Talk:Difference between sub-orbital and orbital spaceflights

Article naming

I suggest this fuzzy article be scrapped in favour of one which describes the difference between non-orbital flights, low-earth orbit, geo-stationary transfer orbit, geo-stationary orbit and non-orbital flights which do not return (hyperbolic or parabolic as opposed to elliptic). One exists: earth orbit. A discussion of the relative energy costs is interesting: There are simple ratios between the speed required for LEO, geostationary orbit and escape velocity, e.g. Paul Beardsell 04:19, 24 Jul 2004 (UTC)

Keep this article, it is not at all a duplication of what is in earth orbit, which is just a list. Expansion of that article would be interesting. If that causes any duplication, some could be deleted from this article, or the two could be merged.--Patrick 06:08, 25 Jul 2004 (UTC)

OK. I would like then to rename this article to something like Types of orbit. What do you think? Do you think it should stay named as is or do you have a better suggestion than mine? Paul Beardsell 22:26, 25 Jul 2004 (UTC)

The current name seems more specific. The article explains the difference between two things, not going into all varieties of one of them, the orbit. Also it does not seem correct to call something less than an orbit a kind of orbit.--Patrick 09:58, 26 Jul 2004 (UTC)

I agree with Paul. A sub-orbital flight in free-fall is in orbit -- it's just an orbit that will intersect the Earth's surface unless something is done about it. Paul's suggestion of categorizing by energy / delta-V is insightful, and will create a much better article. -- The Anome 10:44, 26 Jul 2004 (UTC)

Technically, in a strictly technical sense, The Anome, you're right. But, in all honesty, your definition does seem to me a bit of a stretch when talking to "the rest of us (mere mortals)".

As regards the renaming/reorg proposal, it was me who started this article. I acknowledge and do realize that it's got one long article name. I couldn't however think of a more fitting name (that would have been shorter). I mean, this article is simply an article about this very specific issue. That's not to stop anyone from using some of the information in it in other, more general articles (which might have shorter names). In an earlier paragraph contribution (now reverted), Psb777 seemed (to me) to sound a bit exasperated that this article was even necessary and argued that only a "knowledge of English" was required. I understand that exasperation. But this article probably isn't here for people with Psb777's knowledge. It's here for people who don't immediately understand the difference between sub-orbital and orbital flights. For the benefit of such readers, and there's quite a few of them out there, believe you me, I suggest this article to stay/coexist. That's not to stop Psb777 or indeed anyone from writing a far more detailed and technically more accurate article with a wider scope in addition to this one. Ropers 20:49, 27 Jul 2004 (UTC)

<u>&mdash;</i> teh embassarment

Gee, I sure wish I could correct my mentally challenged edit summaries in the history. Alas, no such thing. I'm just saying. Ropers 20:19, 27 Jul 2004 (UTC)

What are we writing?

I agree with much of what Ropers is saying above BUT I really do believe that English is enough. Almost it is the case that the less technical knowledge the better in understanding the issue of the "difference between sub-orbital and orbital spaceflights". Certainly no technical knowledge is necessary. However, the "different energy requirements" or the "different re-entry problems" do require technical understanding and, failing which, a technical explanation. They do require an encyclopedia, not a dictionary. Paul Beardsell 23:37, 27 Jul 2004 (UTC)

I think the article is interesting and each one of us has contributed to it in a worthwhile way. Certainly some corrections to and re-writing of my text were necessary just as I hope some of mine were of others'. But what are we writing? I think we need a better article title. Paul Beardsell 23:37, 27 Jul 2004 (UTC)

Hm... Seems to me that there's quite a bit of common ground here. However, I still think this article should not be renamed (and, totally in good humor and without any smart-aleckness whatsoever, I do kinda think we're writing precisely this: an article on the difference between sub-orbital and orbital spaceflight ;-) Anyway, IF you still were to want to go ahead and try to get this article renamed (rather than, say, writing another one that might contain some of the same info), then — seeing that Patrick and myself are opposed and The Anome and yourself are in favour of it — well, I think it would probably be a good idea to call a vote before moving anything. Again, that's IF you still feel that you really want to go ahead with a move. Thanks and best regards, Ropers 15:41, 28 Jul 2004 (UTC)

Gravity drag on sub-orbital flights

In this version I said the following (emphasis mine):

"Also, real flights experience atmospheric drag and gravity drag. For an orbital launch, these require an additional delta-v of typically 1.5–2 km/s (see delta-v budget); for a sub-orbital flight, these consume the entire delta-v (and more) produced by the rocket."

