[PART, 1.0.2] Anatid Robotics / MuMech - MechJeb - Autopilot - Historical thread

[drtedastro]

How do I keep landing guidance from trying to go through a mountain that is in the landing path? On Minimus, I have crashed many times due to the landing approach only taking into account the elevation at landing site, and not the terrain along the flight path. Am I doing something wrong? I am new to KSP (love it!!!!!!!!!!!!!!!!) so most likely the problem is me. thanks for any info and help.

DrTedAstro

[Guest]

How do I keep landing guidance from trying to go through a mountain that is in the landing path? On Minimus, I have crashed many times due to the landing approach only taking into account the elevation at landing site, and not the terrain along the flight path. Am I doing something wrong? I am new to KSP (love it!!!!!!!!!!!!!!!!) so most likely the problem is me. thanks for any info and help.

DrTedAstro

You're not doing anything wrong. MechJeb is doing exactly what you told it to, which is "land at this spot". MechJeb is a flight assistance computer, not an autopilot. Planning your landings is important. If you know your target is in a valley area, then start your descent from an appropriately higher altitude that will give you the steeper descent profile you need. If something goes amiss, be ready to take manual control and set it down yourself or abort the landing.

Edited June 26, 2013 by Jack Wolfe

[elfindreams]

Is there any colision between Mechjeb and following mods? : KAS kerbal atachment system, AIES, Firespitter, B9 Aerospace, Kethane, ISA MapSat, Rubberband, Chatterer, or Aviation lights?

I was using mechjeb with most of theese bfore with no problems. But lately Mechjeb behaves strange. The ascent guidance works ok untill cirkularization. Mechjeb controlls the wessel all the way up, then warps to apoapsis, and then does nothing. Same goes for all the space features, like randevouse autopilot, maneuver node autopilot, Smart ass. If i plan maneuver trough mech jeb and hit create and execute, it sets the node, but thats all. if i point the ship to right directon manually mechjeb will fire main engine, but allways owershoots, and i have to constantly correct its course manualy because mechjeb refuses to steer the blasted thing.

Same goes for Smartass. You can push the prograde, retrograde or whatewer button you want all you want, but it does nothing.

In krbin atmosphere mechjeb works fine. but as soon as i go above 70km it just stop working. Sometimes i can get him to work if i reload quick save few times, and some times it works ok all the mision.

Last ship i had problems with was just simple rocket build with stock parts, mechjeb, aviation lights and B9 Aerospace parts, and i vanted to dock it with another ship that was pushet up with mechjeb without issues even if it was much more complcated design, but this second simplier ship i wasnt able to even get to circular orbit as mechjeb was refusing to steer it, and i really suck in keeping the nose pinted right way manually.

Never had theese issues before. Actually i hadnt theese issues till yesterday.

I am using MJ2 fine with all of the above except Rubberband, Chatterer, and Aviation Lights so not sure on those three.

[Guest]

I am using MJ2 fine with all of the above except Rubberband, Chatterer, and Aviation Lights so not sure on those three.

It works fine with Aviation Lights, too.

[mereman]

I am using MJ2 fine with all of the above except Rubberband, Chatterer, and Aviation Lights so not sure on those three.

Working with Chatterer for me.

[JonoRig]

And it works with rubberband for me

[Fyrem]

How do I keep landing guidance from trying to go through a mountain that is in the landing path? On Minimus, I have crashed many times due to the landing approach only taking into account the elevation at landing site, and not the terrain along the flight path. Am I doing something wrong? I am new to KSP (love it!!!!!!!!!!!!!!!!) so most likely the problem is me. thanks for any info and help.

DrTedAstro

best advice for this is to start from a higher orbit. This will cause the end of the flight to be more of a straight up down

[KhaosCorp]

best advice for this is to start from a higher orbit. This will cause the end of the flight to be more of a straight up down

Minmus is not the only place your gonna run into this. Any planet or moon with drastic elevation changes your going to run the risk of smashing into mountains if you start your deorbit to low. Best thing I have found to do is start super high and do your deorbit burn so you basically hotdrop onto your LZ target. Takes a little more overall thrust to do it this way right at the end(just as you actually touch down) but not much.

[drtedastro]

Thanks for the reply's. Trying the higher, hotter, straight down the throat approach now....

[tyler00337]

Thanks to MechJeb, I completed my grand tour of the entire Kerbol system with relative ease. Everything on my ribbons is the grand tour (excluding Kerbin, Mün, and Minmus).

[Stutter]

i'm having this problem too, using the rendezvous planner to get close enough to perform a docking manoeuvre, the other craft is the selected target and when i pressed alt-f2 there were no red error messages

[Good_Apollo]

Will there ever be a way to initiate landing from a parabolic trajectory orbit, for aerobreaking straight in?

