[1.7.3] Community Delta-V Map 2.7

[Kowgan]

Oh, I get it.

Well, as you said, I think that's a problem either on the game engine or on MJ/KER way to calculate things, and my best guess is thhat they gave you the wrong dV info at first place. And during flight, they automatically correct themselves.

Also, NASAHireMe's 1. and 2. points are important to take note.

Either way, I suggest that you take this discussion to either Kerbal Engineer Redux or MechJeb official threads.

[NBZ]

Great. This will replace the old one as the only image for Image Viewer. No need to Alt-Tab, just Alt-I, right there in VAB.

[Kowgan]

Nice! I was looking for a plugin like this Image Viewer; didn't know that one already exists! Definitely a must-download! Thanks for the tip, NBZ!

[ftunk70]

I think KER shows the current delta-v in the current atmospheric preassure. That's why the delta-v on unspent stages rise as you ascend into vacuum. Inside the VAB, you can chose either "atmospheric" or "vacuum" I think, but once you launch it's automatic.

[OtakuD]

Cannot wait for this to be released, so useful!

[EatVacuum]

Cannot wait for this to be released, so useful!

Agreed! I've been playing Rescale so long I'd forgotten the vanilla KSP numbers. From a few hours play and several launches though, it does seem the new aerodynamics model has dropped the delta vee to orbit on Kerbin down to something close to what we had under Ferram (i.e 3500-3600) than the 4550 for vanilla. And I assume the same will be true for the other bodies.

Now to see what the heck it does to the aerobraking altitudes...

[cybersol]

IIUC only the atmospheric values should change. Guesstimating from the stock ratio of deltaV on Kerbin between 0.90 and 1.0, I would guess 8000 dV for ascent from Eve, 1050 dV from Duna, and 2500 dV from Laythe. Those should be enough for planning purposes for actual runs to figure out better numbers Also, Eve will still be especially tough because the further drop in ISP & thrust relative to Kerbin due to its thick atmosphere.

[Kerbas_ad_astra]

Can we have a connection from Kerbin SOI edge to low solar orbit? DMagic Orbital Science includes a survey mission that has to swing through there, and it would be great to have a delta-V number for it!

According to my calculations, it's about 6 km/s -- Kerbin orbits at 9200 m/s, and to drop to 1000 Mm, you've got to decelerate to 3200 m/s.

[Kowgan]

@Kerbas_ad_astra: Done.

WAC's Delta-V Map updated to 1.0.2a

Changelog:

- Updated atmospheric values to match KSP 1.0.2 aerodynamics
- Updated Low Orbit altitude on a few bodies
- Added Kerbol to the map

The new aerodynamics on KSP make it super easy to have different results in atmospheric scenarios. I've made a bunch of tests and picked average results. It's possible to achieve low orbit in atmospheric bodies with fewer m/s, or it may require more, depending on your ascent profile, usage of fairings, etc.

Jool's and Kerbol's ascent dV numbers aren't 100% accurate. They're a guess based on tests. Don't blindly trust those values!

For any changes, I'm always open to suggestions. Hit me.

Enjoy it.

The wiki's giving me an exception error when I try to upload the image there. Will try again later.

Edited May 24, 2015 by Kowgan

[SanderB]

I think the dV cost of kerbin (and preseumeably other atmospheric bodies) are very pessimistic. None of my vessels break 3,400m/s unless I'm trying to launch ready made pancakes into LKO. A couple vessels dont even break 3km/s. There needs to be some sort of disclaimer or a 3,000-3,700 figure for kerbin and something similar on other atmospheric bodies, imo.

Edited May 24, 2015 by SanderB

[Kowgan]

That's great; I never managed to reach a circular LKO with less than 3km/s. Maybe I'm doing something wrong at the ascent profile.

I guess a disclaimer would fit it better. I fear that leaving a range (3,000-3,700) instead of a solid number would make some users confused.

Also, I'd prefer having fuel left in my tanks, rather than not enough when following a chart. Thus, I can learn from the results, and then adapt as I see fit.

[SanderB]

About 2.9km/s to LKO is possible with stock parts:

You might confuse a some users with 3,000-3,700m/s dV but I think that may misinform some others. I realize that that's a trade off.

[Kerbas_ad_astra]

I think it's reasonable to say that the atmospheric ascent values are typical, and that more efficient ascents are possible.

[Kowgan]

Thanks for the input, everyone. I'll surely use your disclaimer suggestion, Kerbas_ad_astra.

