coming in to fast!!!

[Truxton Corp.]

I desperately need help everyone, every rocket I build to go to the mun either crashes on the muns surface or passes the mun by seemingly INCHES!!!! is there anything I can do to prevent this?

[Kasuha]

You need to have some fuel left in your rocket. When the rocket passes by the Mun, turn it against its direction of flight and turn on your engines. That should slow it down. Once you're slow enough, Mun will start to attract the rocket by its gravity. Then you need to use the engine to slow down your fall and put the rocket gently on the surface.

[KerikBalm]

Set your munar PE to about 8-10km, burn retrograde to circularize your orbit... you should now have a velocity of ~550 m/s, instead of whatever you were coming in at.

Next, burn retrograde some more when you feel like it (you're in a stable orbit after all, you can wait), until you see your trajectory intersecting where you want to land (somewhere flat!)

Next, put a maneuver node before where your trajectory intersects the terrain, and pull the retrograde marker all the way back.

Look at your burn time estimation (I often have to give a momentary burst of throttle to get it to display right for some reason...), take whatever time it says the burn will take and start burning when you have 2/3 to 1/2 of that time until you reach your maneuver node.

Suppose it reads 1 minute... start burning 30-40 seconds before you reach that node.

This should put you nearly stopped over your landing area with a bit of altitude, now just come straight down like its a 3d version of that old moonlander arcade/Dos game.

All this supposes, of course, that you've built a rocket with enough dV to do this.

[juanml82]

Get Mechjeb. Delve into it's configuration and you'll find, under surface, two indicators which aren't shown by default: time for impact and, more importantly, "Suicide burn". Load them up in the surface window or any other window of your choosing. You can also get Kerbal Engineer Redux - in its surface tab, you'll find the inclination of the terrain below (once you're low enough).

So, here's what you need to do:

Get your Pe low. 10-15 km will do. You may also lower your Ap. When your orbit is roughly near the place you want to land, create a maneuver node and pull the retrograde until you're falling vertically. What this will do is to kill your horizontal velocity, or at least, most of it. This not only lets your pinpoint your landing, it also saves fuel.

Keep Mechjeb or KER's surface window on sight. You'll have "time to impact" (important), "horizontal speed" and "vertical speed". Needlessly to say, horizontal speed is the speed you're moving across the ground below while vertical speed is the speed you're falling, or climbing.

You should kill your horizontal velocity so you don't tumble when you land. To do so, switch your navball to surface, point towards the retrograde vector and burn until your H/S is below 2 m/s.

Now Mechjeb's "suicide burn" indicator becomes useful. This indicator will tell you how much time you have left to burn full throttle upwards so you hit the ground at 0 m/s. It's only accurate if your horizontal speed is zero. If it's negative, you'll crash and your only chance is to augment your throttle with RCS.

Since it takes time for the throttle to go from zero to full, you should wait until the suicide burn is around 5 seconds, and fire full throttle while you're aiming straight into the sky (at the center of your navball). Once your vertical velocity is below 10 m/s, or less if you feel like, cut your throttle and continue falling. Your V/S and your suicide burn indicators will increase, you can rinse and repeat. Typically, you can land fine with speeds below 10 m/s unless you're landing on your engines. Some rover wheels can resist speeds of 50 m/s (the tires will break) but you will probably rebound.

Just in case, once you're about to land retract any solar panel and activate your RCS. If you aren't landing on a perfectly flat surface, your ship will likely tumble to a side. Use your RCS to keep it centered. Don't use the camera view to check in which direction you need to rotate (ie, press the WASDQE keys), use your navball.

You should also train your landings at Minmus rather than the Mun. It takes more DV to reach it, but landings are far easier due the lower gravity and the easier terrain.

Oh, and about mechjeb, Neil Amstrong and Buzz Aldrin didn't descend by floating a camera nearby and eyeballing their speed.

[Kasuha]

On second thought, I really wonder how can someone "pass the mun by seemingly INCHES" and not figure out how to land on it. I smell fish.

