Kowgan

[1.3+] Community Delta-V Map 2.6 (Sep 29th)

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Community Delta-V Map 2.6 - KSP 1.3

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PDF versions (A4 & Letter)

KSPedia Version

Lights-out Theme (v2.4.1) (Thanks @Siege /u/s13g3!)



Outer Planets Mod adaptation: By Swashlebucky; original by Misucat and his wife

aLDJFIy.png SUhT4as.png

PDF version (v2.4.1)

OPM - Lights-out Theme (v2.4.1) (Thanks @Siege /u/s13g3!)

OPM - KSPedia Version (v2.4.1) (Thanks @AlexSheFF!)

 

Changelog

Spoiler

2.6 (29/09/2017)
- Updated to KSP 1.3
- Fixed Geosync altitude suffix
    » From 2863.3 Mm to 2,863.33 Km
- Updated Antenna values for all planets (and Kerbin moons)
- KSPedia version now respects your eyes and A E S T H E T I C S

2.5 (06/12/2016)
- Updated to KSP 1.2.1
- Updated Geosync altitude
- Added Relay Antenna Comms values (Thanks @Snark and @Malah!)
- Added icon for Return Window Cycle
- Additional Subtitles regarding the two items above
- Updated credits

2.4.1 (09/07/2016)
- Small correction at the total dV value for Bop (6830 to 6840)
- Moved all PDF versions to a GitHub release.

2.4 (27/06/2016)
- Added KSPedia version (Thanks @AlexSheFF!)
- Decreased Moho low orbit altitude to 20km
- Increased Bop low orbit altitude to 30km

2.3.1 (17/11/2015)
- Minor design update on the OPM map (Thanks, @swashlebucky!)
- Eve's total dV fixed (I'm dumb)
- Version number fix (I'm dumb)

2.3 (17/11/2015)
- Added OPM's Thatmo and Neidon
- Added time between transfer windows to return to Kerbin (idea by /u/PM_ME_UR_MONADS)
--- This is the average time between transfer windows from a planet to Kerbin. This data is useful for those who use life support mods, so they know how long they'll have to survive in a planet before the next window to return home.
- Reupdated Eve's Ground-Orbit value
- Archived Galahir950's version (Thank you for your service, @Galahir950!)

2.2 (12/08/2015)
- Spelling correction
- Minor reallignment
- Minor text resize
- Github created to hold development, versions and more maps
- Added Swash's design for the OPM map. Based on @Misucat's Map

2.1.1 (09/08/2015)
- Fixed total-dV values

2.1 (09/08/2015)
- Fixed values to match vacuum-only dV
- Plane change dV is no longer included in the total numbers. Changed text on upper left corner accordingly
- Darker yellow Kerbol line for more contrast
- Spelling correction

2.0 (08/08/2015)
- New print-friendly design by @swashlebucky

1.2.2 (07/08/2015)
- Added license and version to image

1.2.1 (06/08/2015)
- Converted values to be measured as vacuum delta-V
- Added aerobraking arrows towards Kerbin SOI (Thanks @jofwu!)

1.2 (04/07/2015)
- Updated to KSP 1.0.4
- Added disclaimer explaining that dV values are calculated as "Total dV Expended"

1.1.1 (25/05/2015)
- Lowered atmospheric values in Kerbin, Eve and Laythe (Thanks @SanderB, @Kerbas_ad_astra!)
- Extra info and credits

1.1 (24/05/2015)
- Updated atmospheric values to match KSP 1.0.2 aerodynamics
- Updated Low Orbit altitude on a few bodies
- Added Kerbol to the map
- Disclaimer improvement (Thanks @Kerbas_ad_astra!)

1.0 (15/10/2014)
- Initial re-release
- Updated original WAC's Map to match KSP 0.25

GitHub
Check it for development, pull requests and other maps.

 

How do I use it?
It's simple!
1. Pick a planetoid you wish to visit.
2. From your initial position, add up the numbers between every checkpoint until you reach your desired checkpoint.
3. The total is the general Delta-V value needed to reach your destination.

Example:
- Kerbin surface -> Duna Surface
3400+950+130+10+250+360+1450 = 6550*
*Aerobraking can reduce the needed dV to almost zero. Using it would result in the following: 3200+950+130+10 = 4490.
- Eeloo Surface -> Kerbin SOI
620+1370+1140*+1330* = 4460
*Aerobraking can reduce this number to almost zero.
*Numbers outside the stripes are the maximum dV needed to change between planets inclinations. Pay attention to them!

