Need help with mechjeb

[Captain Murphy]

So, after many, many attempts to land at a specific target on the Mun following various people's instructions to no avail, I decided to download mechjeb version 2.0.9. It would turn out that it is even worse than I am at landing in general. Never mind a targeted landing, it cant land for ♥♥♥♥ at a random location. After this many landing failures and all this time wasted on it, I have decided to strongly urge people not to use this mod. No matter what, provided I ask it to land, it decides to either launch me into the sun or to crash at at least 500m/s into the Mun. For anyone saying I don't have enough delta-v, if 6K isn't enough, then how big a rocket do you need to simply land where you want to on the Mun. I got this mod to help me figure out how to land manually, but it has only taught me how to make an impressive fireball on the Munar surface. I've tried a low orbit, a high orbit, a regular rendezvous into the Mun's SOI, and even a return trip from Minmus to try to get it to work. I even launched a simple craft into Kerbin orbit to try to land at the spaceport only to have it decide to crash at about 1400m/s even with roughly 3K delta-v. I honestly have no idea what is up with mechjeb seeing as I've watched more youtube videos and read more forums than I should have for such a trivial thing in the big picture, but nothing anyone says works worth a damn. A ♥♥♥♥ mod in the end, unless you want to transfer orbits or do anything in orbit rather than under direct SOI of anything.

http://steamcommunity.com/profiles/76561198046000613/screenshots/

That picture is coming out of a 30K circular orbit after engaging Landing Guidance about 20-25 seconds before being directly above my intended target. I crashed about a minute after this shot and about a quarter way around the Mun from my target.

[Captain Murphy]

Not sure how the second screenshot got in there, but it was a different launch of the same craft minus the mechjeb attempting to do a targeted landing on the Mun as well. Though it missed the target by about 15Km, it landed just fine by my controlling it; just not where I wanted it to land.

[Maverick]

So what you're saying is you have no idea how to use it properly?

It doesn't take you from launchpad to surface.

You need to launch into orbit with one option.
Fly to Mun and setup orbit using another.
Land with another.

Most users can drop 2 capsules within metres of each other.

I sincerely hope you modify your post to correct the obvious errors and mistruths upon learning how to do it. Otherwise you will look silly.

[Captain Murphy]

To save face from sounding like an idiot, I don't use mechjeb at all until I hit Mun-orbit. That much and landing on Mun is easy enough for me with the rocket I built. I've just been using it to help me learn to land on a specific target. That's where it fails. I set up orbit, or rendezvous, or whatever people suggest to me and I let it it do its thing. Then one of two things happens; I either get sent to the sun, or crash at high velocity into the Mun. It's a very consistent occurence, to the point that I'm about done with even attempting to use it beyond anything but orbit transfers of which it performs very well. I just have a huge problem with actually landing where I want to. Mechjeb just seems to want to crash as fast as it can.

[Captain Murphy]

And for that fail, I stand by what I said. It's a piece of ♥♥♥♥ if it can't help with that. I use it to learn, not to see how well I can explode. I'm looking for constructive advice here, not antagonistic ♥♥♥♥♥♥♥♥. I just want to know if I'm doing something wrong and how I can adjust it. I'm just using the Landing Guidance to learn how to land where I want to and am having a world of trouble getting it to work at all on any planet or moon I try it on

[Streetlamp Le Moose]

I still can't understand what could be happening that would make it so screwy for you. I haven't had a problem with it unless it was something I did. Would be pretty tough to figure out as none of us can see what you are doing in-game.

Are you inputting the coordinates manually or setting the target and clicking "land at target"?

[Captain Murphy]

I am clicking land at target which seems to be getting it theoretically on top of the landed craft. All the markers line up right, mechjeb just seems to like to go full tilt at the target each time and miss wide but at a huge speed

[Streetlamp Le Moose]

Then I'm stumped. Only other thing I could say to try is to manually add a manuever node to where you want to land and make the appropriate burn. Once you are on track towards your target, then enable the landing guidance.

[Captain Murphy]

Tried it. Once I activate mechjeb I just get tossed either into the sun or into the planet. Pretty much why mechjeb gets a huge zero from me. At least for me it's more a crap mod than anything helpful. Pretty much ruining the game for me at this point, but I'm having a lot of trouble landing where I want to without something like it, so I'm at a stalemate here

[Bayliss]

I have no idea what's going on, but just to be sure, can you try this:

Use a small lander, the stock lander if neceessary.

Place yourself, or use mechjeb, to get into an orbit around the Mun, or wherever you want to land: Periapsis = 100km, Apoapsis = 100km, Eccentricity = 0, Inclination doesn't matter.

Just to be safe, enter in the co-ordinates manually. As with clicking the desired destination. It is slightly off. When on the other side of the Mun, as to give MechJeb some time, activate autopilot.

Can you please record or take multiple screenshots or something, and post them here if it still goes wrong.

Also, if you are trying to land a large craft, make your orbit a little larger, and give the autopilot more time. Hope it works :D

[Maverick]

Originally posted by Captain Murphy:

It's a piece of ♥♥♥♥ if it can't help with that.
I'm looking for constructive advice here, not antagonistic ♥♥♥♥♥♥♥♥.

