Talk:Reduced-gravity aircraft/Archive 1

Parabolic or elliptic?
I have always thought that a parabolic orbit occurs when the free moving body has precisely the escape velocity. An airplane cannot reach that speed, so the orbit should be elliptic in order to produce weightlessness. Who can comment? &minus;Woodstone 10:15:12, 2005-08-29 (UTC)


 * You dont have an orbit at all, you're not applying satllite theories. What you need to feel weightless is to accelerate towards the earth with 9.81m/s^2 = 1g. If you do this with an elevator, you'll have a straight line flight. If you take a plane, and have constant velocity forewards, and add constant acceleration downwards, you'll end up flying a parabola. See Trajectory for more info. demo 11:09, August 30, 2005 (UTC)

You get a parabolic trajectory in a homogeneous force field. The Earth's gravity is directed towards the center of Earth and diminishes with distance, so both size and direction vary. For a feeling of weightlessness, the movement must follow this acceleration at every point of its trajectory. It should be indeed a (fraction of) an orbit (that would intersect Earth if prolonged). &minus;Woodstone 17:12:48, 2005-08-30 (UTC)


 * The Weightless Wonder falls only about eight thousand feet at a time. Earth's gravitational acceleration does not vary substantially over such a short distance, so you do get a parabola. The tiny amount of variance is lost in the noise, since the Weightless Wonder's trajectory is also disrupted by air turbulence, the flexion of the plane's body, and other factors.


 * Free fall occurs when an object experiences only one force: its own weight. So an object in orbit is in free fall, but so is an object that has been dropped and is falling toward the Earth in a vacuum. Not all free-falling objects are in orbits. The Weightless Wonder is in free fall, but it is not in an orbit.


 * "Orbit" is defined, as 'the path an object makes around another object while under the influence of a source of centripetal force'. The Weightless Wonder is not going "around" Earth during its trajectories in any meaningful way; it's just falling toward earth (and continuing forward by momentum), like a thrown ball. Tossing a ball forward and upwards would also gives you a parabolic trajectory. -Corvi 00:19, 7 March 2006 (UTC)

The trajectory is elliptical. The "vomit comet" achieves simulated weightlessness in a similar way that the space shuttles do: by making the acceleration (in terms of both magnitude and direction) of the aircraft to be very close to the acceleration due to gravity. The resulting trajectory is an elliptical path with one focus of ellipse at the center of the earth. Not only must the path be elliptical, but also the specific angular momentum about the earth must be constant. If the acceleration due to gravity were the same everywhere, the task of calculating the shape of the trajectory becomes simple enough for a high school physics student and the result is a parabola. However, if one to take into account that the earth isn't flat and infatuate, but rather (approximately) spherical, the mathematics is more complicated but the result would be an ellipse. The parabola matches the ellipse very closely for the relatively short distance that the aircraft typically flies. 4.235.84.197 21:33, 11 March 2007 (UTC)Tim G


 * I tagged the paragraph about the elliptical trajectory as needing attribution to a reliable, published source. It's not enough to be correct; we have to cite verifiable sources that make the claim, and we report it. Wikipedia is not the place for original research. --Jdlh | Talk 04:28, 14 March 2007 (UTC)


 * In the month since 14 March 2007, no-one has stepped forward with a citation for the use of "elliptical trajectory" for this flight path. Today Omegatron added an "accuracy" tag to the section, with a comment, "NASA calls it a parabola. Also see Parabolic trajectory". I sense a rough consensus of editors that "parabolic trajectory" is the better description. I've reversed Tim G's changes of 11 March 2007. I put back the text that was there before, and added a "needs citation tag". It's not perfect, so perhaps others will improve it. --Jdlh | Talk 04:53, 20 April 2007 (UTC)

The path would be parabolic if the earth were an infinite flat plane. But the Earth is a ball, and its gravity points towards its center. So the trajectory of any object in free-fall is some kind of conic section. It would be a parabola or hyperbola if the vomit comet path had enough energy to escape the Earth's gravity (assuming it passes to the other side of the Earth); but the airplane clearly does not have enough energy to do so. So the path is an ellipse. To those who say that it is not an orbit -- the only thing that stops it from being an orbit is that the ground is in the way. If the Earth were shrunk down to a point with the same mass (its gravitational field would still be basically the same), so that the ground is not in the way, then the airplane can indeed make an orbit and come back to where it started; and this orbit would be an ellipse. The difference between an ellipse and a parabola is that a parabola has an eccentricity of 1 and an ellipse has one that is less than 1. The elliptical path that we are talking about here has an eccentricity that is very close to 1, so it is very close to a parabola, but mathematically it is still a ellipse. --164.67.235.138 (talk) 20:53, 1 October 2009 (UTC)

end date
The opening paragraph says the Vomic Comet flew from 1973 to 1995, and then later in the article it mentions events in the 2000s. Which is correct? -- nae'blis (talk) 19:07, 21 March 2006 (UTC)
 * Good question. &mdash; db48x | Talk 02:04, 22 March 2006 (UTC)