This was modified on the following grounds:

"confusing to compare ascending of one system with the whole flight of another"

However, I was actually comparing the entirety of both flights. There is no descending part of a successful orbital insertion, while sub-orbital flights always return to the ground by definition. Hence, I'd like to reinstate this text as it was. Thoughts? --Doradus 20:40, 23 November 2005 (UTC)

Atmospheric drag when ascending requires extra effort to reach a certain altitude, when descending it is helpful to decelerate. What is the point in adding the two?--Patrick 20:52, 23 November 2005 (UTC)

Ok, we can get rid of "and more" if you prefer. --Doradus 23:52, 24 November 2005 (UTC)

It should be clear what you compare. Orbital flights may also have a descending part. Anyway, reentry is a separate subject treated in another section, not requiring rocket propulsion (except on the Moon, etc.), and without gravity drag. This section is about the effort to reach orbit or just a certain altitude.--Patrick 01:28, 25 November 2005 (UTC)

Ok I reinstated it without the "and more". I think it's clear that we're comparing an orbital launch with a sub-orbital flight, so I think this should meet your criteria. Is that alright? --Doradus 15:49, 25 November 2005 (UTC)

So you are saying "When back from a trip, the effort of making the trip has been used up." But what is your point?--Patrick 16:31, 25 November 2005 (UTC)

Actually I was talking about when the ship is at the apex of its trajectory. Then it is (vertically) at rest, so all the delta-V provided by the rocket has been cancelled by gravity drag (and some atmospheric drag). Ok I guess it's possible there's still some horizontal velocity, so that may not be strictly true. --Doradus 20:18, 25 November 2005 (UTC)

Do not forget the 965 kJ/kg potential energy (which is not gravity drag).--Patrick 21:04, 25 November 2005 (UTC)

It's not? Ok I don't understand this as well as I thought. Please feel free to edit the statement as you see fit. --Doradus 19:23, 26 November 2005 (UTC)

Ok, I did.--Patrick 21:25, 26 November 2005 (UTC)

I like it. --Doradus 00:43, 27 November 2005 (UTC)

Possible Bias

This article reads to me like a pamphlet by X-Prize enthusiasts. It seems to imply that the differences between orbital and sub-orbital flights are minor, while bemoaning that the uneducated public doesn't understand both go up really high.

For example, near the beginning it states 'The general public often thinks of orbital spaceflights as spaceflights and of sub-orbital spaceflights as "something less than actual spaceflights". This is not accurate; both orbital and sub-orbital spaceflights are true spaceflights.' Well, yes, by definition, but that doesn't mean they're similar. The actual differences are buried in the calculations: 31.5 times as much energy. That doesn't even include lifting the propellant; although calculations are done, no numeric comparison is given. The numbers are ignored elsewhere. Of the five points listed in the summary, three suggest they are basically the same, one admits a difference without mentioning the scale, and the last makes an unrelated point.

I'd like to pull out extraneous parts of the intro, clean up and finish the calculations, and emphasize the scale of the difference in the intro and summary. But I'm concerned I might be biased myself, so I'm asking for comments here first. :) Bennetto 03:01, 5 November 2006 (UTC)

I agree, i find it biased. I came here expecting to see an article on the very big differences between the two type of flights. While both flights exceed a conventional altitude limit and are indeed spaceflights by definition, in practice suborbital flights are done by little more then pressurized planes with rocket engines. I think the public generally underestimates the difference betwen the two. A brief explenation of what the difference between the minimal suborbital and orbital speeds means in the ammmount of propelant/size and weight of craft needed, as well as perheps economic costs would be more relevant. Things about speeds and energy are mentioned in the article, but not the summary. I think generally the focus is wrong.

Anyway if you want to clean up you have my aproval.--Helixdq 12:56, 9 November 2006 (UTC)

Wrong redirect

This article is now a redirect, but it redirects to the wrong place: oddly, Spaceflight doesn't mention orbital or suborbital flight until Spaceflight#Reaching space. Ugly though it may be, this redirect now points there. Sdsds 04:20, 27 March 2007 (UTC)