Planet Phase Angle Calculations for Difficult Planets

[TokiGlassBlower]

Hello,

I have searched the web and these forums for this question and found mostly nada, I have found the Phase Angle calculators that are on the web and they are ok but seriously lacking in all but the most basic of calculations and I'm unable to find anything on YouTube or reddit or any other site that explains how to do Phase Angle  calculations for the harder planet to planet intercepts, my problem is I want to go from the Mun to Duna which is not a standard calculation, the PS version of the game has a Mun launching facility which I hear the PC ppl do not have? and it allows the ships to be much smaller because of the low gravity and are way cheaper to launch but plotting from the Mun to anywhere else is a pain, anyway trying to figure out the intersect angle from the Mun to Duna eludes me, without an answer I guess Ill have to just figure it out by playing with the maneuver nodes but a mathematical equation  for this sort of thing has to be out there? maybe someone has it written down???...... 

 

Blue Skies

[fleventeen]

Hello,

The "phase angle" you mentioned is an important concept in interplanetary travel, and once you get some experience you can learn to eyeball most transfers from the phase angle itself, but you may have better luck by searching the term "transfer window" or "launch window". Transfer windows are represented by something called a porkchop plot, and show you a window of time where transfers are possible, and also most efficient.

Here is an excellent transfer calculator

For the purposes of calculating your transfer window, just calculate it as if you were departing Kerbin. The windows for departing Kerbin and Mun are essentially the same since they are both located together in the same SOI.

For planning your actual burn to exit the Kerbin SOI, play around with the maneuver tool, but I can tell you that a good rule of thumb is to make your trajectory such that you are exiting the SOI in the retrograde direction of Kerbin's orbit for destinations in the inner Kerbol system, and prograde for destinations in the outer system.

The final tip is to use this handy delta-v map, as it will tell you any additional delta-v required for plane changes, if you ever need to do that.