They have been taking paying passengers on these flights as recently as 2006. DaveApter 09:17, 14 August 2007 (UTC)

Changed aircraft to airplane
I changed aircraft to airplane throughout, because the Vomit Comets have always had wings.--Jtir 15:03, 24 September 2006 (UTC)


 * Unfortunately, the casual use of both "airplane" amd "aeroplane" is highly contentious, so their general use in WP articles is discouraged by WP:AIR guidelines. Therefore, I restored "aircraft" in all cases in the article. Sorry! I think the need for the policy is stupid, but too many on either side of the Atlantic are intolerant of the other side's usage. - BillCJ (talk) 13:44, 6 June 2009 (UTC)

Why is it called the Vomit Comet?
As this anon noticed, the article never explicitly says why these airplanes are called the Vomit Comet. --Jtir 03:45, 26 September 2006 (UTC)
 * Uhhh, well, many, many people have a physical reaction to their first freefall experience. Need I go on? Fan-1967 03:47, 26 September 2006 (UTC)


 * Beginning your talk responses with bullets and "Uhhh" hardly adds to your credibility, Fan-1967.&mdash;QuicksilverT @ 18:41, 16 August 2010 (UTC)

Moon Missions?
It says that astronauts trained for the moon, but also that it started in 1973. Isn't that too late for the moon missions, wasn't the last landing in 72?
 * I agree, that doesn't make any sense. Since there's no citation to back it up, I'm deleting it.  Wbrameld (talk) 14:07, 4 October 2008 (UTC)

I think this doesn't have the right title
This should be called "weightless flight" or something like that and the "vomit comet" name just mentioned as an alternative name.. Also vomit comet should redirect to this article with its new name. Perhaps an article with the proper name already exists and must be linked or merged? One of the disadvantages of this naming is that other languages will have a hard time linking to this page (as only in english does it have such an "alternative" name... perhaps only in certain limited english-speaking regions). Also.. It's not the "official" name, and it makes a duplicate article more likely. --Guruclef 13:39, 29 October 2006 (UTC)
 * I agree that the article should be renamed, because it also describes the ESA's A300 Zero-G Program. Thus the subject of the article is broader than the NASA airplane. The article could also be expanded to mention commercial operators of reduced gravity aircraft, such as Zero-Gravity Corporation and "ATLAS aerospace", which is a Russian company that offers reduced gravity flights in an "IL-76 MDK" wide-body airplane.
 * NASA uses the term "Reduced gravity aircraft", so I will nominate that for the new name.
 * BTW, Weightlessness already links to this article. --Jtir 20:51, 29 October 2006 (UTC)
 * I think it's important to figure out what the topic of this article is. Is it to explain just the nickname "Vomit Comet", or NASA's zero-G flight program, or zero-G flight programs in general?  The article Weightlessness has a summary of zero-G flight programs, which says that it's redundant for this article to try to do the same thing.  I'd suggest a separate article on Zero-G flight programs, to cover all such programs. Then this article can become just a short explanation of the "Vomit Comet" nickname, or perhaps link to an article describing the history of NASA zero-G flight programs. The Weightlessness article could also link to the zero-G flight programs article.  --Jdlh  | Talk 20:48, 29 November 2006 (UTC)


 * Rephrased the first paragraph to downplay/eliminate NASA's exclusiveness. Of course, NASA's history is important here. There are commercial flights now, which expand the opportunity.  And this NYT article about Stephen Hawking refers to 'vomit comet' in the second paragraph.  Though the company providing the ride/flight might resent the phrase, to me it suggests the phrase is generic and is not specific to NASA anymore. Henk Langeveld 00:03, 4 March 2007 (UTC)

Not actual weightlessness
The article is misleading in that it claims the aircraft's flight "provides a nearly weightless environment" and "[allows] the occupants to experience weightlessness during the parabola."

Technically the flight provides a simulation of a weightless environment. The aircraft and its passengers are not weightless, they are in free fall. True weightlessness is not even experienced in the space shuttle – the shuttle and its crew are in constant free fall as they orbit the earth. If the Vomit Comet was weightless, it wouldn't be falling back to earth (just as if the shuttle were weightless, it wouldn't maintain its orbit around the earth).

This is a technicality, but I think it's an important one that should be noted within the article.--MrWhipple 21:12, 10 January 2007 (UTC)


 * Weight (and thus weightlessness) is a relative term (whereas mass is not), and is used in relation to environment. As the occupants and the aircraft they're in are moving at the same speed towards earth, the occupants are weightless with respect to their immediate environment, the interior of the aircraft. Hope this helps. Akradecki 22:41, 10 January 2007 (UTC)


 * See weightlessness. Weightlessness is defined as what people experience during free-fall. --164.67.235.138 (talk) 20:39, 1 October 2009 (UTC)

