Talk:Delta-v budget

message: What's a "Taxing budget"? -- Anon. — Preceding unsigned comment added by 80.168.228.51 (talk) 09:05, 11 October 2004 (UTC)
thread_title:  Taxing budget 

message: Could Delta-V requirements for more locations (lagrange points, other planets, etc.) be given in the Delta-V chart.
Linguofreak 03:30, 19 March 2006 (UTC)
thread_title:  Other locations 

message: It would be nice to add an example of the benefit of a slingshot maneuver (applying delta-v at a point of closest approach). E.g. add the delta-v needed to escape earth's gravity starting from apogee of a geostationary transfer orbit.  Jrvz 14:52, 12 September 2006 (UTC)
thread_title:  Slingshot Maneuvers 

message: The diagram shows 1.6 km/s from moon to low lunar orbit and then another .7 km/s to earth C3=0. That adds up to 2.3 km/s. Lunar escape velocity is 2.38 km/s. Doing a 2.3 km/s burn from the moon's surface would get you an apolune of about 28,000 km. A 0 x 28,000 km orbit would still be well within the Moon's Hill Sphere. HopDavid (talk) 14:59, 13 March 2019 (UTC)
replies: text: You are correct, however the numbers are obviously rounded to one decimal place; this explains the discrepancy.WolfKeeper 13:34, 2 October 2007 (UTC)

text: Comparing with  one of the numbers .7 should be 1.7, and C3 is L5 there.--Patrick 11:44, 2 October 2007 (UTC)
replies: text: Those numbers seem to be correct on the graph in fact- the Strout graph has been flipped and rotated on the diagram so as to fit the Mars-Earth path on the diagonal axis.WolfKeeper 13:34, 2 October 2007 (UTC)

text: Unfortunately the source for the Mars numbers seems to have gone away.WolfKeeper 13:34, 2 October 2007 (UTC)

text: The numbers are taken with good faith from the 2 sources. You're engaging in OR by adding them up! (I could probably list about 5-10 reasons why you're lucky that's it's as close as it is, including orbital planes, LEO altitudes, transfer windows, Oberth effect, rounding etc. etc. etc.) There are *reasons* why it says 'all numbers are approximate' at the bottom of the image!WolfKeeper 10:41, 8 October 2007 (UTC)
replies: text: I understand, but inconsistency is somewhat confusing.--Patrick 11:48, 8 October 2007 (UTC)

text: I haven't done the calculation, but it's probably something to do with the Oberth effect- if you do the Mars insertion burn close to the Earth then you get much better efficiency than if you burn for escape, and once escaped, you then do the Mars insertion burn. In this case the graph goes from the C3 orbit to Mars transfer, and the optimum place for this burn is close to the Earth, where you would be doing about 7.8km/s. Right?- (User) WolfKeeper (Talk) 20:14, 15 August 2008 (UTC)

text: The latest version of the Delta-V diagram is very thin.  A wider version, like the previous ones, would be better. Andrew Swallow (talk) 05:15, 12 November 2010 (UTC)
thread_title:  Delta-V diagram problems 

message: Closest NEO Asteroids stating 0.8 - 2.0
However the table referenced lists 3.813 km/s 
http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html
Just wondering how the 0.8- 2.0 number was derived.  —Preceding unsigned comment added by Simultaneous (talk • contribs) 15:20, 8 May 2008 (UTC)
thread_title:  To-NEO figures 

message: Ooops. I just noticed that some of the C3s are different. If you go from LEO to GTO to C3 you end up at C3 with a perigee at LEO. If you go from GEO to C3, you end up with C3 with Perigee at GEO. If you then go on to say Mars transfer, the delta-v to get from C3(GEO) to Mars transfer is hugely more than to go from C3(LEO) (Oberth effect means you do much better to do the burn close to the Earth). I'm probably going to have to fix the arrow diagram, it shows an arrow going from LLO to C3, but I'm sure that's not the same C3...- (User) WolfKeeper (Talk) 22:12, 15 August 2008 (UTC)
replies: text: Information
The 'Earth–Moon space — high thrust' table shows LEO to C3=0 is 3.2 km/s.
'Interplanetary' table shows C3=0 to Mars Transfer Orbit is 0.6 km/s.  3.2 + 0.6 = 3.8 km/s
also
The 'Delta-vs between Earth, Moon and Mars' diagrams shows LEO to GTO is 2.5 km/s, GTO to Earth C3 is 0.7 km/s and C3 to Mars Transfer is 0.6 km/s.
2.5 + 0.7 + 0.6 = 3.8 km/s
The numbers should agree or an explanation needs adding.  Andrew Swallow (talk) 23:20, 2 November 2012 (UTC)

text: I don't know exactly, but the paper referenced that the 4.3 km/s comes from talks about a 1 km/s perigee burn; sounds like they're doing something suboptimal; the Earth perigee burn would normally be 3.8km/s. I think maybe they're starting from L2, falling down to perigee and then doing a 1km/s burn or something.GliderMaven (talk) 00:45, 3 November 2012 (UTC)
replies: text: That's probably what they're proposing (and it is actually a very good idea), but I'm not sure they're looking at a Hohmann transfer. Andrew is right that the numbers should add up unless they somehow use a different scheme of burns. Martijn Meijering (talk) 09:27, 3 November 2012 (UTC)
thread_title:  C3 issues... 

