called "Types of take-off and landing", or {{Types of take-off and landing}}: that listed (and still lists) over a dozen types of take off and landing, from an aviation-centric point of view. At the time I last saw that template, it listed only the dozen or so types for aircraft. I see today that some editor has recently added a "Spacecraft" line to that template, with the four terms we have been discussing here.

In any case, if the articles for any of these terms don't exist in the aviation-centric article space, it does not change my view. We would still want articles that represent the four conceivable types, as used in spaceflight literature, and spaceflight fiction. Per your suggestion, it still would be fine to have only one article discuss both the spaceflight and aviation-related term(s) and usages. So I don't see it as only about VTVL/VTOL. N2e (talk) 04:59, 6 February 2011 (UTC)[reply]

On another note, are there sources that actually use the terms "HTVL" and "HTVOL"? Also, some sources use HOTOL instead of HTHL. Mlm42 (talk) 22:17, 5 February 2011 (UTC)[reply]

I have just learned that HOTOL is a proper noun, and refers to a specific British SSTO spaceplane that was never built, but is apparently the predecessor from a concept point-of-view of the currently-under-development Skylon HTHL spaceplane. I'm not aware of any literature that uses the term HTVOL, but that doesn't mean someone can't find a use of the term. When they do, if it is reliably sourced, I would assume it would be listed in the appropriate Wikipedia article based on whatever that acronym might mean. N2e (talk) 09:11, 7 February 2011 (UTC)[reply]

Here's a book that uses all four of the terms (VTVL, VTHL, HTHL, and HTVL): Lockheed Secret Projects: Inside the Skunk Works, see p. 97. I think that is how I've usually seen the terms, although some of my reading is, I imagine, space fiction. And here are a couple more on HTHL: Performance and technological feasibility of rocket powered HTHL-SSTO with take-off assist, Japan JAXA: A Proof-of-concept Approach for Horizontal Take-off/Landing Rocket Plane, and here. And one of the (pretty rare, I would guess) HTVL examples: Hyperion SSTO. N2e (talk) 04:59, 6 February 2011 (UTC)[reply]

UPDATE: Looks like my proposal for a specific process we might follow to improve the spacecraft/rocket explication of these terms has failed to find a consensus. So I'm going to take this page off my watchlist for now. If anyone comes along later on and wants to pursue a course of action similar to the steps I outlined above, just ping me on my Talkpage and I'll see if I can't help out. Cheers. N2e (talk) 22:10, 15 February 2011 (UTC)[reply]

Earlier, there was some question on the usage of these terms (VTVL, VTHL, HTHL, HTVL). Well here is a recent NASA source that uses two of these terms—HTHL and VTVL—with respect to several commercial designs being looked at for the NASA Flight Opportunities Program for suborbital science. sRLV platforms compared. Cheers. N2e (talk) 06:36, 10 March 2011 (UTC)[reply]

Are Vertical Takeoff, Parachute Landing (VTPL?) spacecraft in-scope for this article? If so, then a very large group of spacecraft will be added to this article shortly: Project Mercury spacecraft, Project Gemini spacecraft, Soyuz (spacecraft), Apollo (spacecraft), Stardust (spacecraft), etc, etc. I've never seen a source apply the VTVL moniker to that type of vehicle.

I'm asking because a fairly recent addition to the article is a VTPL spacecraft. I'm thinking it is out of scope, but could not find an explicit previous discussion. Opinions from others? N2e (talk) 05:00, 29 October 2013 (UTC)[reply]

What should this say now? Looking through 'see also' links, we appear to have:

1. SpaceX
   1. Falcon9 1.1 FT / 9R / heavy
   2. MCT is this being developed yet?
2. Blue Origin
   1. New Shepard
3. NASA
   1. Pixel Quad (rocket) Originally Armadillo Aerospace but sold to NASA in 2010

Presumably no longer in development: Zarya (spacecraft) cancelled 1989 Kankoh-maru seems to have little detail and dates to 1993. McDonnell Douglas DC-X last flight 1996 Grasshopper (rocket) F9R Dev1 F9R Dev2 Project Morpheus no further development funds last flight Dec 2014

Who was or is the fourth company?

Also not sure how to count rocket vehicles eg is Falcon 9 Heavy separately counted from v1.1FT? 9R separate to v1.1 FT? Is MCT just being discussed while enabling tech is developed with 9R and Heavy so it is not really under development yet? crandles (talk) 10:33, 24 December 2015 (UTC)[reply]

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A discussion is taking place to address the redirect Retropropulsive landing. The discussion will occur at Wikipedia:Redirects for discussion/Log/2020 September 28#Retropropulsive landing until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Soumya-8974 ^talk _contribs ^subpages 18:31, 28 September 2020 (UTC)[reply]

@BilCat: Regarding your removal of the following:

The Young Sheldon episode, "A Patch, a Modem, and a Zantac®" features Sheldon developing the equations for VTVL, only to have them rejected by NASA for lack of the technical capability to implement it at that time. Sheldon concludes that he is ahead of his time. 27 years later, a flashforward in 2016 shows the successful SpaceX CRS-8 mission, followed by SpaceX founder Elon Musk looking over Sheldon's old notebook then hiding it in a desk drawer.

What in WP:IPC leads you to think that this content is inapplicable? It is clearly describing a fictional theory of the original of VTVL (resulting in a depiction of its application). Granted, it is uncited, but is easily citable (see, e.g., Looper, "The Young Sheldon Episode You Likely Forgot Starred Elon Musk"). Cheers! BD2412 T 06:53, 15 April 2022 (UTC)[reply]

"Granted, it's uncited". Exactly. See WP:IPCV. In particular, "In popular culture" sections should contain verifiable information with sources that establish its significance to the article's subject. I'm not certain the Looper mention is significant enough, but you should be able to find something a bit more robust. BilCat (talk) 07:09, 15 April 2022 (UTC)[reply]

In the paragraph about Landing Technology, it is stated that "thrust must be less than weight". Is there a source for that? A rocket for which the thrust is less than it's weight would accelerate downwards, making it impossible to slow down for landing. 2A01:CB19:894F:5E00:6369:E1E0:FEDA:13E5 (talk) 10:03, 25 January 2023 (UTC)[reply]

I second this. Also it doesn't even make sense. The retroactive thrust might be equal to or even *greater* than the weight to achieve decceleration. 47.54.235.85 (talk) 18:36, 18 October 2023 (UTC)[reply]