Targeted Landing advice

[jfjohnny5]

I'm looking for advice on landing at a specific target on a non-atmospheric body. In this case the Mun. I can land easily enough. But I cant land in the same place twice. Which is rough when trying to build a moon base. Should I just flyover, kill my lateral velocity, and drop? Or is there a good way to predict my landing with a more gradual approach?

[Specialist290]

For an airless body like the Mun, it should be easy as dropping your lander into a suborbital trajectory that intersects the ground within spitting distance of the landing site. Don't forget to account for the rotation of the body itself, and also for the fact that, as you burn laterally, you're basically pulling the final landing site towards the point your craft is hovering over.

If you've got plenty of fuel and thrust, you can actually adjust your course a bit in midflight by tilting your lander back in the general direction of your landing site. It does use a lot of fuel, though. Another method is to try short suborbital hops until you're close enough for satisfaction.

I'd hardly call it precision, but I've been able to get within a few kilometers of my target on my initial descent, often close enough that I still have fuel to correct my course once I'm sure I'm going to overshoot. It takes practice, and it's cost me a few landers (none manned, fortunately).

Edited May 17, 2013 by Specialist290

[Merinsan]

It is not an easy task, but with practice you'll get there. My most recent attempt I was out by a few kilometers, however it was a rover so I could drive the rest.

What I try to do is set up a sub-orbital trajectory that overshoots the target a little. I then set up a maneuver node to try and drop down on the point I want, meaning I kill all lateral velocity. This gives me an idea of how much I need to burn. From then on, I attempt to manually adjust just by burning the right way. I also try and set a target on the ground of the base - make sure you don't have the "Target" mode in the nav ball - This helps you to know the direction you need to burn. Also, when in Surface mode, burning above the retrograde vector, about halfway between it and straight up, will kill lateral velocity while not affecting your landing position. Burning straight up extends your trajectory.

Basically to do a good job, you need to practice with burning not on the markers.

I myself am not that good at it either. I often land, then launch again to get closer. It works, but wastes fuel.

[pebble_garden]

It might help to see it done, as shown in my Mun Ferry video starting at about 9:40.

Basically, this is how I did it with a Munar target.

1. Set the landed ship as your target.

2. Starting about 1000km out, set up a trajectory that grazes over the target. (11:00)

3. Set up a maneuver node approx 100-200km from target that overshoots by many kilometers. (11:45) In hindsight, I should have done about twice as much overshoot as you see here.

4. When you reach the node, do the burn. (12:12)

5. Use another mid-course maneuver node to slow down further, and reduce the overshoot. The goal is to convert to a vertical descent right over the target. (12:20)

6. Once you're flying mostly vertical, make small vector offsets to steer your velocity indicator toward the direction of the target. But that's an art in itself, and takes practice.

7. Quicksave (F5) is your friend. If you flub it, hold F9 to try again.

Anyway, that should get you in the vicinity, the rest is just standard landing technique.

[DMagic]

One thing that helps is to make sure your lander has a high TWR. It's a lot easier to accurately land at a specific location if you can quickly kill your horizontal velocity. This way you can wait until you are almost directly over your target, then kill horizontal velocity, then go straight down. It may not be the most fuel-efficient way to land, but it's a lot easier than trying to correctly time a 2 or 3 minute burn.

[jfjohnny5]

It might help to see it done, as shown in my Mun Ferry video starting at about 9:40.

Thanks pebble_garden! I watched a lot (like pretty much all) of your videos when getting started. It's really helpful to see exactly what I'm trying to do in practice. Now I just need to do that myself - practice, practice, practice.

[AnalogAddict]

How I do this is fairly simple (for non-atmospheric landings only), I position my craft roughly on the opposite side of the planetary body from the desired landing site and lower my perigee to 4~5km. When this maneuver is properly completed, the perigee node should be almost exactly above the landing site. As I approach the landing site, I begin to kill my lateral velocity. I've found it easier to start burning before I think I should as to leave a decent amount of lateral velocity to get a more precise landing site in relation to my desired target. Also during that phase I might burn normal or anti-normal to fine tune the final landing location. Your mileage may vary depending on the style of craft you're attempting to land.

