Tokay Gris

This I know. But thats BEFORE I start the maneuver. During execution it seems, the error creeps in. As if the engine was off angle. While it is not. This vessel is pretty symmetric. I need the pretty high TWR to get off Tylo in the first place. Also, I have done this method with TWRs up to 30. And the torque on this vessel is no problem. Plenty of it. I am right now testing another design and a slight modification on the current design. And again: Other designs so far worked without a hitch. MechJeb is not "it" as far as I can discern.

I know. But this is not what happens. What happens is that the marker goes in a direction that is not helping anything at all. Like this: I want to match velocities. MechJeb can make a node for this. Either MechJebs autopilot or I by hand execute that marker and usually this does the trick. Usually and with all my other vessels this works seamlessly. Not so with this vessel. My guess is that the marker is actually correct but in the process of closing in some error creeps in. I looks like the mechanics of the game assume or detect some direction of movement with this vessel that is not exactly in the direction of the thrust applied. Which then, during the last few m/s totally throws off the marker. It wants to compensate (like you said) for something that is not there. Which the looks like the thrust applied (in the direction of the blue marker) is not pro- or retrograde in relation to the target or the orbit, but perpendicular to this. And any thrust applied perpendicular to the movement vector is not changing the movement vector. (Or is my english at miss here? I mean to say "rechtwinklig" or "at a right angle". That is "perpendicular", isn't it?) The marker is the problem, as far as can I see. Not MechJeb, which just executes the node. I think. (Which I really like. Executing nodes by hand is crude and usually - as you say - a bit off.)

Just tested another lander bound for Duna. With parachutes. Landed with 6 metres off target. So my guess is there is some basic problem with my design. But not a problem with MechJeb itself. A problem with the nodes. I have so far no idea whatsoever why this particular design fails so much. I also noticed that with this design, the landing predictions (made by MechJeb) wander off considerably during descent. The deorbiting burn stops within 300 meters of predicted target, then it changes during descent. Which might make sense on a body with atmosphere, but not on one without. And like I just tested (but with another design), it works like a charm on Duna.

I know it does. But that is not the problem here. I am not even sure the problem is actually MechJeb. Because MechJeb just follows the marker. The marker is the problem. But why it shifts in a direction that is actually useless, I don't understand. Not for me, it isn't. I can do it myself, but since I am using quite big ships with many parts right now, docking by hand and in the slideshow this produces is ... well, lets say: Boring.

Just did a test on Mun. Same problems there. Where other vessels pinpointed their landings (10 m off target at most) and made rendezvous countless times, this vessel lands more than 10 km off target and rendezvous using MechJeb is impossible. I haven't tried docking autopilot yet, though.

MechJeb landed just fine, just 10 km from the place where I wanted it to land. Which doesn't help if you want to make rendezvous on the ground with a kethane rig. Expecially if both don't have wheels. MechJeb does this even on closing in on the rendezvous and just burns perpendicular. Kind of in a circle around the target. Like this: target is in the east, MechJeb burns north.

Thats what I did. Drifting of the blue marker is normal, but usually not in a perpendicular direction that does no longer reduce the nodes delta-V. So far, it worked pretty good with some exceptions. But never before was it THAT far off to the point where it didn't make rendezvous. Ususally for me it is about 10 metres off max. To the point where I pay careful attention. More than once one craft landed on top of the other.

Here is the .craft file. With MechJeb on it. http://www.filedropper.com/tylolandermk1f

To illustrate the profile some more. This is what lands on Tylo: And this is what lands on Vall, Bop and Pol:

I build this here lander. It looks a bit complicated but is not, really. The basic plan is to first land on Tylo. For this, the lab and the science module (from top to bottom) are decoupled (to stay with the cruiser). The rest then lands on Tylo. For ascent, the two lateral pylons are decoupled and stay on the surface. Then, the remaining vessel again docks to the science module, is transferred to the next moon (Val, Bob or Pol), decouples from the lab module, lands, lifts up again, docks to the lab again (which is with the cruiser), take data out of the stuff (thermo, Goo, the works), which are then cleared with the lab, transfer to next moon, rinse and repeat. That is the theory. Practical tests had these problems: Landing on Tylo using MechJeb worked, but was off about 10 km. Ascent worked up until only about 0.5 m/s left on the maneuver node, which then shifts to an angle that does not help anymore but keeps burning anyway (MechJeb that is). Stopping this by hand (orbit was achieved, although not an exactly circular one). Then, the rendezvous autopilot has the same problems. Burns the nodes up until about 0.6, the node marker then shifts to a kind of perpendicular position, MechJeb keeps burning, but in a direction that does not help any. Of course, I can do all that by hand, but since this mission profile includes quite a few rendezvous and docking maneuvers, I'd like to really use MechJeb. So what is my problem here? Is it MechJeb? I had some trouble at other bodies as well. Or is it the design? The command capsule below the tank? The "obvious" problems I checked. I did change the controlling part to one of the big docking ports. The one on top as well as the one facing forward in between. And back again to the command capsule. Power is there. Torque is there. No clipping (I can see). Anyone has an idea? I kind of like my design and would hate to redo it. But if all else fails, I will. Too many rendezvous and docking maneuvers, as well as too many landings to be done on this mission. And landings that should be fairly accurate. (Rendezvous on the ground with methane rigs is planned.) Other mods are: KAS (not in this design), S.C.A.N.sat (also not in this design), Kethane (not in this design), Alarm clock and Hyperedit. The only mod part in this design is actually Mechjeb.