It wouldn't be "antagonistic ♥♥♥♥♥♥♥♥" if you came on saying "I'm having trouble, help." You didn't. You came on claiming everything is ♥♥♥♥♥♥, broken, ♥♥♥♥, get's a zero ad infinitum....

Make the call. Is it a ♥♥♥♥ mod or are you prepared to find out wtf is going on? If it's ♥♥♥♥, do it manually.

If you're prepared to stop the rant, I'm more than happy to help - as will many others.

Question 1: Are you using other mods?
Question 2: Is your command module head of lander and are you controlling from there?
Question 3: Are you in proper orbit pre-landing or trying to do it with Pe too high or into surface?

We need info about your attitude pre-landing. (And by attitude I mean your craft, not your hothead).

Ap and Pe? Got enough retrograde velocity? (what engine?) - Craft too heavy for retro? What's it's weight?

Are you using timewarp? Are you clear SOI or stalling at SOI and finishing on the surface?

Data. Data. Data. Not BS. KSP pilots are hard wired gentlemen, not spoiled brats. Read your title and tell me where you started from?

Are we learning yet?

[Fel]

I use MechJeb to land quite a lot, because it tendds to do a better job than I am (reads: wasts way less fuel).

But MechJeb is not a god, it has many requirements in order to properly work.

1. Make sure you didn't rotate what is commanding your ship in the VAB, it tends to make MechJeb assume a lot of things.
2. Give it enough torque so that it can turn on itself relatively fast without RCS.
3. Give it enough thrust and fuel to be able to quickly decelerate before landing.
4. Do not forget that your landing gear have to be manually deployed.
5. Always push F5 before activating the autopilot, you never know.
6. Try to start the Landing autopilot from a 50km orbit or more, it tends to have better results.
7. In case you followed all this and it still wants to land so far away when you ask "land on target", then you might have an other problem.


Personally, the only two ways I found to make MechJeb not do a good landing was by having a ship that would become unbalanced when I put out the landing gear, or with an imbalanced ship from the start, but I know that whet you put the command module upside down, it tends to do stupid things.


Also, this "I get tossed in the sun" doesn't make any sense, as it can't use more than a 100x time warp so close to surface. You might have other problems than just mech jeb, if that's the case.

[dunbaratu]

I despise the concept of using somebody else's autopilot (yes real space programs have autopilots - that they had to write themselves - not that were handed to them from on high already working out of the box like Mechjeb is.)

However, that being said it looks like you're controlling everything right up until 30 seconds before passing over the target, and then handing the controls over to mechjeb to finish, and THAT means all the blame for setting up an utterly impossible landing scenario is yours and yours alone. Look at the starting speed - over 700 m/s for a Mun landing at the 10km point, using an engine that only provides 50 thrust? That's an impossible scenario. No pilot, human or computer, can land from that starting situation. You need to come in shallower. That other screenshot with the insane angle of attack showing on the blue line - if you set that up yourself instead of that being something mechjeb did, then the crash is your own fault. That is not the way to set up for a landing.

To set up for a landing, start from a much shallower angle. An orbit that's between 10km and 20km up and circularized works fine but even a highly eliptical one is fine. Kill the orbital velocity so gravity can make you fall is the way to do it. The way NOT to do it is to be heading toward the surface from a long distance up. That approach makes it so that the Mun's gravity will pull you in faster and faster, and you'll have to be trying to fight that using your retro-burn. If you start from a shallower, lower height, then you're not being pulled down across a distance of 50-100 km but only from a distance of 10km or so, reducing the amount of time your rocket has to be fighting gravity.

I don't care for Mechjebn, but come on be fair. Don't blame it for the bits YOU were in control of, and that approach was your doing. The crash was invevitable before you handed over the controls to mechjeb.

[Captain Murphy]

I'll respond to all your responces to my post since I logged off in order. I'll try to be as brief as I can but answer you all.

Bayliss, I used to stock lander from the load menu and brought the craft straight up and told it to land at the spaceport several times. The ascent Guidance worked fine, but once I either manually typed in coordinates or clicked on Land at KSP, it would go full throttle right back to the pad and explode. Every single time, without fail.
For Mun orbits, Ive tried huge orbits at the edge of Mun SOI, and tiny orbits of only roughly 20K, and as many sized orbits in between that time allows for. I know my craft is a bit large once it gets into orbit, so I prefer to keep larger orbits to allow the autopilot time to correct itself. This is where I run into another huge problem. On autopilot, my craft will hang at the apoapsis self correcting literally forever. Either I let it run out of fuel and crash, or sometimes I like to turn on infinite fuel and just leave it for a few hours. I'll come back and its exactly where I left it even though the target has orbited to the other side of the planet by then.