message: Since spacecraft using electric propulsion cannot (or have difficulty) using the Oberth Effect the Delta-V tables do not apply to them.  I have added the value for Mars C3=0 to Earth C3=0.  The values for Earth orbits can usefully be added if anyone can find a source. Andrew Swallow (talk) 04:51, 4 October 2009 (UTC)
thread_title:  Electric propulsion Delta-V 

message: This is coming back bad for me...  TREKphiler any time you're ready, Uhura  06:24, 22 August 2010 (UTC)
thread_title: Bad link

message: A surprisingly high delta-v is needed to go from the point EML-1 to a HALO orbit around it.  A spacestation will probably be in the orbit since staying at a single point that moves is difficult.  This delta-v may need adding to the tables and a double check making to ensure that it is not already in the figures.  Andrew Swallow (talk) 21:08, 6 December 2011 (UTC)
replies: text: Very interesting. How high is the added delta-V? Does it depend on the amplitude of the halo orbit? What about the delta-V requirements for transfers between an EML-1 Halo and other orbits, e.g. LEO, GEO, LLO and escape--are they higher or lower than for L1 proper? And of course, can you point to a source?--agr (talk) 12:10, 7 December 2011 (UTC)
thread_title:  EML-1 to HALO orbit around EML-1 

message: This article seems to be written from the point of view of the physicist, rather than the engineer. That's unfortunate, since the concept is widely used in human spaceflight. And no real-world examples are given; it would be nice to have the delta-v of the Gemini and Apollo spacecraft, Space Shuttle, etc. JustinTime55 (talk) 20:03, 8 February 2012 (UTC)
thread_title:  Too technical 

message: This paragraph is not well written:
:"Current electric ion thrusters produce a very low thrust, so the Oberth effect cannot normally be used. This results in the journey having a higher delta-V and frequently a large increase in time. The high specific impulse of electrical thrusters may significantly reduce the cost of the flight but due to the extra time are not viable for humans (interplanetary flights are an exception). The delta-v is in km/s, normally accurate to 2 significant figures and will be the same in both directions unless, say a heat shield is used."
The statement about "not viable for humans", and then the exception for interplanetary flights, is unsupported and probably opinion, in the absence of a citation. JustinTime55 (talk) 22:22, 8 February 2012 (UTC)
thread_title: Original research

message: The lead image contains a bit of potentially confusing information, and this sentence added to the caption is incomplete and incorrect:
:"Note that for the last mission phase, trans-Earth injection, fuel requirements differ depending on whether the Service Module Propulsion System (SPS) or the Lunar Module's Descent Engine (DPS) is used, however the required delta-v is the same for either burn."
The first clause is incomplete; "whether the SPS or DPS is used" ... for what? The DPS was never used for trans-Earth injection; it was left on the Moon at the landing site, with next to no fuel left! The SPS/DPS choice applied to the Descent Orbit Insertion maneuver, which isn't even shown on this graph. Originally the DPS was used; which left more fuel in the Service Module; therefore a greater fuel requirement for TEI. The SPS was used on later missions, to conserve LM descent fuel. (Notice the effect on required LM delta-V and fuel burn isn't even shown on this graph.) This left a lighter Service Module, therefore a smaller fuel requirement for TEI. This is probably too much information to try to cram into the picture caption.
Also, delta-V budget is relative to a particular spacecraft, and the Apollo mission involved two separate spacecraft. Therefore, I don't think it doesn't make a lot of sense to put LM and CSM maneuvers on the same graph. Is the original source available to check what NASA had in mind from this 1966 (thus before-the-fact) graph? JustinTime55 (talk) 16:13, 15 December 2014 (UTC)
thread_title:  Don't try this at home 

message: I needed to find out how long it takes to transfer from Earth to Venus and was surprised not to find it here. Why only Mars in the tables?
Venus is closer. Transfer time of 146 days instead of 245 days. See Fourth page here. And you can get to it more often as well by this method. 
This page gets linked to from other parts of wikipedia not just the Mars section, e.g. from Interplanetary spaceflight. We have sent many more spacecraft to Mars than to Venus true, but we have also sent several to Venus. And for human spaceflight, then Colonization of Venus is a suggestion, cloud colonies in the upper atmosphere.
I suggest we include Venus in the tables. But as well as that - why not also have a complete list of Hohmann transfers to all the planets? It's true that we do gravity assist to go further than Venus or Mars in both directions. But you can also theoretically do a Hohmann transfer, and for instance, Mars isn't always in the right place for a gravity assist, some missions do Hohmann transfer direct to Jupiter. Voyager 2 for instance. So I think we should at least include Jupiter. And why not include them all? Robert Walker (talk) 11:20, 1 November 2015 (UTC)
thread_title: Suggestion: to include Hohmann transfer times to Venus and Jupiter

