people who haven't played kerbal space program (with mechjeb for data) usually don't fully understand how expensive, in terms of delta V, a large inclination change maneuver is.
I think the idea is that you plunge into the atmosphere, use lift to perform the orbital inclination change and then you raise your periapsis again.
I think you only need very little delta V to plunge back into the atmosphere from LEO.
The question is how much lift vs drag + delta V to lower and the raise you periapsis.
I think the space shuttle only had about 250m/s delta v once the yellow tank was exhausted, so those 250 m/s were enogh to complete both rasing the periapsis and then lowering it to de-orbit.
Think of a space-glider with one tip of its wings pointed straight down and the other straight up, if it has very little drag and a lot of lift, it could use its wings to maneuver north-south, change its orbital inclination, then when it gets out of the atmosphere again, once it reaches apoapsis it will spend some fuel to raise its periapsis again above the atmosphere, but KSP intuition is that if drag is low enough and lift is high enough, it could be better than to do an inclination change in vacuum.
Yes. Some mods like kerbal engineer and machine everywhere makes thing less annoying, not easier. It’s the engines, fuel tanks, and science payloads that can break the balance.
As for mechjeb in particular, I never found it all that useful except when calculating rendezvous. I could do it myself, but I don’t want to bother with a protractor and calculator.
Mechjeb can help you with the boring parts. First couple dozen launches or orbital intercepts are super-fun. But once your goals shift from "let's land on the Mun" to "let's send a 250 ton ship to Duna", assembling it in orbit from a dozen launches starts to feel like a chore.
Mechjeb was far more useful/necessary 3-5 years ago. The stock game has added so many features at this point that I really didn't feel the need for any mods at all when I picked it up again a few weeks ago.