 

Elliptical or Low Orbit? What's the difference?
A Low orbit assumes a circular orbit 10km above the nearest obstacle/atmosphere.
Elliptical orbits have the Periapsis at Low Orbit altitude and the Apoapsis at the planet's SOI edge.
I added the Elliptical orbit checkpoint for two reasons:
          1. It shows you the required dV needed to get your vessel grabbed into the planet's SOI, disregarding the value needed to circularize on a low orbit.
                    1a. It assumes you have set your encounter to the lowest periapsis possible, during the encounter maneuver.
          2. If your destination isn't the planet, but instead, its moons, you don't need to count the whole dV needed to circularize around the planet's low orbit, since you won't use that. Instead, a simple capture/elliptical orbit is enough to transfer to a moon. That way, you can reduce the needed dV for a trip drastically.

I hope this helps. Enjoy!

 

License

This work is licensed under CC BY-NC-SA 4.0.

  • You are permitted to use, copy and redistribute the work as-is.
  • You may remix your own derivatives (edit values, design, etc.) and release them under your own name.
  • You may not use the material for any commercial purposes.
  • You must use the same license as the original work.
  • You must credit the following people when publishing your derivatives in the material:
    • JellyCubes (Original concept)
    • WAC (Original design)
    • CuriousMetaphor (Original out-of-atmosphere numbers)
    • Kowgan (Design, original in-atmosphere numbers)
    • Swashlebucky (Design)
    • AlexMoon (Time of flight)
    • Official Wiki (Relay Antenna calculations)

 

--
This was originally a continuation from WAC's Delta-V Map from KSP 0.23. Since then, a lot of people (credits above + advice from people in this thread and over the internet) have contributed to improve this chart and keep it up-to-date with the latest KSP version. I am very thankful to all those who helped make this chart possible. Seriously, thank you guys. :)

Edited by Kowgan
Updated to KSP 1.3
  • Like 91

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Mods, maybe sticky this? I have the subway-style d-v map open in my browser at all time, it's incredibly useful. Nice work Kowgan!

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Thanks, SunChaser. The compliment is much appreciated. I personally would save the image to my desktop and open it whenever I play KSP. ;)

Although, I don't think this is a case of stickying the thread. I guess the idea is just to spread the map, so more people can make use of it. Maybe putting it into the KSP wiki would be enough? I don't know.

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Jool intercept 2 years 263 days, Eeloo intercept 396 days? Something doesn't seem right there...

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Jool intercept 2 years 263 days, Eeloo intercept 396 days? Something doesn't seem right there...

As said in the subtitles, "Flight time is based on 10 years of average flight possibilities simulated on Alexmoon's Launch Window Planner, from day 1."

93e3f84873.png

I've decided to do it because someone said they weren't satisfied with the flight time specified in the previous chart. I decided to run a simulation and get the average results from it, as shown in the picture above, but I haven't tested it at all.

Anyway, that was my approach of showing the flight time projections. If you have a better suggestion, I'd love to read. :)

(maybe I should take the shortest time shown by default on Alexmoon's planner? e.g. Kerbin Jool gives me a minimum flight time of 561 days. Should I use that, instead?)

I've thrown up a link to it on the Drawing Board. Excellent work k_smiley.gif

Thank you very much for the highlight on the Drawing Board! I'm glad to be useful there! :D

Edited by Kowgan

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Is that dV map made according to stock aerodynamic model? Because using FAR you will have completely different amount of dV needed to go to Kerbin orbit. It's like 2000-2700 m/s. So, any other value will be different.

I wish such map for RSS configuration aswell. But you know what? This is great job anyway. I will definitely use that.

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Thanks, folks. Really appreciate it.

Smysha, I don't have the calculations for the required dV's while using FAR. This is all stock, and all based on metaphor's chart. But this is all open source, until any of the original creators decide to protect their work and prevent us from editing it ;). I've released the master file in the OP, so anyone can edit the numbers there. So, if you have any the dV calculations for FAR, I - or even you - could make a FAR version of it.

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Yesterday, I was having a discussion about some delta-V charts not being precise enough, and a more accurate delta-V chart has been pointed out.

But because the chart posted above isn't very easy-reading, I took the liberty to edit WAC's Subway-style Delta-V Map, updating the dV numbers and adding some extra info, based on the data provided by the chart above.

Thanks for making an update to the chart.

I believe, it should replace the one on http://wiki.kerbalspaceprogram.com/wiki/Cheat_sheet.

