What's the most efficient way to land on Mun

[JLE]

Hi,

 

Can you tell step by step the best way to land on Mun or any other planet?

Thanks!

[qromodynmc]

Point your rockets nose to the mun, burn till you crash to the mun.

Oh wait, this wasn't efficient but it was guaranteed way. For efficient way;

Use Hohmann.

[solarbearman]

Check the tutorial

It's the best way to learn it

[Mastikator]

From low Kerbin Orbit do a single burn to the mun with a low periapsis. Periapsis should be 10km.
Then at the mun periapsis do a retroburn until your peri and apo are both 10km. The height depends on the tallest mountain of the planet.
Then do a short retroburn that puts you onto a crash course into the ground you want to land on.
Finalize with near horizontal suicide burn.

The higher TWR the more efficient, but high TWR usually means lower overall delta-v. I don't know what the sweet spot it, probably around 2-3 on the mun.

If the planet has an atmosphere, use heat shields, airbrakes and chutes. And try not to burn up.

[KSP Bro AE]

The absolute most efficient way is to launch when the mun is ~15 degrees away from the KSC, and burn straight up until you get an encounter. Minor maneuvers will be necessary.

[Curveball Anders]

45 minutes ago, KSP Bro AE said:

The absolute most efficient way is to launch when the mun is ~15 degrees away from the KSC, and burn straight up until you get an encounter. Minor maneuvers will be necessary.

Erh, no.

Or rather, not if efficient is calculated in dV.

The majority of that precious dV is getting from the KSC to orbit, and burning straight up isn't the most efficient way to reach orbit.

The most efficient way must be get an optimal launch with an AP just outside the 70k boundary and right then catching the optimal window to the Mün.

But that might not be the most efficient in terms of time, or fun

Edited May 9, 2016 by Curveball Anders

[Tatonf]

1 hour ago, KSP Bro AE said:

The absolute most efficient way is to launch when the mun is ~15 degrees away from the KSC, and burn straight up until you get an encounter. Minor maneuvers will be necessary.

Oh God. Not this again... This is the most inneficient way of doing it. Each second you pass burning strictly vertical, you lose 9.81 m/s. Which is quite a lot.

Here's the best theoretical way of doing it : Get an orbit where, at some point, you would graze the ground, then immediately cancel all of your velocity above it, and land. The idea is that you would not gain any speed due to Mun's gravity, and therefore you would consume the strict minimum for landing. However there's a slight problem here : it would require an infinit TWR. Plus, you never clearly know where to put your orbit and there's a high probability that you would crash on the ground instead of grazing it.

The only thing you can do is to get as close to this theoretical landing as possible. Via a Hohmann transfer, lower your periapsis as low as you dare, and when you visually see that you're not very far above the ground, burn with the highest TWR you can get.

Of course, as Mastikator stated, getting an high TWR means you need powerfull engines, which are heavy, and therefore the rest of the mission might require bigger rocket to be accomplished. You're the judge.

Finally I link you to a video where I performed an efficient landing with 599 m/s (strict minimum is 580 m/s according to the delta-V map). It starts at 16 minutes.

 

Note : It is possible to save even more delta-V by lithobreaking. Certain legs have a crash tolerance of 12 or 14 m/s. Hell, the Mark 1-2 Pod have a crash tolerance of 45 m/s, so you could land on it if you dare.

Edited May 9, 2016 by Tatonf

[DChurchill]

I think the OP is probably looking for some noob help, judging by their post count, not a lesson in orbital transfer mechanics. But I could be wrong.

To the OP: you just want to know how to land, or do you want the whole schpiel, from vessel construction to touchdown?

[TMS]

Old but good...

 

[Tatonf]

Well the words "most efficient" and "best way" let me thought he was looking for delta-V efficiency, but I could have misinterpreted his question.

[Curveball Anders]

8 minutes ago, Tatonf said:

Well the words "most efficient" and "best way" let me thought he was looking for delta-V efficiency, but I could have misinterpreted his question.

It was my first reaction too.

But then I realised my own credo "it's a game, the point is having fun".

And while calculating dV is fun for some of us, it's not the only way to have fun (or so I've been told).

 

[DChurchill]

1 hour ago, Curveball Anders said:

It was my first reaction too.

But then I realised my own credo "it's a game, the point is having fun".

And while calculating dV is fun for some of us, it's not the only way to have fun (or so I've been told).

That's what MJ or KER is for. I spend all day with SQL queries and spreadsheets. The idea of calculating my own dV makes me cringe.

[Curveball Anders]

Just now, DChurchill said:

That's what MJ or KER is for. I spend all day with SQL queries and spreadsheets. The idea of calculating my own dV makes me cringe.

I stand corrected, I don't calculate dV, I leave that for MJ.

But I do find some form of, probably perverse, enjoyment of reaching orbit or other goals with as little dV as possible

 

[DChurchill]

12 minutes ago, Curveball Anders said:

But I do find some form of, probably perverse, enjoyment of reaching orbit or other goals with as little dV as possible

Absolutely. If I get to orbit and drop the last stage only needing to burn the next for 20 m/s worth of dV, it's a good feeling. Nailed it.

[Curveball Anders]

8 minutes ago, DChurchill said:

Absolutely. If I get to orbit and drop the last stage only needing to burn the next for 20 m/s worth of dV, it's a good feeling. Nailed it.

With the last bit of the lifter burning out just shy of orbit (so it would technically de-orbit itself).

Edit:
I admit that I delete debris, but only if it's sub-orbital.

Edited May 9, 2016 by Curveball Anders

[Plusck]

2 hours ago, Curveball Anders said:

Erh, no.

Or rather, not if efficient is calculated in dV.

The majority of that precious dV is getting from the KSC to orbit, and burning straight up isn't the most efficient way to reach orbit.

 

 

2 hours ago, Tatonf said:

Oh God. Not this again... This is the most inneficient way of doing it. Each second you pass burning strictly vertical, you lose 9.81 m/s. Which is quite a lot.

While I absolutely agree with both of you...

I did some tests a while ago and, if you start with a crazy high TWR (around 10 on Kerbin), you can actually break even with a proper, sideways-into-orbit burn at about the time you raise your Ap to the level of the Mun.

As you say, every second burning straight up is a loss of 9.81 m/s. However, once you stop burning the losses to gravity from a straight-line path to the Mun compared to the highly-eccentric orbit from LKO to the Mun are very similar (still slightly less on a proper transfer, but only slightly). So that leaves atmospheric drag - if it counts for more than the difference between those straight-line and eccentric-orbit paths, then you can actually win by going straight up. Utterly wasteful in terms of engines, mass and so on, but almost even-stevens on going to the Mun (or further).

[Warzouz]

For a first Mun landing, I would suggest deorbiting from a 30 km (or even 50km) rather than 10km. It's a bit less efficient, but maybe less frightening for a new player.

Recommendation : Test the round trip in sandbox using stock Kerbal-X. It's an easy rocket to fly with plenty of fuel and good TWR. You'll be easy with it when you can do the round trip in less than 30 minutes.

As for other bodies, it's quite the same but you may need a higher TWR and/or more fuel (Delta-V). And for atmospheric bodies, they'll allow you to save fuel...