Maverick, I had posted several threads asking for help, but it seemed being nice wasn't getting me anywhere and in a bit of a drunken haze got pissed that after watching tons of tutorials and reading other forums, I was still having the same problem no matter how I approached it. So I can see how you percieve me as an ass, and I was. I do want to learn what is going wrong, but no matter how I approach the Mun (be it from an established orbit or just a rendezvous with the Mun's SOI) it ends the same way every time. 500m/s+ crash way off target. Now on to your three questions.
1. I tried to keep this game vanilla, and as such have no other mods on this game, and really don't plan on adding anymore either.
2. Yes, my command module is at the top of the ship, save for a parachute for return trips. Other than the command module, I have SAS, the slim photovaltaic cells (4) a ladder, one small rcs tank, a couple radial monopropellant tanks for extra RCS, all sitting on FL-T400 fuel tank, and boosted with the LV-909. I can land this setup in random parts of the Mun and Minmus with absolutely no problem, and return to orbit because I weigh in at that point barely over a ton.
3. I start in proper orbit pre-landing. For a while I set it manually but wasn't too efficient at getting it just right, so I used mechjeb to set it up and landed a few times myself in random areas just to get better acquainted with how to do it all correctly.
As for attitude, I usually try to orient myself towards retrograde so I can slow myself down, but have also tried various other orientations to various degrees of success/failure. After watching a video on youtube of someone doing a manual landing to within a few meters of another craft, I have been keeping closer to the edges of the retrograde symbol to more or less fine-tune my landing, but due to my noobish-ness, haven't gotten to good at it yet (usually a too-little-too-late type deal).
For ap and pe, I have tried various combinations of distance, and have more than enough retrograde velocity seeing as I have landed on my own many times just fine with my roughly 1 ton lander.
No timewarp while I have mechjeb running, seeing as if I warp time with it on, it goes all haywire on me, so when its activated, I let it set warp for orbital transfers on its own. I've also noticed that decoupling spent stages while mechjeb is active seems to make it go haywire as well, forcing me to reset the maneuver. And for the SOI part, both. As I've said, I've tried pretty much everything people have suggested with the same outcome each time.

Fel, I understand mechjeb is not a god, but a learning tool.
1. Never rotated command module
2. Plenty of torque without RCS, I typically dont have RCS engaged in order to save it up for if I really need it. I have used RCS to return to Kerbin a few times.
3. It has enough thrust to get me to drop speed at about a rate of 200m/s every 20-25 seconds or so. So, provided I have about a minute of time, I can go from a high veleocity of 500+m/s to a nice landing velocity of 3.5-5m/s and coast to the surface on my own. Mechjeb for some reason isn't cutting velocity and is deciding to just rocket into the Munar surface at full throttle.
4. I always deploy my landing gear.
5. I have a quicksave of the craft set up about an hour or so from reaching Mun's SOI in order to try various maneuvers and angles of entry and such. Sometimes I establish an orbit, sometimes I just pass into Mun's SOI and rendezvous.
6. Tried many heights, from the edge of orbit, to a very low orbit.
7. That's what I'm worried about. Even with all the different pieces of advice I've found, its the same result. I'm hoping something isn't busted in the program, because I'd have no idea how to go about fixing or even tyroubleshooting something like that (definitely not a programmer or computer whiz here).
And for the sun part, it's not so much being tossed into the middle of the sun and burning up, but more rather getting tossed into the sun's orbit between Moho and Eve. I did use that opportunity though to make a landing attempt on Duna through expanding my apoapsis out to its SOI.

Madings, I have tried shallow approaches as well as near vertical approaches (both have been suggested to me many times, and though I prefer steep landings for when I control my landing (typically to a random spot to just try to land), with mechjeb enabled, shallow or steep approaches don't change the outcome or the events leading up to the outcome. It will always full throttle and crash. I typically try to keep my speed low on approach and try to maintain somewhere between 80-150m/s until I close in for a landing, to which I'll slow myself to 3.5-5m/s and maintain until touchdown. Even with a start speed that slow, once mechjeb is initiated (even from a high orbit) it will always just gun it to the surface and get up to a speed I can't slow down. Hence the picture I posted. I had initiated mechjeb at about 150K with a speed of 87.8m/s. Then mechjeb shot up to that speed and I crashed about 30 or so seconds after that picture was shot. I took the screenshot in the middle of the descent to display what was happening. Not the beginning of the approach, or the end (which as I think back, I should have taken more screenshots of that approach to better illustrate what was happening.

Sorry for the novel everyone, but I hope it answered your questions to me, and gave enough detail on what is going on so that a solution can be reached. I totally understand if no one reads this, as it is long as all hell, and I'm sure my grammar leaves something to be desired, but if you do read this, and have advice or some tricks to try out, thank you. And drunk me apologises for the bratty rant at the start of this thread.

[Slye_Fox]

This is why you are wrong about MechJeb being a load of hearts;
http://i.imgur.com/ttmI5c5.jpg

This base is made of 8 seperate ships that were all landed with MechJeb and docked manualy useing RCS.

[Captain Murphy]

I've seen many really impressive Mun bases that used mechjeb to land. I'm just having trouble getting my mechjeb to land, and want/need some help getting it to work for me. I went into the issue I'm having above so I don't really think it bears a protracted reply more than, I try different suggestions, turn on mechjeb, fly fast into the surface the same way every time.