[jfjohnny5]

Oooo putting the Periapsis right above the landing site is a really good idea actually.

[Vanamonde]

Since it's so hard to land precisely, I give my buildings wheels that can be ejected when they reach the desired position. Then it doesn't matter if you're a kilometer or two off.

[AddMeGamers]

I'm looking for advice on landing at a specific target on a non-atmospheric body. In this case the Mun. I can land easily enough. But I cant land in the same place twice. Which is rough when trying to build a moon base. Should I just flyover, kill my lateral velocity, and drop? Or is there a good way to predict my landing with a more gradual approach?

Check out

there is a targeted landing tutorial , should help you out

[beelzerob]

Check out

there is a targeted landing tutorial , should help you out

Sorry to raise this old thread, but Google led me here, and that video was AWESOME! I went from multiple smashed vessels scattered across the Mun, to two near-perfect landings right where my base is. That method is AWESOME. Thanks so much.

[Alshain]

Sorry to raise this old thread, but Google led me here, and that video was AWESOME! I went from multiple smashed vessels scattered across the Mun, to two near-perfect landings right where my base is. That method is AWESOME. Thanks so much.

Just watched it, It really isn't. I mean it technically works but he uses SO much fuel to do it. Making your orbit vertical that height is a terribly inefficient way to land. You need to learn how to land without killing your lateral velocity till your not far from your landing site.

, try not to come in so far off target as he does though, changing your plane needs to be done as far from the planet as possible, but in a pinch it's still better than making your decent vertical at 20km. Edited July 22, 2015 by Alshain

[GoSlash27]

Just watched it, It really isn't. I mean it technically works but he uses SO much fuel to do it. Making your orbit vertical that height is a terribly inefficient way to land. You need to learn how to land without killing your lateral velocity till your not far from your landing site.

, try not to come in so far off target as he does though, changing your plane needs to be done as far from the planet as possible, but in a pinch it's still better than making your decent vertical at 20km.

The easy way to do it is the reverse gravity turn .

With a little practice you can drop a lander right on a dime and make change and it doesn't take the ridiculous amount of propellant that the stop 'n' drop technique requires.

Best,

-Slashy

[Alshain]

The easy way to do it is the reverse gravity turn .

With a little practice you can drop a lander right on a dime and make change and it doesn't take the ridiculous amount of propellant that the stop 'n' drop technique requires.

Best,

-Slashy

That is what the video I posted did.

[GoSlash27]

That is what the video I posted did.

Alshain,

Not quite. The reverse gravity turn has the trajectory intersecting the landing zone throughout the approach and uses a single continuous burn to touchdown. Very similar though.

Best,

-Slashy

[Alshain]

Alshain,

Not quite. The reverse gravity turn has the trajectory intersecting the landing zone throughout the approach and uses a single continuous burn to touchdown. Very similar though.

Best,

-Slashy

Ah, I see what you mean then. Though I doubt that saves you much more fuel and it is a lot more difficult to do it in a single burn.

[GoSlash27]

Ah, I see what you mean then. Though I doubt that saves you much more fuel and it is a lot more difficult to do it in a single burn.

Alshain,

Surprisingly, not so much. I can't speak to the fuel savings, but keeping it in a single burn actually simplifies the problem and makes it easier rather than harder. The pilot's job becomes 1) keeping the ship mid-way between apoapsis and the surface (done with throttle) and 2) keeping the touchdown point in the target area (done with pitch and yaw). Sorta like flying final approach to a runway.

It requires no previous experience or practice to make it work. You can simply build a lander to spec and have full confidence that you can drop the lander right where you need it even though you've never shot the approach before.

Best,

-Slashy

[Kurld]

Aside: is there a mod that will show you your impact point while you are in flight view? I know of one that will do it in map view, but, well it's not super useful for precision landings since map view is zoomed out so far.