And since the more accurate delta-V chart is a bit difficult to get used to, it's author metaphor made a simplified version of it available some time ago.

Edited by mhoram

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Thanks for this! I'm confused about the Elliptical Orbit bit that you've added to the chart though.

Do the values shown between "Elliptical Orbit" and "X Planet Intercept" have to be added up again to the Delta V total when returning from X Planet's surface to Kerbin?

So for example, if leaving from the surface of Duna to arrive back in the Kerbin SOI, would the total delta V be 1300+360+250+130=2040?

And if you're leaving the orbit of a planet to arrive in the orbit of one of it's moons, do you ignore the Delta V shown between "X Planet Low Orbit" and "Elliptical Orbit?" and just use the Delta V shown between "Elliptical Orbit" and "X Moon Intercept"?

So for example, if leaving from Low Jool Orbit to arrive in Low Laythe Orbit, is the total Delta V 2810+930+1070=4810? Or is it simply 930+1070=2000?

Basically, my question is do you always add every single number along the way from Point A to Point B no matter what, or are there situations where numbers along the way are skipped depending on what direction you're moving?

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Just a tip - the Mun is named Mun, not "Mün" :P

The way it is written on the side of Jeb's rocket on the title screen is actually a so-called metal umlaut, a decorative element intended to make something look more hardcore, but not intended to change the pronunciation of the word. The self-motivating "Mun or bust!" chant is meant for the Kerbals to psyche themselves up in the face of a difficult challenge, and as such, making it more "metal" by adding the umlaut diacritic is a perfectly good way to increase the motivational value. It doesn't make any statement about the real pronunciation or written form of the name of Kerbin's first moon, however. :wink:

Edited by Streetwind
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Just a tip - the Mun is named Mun, not "Mün" :P...

Please quote your definitive source for the pronunciation (or even spelling!) of this.

In English (we could get into language, dialect or even accent difficulties here ...) I've always assumed it wasn't 'Mun'-rhymes-with-'Bun' because of the umlaut.

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As said in the subtitles, "Flight time is based on 10 years of average flight possibilities simulated on Alexmoon's Launch Window Planner, from day 1."

I've decided to do it because someone said they weren't satisfied with the flight time specified in the previous chart. I decided to run a simulation and get the average results from it, as shown in the picture above, but I haven't tested it at all.

Anyway, that was my approach of showing the flight time projections. If you have a better suggestion, I'd love to read. :)

(maybe I should take the shortest time shown by default on Alexmoon's planner? e.g. Kerbin Jool gives me a minimum flight time of 561 days. Should I use that, instead?)

Maybe I should have been clearer - the Jool flight time seems roughly right. Eeloo is way out though. It's not 396 days to get there (<1 year!), more like 4.5 years. :)

(4 years 184 days according to a quick test on year 1 of Alexmoon's planner, maybe with an error of 20-30 days either side.)

Edited by Kerano

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Please quote your definitive source for the pronunciation (or even spelling!) of this.

In English (we could get into language, dialect or even accent difficulties here ...) I've always assumed it wasn't 'Mun'-rhymes-with-'Bun' because of the umlaut.

Source: Any and all mentions of the Mun by Squad on official portals, ever. Example: http://kerbaldevteam.tumblr.com/post/95327175669/video-wednesdays-kolonizing-kerbals

In contrast to that, I assure you you will not find the umlaut used anywhere but in the scrawling on the flank of the rocket on the title screen :P

There are also video interviews, Squadcasts, recordings of presentations and other audio sources that allow you to hear exactly how members of the dev team pronounce "Mun". They pretty much say "moon", except with maybe the vowel a little shorter, and I'm fairly sure this is intended. I think the only reason it's even written "Mun" and not "Moon" is because they needed a way to make it different because the Kerbal universe is different. Yet at the same time they wanted to preserve phrase "going to the Moon" in some manner, since it's like THE dream of spaceflight made manifest. "Going to Minmus" just doesn't have the same ring to it, doesn't inspire quite the same sense of innate awe and anticipation. You can't have a rocketry and space travel simulator without "going to the Moon". That's like asking McDonalds to print a menu without mentioning the Big Mac!

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Thanks for this! I'm confused about the Elliptical Orbit bit that you've added to the chart though.

Do the values shown between "Elliptical Orbit" and "X Planet Intercept" have to be added up again to the Delta V total when returning from X Planet's surface to Kerbin?