[Payload]

Will there ever be a way to initiate landing from a parabolic trajectory orbit, for aerobreaking straight in?

You can already do that. Click show landing predictions under the landing auto-pilot. I do it all the time. If you are asking if you can get MJ to control you through aero-capture and then to descent. Then I don't think you understand the "gravity" of the situation.

When it auto lands it is just waiting for a window. Aero-capture is a much more dynamic event.

[Good_Apollo]

You can already do that. Click show landing predictions under the landing auto-pilot. I do it all the time. If you are asking if you can get MJ to control you through aero-capture and then to descent. Then I don't think you understand the "gravity" of the situation.

When it auto lands it is just waiting for a window. Aero-capture is a much more dynamic event.

No I guess I don't, for the same reasons I don't understand why Space Plane Guidance can't initiate a deorbit burn...or work at all in most respects. Mechjeb Descent AP requires to you to either be in an orbit for deorbital burn or be already on a capture trajectory. It can't seem to move you into one automatically and then switch to descent maneuvers. That's what's always annoyed me about MJ...you have to constantly switch between different modules or your own maneuvers to get it to function. I'm not really blaming the devs, as it's not an easy task to construct what MJ does...but it does have irritating limitations.

Especially annoying is the fact that you can't really do MJ interplanetary transfers. I always have to do them by hand because MJ doesn't do the time acceleration at the pad, instead doing them on orbit (which is horrible for anything sub-600KM) and more often than not skips the window and continues to time accelerate because of minor orbit changes during that time.

Edited June 26, 2013 by Good_Apollo

[antiwesley]

This may not be the exact place to post, so I apologize, but I've been looking for a guide on how to use MechJeb to enter Mun orbit. I can rendezvous and crash into the Mun, but not orbit it.

I couldn't find anything in the search and even my Google-Fu isn't helping.

Thanks!

[Guest]

No I guess I don't, for the same reasons I don't understand why Space Plane Guidance can't initiate a deorbit burn...or work at all in most respects. Mechjeb Descent AP requires to you to either be in an orbit for deorbital burn or be already on a capture trajectory. It can't seem to move you into one automatically and then switch to descent maneuvers. That's what's always annoyed me about MJ...you have to constantly switch between different modules or your own maneuvers to get it to function. I'm not really blaming the devs, as it's not an easy task to construct what MJ does...but it does have irritating limitations.

Especially annoying is the fact that you can't really do MJ interplanetary transfers. I always have to do them by hand because MJ doesn't do the time acceleration at the pad, instead doing them on orbit (which is horrible for anything sub-600KM) and more often than not skips the window and continues to time accelerate because of minor orbit changes during that time.

MechJeb is not an autopilot. It's a flight computer. The purpose of a flight computer is to assist the pilot (that us carbon-based lifeform types) in flying to wherever we want to go. That's why there's no "Whee! Let's go to Duna" button. You control the phases of the flight, MechJeb handles the scutwork.

[Montieth]

Possible suggestion for improved staging functionality. When initiating a stating function could MechJeb zero out control inputs for a short delay prior to and after the staging function so as to allow for those spent components to drop free without a pitch or yaw input? Normally on my launches with large parallel boosters I have to stab "T" for a moment to keep the craft from a pitch or yaw moment and prevent a strike between my active stages and the spent stages as they drop away.

[Guest]

Possible suggestion for improved staging functionality. When initiating a stating function could MechJeb zero out control inputs for a short delay prior to and after the staging function so as to allow for those spent components to drop free without a pitch or yaw input? Normally on my launches with large parallel boosters I have to stab "T" for a moment to keep the craft from a pitch or yaw moment and prevent a strike between my active stages and the spent stages as they drop away.

I'm hoping the rework of SAS/ASAS in 0.21 will help null out this behaviour. I agree, it's a pain!

[KOCOUR]

Is there any colision between Mechjeb and following mods? : KAS kerbal atachment system, AIES, Firespitter, B9 Aerospace, Kethane, ISA MapSat, Rubberband, Chatterer, or Aviation lights?

I was using mechjeb with most of theese bfore with no problems. But lately Mechjeb behaves strange. The ascent guidance works ok untill cirkularization. Mechjeb controlls the wessel all the way up, then warps to apoapsis, and then does nothing. Same goes for all the space features, like randevouse autopilot, maneuver node autopilot, Smart ass. If i plan maneuver trough mech jeb and hit create and execute, it sets the node, but thats all. if i point the ship to right directon manually mechjeb will fire main engine, but allways owershoots, and i have to constantly correct its course manualy because mechjeb refuses to steer the blasted thing.