Here's what I plan for the update regarding atmospheric ascents, but I'd like to know your opinions first:

Kerbin: 3300m/s

Duna: 1300m/s (as it is now, and as it was on .90)

Eve: 6000m/s

[Kerbas_ad_astra]

For 3300 m/s, I'd want a disclaimer that less efficient ascents are possible. I don't know that I've gotten one that efficient (though I've only just gotten fairings in my career save -- 3400 or so is my best with the Kerbal X, most of my fairing-less ascents have been in the range of 3600-4000 m/s).

[Kowgan]

How does that sound?

Atmospheric ascent values are typical. Less or more efficient ascents are likely, depending on ascent profile and fairings usage.

[Kerbas_ad_astra]

Fair enough.

[Kowgan]

Updated to 1.0.2b:

- Lowered atmospheric values in Kerbin, Eve and Laythe
- Extra info and credits

Added Galahir950's version to the OP. His version contains pre-calculated results and a small chart for quick view. Go check it out!

Edited May 25, 2015 by Kowgan

[pacbard]

This is probably OT, but how do you guys get in orbit from Kerbin with 3300 m/s of delta v? Is it vacuum dv or dv on launchpad? As a (probably) mediocre KSP player, the delta v maps really help me a lot in designing my missions (and I prefer this subway map to the other one with the straight lines). And yes, I have read the disclaimer about ascent profiles and fairing use.

Doing consistently worse than the suggested delta v budget feels like against the principle of having a delta v map to begin with. For example, a Mun rocket is supposed to have 5050 m/s of delta v, but then do I need to add 1000 m/s to it because I am not a good player?

Wouldn't it be better to include an upper estimate for atmospheric delta v with the understanding that better players are able to calculate how much they can save rather than expecting new players to figure out how much delta v they need to pack over the recommended amount?

[Kerbas_ad_astra]

This is probably OT, but how do you guys get in orbit from Kerbin with 3300 m/s of delta v? Is it vacuum dv or dv on launchpad?

All values are vacuum dV. So, if I design a 3300 m/s rocket, it will probably show less than 3300 m/s on the launch pad, but with efficient flying, I can get it into orbit on that much fuel alone.

[Kowgan]

@pacbard: Vaccum values are for vacuum Delta-V. Atmospheric values are a mix between atmospheric and vacuum.

Of course, there is a transition when going into orbit. The percentage of each dV amount depends on your orbit altitude. But for the ones listed on the map, I'd say they are ~80% atmosphere and ~20% vacuum.

On my tests, I've recorded the "Amount of Delta-V Expended" through MechJeb. This data doesn't differentiate between atmo and vacuum. So, those are the values in the map.

Now, this isn't about "better or worse" players. One isn't a better player than the other for going into space more efficiently.

As you've read in the disclaimer, there are more and less efficient ways to reach space. The values are there to point that it is possible to do so. And more importantly, the values are there to serve as a base to your missions. So,

do I need to add 1000 m/s to it?

If you know how much dV you need to bring, even if you need to add or subtract from the map value, then the map is fulfilling its objective.

Sorry for the long blabbering. And if you want an example of a less-than-3000dV-to-orbit, check the video at the previous page.

Edited May 29, 2015 by Kowgan

[pacbard]

On my tests, I've recorded the "Amount of Delta-V Expended" through MechJeb. This data doesn't differentiate between atmo and vacuum.

Ah! That explains it. I was trying to figure out the values with Kerbal Engineer and I was getting frustrated. Sorry if it sounded whiny.

For example, build a rocket with a MK 1 pod, 2 FL-T800 tanks, and an LV-T45 engine. KER will tell you that it has 3836 m/s of vacuum delta v with a TRW of 1.80 or 3237 m/s of delta v at sea level with a TRW of 1.52. When you put the rocket on the launchpad, KER simulates it to have 3244 m/s of delta v available with a current TRW of 1.52.

If you used the "Amount of Delta-V Expended" for the map that explains why the rocket was not getting in orbit even if it should have more than enough vacuum delta v. BTW, that rocket should be able to get in orbit no matter how you flight it because it does not have enough TRW to be efficient.

I saw the video but I do not think that that is an example for a common launch, but more as a proof of concept.

Thank you for the clarification! The map makes much more sense now.

[Kowgan]

I'm glad I could be helpful.

[problemecium]

*reads revised map*

Hmm, those transfer numbers are smaller than I remember - but wait! These are interplanetary transfers! They shouldn't have changed...

*realizes latest mothership may be overdesigned by a factor of eight*

xD

EDIT:

*redoes math*

*realizes latest mothership is underdesigned by 30%*

I might just be bad at math...

Edited May 29, 2015 by parameciumkid

[smjjames]

Oh hey, updated version of the DeltaV map that I like.

Wonder when the Wiki page one will be updated.