What is the most efficient way to launch to the Mun from 21 Degree Latitude?

[Voodoo8648]

I have the KerbinSide mod installed and I am launching from The Great EZ Kape. The latitude of the launch pad is around 21 degrees North (similar to the Kennedy Space Center in Florida). I am trying to perform a launch to the Mun similar to how Apollo did, however the inclinations are very different! What is the most fuel efficient way to launch to the Mun and get a "free return" trajectory back to Kerbin?

Edited November 4, 2017 by Voodoo8648

[Aegolius13]

I think you would want to do your ejection burn at the AN or DN with respect to the Mun, so you can include a plane-match normal burn with your prograde burn and get that "pythagorean" discount.  Of course, you can only due this when the Mun is in the right place (i.e., where burning at the node puts you at the right phase angle), but that should happen every 3 days.  

Edited November 4, 2017 by Aegolius13
Meant normal, not radial burn

[bewing]

Basically, the efficient way is never to match planes. Launch to an orbit so that your orbital plane is rotated 90 degrees WRT the Mun (or after you're in orbit, wait for the Mun to reach that 90 degree position). Raise your Ap high enough to get a good low-Pe encounter at the Mun.

When you do your capture burn at the Mun, lower your Ap just enough to get inside the SOI. Then at that new Ap, do any plane changes you wish to.

If you want it to be a free-return trajectory, then you need to make sure that your Munar Pe is on the front-side of the Mun, instead of the backside.

 

Edited November 4, 2017 by bewing

[Pand5461]

You need a configuration like this:

Ejection burn slightly after the node (i.e. below DN or above AN), the maneuver dV must be at least 870 m/s, otherwise you won't get the free return.

Plane matching is, strictly speaking, not needed. Equatorial orbit is helpful for Apollo-style missions with low Mun orbit rendezvous, so that the orbit of mothership does not get away from landing site due to Mun rotation. For direct-ascent missions, inclination change is absolutely redundant.

[Kryxal]

9 hours ago, bewing said:

Basically, the efficient way is never to match planes. Launch to an orbit so that your orbital plane is rotated 90 degrees WRT the Mun (or after you're in orbit, wait for the Mun to reach that 90 degree position). Raise your Ap high enough to get a good low-Pe encounter at the Mun.

When you do your capture burn at the Mun, lower your Ap just enough to get inside the SOI. Then at that new Ap, do any plane changes you wish to.

If you want it to be a free-return trajectory, then you need to make sure that your Munar Pe is on the front-side of the Mun, instead of the backside.

 

Actually, you can do a free return trajectory in either direction, it just involves more delta-v and time than going the other way.

[OhioBob]

The correct phase angle for a trip to Mun is about 120 degrees.  That is, we place the maneuver node on the orbit line at a position that is 120 degrees behind Mun's position at the time of burn.  Therefore, when the launch site is not on the equator, what I like to do is launch due east when KSC is at a position that is 90 degrees from where I plan to place the maneuver node, or when the phase angle with the moon is 210 degrees.  What this does is it places the spacecraft in an orbit that crosses Kerbin's equator just at the point were we plan to place the maneuver node.  In other words, we've created a condition in which the ideal maneuver node position corresponds exactly with the spacecraft's descending node (or ascending node if the  launch site is at a southern latitude).  Since Kerbin's equator is coplanar with Mun's orbit, this means we're placing the maneuver node in Mun's orbital plane.  By ejecting into the transfer orbit while passing through Mun's orbital plane means we can get a good intercept with Mun with minimum fuss and delta-v.

[fourfa]

Looks like all the right answers are here above. In case you are looking for the LAZY answer - launch to orbit any old time, set your ejection burn 120 degrees ahead as stated, raise your Ap to the target body’s orbit without worrying about inclination or intercept. Halfway there, fiddle with a mostly normal/antinormal maneuver to get an intercept. Then if necessary clean up the final inclination at the highest An/Dn once in the target SOI. Shouldn’t cost more than 50-60m/s extra, maybe 100 at the absolute worst. Plane changes can be cheap if you’re going slowly