Anyone got some tips for getting to Mun and not exploding?

[OneRedBlock]

I'm trying to get a rover there to do some Kethane scans and exploration, but no luck so far.

[Noticeably FAT]

Step 1: Go to the Mun

Step 2: Don't explode

Good luck!

I'm sorry, I can't help myself most days. I'm sure someone else will come along with actual suggestions, but it will likely help if you give some more details as to what's going pear shaped on you and when. There's a lot of discrete steps between taking off from Kerbin and landing on the mun, and if any of them go wrong you likely won't get where you want to go.

[OneRedBlock]

Thanks for the help, if you could call it that. My main problems are managing to circularize (is that a word?) the Mun orbit, or balance the fuel-to-lift ration to actually make it on an intercept course with Mun. Oh, and actually landing slow enough to not shatter on impact.

[RoboRay]

Land more gently?

[OneRedBlock]

I tried, good sir Ray, to use parachutes. They failed. I then tried to use rockets. My lander exploded.

[RoboRay]

Hah, well, you are far from the first. "Just keep exploding until you get it right" is really standard learning procedures in KSP.

My first couple of Mun landings, I came down way too fast. After that, I came down too slow and wasted a lot of fuel. Eventually, I figured out a manageable descent rate.

Here's a suggestion: Try going to Minmus first. The lower gravity makes landings much easier.

[Reavermyst]

Well when making any landing on the Mun, you have to realize that even though there is less gravity, there is no atmosphere to slow you down. So how do you slow your decent with a rover? Well you don't unless you intend on making a massive rover. What you should do, is either place it on a lander(if it's a Kerbal driven rover) or use a skycrane. Essentially, a skycrane is a vessel that moves objects in low gravity. They're usually built with a docking port or decoupler on the bottom of the craft to hold the object, and have struts to hold the thrusters just far enough to keep from damaging the object it's carrying. Feel free to look up skycranes, they're commonly used.

So once you have your skycrane and rover on a rocket that can take you to the Mun, you go through your usual deal to reach Munar orbit, then release the rover and skycrane to make an de-orbit burn(Simply burn retrograde until your path leads toward the Mun). if you plan on landing the skycrane, gradually decrease your velocity as you get closer by burning retrograde. I personally strive for a safe landing speed of under 10 m/s but I think you'll be able to get away with slightly higher speeds.

If you don't plan on landing the skycrane, do the same deal, but HOVER just above your landing point before releasing your rover. This is trickier to do, as being too low could result in you running your exhaust over the Rover and being too high can cause it to break on landing. The plus side is that it's easier to build a skycrane that doesn't land with it's payload.

Also, don't trust the altimeter to be 100% accurate because that measures your distance from sea level or in this case(if I'm correct) the Mun's lowest point.

Anyway, good luck on your Mun landing!

[Pulstar]

If rocket is exploding when you jettison stages because they crash into it - add seperatrons to ensure they fly away and not into your rocket

If engines are exploding mid-flight when nothing hit them - they're overheating, throttle down and watch their temperature bars

If rocket explodes suddenly in flight for no reason - you're accelerating way too fast, either throttle down or add struts to reinforce the structure as parts start falling off and crashing into other parts

If lander keeps crashing into the Mun - kill your vertical velocity, basically burn retrograde until your retrograde marker (the crossed out circle) on the nav ball is pointing up at 90 degrees relative to the ground. For landing legs the wider the base of the lander is the better, landing a tower is hard, landing not so tall but wide craft is easier.

Edited May 8, 2013 by Pulstar

[itsme86]

I tried, good sir Ray, to use parachutes. They failed. I then tried to use rockets. My lander exploded.

Since the mun has no atmostphere, parachutes won't do you any good. You're going to have to reach the ground at a very low vertical velocity (I shoot for around 3-5 m/s) in order to survive the landing. you can toggle fine controls by pressing CAPS LOCK which can help you in landing situations.

P.S. Your inability to ask a proper question is striking. i.e. "tried to get a rover to the mun, no luck" and "tried to use rockets, but the lander exploded".

Edited May 8, 2013 by itsme86

[thes50]

I tried, good sir Ray, to use parachutes. They failed. I then tried to use rockets. My lander exploded.

The Mun has no atmosphere, therefore parachutes won't work. The only places which do have atmospheres are Eve, Kerbin, Duna, Jool and Laythe. Parachutes will only work on these Planets/Moons.

Using rockets to land make sure that you begin your trograde burn (to slow yourself down) early enough so that you're roughly 0m/s while within 100m-200m above the surface. If you leave it too late you run the risk of either crashing and destroying everything or crashing and only breaking a few things. Removing your speed too early can be inefficient and will waste fuel (as you're stopping at a higher altitude gravity is going to cause you to accelerate again).

TL;DR: Parachutes won't work. Burn earlier to prevent crashing/broken lander legs.