So for example, if leaving from the surface of Duna to arrive back in the Kerbin SOI, would the total delta V be 1300+360+250+130=2040?

And if you're leaving the orbit of a planet to arrive in the orbit of one of it's moons, do you ignore the Delta V shown between "X Planet Low Orbit" and "Elliptical Orbit?" and just use the Delta V shown between "Elliptical Orbit" and "X Moon Intercept"?

So for example, if leaving from Low Jool Orbit to arrive in Low Laythe Orbit, is the total Delta V 2810+930+1070=4810? Or is it simply 930+1070=2000?

Basically, my question is do you always add every single number along the way from Point A to Point B no matter what, or are there situations where numbers along the way are skipped depending on what direction you're moving?

Bump?

I'm getting ready to start a bunch of interplanetary missions so answers to these questions would be really helpful. Thank you.

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So for example, if leaving from the surface of Duna to arrive back in the Kerbin SOI, would the total delta V be 1300+360+250+130=2040?

Yes, 2040 m/s should bring you to an intercept with Kerbins SOI. However the 130 will probably vary a bit, since it is taken from the viewpoint of LKO.

So for example, if leaving from Low Jool Orbit to arrive in Low Laythe Orbit, is the total Delta V 2810+930+1070=4810? Or is it simply 930+1070=2000?

As far as I understand the chart, this should be ((2810 - 930) + 1070) m/s

(2810 - 930) m/s is the Delta-V needed to get from Low Jool Orbit to an intercept with Laythe (This transfer orbit has a Periapsis of ~150km and Apoapsis of ~27184km)

1070 m/s is needed to circularize in Low Laythe Orbit.

All of this is based on the numbers in the OP-chart and assuming that no gravity assists or aerobraking is used.

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How should I feel about necroposting on my own thread?

Something must have happened, but I never noticed this reached two pages. Thank you, guys! :)

For the (late) answers:

Thanks for this! I'm confused about the Elliptical Orbit bit that you've added to the chart though.

Do the values shown between "Elliptical Orbit" and "X Planet Intercept" have to be added up again to the Delta V total when returning from X Planet's surface to Kerbin?

So for example, if leaving from the surface of Duna to arrive back in the Kerbin SOI, would the total delta V be 1300+360+250+130=2040?

And if you're leaving the orbit of a planet to arrive in the orbit of one of it's moons, do you ignore the Delta V shown between "X Planet Low Orbit" and "Elliptical Orbit?" and just use the Delta V shown between "Elliptical Orbit" and "X Moon Intercept"?

So for example, if leaving from Low Jool Orbit to arrive in Low Laythe Orbit, is the total Delta V 2810+930+1070=4810? Or is it simply 930+1070=2000?

Basically, my question is do you always add every single number along the way from Point A to Point B no matter what, or are there situations where numbers along the way are skipped depending on what direction you're moving?

You're right. The proccess is to add numbers between every checkpoint. On your math, you forgot to add the Maximum possible dV required to change angle inclinations, which is marked by that black number above the Metro stripes. In Duna's case, that's only 10m/s (above "130"). So, to go from Kerbin's Low Orbit until Duna's Surface (without using aerobrake), you should add: 950+130+10+250+360+1300=3000. Naturally, you can use aerobraking to reduce some of those values to 0, but I wanted to make sure everyone understands the math. The same proccess occurs on the opposite way, but as mhoram stated above, the values vary a bit on the return to Kerbin. Usually, you need less than what's specified on that chart. :)

I put that "Elliptical Orbit" there to make things more detailed/easy when approaching a planet's SOI, or flying from a planet to it's moons. The Elliptical orbit is simply an orbit with the Periapsis = Low Orbit Altitude and the Apoapsis = Planet SOI edge. So, you don't need to spend way more dV to circularize before moving to a planet's moon.

Just a tip - the Mun is named Mun, not "Mün" :P

The way it is written on the side of Jeb's rocket on the title screen is actually a so-called metal umlaut, a decorative element intended to make something look more hardcore, but not intended to change the pronunciation of the word. The self-motivating "Mun or bust!" chant is meant for the Kerbals to psyche themselves up in the face of a difficult challenge, and as such, making it more "metal" by adding the umlaut diacritic is a perfectly good way to increase the motivational value. It doesn't make any statement about the real pronunciation or written form of the name of Kerbin's first moon, however. :wink:

Updated. :)

Maybe I should have been clearer - the Jool flight time seems roughly right. Eeloo is way out though. It's not 396 days to get there (<1 year!), more like 4.5 years. :)

(4 years 184 days according to a quick test on year 1 of Alexmoon's planner, maybe with an error of 20-30 days either side.)

