Help reading Delta-V maps!

[IriathZhul]

So I'm looking at this map, and I just know I'm missing something here.

http://forum.kerbalspaceprogram.com/threads/41652-A-more-accurate-delta-v-map

According to this map, it takes 380 delta-v to get to Duna from Kerbin escape (meaning, after I've broken Kerbin's orbit).

Now, that is about 1/3 the best I've ever been able to do. Even with MechJeb's creepy precision, it still takes about 1000. So either:

1) The map is wrong (I doubt this)

2) I'm reading it wrong (Moderate doubt)

3) There's some magical super-efficient way to get around that I've apparently yet to stumble upon after 200 hours of playing (Moderate suspicion)

Please, enlighten me.

[Mr.Rocket]

No, you are reading it right. What you may not know however (it took me a long time to learn this) is do the burn for Duna while still in Kerbins gravity. You will get a boost from kerbin (oberth effect), and so it costs less delta-v than burning in solar orbit. So technically it's only an addiational 380 added to the delta-v you need to escape Kerbin.

Hope i helped

[I_Killed_Jeb]

I think the issue is that interplanetary burns are more efficient in LKO than HKO, so IMO the proper way to read these maps is to sum it up from low orbit as opposed to calculating it from where you are?

[Kerbart]

I assume your 1000 dV is based on reaching a parking orbit around Duna, which means you're spending a ton of dV on getting captured (reducing your speed to orbital velocity)

The red arrow at the 250 pointing from "Kerbin/Duna Transfer" to "Duna Capture" indicates aerobraking. So the 380 really is for the transfer between the two orbits, and you're not paying any delta-v for capturing.

[MajorThomas]

When I go to Duna it takes about 1000 m/s delta v starting from low Kerbin orbit. So the 1000 includes Kerbin escape and transfer to Duna.

If you merely escaped from Kerbin but didn't raise your orbit around the sun, then this map says it takes an additional 380 m/s to Hohmann transfer to Duna. I could believe that figure.

[Taki117]

the dV map makes one critical assumption, and that is that you launch during the resulting transfer window. If you launch to solar orbit first, and then do a Hohmann transfer to Duna orbit you will use more dV than if you waiting for proper planetary alignment to do your burn.