Mun Landing training woes

[Confutus]

I keep trying the Mun landing training in unmodded Kerbal 1.8.1. and I keep crashing. I'm trying to follow the instructions, keeping one eye on the target indicator on the Navball and the other on the instructional window,. which claims to be gives altitude above the surface, vertical speed, and a throttle up/down indicator.  Apparently this instructional window is erroneously giving me altitude above "sea" level  instead of altitude above the surface, because I keep having unfortunate encounters with the Munar highlands about 3 km above where the surface is supposed to be.  After several attempts (Not all of them quite so disastrous) I have determined that  my reactions are sluggish and my piloting skills atrocious, but no matter how careful my piloting is, it's useless if the instruments are lying to me. Any suggestions?

[Superfluous J]

32 minutes ago, Confutus said:

I have determined that  my reactions are sluggish and my piloting skills atrocious, but no matter how careful my piloting is, it's useless if the instruments are lying to me. Any suggestions?

I'm going to try this tutorial in a bit to see what it does (I've never done one. They didn't exist when I started) but you can click the "waves" button up at the top of the screen where the altitude readout is and it'll change to a "mountains" button to give you your ground altitude. Use that. Also, watch your ship's shadow as you get close to the ground to get an a more intuitive sense of where you are and how fast you're moving. Also, don't get tricked into watching your ship when turning, the Navball is oriented to the ship, always. The ship on the screen is oriented to whatever direction it happens to be facing, which may not match your keyboard.

Finally, poor reactions and atrocious piloting is merely an indicator that you're Human. I crashed dozens of ships on the Mun before I had a successful there-and-back, and I've crashed hundreds more since (mostly when I try something stupid these days).

Keep at it. A nice solid landing is a thing of beauty and the hardships will only make it more beautiful when you get it.

[Superfluous J]

Just tried it. Yeah I would ignore all that THROTTLE DOWN and THROTTLE UP stuff. It's way too picky. Just make sure you can come to a full stop in a second or two in an emergency and make sure you're coming down vertical at the end on a flat area.

In the tutorial window, the vertical altitude always seemed correct to me. Not sure what's going on in your game.

[Confutus]

Perhaps it's not the altitude indicator that's in error. Apparently sticking rigidly to 1/3 throttle doesn't slow me down enough once I start angling down toward the surface, so I pick up downward speed too fast and don't kill horizontal speed fast enough.  I have finally completed a landing without breaking or toppling the lander. It wasn't beautiful,  but I got it done. Moar practice.

[Vanamonde]

Were you aware that you can click on the altimeter to change it from reading above sea level 

to above local ground level? 

This was added relatively recently and probably is not mentioned in the tutorial. 

[Confutus]

I had thought of trying that but hadn't done it yet.  I have now, and  the altimeter and tutorial window matched readings. I decided my instruments were not lying after all and the problem was pilot ineptitude.  Since I hate crashes, (most un-Kermanlike) I'd like to practice that kind of landing on Kerbin before going out to the Mun, but early in the game the solid fuel engines don't have throttle control, the bell on the "Swivel" and "Reliant" engines is too big for the available landing gear, and the Terrier engine doesn't have enough thrust at Kerbin sea level.

[Vanamonde]

You can put a ship in Mun orbit, save game, and just keep loading the save to practice landings. 

[AHHans]

8 hours ago, Confutus said:

but early in the game the solid fuel engines don't have throttle control

I'm sorry to have to break it to you, but even late in the game the solid fuel engines don't have throttle control. (SCNR! )
(But in case you didn't already know: not being able to throttle or stop before burn-out is the most defining feature of solid rocket motors.)

To add some constructive text to an otherwise mostly useless post: the most fuel efficient way to do a propulsive landing is a suicide burn, wait until the last moment and then burn full throttle until you come to a stop just as you touch the ground. This is called "suicide burn" because it leaves no margin for error, I still occasionally crash land because I wanted to do it too nice and misjudged the timing. A safer way to land is to come to a stop (relative to the surface!) fairly high above the ground, and then keep your speed in the survivable range (below 10 m/s for most craft) while you make your way to the ground.

My suggested way to learn propulsive landing is to start with the second method (bring enough fuel!) and then gradually modify your technique to be closer to a suicide burn (come to a stop later, don't fully come to a stop, etc.) as you get a feeling for it.

[Confutus]

1 hour ago, AHHans said:

I'm sorry to have to break it to you, but even late in the game the solid fuel engines don't have throttle control. (SCNR! )
(But in case you didn't already know: not being able to throttle or stop before burn-out is the most defining feature of solid rocket motors.)

Ouch. Yes, I did know that. I was thinking there might be other liquid fueled engines further up the tech tree that can do the job...I haven't yet climbed that high, so I don't know.

