What am I missing with the MUN landing in terms of speed reduction/burning back up???

[Somethingface]

Hi all,

I'm playing without mods or upgrades and I've taken the long road to this point, but the result is that I don't struggle with construction according to purpose after so many hours of trial and error. I can get to the Mun off a 2 stage burn into my initial Kerbal orbit and leave myself with an entry stage that gets me slowed below 100 m/s and I can keep that from around 50000m to 10000m. I have enough fuel to likely do what's needed in that stage, but its around this point that I can't seem to find a balance between coming down at a survivable speed and sending myself back out again. I've dropped that stage in an attempt to use the 4 engines on my landing shuttle to form a wider base of propulsion(no idea what I'm talking about, but grasping for straws at this point) but the same problem exists. Either I let it drop and can only slow it to 50 or 60m/s or I get it to around that descent rate and it starts burning back up again. Because it seems to all go south around the 50 or 60m/s mark, I've wondered if my lander is just too heavy and have no issue rebuilding, but it's also made me wonder about the science of it that I may not be grasping. Is there a height where I should be starting the burns to achieve some form of plateaus in speed reduction? Something else I'm oblivious to? Do I need a mod? Of all the frustrating, turned rewarding hours I've put into this game, slowly yo-yoing around the Mun in vain attempts to land while I could be going to other places, is killing me. Of course, I don't feel like I can move on until I've conquered the Mun landing, like the stubborn man I am. First time I've ever been on a forum, lol. Only this game could draw me out...killer game!!!

[Norcalplanner]

Is your nav ball in surface mode or orbit mode? Sounds like it might be the latter - trying to land while the velocity readout still includes the orbital component is misleading and difficult.

And enjoy this. You only land on the Mun for the first time once.

[Norcalplanner]

To be more precise, do the following (which assumes either a decent probe core or a level 1 pilot) -

Burn orbital retrograde until your orbit line looks like it's coming down at a suitable spot. Lock your craft's orientation to the retrograde marker (left of navball, second row, right button) and change the navball mode to surface by clicking on the velocity readout. Burn your descent motor as needed to slow your descent, keeping in mind that the lower you burn, the more efficient it is. Swing the camera around so that you can see the shadow of your craft to help you gauge your altitude above the terrain. Keep in mind that some terrain on the Mun is thousands of meters above sea level. As you get close to the surface, you should be nearly vertical. Once you're close to the surface, switch to a standard SAS mode from the retrograde hold. If you don't switch, you run the risk of your craft flipping if you thrust just a bit too much. Try to keep the final descent less than 2 or 3 meters per second. Kill the throttle and SAS as soon as you touch down. Then take a screen shot and have a celebratory beverage. :-)

[Srpadget]

My advice:  go to Minmus first, and practice landing there.  It takes barely any more delta-v to get to Minmus than it does to get to Mun, and Minmus's gravity is so minimal that everything about landings happens in slow motion with lots of time to recover from errors.  Minmus is a SLIGHTLY trickier destination, navigation-wise, but it really is the "training wheels" world that I used for my first attempts at practically every new skill I ever picked up in this game.

And then for tips on how to land efficiently, search on the term "suicide burn".  (Yes, I know, unfortunate name.)

(That said, your description of yo-yo-ing up and down sounds as though you're trying to control your landing with only two throttle settings: "off" and "floor it".  For final descent, partial throttle is your friend.)

[Snark]

4 hours ago, Srpadget said:

And then for tips on how to land efficiently, search on the term "suicide burn".

^ This.  This right here is what you want.

4 hours ago, Srpadget said:

(Yes, I know, unfortunate highly apt name.)

Fixed that for ya. 

Here's the warning sign:

10 hours ago, Somethingface said:

leave myself with an entry stage that gets me slowed below 100 m/s and I can keep that from around 50000m to 10000m.

...you're trying to do a long, slow descent under power, which is about the worst possible thing you can do in terms of efficiency.  What you want to do is free fall until the last possible moment (judging that moment is the tricky bit, thus the name for this maneuver), then slam on the throttle full power so that you brake to a halt right as you get to the surface.

There are various techniques to help with this, either in stock or with mods.  As @Srpadget said, search for the term "suicide burn" and you'll get a lot of useful info.  Here's a simple, stock technique (no mods needed) that works pretty well:

There are mods, of course, but I'd like to echo this excellent advice:

7 hours ago, Norcalplanner said:

And enjoy this. You only land on the Mun for the first time once.

^ this.  There's only one first time.  Do it in stock the first time.  You'll be glad you did. 

[Vanamonde]

I suspect your only problem is insufficient practice, though do I understand correctly that your lander has 4 engines? If so, yes, that is probably too big for the job, making piloting harder. 