D'oh, you're right! Fixed.

I added the updated map to the wiki. I hope nobody minds.

Again, my apologies for not answering your questions in time. For some reason, I didn't notice that second page, and I assumed the thread had died, so I stopped checking it. But I'll switch the Subscribe button and keep an eye on it regularly.

I hope I've been of some help!

Edited by Kowgan

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I added the updated map to the wiki. I hope nobody minds.

Actually, I found this thread after seeing the new map on the wiki.

Three suggestions:

- If you have Steam, please take a look at your image in the Cheat Sheet page, as viewed in the Steam Overlay browser. For me, it's ginormous, though I am running at a mere 1600x1200.

- Perhaps a visual legend would be clearer than just the text description? It took me a while to figure out what the new numbers were. (Actually, this is something the map could have used from the beginning.)

- Regarding the discussion of what transfer durations to show, I like your ten-year-averaging method, but I think it would be useful to show the minimum and maximum for each as well - though I am not sure if, visually, it would fit well.

Thanks!

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- Regarding the discussion of what transfer durations to show, I like your ten-year-averaging method, but I think it would be useful to show the minimum and maximum for each as well - though I am not sure if, visually, it would fit well.

Metaphor has a great map with those max and min delta-v figures as well. The thing to realize, however, is that in most cases your best bet is to consult Ksp.olex or, even better, Alex Moon's Launch Window Planner and don't even both with an interplanetary transfer except for one of the ideal launch windows.

At this point I've pretty much abandoned the subway-style map available on the Wiki in favor of Metaphor's map. It's a lot more accurate, if a little less aesthetically pleasing.

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...and don't even bother with an interplanetary transfer except for one of the ideal launch windows.

PFF! You should know the response to that: MOAR BOOSTERS!

At this point I've pretty much abandoned the subway-style map available on the Wiki in favor of Metaphor's map. It's a lot more accurate, if a little less aesthetically pleasing.

Yeah, for some reason, Metaphor's map is much harder to read. Thanks for the links, though!

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Actually, I found this thread after seeing the new map on the wiki.

Three suggestions:

- If you have Steam, please take a look at your image in the Cheat Sheet page, as viewed in the Steam Overlay browser. For me, it's ginormous, though I am running at a mere 1600x1200.

- Perhaps a visual legend would be clearer than just the text description? It took me a while to figure out what the new numbers were. (Actually, this is something the map could have used from the beginning.)

- Regarding the discussion of what transfer durations to show, I like your ten-year-averaging method, but I think it would be useful to show the minimum and maximum for each as well - though I am not sure if, visually, it would fit well.

Thanks!

- The image size is intentional. It's easier reducing it for each personal needs than making it bigger and losing quality. :)

- How would you imagine the visual legend? Any suggestions?

- If I am to put a minimum and maximum time of flight on the chart, I would have to add minimum and maximum Delta-V requirements there as well. But I am keeping the purpose of that chart the same as I think WAC's was: To be a chart. It's a quick handbook... Uh... Chart. It's not meant to be a complete-and-super-detailed guide on interplanetary travels. Instead, it's made for quick consultation, so one can have a general idea of how much delta-V to pack in his vessel. For those advanced purposes, as NASAHireMe said, you can check the awesome tools and maps by Metaphor, Alex, Olex, and many others out there. :)

Thinking of all those extra possibilities to come, like the one you just brought to us, I've anticipated myself and released the master file on the OP. Anyone can download that and the free-trial version of the software I used to (re-)make it, and edit as you wish.

Edited by Kowgan

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I have an odd question that is kind of confusing me, and maybe someone clarify for me somewhat. Is the total what I need at time of launch or does this take into account the change in a ship as it goes from atmosphere to space? To go from Kerbin to Moho by this it says I will need 11190 dv total, but according to KER my full dv value is 10606 dv. However this does seem to change as I shed the launch stage to the transfer stage giving me an increase, or rather it changes the values as I stage parts. I hope someone can clarify it some, the chart makes sense to some degree but maybe I am missing something. Thanks

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I have an odd question that is kind of confusing me, and maybe someone clarify for me somewhat. Is the total what I need at time of launch or does this take into account the change in a ship as it goes from atmosphere to space? To go from Kerbin to Moho by this it says I will need 11190 dv total, but according to KER my full dv value is 10606 dv. However this does seem to change as I shed the launch stage to the transfer stage giving me an increase, or rather it changes the values as I stage parts. I hope someone can clarify it some, the chart makes sense to some degree but maybe I am missing something. Thanks

I spent the last hour looking for this Kerbal Engineer Redux feature that shows you the estimated dV for interplanetary burns, with no luck. So, I'm really confused about where did you get that 10606 value.

