Is my delta V map wrong, or am i crap at maneuvers :P

[ohlookabirdie]

So the dV chart i printed off says 4550m/s to lko, then 950m/s for kerbin escape... so far i agree, the next bit is what get me. 80m/s to eve intercept... i dont even get close to this value when i try to get to eve... is it the chart or can someone teach me (without vids) how to do planetary intercepts with that little dv?

[HazelPine]

I think it means you need to do that burn while burning out of kerbins SOI, because then it makes use of kerbins gravity well. I know that if you do the burn outside the SOI then you will need a lot of delta-v.

[ohlookabirdie]

how do you get the right plane from inside kerbin's SOI? i wouldnt even know where to start on how to calculate that burn

[Yasmy]

The delta-v maps generally don't include plane change maneuver delta-v. If you are not near the line of nodes when you begin your transfer, the plane change maneuver can be quite large, as you've noticed. Alex Moon's launch planner will give you a low delta-v window, which typically occurs along the line of nodes.

[Kasuha]

Delta-v maps are often misleading and usually based on some assumptions which may not be even described in them. For instance in this case the value means it is 1030 m/s from low Kerbin orbit to Eve intercept - if Eve is in ideal position.

It is better to learn to use some transfer calculator, e.g. alexmoon calculator. Not only will it tell you how much dv you are really going to need for your travel, but it will also tell you when you need to go and in which direction.

Transfer burns and circularizations/braking to orbit are usually best to do in as low altitude as possible due to Oberth effect. Ejecting just behind the Kerbin's SOI and then making transfer burn to Eve is going to cost WAY more dv than a burn directly from low orbit.

Edited May 17, 2014 by Kasuha

[allmhuran]

4550 to LKO is clear enough, you obviously understand that one. The result of this is to put you in a parking orbit at about 75km.

When you add 950 m/s for Kerbin escape, the result would be to put you in an orbit very similar to Kerbin's orbit around the sun - depending on the direction you left, see below.

If instead you had added 1030 m/s from your 75km orbit, you would have added enough to get to Eve (because to get to Eve, you clearly need to escape Kerbin first! So you add the 80 onto the 950)

However, I wonder if understanding the chart itself isn't where your confusion lies, but rather, understanding when to begin your burn from LKO in order to get to Eve. So let me try to explain that too. Eve is at a lower altitude than Kerbin, so you're going to need to reduce your solar velocity. This will leave you with your apoapsis near Kerbin (because that's where you left from), and your periapsis at Eve.

In other words, you want to leave Kerbin going slower around the sun than Kerbin does. Which means that when you leave Kerbin, it should be "getting away from you". Which means that you want to head away from Kerbin in a solar retrograde direction. By this I don't mean that your orbit will be opposite to Kerbin's. I just mean that relative to Kerbin, you want to be heading off in the opposite direction to it. You won't be going "backwards around the sun", you'll just be going forwards slower than Kerbin is, because you spent about 1000 m/s slowing down your solar orbit when you left Kerbin.

In order to do this, you want to start your burn on the sunny side of Kerbin, some time in the morning. If you leave on the dark side of Kerbin, say, 9pm, then your ejection angle will send you out ahead of Kerbin's solar orbit, which will take you higher, to Duna for example. If you leave so that your escape is radial in or radial out then your solar velocity will barely have changed at all and it will cost you a fantastically large amount of delta V to get anywhere.

Obviously trying to explain this without any visual aids is not easy, so despite your "without vids" request, I do have an in-depth video on escape trajectories and gravity slingshots that might make things a LOT clearer:

Edited May 18, 2014 by allmhuran

[voneiden]

Consider taking a look at the illustrated tutorial in my signature. It teaches how to do a interplanetary transfer with a mid-course plane change in a relatively fuel efficient manner. I've gotten good feedback on it, so I think it should be quite easy (and quick) to follow.