Spricigo

Let's try again. I get that Kerbin is not the Sun and Mun is not Kerbin. But the physics is the same.

No. I'm just considering the physics of the situation and wondering why you assume that it will be different when it happens a 2nd time. Why you think one cannot do this?

I wonder why you assume this. Multiple gravity assist from the same celestial body were used extensively both in KSP and in real life.

Yep. Quite easy to put together the parts to make a craft that looks like but it then fly like a hippopotamus.

Yep. Sepratons can be useful too, pushing the tank further away from your patch. Unfortunately i can't say there was no incidents in my attempts. But eventually it works

Well, I play with extraplanetary launchpad. Which means my lander are considerable smaller since they almost never include the return vehicle. And thus I didn't get a lot of practice with bigger landers. (made a few to know I can and that is it). I realize that there is something I'm not getting right when scaling up, but beat me if can figure out what it actually is. (also, is not like I'm having trouble to bring the extra fuel for a propulsive capture)

Personally, I don't see those as separated issue. The "correct" flight profile will be the one the vessel is designed to follow. In my experience, the kind of craft the Op is using tend to work with the flight profile Snark is suggesting. Big landers intended to return from the surface not quite so.

I had some good result with the tank in front. But needs some trickery to secure a clean separation. In any case, the real trick was to come up with a reason to make a shuttle instead of anything else.

I'm guessing there, but if early on you stumbled into a method that "just works" the concessions you make for this method to work just seems natural for you. Developing a different procedure latter seems harder and if you really don't need it... Anyways, there is many ways to cook a Eve probe. Myself, I'm found on pancake shaped vessels that can "belly flop into concrete"

Funny thing, I considered posting that method in a "for the sake of completeness" answer. But on a second thought, I decided that it is overcomplicated and would just confuse you. Seems I was wrong. In any case, there under "cheats" this "+100" button:

Something makes me think it can be done.

With infinite deltaV? Just point normal or antinormal and burn, err...kraken?! Whatever! Add this normal/antinormal component while you accelerate towards the target planet and keep an eyes for where the AN/DN go.

Oh noes, that is fair game. We really appreciate people making easy to find a answer/solutions around there, both for the original poster and for the other people that will stumble into the thread with a similar problem later on.

You can set the thrusters to only respond to translation inputs: Enable Advanced Tweakables Open the Part Action Window Click Show Activation Toggles Turn off Yaw, Pitch and Roll

Contracts in general are little more than an excuse for the game throwing rewards at us. Case in point: after completing the contract the vessel is yours for whatever use may be found. Regarding the question I'm also under the impression that launching it in modules and assembling will complete the contract, even if you are not "supposed" to do that way. Unless it is a modded contract, maybe the modded found a clever way to prevent the completion of the conttract i that way.

yes. ( @jimmymcgoochie nailed it: imbalance and overcorrection) Also don't help if you didn't designed the craft to minimize the issue.

Oh! I'm in perfect agreement that good Duna planes can be designed. But, I'd rather not design such kind of vessels. Just a preference.

As I see, It's more a case of aerodynamic flight, despite of the elegance, not working that well with Duna. Engines are not without their own issue but It seems more straightforward to deal with for me. The checklist goes as: there is enough thrust? thee is enough fuel can keep the right attitude? Of course, there is my bias in it. The way I play planes don't have much use except for Laythe and Eve.

Well, as most things in KSP: practice there is a mod for that I suppose it can be done with control surfaces and airbrakes, but I just use engine(s) and MoarFueltm

The impressive parts is that you used stock air intakes.

You instinct is right, they are kind of the same. I'm just speculating there but I think what is most often the cause of confusion is that the craft depart from "an orbit withing an orbit". It's not so obvious that the maneuver is intended to change the current orbit the craft sares with Kerbin to an orbit that will intercept Duna (or whatever other pair of celestial bodies) and even then it add anothe leyers of complexity. Does it makes sense to you? edit:because @paul_c just beat me with a cleaner explanation.

Similar experience there, I did the hard way a few times to prove to myself that I can, then I started to use mods and other resources to make it easy. Kerbin<>powered assist at Eve<>Moho is my preferred method. But I screw up sometimes.

Sorry, I can't agree with that. I understand that you put a lot of effort in answering the question and don't want to feel that was for nothing. But telling him to not ask is not a solution, you are just asking for a fellow player to move away. Would you like to be asked that? Well, I didn't. I don't want anyone moving away, I rather want that we understand each other. Unfortunately there are many things in KSP that may seem impossible when you first try, yet you find veterans that have it so ingrained that they don't even remember why it was difficult in the first place. More likely than not you will have trouble understanding them and they will have trouble understand you. We don't know how many of this things are ahead of you, we don't know if will be better to stick around or say "I quit" now. You can only decide by yourself with limited information. I hope you find what is better for you.

Figuring out the correct time to depart to another planet is not a trivial task. Yes, some veteran make it looks easy, but most us struggled with this at some time. ..some still have trouble. So, what you can tell about transfers windows? What is your technique to find it out? Or you rely on some tool? Or are you still struggling with it and have your own questions about it? In any case, you are welcome to share your thoughts. This is not a typical question, of someone looking for help with an specific issue it rather meant to be an opportunities, for some people learn about an important thing in KSP, for other to share what they know about it. I hope to be right in my assumption that both are things this community enjoy.