Ehm.... all the time? My current "Prospector"-type ships weight fully fueled more than 300 tons. Can't get it to orbit fueled, so I need fuel tankers. And those are well above 130 tons each.

Usually I hate to many exclamation marks. But in this case, you would have been entitled to quite a few. Congrats! Once you accomplished this, the Kerbol system is your oyster. What I did? I launched a mining research ship to Moho, staged another one earmarked for Dres and caught a class B asteroid.

The color and font stuff is really not helpful. But anyway: Go to your Finder, then "Go" at the top, hold down the "Alt"-key, go to "Library" (not visible otherwise). Somewhere in there are the files. If you use Steam, then its under Application Support/Steam/SteamApps.

Lets see if I understood this: So, you leave Kerbin opposite Mohos perigee. So to speak, when Kerbol is between Kerbin and Mohos periapsis. Right? Then, you make your periapsis the same as Mohos. Then, you change your apoapsis that you meet Moho next time around. Why not Mohos apoapsis? Should work as well, shouldn't it? And at that point, Moho is closer. Shouldn't that also mean less delta-V?

If finishing the career mode is your goal - namely, finishing the tech tree - you don't need Moho. Heck, you don't even need to leave Kerbins SOI. There is enough science within Kerbins SOI to finish the tree. And most of it not hard to find. The only thing that is not that simple is a landing on one of Muns poles. The north one is a pain. And you need a little luck with the south one. IIRC, you need only one of them anyway. And you don't need it, really. I just finished Mun and Minimus (there, the "slopes" are the problem. At least for me) and only random landings on Kerbin. And finished the tree with about 5000 (or so) left over.

You edit the first post, "Go advanced" and there you can change that.

Please don't misunderstand me. I am not critisizing your design. Well, I am, but in a - I hope - constructive way. I like it! Especially the small tank in the middle. As soon as I finish downloading KSP on this mashine (not mine... like I said, mine is "drunk". On white wine actually. Which is propably ok if you are human, but not so good for a laptop, it seems), I will use something very similar. I am just thinking of how to improve on it. And - which shows how much I like your design - the only thing I CAN argue is RCS. I seems to me the way to use it just for drift is not necessary, doesn't make it that much easier (actually, I think it makes it more complicated) and adds weight. I will, however, try your method of landing. And see if it makes it easier. A gut feeling says that it doesn't. But I will test it.

Good for you! Did you find out which Mod was the problem? What mods did you use?

I meant, is the tab to the right of the screen there in the VAB?

But in the VAB you have it? Or is it there missing as well?

As far as I see, it is still possible to max out the techtree with only parts of Kerbin, the Mun and Minimus. Specifically, without using any asteroids and leaving Kerbins SOI.

I found it quite as easy to just point the vessel a little bit to do this. Your way of doing it is new to me. That is all. Haven't done that myself. But will try your way next time.

That is what i don't understand. But I can't watch the video right now. No idea why... So you use the RCS to stabilise for the drift? The way I see it (and please keep in mind that I still like your design), you could land without it. And you could do it without the RCS. And this way reduce the weight. Not quite sure how much the RCS-tanks weight, but since the whole vessel is rather light, it could be significant.

Ok, was able to see a little more of the video. I take back the comment about no solar panels. There are some. Still: Why RCS-capability? It doesn't need to dock. It can't even dock, since there are no docking ports. (It would be easy to add one, thouh. The small 'chute on top seems to be superfluous.) That way, you could reduce the weight and with that increase the delta-V. I like the design, though. Smaller than my "there and back"-lander.

For some reason I could only see the first 20 seconds or so of the video. What I saw looked not bad. But I do have a few questions: - Why does it have RCS-capabilty and no docking port I could see? (Maybe I just didn't see it) - Why additional batteries? - Didn't notice any solar panels, but somehow youtube does not work as expected on this computer.... So it is very possible I just did not see them. ... Could you probably post a picture of that vessel? It gave me a few ideas.