Same goes for Smartass. You can push the prograde, retrograde or whatewer button you want all you want, but it does nothing.

In krbin atmosphere mechjeb works fine. but as soon as i go above 70km it just stop working. Sometimes i can get him to work if i reload quick save few times, and some times it works ok all the mision.

Last ship i had problems with was just simple rocket build with stock parts, mechjeb, aviation lights and B9 Aerospace parts, and i vanted to dock it with another ship that was pushet up with mechjeb without issues even if it was much more complcated design, but this second simplier ship i wasnt able to even get to circular orbit as mechjeb was refusing to steer it, and i really suck in keeping the nose pinted right way manually.

Never had theese issues before. Actually i hadnt theese issues till yesterday.

Ok i found the source for the problem. i deleted all traces of all mods in my KSP instalation. and then i instaled them all back. Now is jeb behaving as i expect it to.

[Troberg]

Another suggestion: MechJeb is an excellent learning tool, and in some cases, for example ascent and landing, it's quite verbose in telling what it's doing. However, in some cases, it's not as informative.

It would be very nice to have a status window, where MechJeb tells exactly what it's doing (or waiting for). That way, a newbie could easily pick up the basic principles just by watching. Also, it would provide a way to see if MechJeb has misunderstood something and is about to mess up (which, occasionally, happens) before it actually mess up.

[willow]

Possible suggestion for improved staging functionality. When initiating a stating function could MechJeb zero out control inputs for a short delay prior to and after the staging function so as to allow for those spent components to drop free without a pitch or yaw input? Normally on my launches with large parallel boosters I have to stab "T" for a moment to keep the craft from a pitch or yaw moment and prevent a strike between my active stages and the spent stages as they drop away.

The normal mechjeb settings cause the craft to go into a strong gravity turn at about 10km, causing it to do a lot of steering. This also often coincides with dropping your second stage. Steering and dropping the second stage often lead to fireworks. Especially on big rockets.

I find that if you set the beginning of the gravity turn at below 1km (250 meters for me) and change the graph to 70 (Sorry the name slipped my mind but I believe it defaults at 60). Then the result is a much more gradual and controlled turn along your entire ascent. The fuel drain isn't noticeably bigger. It leads to a much more reliable ascent, less explosive separations (I don't even need to use sepatrons on the big rockets) and the sudden loss of control problem around the 12km mark is gone.

I totally recommend it.

[mereman]

This may not be the exact place to post, so I apologize, but I've been looking for a guide on how to use MechJeb to enter Mun orbit. I can rendezvous and crash into the Mun, but not orbit it.

I couldn't find anything in the search and even my Google-Fu isn't helping.

Thanks!

How I do it. First a Hohmann transfer to Mun. Then time warp to capture then set periapsis to desired height, I normally set to about 80 K, then circulaise at periarsis. you should then have orbit. This using mechjeb 2.0.8-68

[Gary_P]

I agree. I'm using it to learn how to dock. I was making notes last night as I watched.

[viperwolf]

This may not be the exact place to post, so I apologize, but I've been looking for a guide on how to use MechJeb to enter Mun orbit. I can rendezvous and crash into the Mun, but not orbit it.

I couldn't find anything in the search and even my Google-Fu isn't helping.

Thanks!

These are the steps i take.Im sure there is a better way. But this works everytime for me.

1 Ascent 100 orbit

Manuever Node Planner

2 select mun target

3 H transfer to target

4 once you get an encounter, change P to your desired orbit distance.

5 circularize at P -just tie 4 and 5 together and hit execute all nodes. example: A. change P to 80. B. then create new node and circularize at P and hit execute all nodes

that should get you a in orbit. then you can change your inclination very easy and also target land easy.

Edited June 27, 2013 by viperwolf

[KhaosCorp]

Possible suggestion for improved staging functionality. When initiating a stating function could MechJeb zero out control inputs for a short delay prior to and after the staging function so as to allow for those spent components to drop free without a pitch or yaw input? Normally on my launches with large parallel boosters I have to stab "T" for a moment to keep the craft from a pitch or yaw moment and prevent a strike between my active stages and the spent stages as they drop away.

Learn to properly use Seperatrons and this would not be an issue.

My SHLV (that's SuperHeavyLaunchVehicle) is 386 parts, made of the orange rockomax tanks, and has 10 stages just for accent into LKO. I have NEVER had an issues with spent stages getting in the way, and MJ2 can get that badboy into LKO all on his own with a 150ton payload.....

Your issue is not with mechjeb, but rather how you choose to build launch vehicles.