1 hour ago, AHHans said:

To add some constructive text to an otherwise mostly useless post: the most fuel efficient way to do a propulsive landing is a suicide burn, wait until the last moment and then burn full throttle until you come to a stop just as you touch the ground. This is called "suicide burn" because it leaves no margin for error, I still occasionally crash land because I wanted to do it too nice and misjudged the timing. A safer way to land is to come to a stop (relative to the surface!) fairly high above the ground, and then keep your speed in the survivable range (below 10 m/s for most craft) while you make your way to the ground.

Fuel is cheap compared to parts and pilots.  Yes, I saw the video SpaceX  put out on "how not to land a spacecraft", and I'm not especially anxious for the live-action version.   I don't think my wetware is up to the job. I'd rather leave that kind of fuel efficiency to mechanical pilots with electronic reflexes.

[Curveball Anders]

When testing a new lander/rover I usually build the payload and then a best guess version of the lander.

Then using the cheat menu to set lowest possible orbit and the body in question and try to land (most using MJ in my case).

If it doesn't work I revert to VAB, tweak and repeat.

Once it works as a want (or close to it) I build the launch/transport parts.

To minimize the risk of messing up my career save I either make a copy of it and use that or use my "JPL" sandbox save, copying the craft to my career save when good enough.

 

[AHHans]

1 minute ago, Confutus said:

Ouch. Yes, I did know that.

I thought so, but not everyone who is new to the game necessarily does. And I hope you don't mind my cheap joke (too much).

8 minutes ago, Confutus said:

I was thinking there might be other liquid fueled engines further up the tech tree that can do the job.

Well, for landing on airless bodies (like Mun or Minmus) the terrier is an excellent engine. So if I don't need higher thrust then that's what I use. The next go-to engine for me is the poodle, but this needs larger landing legs. For all other engines - and usually also the poodle - I build some kind of structure so that I can mount the landing legs lower than the mounting point for the engine itself.

On bodies with air I usually just use parachutes. Except for Duna where I use both: parachutes for deceleration and stabilization and (vacuum-rated, i.e. terrier or poodle) engines for final landing.

16 minutes ago, Confutus said:

Fuel is cheap compared to parts and pilots.

Well, more fuel for the lander means more or larger fuel tanks, both of which increases the mass of the lander so the transfer stage from LKO to the target needs to be bigger, further increasing the mass that you need to lob from Kerbin's surface into LKO. My first Eve return vehicle got bigger and bigger until I got to using Mammoths to power strap-on boosters to get the thing off the launchpad. (At which point I stopped the project and fired the engineer.)

23 minutes ago, Confutus said:

Yes, I saw the video SpaceX  put out on "how not to land a spacecraft",

Well, they have to do a suicide burn (even though they call it a "hoverslam") because they cannot throttle the engines down far enough.

[Confutus]

13 minutes ago, AHHans said:

Well, for landing on airless bodies (like Mun or Minmus) the terrier is an excellent engine. So if I don't need higher thrust then that's what I use. The next go-to engine for me is the poodle, but this needs larger landing legs. For all other engines - and usually also the poodle - I build some kind of structure so that I can mount the landing legs lower than the mounting point for the engine itself.

That idea has occurred to me, but I haven't yet sat down and designed the structure; it's not that high a priority.

18 minutes ago, AHHans said:

Well, more fuel for the lander means more or larger fuel tanks, both of which increases the mass of the lander so the transfer stage from LKO to the target needs to be bigger, further increasing the mass that you need to lob from Kerbin's surface into LKO. My first Eve return vehicle got bigger and bigger until I got to using Mammoths to power strap-on boosters to get the thing off the launchpad. (At which point I stopped the project and fired the engineer.)

I don't blame you. See, this is why I would seriously think about assembling such a vehicle in orbit from smaller pieces sent up from Kerbin, rather than trying to launch the whole thing at once.

[AHHans]

12 minutes ago, Confutus said:

See, this is why I would seriously think about assembling such a vehicle in orbit from smaller pieces sent up from Kerbin, rather than trying to launch the whole thing at once.

Well, my solution was to not land everything that I need to get back to Kerbin on Eve. The result was much smaller. (And then BG came out and I started making solar powered Eve planes...)

[Zeiss Ikon]

46 minutes ago, AHHans said:

Well, they have to do a suicide burn (even though they call it a "hoverslam") because they cannot throttle the engines down far enough.

As I recall, the Merlin engine can be throttled to something below 50% (which is pretty deep for a real-world rocket engine), but even burning only the single center engine, with the nearly-empty tanks they have at landing (for performance reasons, they'd like to land just before the engine flames out due to lack of propellant, but not let the engine actually flame out because a mixture imbalance during a burn can damage stuff), that's still too much thrust to genuinely hover.  On the bright side, they have a computer flying the beast, and a bunch of failed attempts (which yielded a lot of data on what they could and couldn't get away with) preceded the current long string of successful landings, so they can manage with this.

The other side of the hoverslam is that, as noted, it's the lowest fuel consumption landing possible -- which means less fuel need be reserved from the booster's main job of accelerating the second stage and payload toward orbit.  The very fact they can reserve fuel while launching commercial payloads is a testament to the performance of the Falcon 9.