You are mistaking the term weightless for zero g. They are in fact weightless. They are not in zero g. Not even in orbit in zero g. There is no where in the universe that has zero g. Weightlesness is a simulation of zero g. This argument stems from an older argument where the term zero g was commonly used for weightless. It was easier, shorter, and convienient. Then it was correctly argued that zero g doesn't exist. That the term weightless, though less convienient, was correct, and should be preferred so as to not mislead. Seems in this wikifight the reverse is being argued. I bet the reverse wikiwins. 98.164.66.166 (talk) 05:56, 26 April 2020 (UTC)


 * An astronaut in orbit is in the same situation as a springboard diver when the diver is in free fall (typically along a parabolic path). They have weight but the ground reaction force acting on them is zero. When the ground reaction force acting on a person is zero, the person is likely to describe the sensation as weightlessness although, strictly speaking, this is only a sensory illusion, and it is only in non-scientific language that it is common. Scientifically speaking, the weight of any object is the mass of that object multiplied by the strength of the local gravitational field (expressed as the local acceleration due to gravity.)
 * An astronaut is typically in a state of zero ground reaction force for hours or days whereas a springboard diver is in that state for less than a second. It is clear that the weight of the diver does not reduce to zero just because he leaves the springboard, and does not return to normal when he enters the water. It should be equally clear that the weight of an astronaut does not reduce to zero for the duration of his time in Earth orbit. In both cases it is the ground reaction force that briefly reduces to zero. Dolphin ( t ) 06:15, 26 April 2020 (UTC)

US-centric yet again!
The Russians also have a Vomit Comet - why isnt it mentioned? Oh I forgot - the world ends at the shores of Amerika. 80.2.213.89 (talk) 22:47, 27 February 2008 (UTC)
 * Do you have information about the Russian version of the Vomit Comet? Great! Be bold and contribute it.  Please cite reliable sources as you do so. Welcome to Wikipedia, we're glad to have you. --Jdlh  | Talk 21:56, 28 February 2008 (UTC)

In other uses of the term...
It says: "In Sim City the "Vomit Comet" is a fairground attraction."

I believe the Vomit Comet is actually a fairground attraction of the game "Roller Coaster Tycoon". I could be wrong, tough, so it would be good to get a confirmation (I haven't played RCT in many years). Uberflaven (talk) —Preceding comment was added at 01:24, 7 March 2008 (UTC)
 * I don't think the quoted piece of information is important and should be removed. It is useless trivia. JDCAce (talk) 02:28, 18 April 2008 (UTC)

Weightlessness In Movies
Is this how weightlessness is portrayed in films such as Apollo 13? If so, I believe this should be mentioned. I have always wondered this, because, for obvious reasons, film crews cannot film in space. JDCAce (talk) 02:28, 18 April 2008 (UTC)


 * http://findarticles.com/p/articles/mi_m1590/is_n3_v52/ai_17425130?tag=untagged this article says that's indeed the case. There are probably more/better articles describing this as well. But it's already been edited into the article (oops on my part) so this is pretty redundant. A Caffeinated Fool (talk) 01:42, 7 October 2008 (UTC)

title - Reduced gravity aircraft vs. Vomit Comet
Hello BillCJ, you reverted my move of this article Vomit Comet to Reduced gravity aircraft, giving as reason "moved Reduced gravity aircraft to Vomit Comet over redirect: Revert move based on a 3-yerar-old discussion with no clear concensus, and per Wikipedia:Naming conventions (common names) - previous name is clearly much more common, plus the new n".

Please -- Flipote (talk) 21:40, 1 July 2009 (UTC)
 * 1) source in what context the phrase "vomit comet" is "clearly much more common" than the term "reduced gravity aircraft"
 * 2) clarify what discussion proposed and rejected the lemma "reduced gravity aircraft"
 * 3) if you second the above mentioned notion that this article was about the nickname rather than about the class of aircraft, please clarify in what article the class of aircraft is described in greater depth
 * 4) clarify how a nickname/slang term of a technical item should be of greater encyclopedical relevance than the item itself
 * 5) point out your final reason cut off in the edit comment.


 * "... plus the new name sounds like some kind of anti-gravity experiment." In other words, it's vague and unclear. The rest should be understandable as written. You made a move not based on any recent discussions, and I've reverted it per WP:BRD. Now, the next step is yours: YOu make a formal move proposal, whith a clear rationale, or you move on. - BillCJ (talk) 22:22, 1 July 2009 (UTC)


 * The title of the article 'vomit comet' is plainly wrong. It is only a nickname for the much more descriptive 'reduced gravity aircraft'. I fully support the move from vomit comet to reduced gravity aircraft. AugustinMa (talk) 20:24, 24 August 2009 (UTC)

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"Zero G flight" listed at Redirects for discussion
An editor has asked for a discussion to address the redirect Zero G flight. Please participate in the redirect discussion if you wish to do so. signed,Rosguill talk 05:21, 17 February 2020 (UTC)

Inventors missed
Originators of the Parabolic flight were the brothers Fritz & Heinz Haber in 1950. — Preceding unsigned comment added by 77.188.229.59 (talk) 20:43, 18 March 2012 (UTC)