Especially if he already designed a fighter jet named Hellhound with auto pilot capabilities.

[capi3101]

While you're doing your braking burn over Mun prior to landing, make sure your speedometer is set for Surface mode and keep an eye on your vertical ascent/descent meter. If you start descending, pitch yourself up towards the vertical - not too much; as a rule you don't want to start ascending at a rate much more than 5 m/s. Make sure you're burning retrograde. Lower to 2/3 throttle as your speed goes below 100 m/s, then again as you slow past 30 m/s or so. Once you're roughly vertical, go IVA and find your radar altimeter. You're generally okay to freefall until that starts twitching - but keep your speed low (no more than 50 m/s). Once it starts twitching, you'll have an idea of the location of the deck. At that point it's just keeping speed under control; you don't want it greater than 12 m/s if you want to survive landing, and generally 5 m/s or less assures that nothing will break.

Those are just general guidelines; for a better walkthrough, I'd need to see your lander.

[MartGonzo]

I came across a handy little tip on one of the threads here, I can't remember who posted so apologies to that person

place a maneuver node at the point where your trajectory meets the moons surface and drag the retro handle until the speed reaches zero, that will give you a burn time for doing suicide burns.

Thankfully it's a little on the forgiving side so you should never crash into the surface.

I hope my explanation is clear, it's sort of difficult to explain.

[Pecan]

I'm not sure landing is even the question here, but the whole process of flying to Mun, or anywhere else.

So, OP - how are you going to Mun at the moment? Hohmann transfer from LKO or what? Where do you have the problem - getting an intercept (presumably not), orbital insertion (probably) or landing?

[Truxton Corp.]

On second thought, I really wonder how can someone "pass the mun by seemingly INCHES" and not figure out how to land on it. I smell fish.

Especially if he already designed a fighter jet named Hellhound with auto pilot capabilities.

Well that my friend is aided by the laser mod which allows you to add auto pilot capabilities to ANYTHING...is does not work to well with rockets though...best with space planes

and second...sometimes my timing is off and i burn all my fuel trying to adjust my trojectory towards the mun (I would rather have a direct tragectory towards the mun than me bashing my ship at high speeds on the side of the mun:D)

and thanks guys your tips and assistance is really helpful, ill upload the pic of the capsule landing safely on the mun here!

Pecan...part of this problem MIGHT just be getting an orbital insertion...do you think you could help me with that to?

Edited August 23, 2014 by Truxton Corp.

[Truxton Corp.]

Edited August 24, 2014 by Truxton Corp.

[Pecan]

How to get to Mun from LKO:

1. Switch to map mode (M), click on Mun and 'set as target'
   
2. Create and execute a manoeuvre node at the next AN/DN burning normal/anti-normal (pink icons) to match planes with Mun (makes the new AN/DN difference 0 degrees or, if perfect, 'NaN' which is computerese for 'Not a Number')
   
3. Create but do not yet execute a manoeuvre node anywhere on your orbit burning prograde (green icon) to raise your apoapsis to Mun orbital height (should be around 940m/s deltaV).
   
4. Drag this manoeuvre node around your orbit until it gives you an intercept with Mun.
   
5. Point to the manoeuvre node on the navball and start the burn half the burn-time before you reach it (eg; if KSP says it'll take 1 minute, start the burn at T:-30s)
   
6. Timewarp until just before you transition to Mun's SOI then wait at normal time until you have switched
   
7. Make a small burn (shouldn't be more than about 50m/s deltaV) to set your periapsis at the height and orbital inclination you want (8km is good)
   
8. Create a manoeuvre node at your periapsis, burning retrograde, to circularise the orbit at that height (should be roughly 230m/s deltaV)
   
9. Burn as indicated, starting at the appropriate time before you reach the node
   
10. Once circularised separate your lander, pick your landing site and go for it!
    

Which of these gives you the problem? (See Chapter 5 of my tutorial for a couple of designs that are suitable for Minmus and Mun landings and return if you need ideas).