Advice on research & burn timing

[Mister Spock]

I've researched most of Tier 1 of the tech tree, as well as the Medium Orbital Rockets and Medium Launchers techs in Tier 2. I'm struggling to carry enough fuel to make round-trip Apollo-style Mun landings, and so I'm wondering what to research next. I have 523 research on hand. I see Fuel Lines are available, and the descriptions hints that asparagus staging is still a thing.  But I haven't played KSP for a couple years, it's been longer than that since I last tried asparagus staging, and I've mostly forgotten how it works. Would it help me? Or would I be better off getting , say, Expanded Construction (which might help me build better landers or rockets), or work toward Atmospheric Science?

Also, I'm sure I'm not timing my burns optimally. I know enough to burn at PE to affect the AP, and vice-versa. But when landing on the Mun, is it best to slow down far from the surface, or close to it? Or is a gradual slow burn best? (I know there are excellent autopilot mods that can do this better than I possibly can, but I've always enjoyed flying manually.) Likewise, when coming home to land on Kerbin, is it best to establish a low circular orbit, or can one just get away with establishing an elliptical orbit with high apopapsis and low periapsis, and then just burning retrograde from the periapsis?

Thanks in advance. Apologies if I've chosen the wrong forum for these sort of newbish questions.

[dmsilev]

For landing in a vacuum, the optimal approach is a "suicide burn", where you do a de-orbit burn, coast until you're almost at the ground, and then brake all at once, coming to an exact stop at exactly 0 meters above ground level. That's ...challenging to do by hand, though people have certainly done it, so a safer approach is to plan on coming to more or less a full stop 1 km or so above the terrain (set nav ball to surface retrograde, burn until velocity is nearly zero), then switch to Surface Up orientation, do a controlled fall, and bring the velocity down as you get close to surface. How slow you fall depends on how good a feel you have for your ship's acceleration when you ramp up the engine. Faster with a single sharp burn at the end is more efficient, but slower can be easier when you're first trying. 

For getting home, an elliptical orbit is fine. Just set the PE to be a reasonable depth within the atmosphere and you won't even need the retrograde burn. Doesn't hurt to burn off any remaining fuel to bleed off speed just before reentry, but it isn't necessary. 

Asparagus staging is definitely still a thing in KSP2. Set up a central core  (tank and engine) with three radial decouplers. To each decoupler, add a fuel tank, an engine, a nose cone, and a fuel line going from the outer tank to the central one. Finally, under staging, have the first stage be all four engines, the second stage be the radial decouplers, and the third stage the central decoupler for dropping the central stage. 

[Mister Spock]

Thanks for your reply! That was exactly the kind of information I was hoping for.

So I assume asparagus staging is more efficient than just slapping on some solid-fuel boosters, which is what I’ve been doing.  From an aesthetic perspective, I don’t love the look of either solution. I want my Apollo missions to lift off in a Saturn V!

Still, I think I’ll try it. I can get Kerbals to the Mun, but I’m struggling making it a round-trip. And I hate stranding them there.

[Guest]

I stairstep. Like for the Mun, first brake to 350 m/s, then 250 m/s, then 150 m/s, and when at around 500-1000 m depending on my TWR, to 50 m/s. All of these at full throttle. The last couple of hundred meters I burn continuously, controlling descent by throttle, gradually slowing to 15 m/s or so; when really close to the ground I bring it to about 4 for a soft landing. 

It’s pretty economical and makes for a nice controlled landing, I can get to within a few hundred meters of my target without wasting much fuel because I can adjust with each of the burns.

This works for any airless body, even Tylo, although there the landing will likely be a bit rougher.

[Mister Spock]

Thanks for that advice, @Periple. I just watched a video by a YouTuber who does exactly what you do. I'll give it a try. Thanks!