[Specialist290]

One other tip that might help: Drop into a very low Mun orbit (AP and PE at ~7 km or so) before actually beginning your landing. The lower your orbit, the less (in a relative sense) danger you'll have from either impacting the ground too hard or running out of fuel before your lander lands.

[Spatzimaus]

If you're running out of fuel before landing, then you need more fuel or a smaller payload. As nice as it might seem to have a rover with everything built into it already, anything that adds extra weight requires you to add about ten times as much weight in fuel. For instance, in the first post you mention "Kethane scans" for your rover. This is a mistake; what's the point of a kethane scanner on the ground, where it can only examine one location at a time? Put it on a satellite in a low orbit, instead, and use 100x time acceleration to do a rough scan of the entire surface in a few dozen orbits. (The only time you should put a K-scanner on a ground vehicle is if that vehicle will be mining the Kethane as well.) That saves you a little weight. Or, like I said, add more fuel, which is the answer to a lot of things in KSP. This also assumes you actually have enough engine power on the descent stage to land safely (a local TWR of at least two or three, minimum), but without seeing your design we can't make suggestions on that one.

Also, there's a question of efficiency on your orbit. The Apollo program did its landings in the safe-but-inefficient way: thrust sideways to kill almost all horizontal velocity, and then drop straight down before thrusting vertically to kill your descent speed. This is also the easiest way to do things in KSP, especially if you're trying for a specific landing site, but it's not the most efficient; thrusting retrograde as you go down to kill both velocities at once takes less fuel, it's just a lot harder to land on a specific location.

Beyond this, you need to build your designs more sturdily. It's one thing to say that a couple parts fell off on impact, but "exploding" means you either hit the ground REALLY hard (i.e., not even close to a safe speed) or your design fell apart from the shock (in which case you need more struts).

[RoboRay]

Also, there's a question of efficiency on your orbit. The Apollo program did its landings in the safe-but-inefficient way: thrust sideways to kill almost all horizontal velocity, and then drop straight down before thrusting vertically to kill your descent speed. This is also the easiest way to do things in KSP, especially if you're trying for a specific landing site, but it's not the most efficient; thrusting retrograde as you go down to kill both velocities at once takes less fuel, it's just a lot harder to land on a specific location.

Well, no, that's not exactly what they did. They brought their Pe down to 10 miles (if I remember correctly), then retro-burned from there to cancel out their horizontal velocity and descend simultaneously. That's far more efficient than simply killing your horizontal orbital velocity and dropping straight down, but still gives up some efficiency for safety.

[leax256]

try using mechjeb 2.0, watch what it does. or you can look up scott manely on youtube. anyone here will agree he is one of the best people to learn from.

[Kerba Fett]

You. Don't mention if your problem is getting to the Mun or landing once you're in orbit.

If its getting there that's the issue make a maneuver node as soon as you're in orbit around Kerbin. Pull out the prograde marker (green one) till your flight path shows a Mun encounter. You can move the maneuver node on your orbital path or adjust the radial marker (blue one) till your projected path lines up. You then,line up the blue node marker on the navball and do your burn. At the Mun you burn retrograde till you're in orbit.

Using the Smart ass module in Mechjeb will help a lot with landing.

Set it to hold retrograde and burn till you're near the ground then switch to rad+ for the last part of the descent. Multiple small engines on action groups help too since you can control your descent easier with less power available.

You could also use one of the cheater ships out there that have pretty much unlimited fuel to practice your Mun missions. Once you learn how to do it with those it should give you less problems using a normal ship.

The Wayland Space 1999 eagle or Dishy's M209 sphere probe will get you from Kerbin to the Mun easy enough.

Edited May 8, 2013 by Kerba Fett

[falofonos]

A more important point is that using a rover instead of a polar orbiting sat to find kethane will take forever...

[SkyRender]

I refer you to the experts on interplanetary travel themselves, NASA.

The best technique that has the highest levels of not-crashing-horribly-into-the-surface risk mitigation is to come in relatively low and then kill your horizontal speed first. As long as 1.) you don't come in too low and 2.) you have enough thrust-to-weight (and fuel), you will land perfectly safely and waste almost no extra fuel in the process. How low you have to come in depends on your TWR: the higher it is, the lower you can go before it gets dangerous. My general rule of thumb is to circularize at 10KM after transferring from Kerbin orbit, then adjust to a 5KM periapsis over my target landing site, and do the landing burn once I hit said periapsis (which gives me some extra vertical time when landing).

If what you need is advice on how much fuel you're going to need, the answer there is "it depends on how much you're taking with you". One key tip, though: mount a pair of nuclear engines to the sides of the fuel tank on your final stage. This will give you a good mix of thrust and efficiency, and let you accomplish a lot more with what fuel you have. Just make sure that you're out of the atmosphere before you get to that stage.

Edited May 8, 2013 by SkyRender