Either way, to answer your questions, by parts:

- does this take into account the change in a ship as it goes from atmosphere to space?

Yes, for every atmospheric body. Good thing that it's splitted into several parts, so you know which ones are referring to a in-atmosphere burn, and which aren't.

The 4550m/s estimated by the chart in order to get into a low Kerbin orbit accounts the two burns: The atmospheric one (Launch pad until your Apoapsis reach 80km) and the circularization burn, which happens outside of atmosphere. After some tests here, I found that, in order to get into a 150km circular orbit, I spend about 3800m/s on the first burn, plus 1200m/s on the circularization. Total is 5000m/s. So you can have an idea what's needed for the 80km orbit.

- To go from Kerbin to Moho by this it says I will need 11190 dv total, but according to KER my full dv value is 10606 dv.

That's not a question.

- To go from Kerbin to Moho by this it says I will need 11190 dv total, but according to KER my full dv value is 10606 dv?

Maybe. As said previously, I couldn't find that feature on KER, but here's what I think it is the cause of these differences:

"11190m/s" is the dV required from Launch until Low Moho Orbit. It includes the little "2520" number over the Moho Intercept number.

BUT!

That number represents the maximum possibly necessary dV in order to do a plane change (that "Ascending" and "Descending" nodes stuff; the angle difference between planets).

That means this number may vary considerably, depending on Kerbin's and Moho's position relative to Kerbol. Depending on the transfer window date, you may need less dV than what's specified there.

TL;DR:

Yes, the chart takes into account the atmospheric burns.

The Plane Change dV (number outisde of the Metro Stripes) is the cause for the dV variation between the chart and KER.

I'm sorry for the wall of text. I have this bad habit on me, and it's very hard to get rid of it. I've gotta filter my text several times before posting.

I hope that answers your questions.

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I spent the last hour looking for this Kerbal Engineer Redux feature that shows you the estimated dV for interplanetary burns, with no luck. So, I'm really confused about where did you get that 10606 value.

No, Liowen isn't saying that KER gave him/her a 10606 value for a full journey to Moho, but rather that when building in the VAB, the 'Total DV' of his ship was 10606.

He understands that 11190 is an approximate target for that trip. What he's asking about is, occasionally, KER (and MechJeb too, I've witnessed the same phenomenon with MechJeb and that's why I recognized his question) will change DV values in-flight.

I wish I was on my home computer, b/c then I could provide screenshots to prove it. Best way I can describe it is, you have a typical three-stage asparagus rocket, with all fuel lines and decouplers properly organized. Let's say the Total DV calculated by KER or MJ is 10000 dV, split among the stages 2000+2000+6000. Upon launch, with MJ's delta-v window open so I can see the readouts, the first stage burns through its 2000 dV over a period of X seconds. But while this is happening, the second stage will 'magically' begin to GAIN both vacuum and atmo delta-v. Usually the gains are very small-- somewhere around 5%, or a few dozen dV by first stage burnout and second stage ignition. The third stage will also show gains, but to a lesser extent. Together, these 'additional' gains may be enough to push the total dV to the 11190 for Moho.

Theoretically, this shouldn't happen. Any mass above the first stage ought to be considered as static payload weight, as per the Rocket Equation. I have a few guesses as to why the delta-v creeps upwards during flight, all related to HOW MJ and KER calculate dV. Obviously, the physics are right, it's the estimations that are 'wrong'.

1. Engines have different ISPs depending on atmospheric pressure, and the change in ISPs is a smooth curve, not an instantaneous jump. KER and MJ only utilize vac and atmo ISPs in their calculations, ignoring the first 300 seconds after launch when those ISPs are changing (in the case of the nuclear, quite drastically).

2. MJ and KER don't know your exact launch profile. They have to make estimates based on a standard gravity-turn flightpath. But if your flightpath deviates significantly from that assumed path, then its calculations are messed up, because of reason #1 above.

I have a few more guesses but I'm at work and shouldn't be on here anyways, so it'll have to wait. BTW, this is a good enough question for a separate forum post.

Edited by NASAHireMe
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