[Superfluous J]

While the suicide burn is more efficient, until you're comfortable I suggest stair-stepping your way down. Don't just hover-drop your way down at 100m/s, but let yourself free-fall until you're maybe 5km up. Then hit the gas full power and watch your speed decrease. Note how long it takes your rocket to slow down. Get down to about 100m/s, and then let yourself fall for a while more. When you get closer, punch the gas again and slow down to 50m/s or so.

After a few crashes attempts to get the feel for it, you should be able to know by intuition when to burn. Then, you can on your next attempts stair-step less and less. Or keep them up. It's not as efficient as a gravity turn, but it's not nearly as inefficient as hovering your way all the way down and that extra control is worth a bit of fuel a lot of times.

As in all things, it's about balance. You don't want to have to bring a Saturn V's worth of rocket all the way to Mun orbit, but you don't want to have to time your burn to the millisecond. Somewhere in between is that sweet spot.

[jarmund]

First of all, instead of going for a powered decent from high up, burn orbital retro until your periapsis is maybe 5000 meters above the ground, coast halfway around the mun to the new periapsis, and go from there.

 

Secondly, it sounds like your navball is in orbit mode. When at your new periapsis, click the speed readout until you're in surface mode. 

 

Then start a powered decent from there. A suicide burn is a lot more efficient, but also a lot harder to time right and survive. Try to keep a groundspeed of around 50-100 until the 1000 meter mark and then slow down to 10-20 and lastly 1-5 when under 100.

 

Stay locked onto retrograde the whole time.

 

And most important: Savor the moment when you finally land.

[Pecan]

On 9/22/2016 at 6:37 PM, Somethingface said:

... I can keep that from around 50000m to 10000m...

Apart from anything else, I'd say you're trying to start from way too high.  The highest mountains on Mun are around 8km so first get yourself into a comfortable, circularised orbit at 9 - 10km (to be safe).  The other important thing is F5 once you've got that - falling from 10km will kill you just as well as falling from 50km but being able to quickload makes the 'practice' and 'simulation training' (no-one ever messes-up real flights, honest ^^) much quicker.

[Gojira1000]

My lazy,  inefficient landing sequence -

1) Reach an 11 KM orbit. Hit f5. From a 11K orbit burn retro to get yourself in a nearly vertical drop onto your chosen landing spot.

2) Put the navball in Surface mode, click hold retrograde

3) Punch engines up to max at around 2000 meters to get a feel for how quickly you are able to slow down

4) Punch again at 1000 meters with an eye to slowing to about 50 m/s

5) Fiddle with the throttle in the last 200-300 meters so that (optimally) you wind up at about 10 m/s at 100 meters.

6) Much lighter fiddling, your goal should be about 5 m/s at 50 meters then ease it down to land at about 1 m/s

7) Hold f9 if one of the above steps fails abysmally

8) Plant flag

Edited September 23, 2016 by Gojira1000
spelling

[magnemoe]

21 hours ago, Srpadget said:

My advice:  go to Minmus first, and practice landing there.  It takes barely any more delta-v to get to Minmus than it does to get to Mun, and Minmus's gravity is so minimal that everything about landings happens in slow motion with lots of time to recover from errors.  Minmus is a SLIGHTLY trickier destination, navigation-wise, but it really is the "training wheels" world that I used for my first attempts at practically every new skill I ever picked up in this game.

And then for tips on how to land efficiently, search on the term "suicide burn".  (Yes, I know, unfortunate name.)

(That said, your description of yo-yo-ing up and down sounds as though you're trying to control your landing with only two throttle settings: "off" and "floor it".  For final descent, partial throttle is your friend.)

Yes, its smart to go to Mun orbit first but Minmus is far easier to land on, the planes has the benefit of being at 0 attitude and flat making it the perfect first place.  
After doing some Minmus landings mun is far easier. 

[Somethingface]

Thanks everyone. I had a quick skim through and immediately saw a few interesting pointers. Been busy, so sorry for the late response. The Mun will be mine!

[Srpadget]

 

Re: "suicide burn"

22 hours ago, Snark said:

On 9/22/2016 at 5:06 PM, Srpadget said:

(Yes, I know, unfortunate highly apt name.)

Fixed that for ya. 

