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Modern dV map?


CastleKSide

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So Im designing an efficient LKO launch vehicle and went looking for the subway dV map. But the one on the wiki says its outdated and has a dV cost of 3400 m/s to LKO. I have done some searching but have failed to find a map with a different value. Does anyone have a modern dV map for current versions of Kerbal? Or barring that what is the correct dV for LKO these days

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Why do u need a Dv Map anyways, just add moar boosters, I tend to put ~3800 m/s on my orbital launchers, mainly to serve as a way to push a slightly larger payload or if I am not perfect with ascent, the Dv map is assuming you are perfect, so its best to add ~400 m/s for getting to orbit, then, ~100m/s extra per step(so not being perfect won't end your mission, also accounts for any small correction burns you may need to do)

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1 minute ago, kspnerd122 said:

Why do u need a Dv Map anyways

I am trying to design efficient, like i said in my post. I like the challenge and try not to do the "Moar Boosters".  Imo any problem can be solved that way and it takes the fun out for me. To each their own

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Well still, not having a fudge factor is a problem unless you are using mechjeb or KOS, otherwise, add extra fuel, you will need it, btw, the Dv requirements have barely changed, but its best to have ~3600 m/s Dv on a kerbin launcher

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23 minutes ago, CastleKSide said:

So Im designing an efficient LKO launch vehicle and went looking for the subway dV map. But the one on the wiki says its outdated and has a dV cost of 3400 m/s to LKO. I have done some searching but have failed to find a map with a different value. Does anyone have a modern dV map for current versions of Kerbal? Or barring that what is the correct dV for LKO these days

The outdated label is probably what's wrong with the map on the wiki -- the values have changed little if at all since around 1.1, and minimally since 1.0 (where LKO went from 4500 m/s to 3400 m/s)

Edited by UmbralRaptor
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Do you mean this one?  That’s the most current version I could find, but yes it is outdated.  It is still appropriate to use that one for a few reasons.

  • The game hasn’t changed that much.  The planets and moons are still in roughly the same orbits.
  • You should take those values as a very rough estimate anyway.   The DV required to reach orbit from any body, especially bodies with atmospheres, will vary greatly with your ship design, engine thrust and efficiency, and your piloting skills.
  • Same goes for transfers between bodies.  Your thrust, efficiency, and navigation skills can produce fairly large differences in the actual DV used.
  • In general, it is almost always possible to do better than what the DV map says.  Just depends how your ship is designed, and how much time you are willing to spend optimizing your route.

I think the reason nobody has updated the map is because the existing one still works exactly as intended- to give you a rough idea on DV requirements..

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I usually leave about 3300 m/s for orbit, unless my ship has really low acceleration or poor aerodynamics that warrant a less efficient steep ascent, in which case I'll add more. I haven't really done any testing for minimum delta-V to orbit, though, I should see what I can do.

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For missions where you have an atmosphere, delta-v becomes a bit unwieldy of a metric, due to the changing specific impulses of engines, plus the fact that in a single stage launch you usually switch engines at some point. My preferred metric is mass fraction, i.e. how much payload you can put in orbit with this much mass of launcher.

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On 6/9/2021 at 2:16 AM, camacju said:

For missions where you have an atmosphere, delta-v becomes a bit unwieldy of a metric, due to the changing specific impulses of engines, 

Yes, well, technically no, but yes.

The dV needed doesn't vary with impulse, but the dV readout that you need does.

A mammoth won't need as high of a vacuum dV readout as a kr-2l or skiff, because those engines have a much higher difference between SL isp and vacuum.

In stock, this factor really only applies to kerbin, eve, abd laythe.

All engines get very close to vacuum dV on Duna.

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