message: Hello fellow Wikipedians,
I have just added archive links to  on Delta-v budget. Please take a moment to review my edit. If necessary, add  after the link to keep me from modifying it. Alternatively, you can add  to keep me off the page altogether. I made the following changes:
*Attempted to fix sourcing for http://www.pma.caltech.edu/~chirata/deltav.html
When you have finished reviewing my changes, please set the checked parameter below to true to let others know.
Cheers.—cyberbot IITalk to my owner:Online 17:05, 8 January 2016 (UTC)
thread_title:  External links modified 

message: Hello fellow Wikipedians,
I have just added archive links to  on Delta-v budget. Please take a moment to review my edit. If necessary, add  after the link to keep me from modifying it. Alternatively, you can add  to keep me off the page altogether. I made the following changes:
*Added archive http://web.archive.org/web/20120426010349/http://www.futureinspaceoperations.com/papers/HumanOps_Beyond_LEO_11_2010.pdf to http://www.futureinspaceoperations.com/papers/HumanOps_Beyond_LEO_11_2010.pdf
When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at ).
Cheers.—cyberbot IITalk to my owner:Online 18:40, 28 February 2016 (UTC)
thread_title:  External links modified 

message: Hello fellow Wikipedians,
I have just modified  on Delta-v budget. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added archive https://web.archive.org/web/20070209033934/http://science.nasa.gov:80/headlines/y2006/06nov_loworbit.htm to http://science.nasa.gov/headlines/y2006/06nov_loworbit.htm
When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at ).
Cheers.—InternetArchiveBot (Report bug) 14:06, 10 December 2016 (UTC)
thread_title:  External links modified 

message: Besides the performance penalties for atmospheric and gravity drag, perhaps should we mention backpressure drag; i.e. suboptimal expansion of the exhaust gas jet ?? This is a major and unavoidable drag term for rockets going from the surface to orbit. Bell type exhaust nozzles cannot be optimized for perfect efficiency at all altitudes, though I understand that the "free expansion ramp", or so-called aerospike does just this. See Rocket nozzle, "Aerostatic back-pressure".Wikkileaker (talk) 13:32, 11 October 2017 (UTC)
replies: text: Does backpressure belong in Delta-v budget or the page on rockets? Andrew Swallow (talk) 22:37, 11 October 2017 (UTC)
replies: text: That's a design issue, nothing to do with delta-vee (except in an extremely broad sense).  TREKphiler any time you're ready, Uhura 17:03, 18 October 2017 (UTC)
thread_title:  Budget / Launch to LEO 

message: Hello fellow Wikipedians,
I have just modified one external link on Delta-v budget. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added archive https://web.archive.org/web/20110807131403/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/15789/1/00-1530.pdf to http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/15789/1/00-1530.pdf
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
Cheers.—InternetArchiveBot (Report bug) 08:52, 8 November 2017 (UTC)
thread_title:  External links modified 

message: The Low Earth orbit (LEO) to Lunar Gateway delta-v of 0.900+0.180+0.240 = 1.32 km/s feels too low to me. Should there be an extra term to cover say trans lunar injection? Andrew Swallow (talk) 14:59, 11 October 2019 (UTC)
replies: text: Yes, it is wrong and all generally misleading. I'm editing to fix it based on the included cite. 158.71.68.169 (talk) 19:26, 18 October 2019 (UTC)
thread_title:  Too low a figure? 

message: An undergraduate paper from the University of Leicester shows the following delta-V costs:
* Earth to LEO: 
* Hohmann transfer to ISS: 
* Hohmann transfer to GEO: 
Reference:
:
Praemonitus (talk) 22:42, 26 February 2021 (UTC)
thread_title:  Earth to GEO delta-V 

message: "In astrodynamics and aerospace, a delta-v budget is an estimate of the total change in velocity (delta-v) required for a space mission." is the first line of the article. Surely, a change in speed, and not in velocity is what requires fuel consumption? The next paragraph starts, "Delta-v is a scalar quantity dependent only on the desired trajectory and not on the mass of the space vehicle." Speed is a scalar but velocity is vector. So again, surely, delta-v is not a change of velocity?  Arctic Gazelle (talk) 18:43, 1 September 2021 (UTC)
replies: text: In English, sometimes "velocity" and "speed" are taken to be synonymous. We all have to learn to live with that. In such cases, whether a scalar or a vector is meant, should be clear from the context. That is the case here.  - DVdm (talk) 19:39, 1 September 2021 (UTC)

text: Velocity is actually the correct term here.  Delta-v is actually the change in speed in a particular vector (It is after all delta v, what do you think the v stands for?).  If you try to change your speed in multiple vectors then the total amount of energy is higher and really the use of delta v is for determining how much energy is required to make a particular maneuver.  Therefore, it is critical that the change in velocity is for a particular vector hence the use of velocity.  You are trying to get all fancy with showing some deeper understanding of speed and velocity but, in this case, it is entirely appropriate and hence when the engineers who originally coined the term were looking at change in velocity they shortened it to delta-v. Jponline77 (talk) 18:49, 8 February 2022 (UTC)
thread_title:  Delta-v is related to speed not velocity?