Only if you get it wrong...  ;-)

 

[Somethingface]

Hey folks, 

I haven't even started at that landing yet, as I discovered a glaring issue with my science probes floating all over the place and gained myself a massive (to me anyways) 800 science, so I've been playing with that. In the meantime, a friend suggested mechjeb2 very strongly, suggesting I learned enough and it's time to make things more functional. Of course, now I have a question from my useless computer mind. This may not be the place for it, so just tell me to go to hell if so. I installed it and it's in my inventory and I've even attached it, but I have no idea how to make it function. Needless to say my very persistent friend had never used it himself because he got frustrated early and quit playing...could have told me that before I went for it!! Anyways, I searched around with my limited skills and found out (I think) that I needed some toolbar mod and everything was pointing to a very specific one and I placed the file where it said to place it. Problem being that it says I have a non supported version as it loads up the game and I see no toolbar upon entry. I'm playing 1.2 prerelease version of the game and I even figured out that I could go back to a previous stable version of the game, but that's too far back I think?? To even figure out what I have so far is a huge advancement in gaming, computer and internet usage for me, but at this point the discussions seemingly relevant to my issue get so muddled in version and numbers that my lack of experience is giving me a migraine. Any help or suggestions on this one? Again, sorry if this is not the right place for the question, but I was answered so well last time, that I feel like I may get the most direct and applicable response here. Also sorry if this is a complete dumbass question and I'm just being stupid.

[Somethingface]

And deadly name Gojira1000! Lol

[Guest]

I would discourage you from using MechJeb until you've figured out how to play the game "manually." You won't be able to make much use of it if you don't understand how things work... and you'll be ruining the fun of learning for yourself, even if you do. MechJeb is invaluable for pulling off really precise manoeuvres and to take the drudgery out of "routine" things, but it's not a good way to learn to play the game IMO. And no, it won't work with 1.2-pre until it's updated.

The advice on landings is good. I recommend the "stairstepping" technique -- that's what I've been using, and I've gradually gotten down to fewer and fewer steps when using landers I'm familiar with. It does take some practice but it's ultimately not all that hard... and yeah, Minmus is a good place to practice.

 

[Srpadget]

6 minutes ago, Brikoleur said:

I would discourage you from using MechJeb until you've figured out how to play the game "manually.

I STRONGLY agree.  If you let the computer do all the tricky bits, you will never REALLY experience the incredible rush of triumph at having done something really tricky All By Yourself(tm).

 

2 hours ago, Somethingface said:

a friend suggested mechjeb2 very strongly, suggesting I learned enough

If you have not yet done a soft landing on an airless body, then to my mind you've not yet learned enough to turn over these sorts of activities to MechJeb.  What you're doing right now--asking people on the forums how to do it better, so that YOU can actually DO it, rather than turning into a spectator while the game plays itself--is going to be much more satisfying in the long run.

If it's any consolation, the Mun may be where most people go first, but it is one of the most difficult bodies in the entire game to land on.  Once you can land there and return, pretty much the entire solar system is yours.  ("All these worlds are yours...except Europa Tylo. Do not land there.")

[Somethingface]

Thanks again.

I never really intended to use it for the Mun anyways and landed a smaller version (minus the science lab, therefore minus some fuel and engine weight as well) a few minutes ago, though it was a basketball landing that took out my landing gear, my lights and all my science aside from the Jr I slapped on it. Also took out my comms. So useless landing that will not count(fro me) in it's miserable, laying sideways state, but closest to successful yet. I used the stairstepping and a little unexpected and not sufficient suicide burn. The mods will be for later use if they are as efficient as I've read, I was more concerned with setting it up properly, but if there is no update yet, then all seems properly set up and by the time an update is out, I may be ready to use it. Figured out 800 science, learned how to mod and left some junk on the Mun today. I think I've earned a space cigarette  Thanks again everyone, you've helped the helpless, lol.

[Guest]

You're trying to land a science lab first thing? Wow, that's a handful. I don't do that until pretty late in my career, I leave them in orbit instead, and use very light single-person landers instead. This time around the biggest lander I've used is a hitchhiker container + lander can for five occupants, and that I only used on Minmus.

Heavy Mun landings are totally doable -- I have landed a pretty big surface station with a crew cabin, heavy refinery, heavy drill, and tanker, for a total of 35 tons or so -- but the bigger they are, the harder they fall, as they say. For one thing, they're a lot less easy to manoeuvre.

I.e. I would recommend that you start small and work your way up from there.

I did my first Mun landing in a bit of a brute-force lander -- I think it was the flat Rockomax tank with two or three Thuds, landing struts, and on top of that, split with a stack separator, a Mk 1 module with heat shield. I took the whole thing down, then back up, pointed it back to Kerbin, decoupled when close to re-entry, and re-entered successfully. Unfortunately Jeb landed right on top of a mountain and the Mk 1 module rolled down the slope, fell into a ravine, and killed him. I still count that as a success, Kerbal style, and besides Jeb was going "whee!" all the way when rolling down the mountain.

If you can already handle docking, though, it's easier to have a lander and orbiter as dockable modules. The orbiter packs more fuel and will take you down to a circular 9...10k orbit. From there, undock and land. Then take off, RV with the orbiter, and continue wherever you want. This way you'll only need the minimum of fuel on the lander, which is good because hauling fuel down and then up a gravity well is really wasteful.