Well, I'm not a math ninja. In fact, I'm not sure I even qualify for a yellow belt.
Transfer angle is new to me, so not sure what 3 points (ie what angle) on the Planet Approach page I should be looking at.
I'm acting as a translator here, jarmonik is way smarter than me, but english isn't his native language. Every single thing he said is "Gospel Truth", but it can be hard to understand how to apply that to the current scenario. I'm trying to apply a few years experience with IMFD, and with jormo's manuals, and put it in terms the (likely less intelligent) rest of us can actually understand.
For starts, a TEj of 6400 seconds is a guess - not terribly accurate, but close enough.
One of the "tricks" to mastering Orbiter is knowing how much "slack" needs to be cut at any given stage. For this flight, cut a lot of "slack" on PeA and Pe Longitude during the TEI, focus on PeT (dVf is efficiently adjusted during the eject burn) and PeA and Pe Latitude (planar) are best adjusted during the MCC (when dVi and dVp are efficient, and dVf isn't). The Oberth Effect matters, so make changes to the amount (dVf) of your velocity when your velocity is high, and make changes to the direction (dVp and dVi) of your velocity when velocities are low. You can use burn view to see the individual axis of thrust IMFD is calling for.
IMFD offers a variable level of usefulness. It can perform simple transfers in the simplest way. Or it can perform very complex maneuvers, but not as easily. It can take a given situation, and help you find the lowest dV solution to that particular situation. It doesn't always help you find a "situation" that allows the lowest dV.
What I'm saying is that, while IMFD makes it relatively easy to make a basic transfer, the accuracy and efficiency of that transfer will be largely dependent on your understanding and skill.
1st I think I made an error with regard to TEj and GET. I kept thinking that a Tej of 6400s and a GET of 22hr meant that the mission elapsed time would be close to 24hrs
Maybe close enough for planning purposes, but a Time Of Flight of 20:13 would have been closer. Add the time it takes to getting from ("now" to the ejection point) + the time from Lunar ejection to Earth Pe, I think you subtracted. Just make sure that your actual PeT matches the plan. You won't be perfect on the ejection unless you launch at exactly the right time. If you figure out how to do that, please let me know!. Sure, the closer you are to "perfect" the more efficient you can be, but really, an hour or two either way isn't significant. PeT is much more important than TEj, and even that has some "slack". Everything has a "window" - there's a very short "perfect" window, and a much longer "darn near perfect" window where the difference is only a few m/s. Given the accuracy limitations of even IMFD's Map, it's OK to be "close, but not perfect" during TEI. PeT is much more crucial (especially at lunar ejection) if you want a short (in time and distance) but survivable entry.
Transfer angle is new to me, so not sure what 3 points (ie what angle) on the Planet Approach page I should be looking at.
On a minimal energy Hohman Lunar-Earth transfer, we reach our periapsis at the opposite side of the (non rotating) reference. This is a transfer angle of 180 degrees. For a quicker transfer, our trajectory will be (from Earth's point of view) an incoming hyperbolic trajectory. This being a "flatter" trajectory, our Pe won't be on the opposite side, it will be nearer. Trajectory Angle is the angle between the vessel's position at lunar ejection and the angle at vessel's Pe. The faster the transit, the shorter the angle, but 90 degrees is the absolute (and non-attainable) limit at the lower end. I'll take jarmonik's word that 150 degrees is close enough for a 24 hour trip.
Still not sure on the difference between deg of orbit and deg of longitude.
Unless you are referring to deg of arc?
Degree of arc is probably the correct term. I'm not real mathematical, but that sounds like the correct term. I mean that a 120 degree anticipation doesn't mean your Pe should be 120 degrees (longitude) west of your target's longitude (unless you are in an equitorial orbit and your target is on the equator). Rather, it should be 120 degrees around a non-rotating reference (the planet's Center of Mass in a constant frame).
Also, keep in mind the difference between PeA and Re-entry Interface. If you have Re-entry Interface set to the same as your desired PeA, you should have a ReA close to zero. Personally, I leave the Entry Interface at 120k, and adjust the Ant for the extra distance. Being consistent on the Aero-capture and Re-entry stages helps - practice, practice, ... . And again, I'll stress that the more range your vessel has the more slack you can cut. A capsule has very limited range and even less cross-range so accuracy counts. A DG or similar can handle just about anything - but getting it "right" will mean an easier and faster re-entry.
From your last post, you are close to getting it. Hopefully this helps a bit, but I know I'm not explaining it very well.
As I said earlier, timing is everything - especially PeT. If you end up with a very steep ReA, you are arriving at the wrong time (and the window for arrival at a given position is VERY short), probably too soon. If you are arriving too late, Base Approach will call for a larger dVf value - and this is quite inefficient except at the ejection point.
As with all operations, proper planning is the key to efficiency. Know your 6 datapoints in advance, and follow the plan. Know when to cut "slack" and for what variables. At ejection, cut slack in the dVi and dVp vectors, and be precise in the dVf vector. Be picky about the Earth PeT, and not the PeA or Plane. At MCC, do th opposite, and be picky about PeA and Pe location (but not so much PeT - as long as the location and Ang are correct).
Above all, experiment. It's clear you do that, never be afraid to try adjusting something without being told to first. Pay attention to what variables can be adjusted, and try to imagine how it will shape your trajectory. Especially pay attention to what programs like Planet Approach and Base Approach do. First you'll learn how to set up the flight better (ie, using Planet Approach in such a way that it minimizes the burn needed by Base Approach.) Both Planet Approach and Base Approach are handy, but they have limited accuracy (they use a two body solution) compared to Map (but sometimes you can "fudge" things to get a better result in Map - ALWAYS trust Map over any other program). They also need to be within "range". Planet Approach isn't reasonable accurate until you are within 2 or 3 "SOI's" away, and Base Approach not until within the body's SOI. I tend to use Delta-V program for the MCC's, coupled with Map it is much more accurate (and reasonable accurate much sooner), and , for me, easier to find the most efficient trajectory.
i suppose I should point out that for me, fuel efficiency is the primary goal. I'm also not bad at atmospheric re-entries so I'm happy to save a few m/s dV even if it means a less than optimal Pe location.
I mentioned Capsule Re-entries earlier, and for those who are interested - you are likely re-flying the Apollo missions. Follow the mission time-line correctly and landing on target should be fairly easy. If on your own mission, you will need to plan ahead and be fairly precise.
