Changes in Delta V maps

[Bookz]

Hi All.

I got a new delta v map of the web when 1.0 came out and noticed that the delta v for landing on the Mun had changed on it. Specifically that required to go from Low Mun Orbit to the surface. I then noticed that a few others had also changed like Dres and Eeloo. These two map from the KSP wiki show when the change happened.

http://wiki.kerbalspaceprogram.com/images/archive/7/73/20141222045506%21KerbinDeltaVMap.png, form May 2013.

http://wiki.kerbalspaceprogram.com/images/7/73/KerbinDeltaVMap.png, from December 2014.

I then tried to land on the Mun using a lander with only 580m/s delta V, under mechjeb control, and crashed into the Mun going fairly fast. The lander was placed in a 14km orbit around Mun by Hyperedit, Kerbal Engineer said it has 585m/s delta V and Mechjeb tried to land it at a point along the orbit.

Are the new values correct and if so what am I doing wrong?

Edited August 17, 2015 by Bookz

[FancyMouse]

What's your TWR? The map may reflect optimal scenario when you have huge TWR.

[Wjolcz]

This is strange... The dV requirements should change only for bodies with atmospheres in 1.0.

[FancyMouse]

The two maps OP compared doesn't even cross 1.0 boundary, so I assumed it was because some user report of a more efficient landing/ascent. And it does make sense - assume infinite TWR, then you should immediately build horizontal speed to make apoapsis to low orbit, then circularize. And that should be close to 580 (not on pc, can't do math now). It's just for a normal lander you don't have the luxury of that TWR and you have to be somewhat less efficient to do the same thing.

[Pecan]

I've been using 580m/s for Mun for a long time, thanks to http://i.imgur.com/NKZhU57.png, which I usually found fitted my piloting style (or otherwise) better than the one given by the OP.

For up to date information, the best-checked that I'm aware of is http://forum.kerbalspaceprogram.com/threads/96985-1-0-4-WAC-s-Delta-V-Map-continued-2-1-%28Aug-13th%29-Swash-transition, although I haven't been many places far in 1.0.4 yet.

Are the new values correct and if so what am I doing wrong?

I'd say they are correct, but need more information to know why they aren't working for you. Three immediate points are - i) What does MJ say the dV is? It and KER sometimes disagree, ii) My low Mun orbit is 8 - 10km, so you might want to start from lower, iii) What's the TWR? If it's less than about 2 relative to any particular body MJ can have a hard time landing.

Edited August 16, 2015 by Pecan

[Alshain]

Whether or not they are correct is subjective. Some people can do it with less, some people can only do it with more. It depends on your abilities.

[Bookz]

Thanks for the information.

I tried the landing a few times again with different TWR values and some more delta V. I found that the delta V on the map is the perfect suicide burn with a very high TWR.

I now know that the values on the map are the absolute minimum values and you should always add at least 150m/s for the landing.

[Pecan]

Thanks for the information ... I now know that the values on the map are the absolute minimum values and you should always add at least 150m/s for the landing.

Thank you for the testing - now we all have your experience to add as well :-)

[xtoro]

MechJeb has crashed me several times. I find it also gets confused if you time warp during the descent. Now I usually just manually land until my speed and altitude are low and then I click the "land somewhere" button for it to do the last little bit.