[Wemb]

Aside: is there a mod that will show you your impact point while you are in flight view? I know of one that will do it in map view, but, well it's not super useful for precision landings since map view is zoomed out so far.

NavHUD perhaps?

Wemb

[Nich]

Define close? 10m or 10km. I can get within 1km of my target but that is about the best I can do. I kill all vertical velocity about 1-2km over the target by setting a maneuver node over the target when I am 3-4 minutes out. I start burning early (20%) to lower PE. It normally starts out 3-5 km over the target but be carefull not to smack a mountian. Lower your orbit into the ground past the target. Maneuver node should still be over the target if not move it. Switch out of map mode do a full burn at time/2 left and you should be right over the target.

I have not tried retrograde pushing on a landed target. Might be interesting so see how close I can get but I suspect I would end up short doing a suicide burn retrograded push (or in the ground)

[ajburges]

It's on the wish list for the trajectories mod. Though most development on that mod is geared towards improving stock aerodynamic simulation currently.

[GoSlash27]

Define close? 10m or 10km. I can get within 1km of my target but that is about the best I can do. I kill all vertical velocity about 1-2km over the target by setting a maneuver node over the target when I am 3-4 minutes out. I start burning early (20%) to lower PE. It normally starts out 3-5 km over the target but be carefull not to smack a mountian. Lower your orbit into the ground past the target. Maneuver node should still be over the target if not move it. Switch out of map mode do a full burn at time/2 left and you should be right over the target.

I have not tried retrograde pushing on a landed target. Might be interesting so see how close I can get but I suspect I would end up short doing a suicide burn retrograded push (or in the ground)

Nich,

About this close.

Best,

-Slashy

[Sheppard]

Set your suborbital trajectory to get as close as possible above the target (a few km). Above the target set a maneuver node to kill your lateral velocity (that way you know when to start the burn). Now you should be dropping pretty much above your target. You can fine tune the rest on the descent.

[lugge]

The easy way to do it is the reverse gravity turn .

With a little practice you can drop a lander right on a dime and make change and it doesn't take the ridiculous amount of propellant that the stop 'n' drop technique requires.

Best,

-Slashy

Funny thing: this Thread just showed up on the forum when I was thinking about a moonbase (and thus, target landing) by myself. The informations here really helped alot.

Yesterday, I did my first try following the instructions in GoSlash's link, and it worked fine for me.

However, my first shot only brought me in an about 2-3 km distance to my target. Close enough :-)

GoSlash, your instructions are fine, but one question:

My target is not on the equatorial plane.

However, from my target position, I launched a small sateliite directly westwards, this means I now have an object in lower Minmus orbit which I can use to get my transport ship to the right inclination (targets on the surface don't show an ascending/descending point :-( ).

When my transporter is in the desired orbit, I have to wait till my surface target intersects my orbit. This only happens once per Minmus day.

Maybe this introduced my 2-3km distance? I guess I always have to add some normal/antinormal component to my burn because you never get exactly the right point?

Is there a way to improve target landing when the target is not on the equator?

And, more generally, is it a good idea to place a surface outpost in such a spot?

And, one more time: your instructions rellay helped a lot! :-)

Edited July 24, 2015 by lugge

[Alshain]

Define close? 10m or 10km. I can get within 1km of my target but that is about the best I can do. I kill all vertical velocity about 1-2km over the target by setting a maneuver node over the target when I am 3-4 minutes out. I start burning early (20%) to lower PE. It normally starts out 3-5 km over the target but be carefull not to smack a mountian. Lower your orbit into the ground past the target. Maneuver node should still be over the target if not move it. Switch out of map mode do a full burn at time/2 left and you should be right over the target.

I have not tried retrograde pushing on a landed target. Might be interesting so see how close I can get but I suspect I would end up short doing a suicide burn retrograded push (or in the ground)

If you're only a km away, just do a Neil Armstrong. Yes that does consume fuel, but if you keep practicing you will start to realize you start to get better at it and pretty soon you will hit perfectly.