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

[stickman939]

I haven't upgraded to 1.0 yet, so I was wondering if this was still compatible with .90.

[NathanKell]

Note that this guide was written for RSS (i.e. FAR) but will work on stock kerbin and newAero.

https://github.com/KSP-RO/RealismOverhaul/wiki/MechJeb-Ascents

General rules:

turn start = (alt where you hit 100m/s, or slower if high TWR)

turn end = something like 30-60km, again depending on TWR

final angle = 0

turn shape = whatever keeps you prograde-aligned throughout (or maybe you start pitching below prograde at >20km, that can be more optimal...try it out).

[Mokmo]

I haven't upgraded to 1.0 yet, so I was wondering if this was still compatible with .90.

you can fetch an old dev version, #429 is my last .90 i had

[CMH]

Tried to launch and activated auto-sequence, but it didn't work.

Define "didn't work". That really could mean almost anything.

It doesn't do anything at all. Before, it would start detaching my used boosters/etc, but now it does nothing, even when all fuel is gone from all rockets, not just on that particular stage.

Btw, I just realised I meant auto-staging, not sequence.

[smjjames]

It doesn't do anything at all. Before, it would start detaching my used boosters/etc, but now it does nothing, even when all fuel is gone from all rockets, not just on that particular stage.

Btw, I just realised I meant auto-staging, not sequence.

What mods are you using? I actually had similar behavior with SpaceYs "Moa" engine where the decoupler I put under it somehow disappeared off the staging bar, which confused MJ I guess. Removing and replacing that decoupler fixed it.

[Galane]

Rocket stability. http://exploration.grc.nasa.gov/education/rocket/rktcp.html

The basic thing is the center of pressure must stay behind the center of mass at least as long as the rocket is in an atmosphere. Same effect as a weathervane.

[smjjames]

Is the center of pressure the same thing as center of lift?

[stickman939]

you can fetch an old dev version, #429 is my last .90 i had

Yeah I managed to acquire a previous release with a bit of rummaging through the webs.

[Ozy]

Is the center of pressure the same thing as center of lift?

Yes

[CMH]

What mods are you using? I actually had similar behavior with SpaceYs "Moa" engine where the decoupler I put under it somehow disappeared off the staging bar, which confused MJ I guess. Removing and replacing that decoupler fixed it.

I'm not using any other mods.

[DerekL1963]

Gravity turn should be based on velocity not altitude.

Mechjeb's settings are based on altitude, so the current discussion is based on altitude.

You should be starting the gravity turn well below 10KM. I have mine set to start at 1KM with a TWR of no more than about 1.5 - 1.6.

This is the same setting I used in 0.90 with FAR and works well for the majority of the rockets I build. I've never needed to limit AoA in ascent guidance.

Nobody is talking about starting a gravity turn at 10km.

And knowing your setting for the start of the gravity turn is, by itself, useless - there are three other settings that determine the shape of Mechjeb's ascent trajectory. (In particular turn shaping goes a long way towards determining AoA at low altitudes.)

[Cebi]

Ah ok, so how does one do that? Just wait until the AN/DN is over the Space Center then launch? Is there some way Mechjeb can do this as it sounds complicated as.

Exactly. This is as simple as it gets. You will get your head around it in time. I am sure. You can try this also -->

If you set as target object on orbit around planet you are trying to ascend from you have the option to "launch into plane of target " in ascend autopilot tab. That will simply time your ascend to match aprox inclination of said target. However you cant target those orbit lines so i advise you to watch first how mechjeb handles launch and then you can try it yourself. And as always play tutorials and learn navball . Happy flying!

[DJToxica]

Good mornin out there

My first post but i not my first time in KSP at all.

I have the problem, that MechJeb doesn't load properly after launch.

The Parts appear in the game and the TechTree, but if i put the MechJeb Pod or the AR202 Case on my Rocket, nothing happens.

No Windows Appear neither in VAB nor on the launchpad.

After a quick Search in my logfile i found this:

Non platform assembly: D:\Steam\SteamApps\common\Kerbal Space Program\Plugins\MechJeb2.dll (this message is harmless)
AssemblyLoader: Exception loading 'MechJeb2': System.Reflection.ReflectionTypeLoadException: The classes in the module cannot be loaded.

  at (wrapper managed-to-native) System.Reflection.Assembly:GetTypes (bool)

  at System.Reflection.Assembly.GetTypes () [0x00000] in <filename unknown>:0 

  at AssemblyLoader.LoadAssemblies () [0x00000] in <filename unknown>:0 

Additional information about this exception:

 System.TypeLoadException: Could not load type 'MuMech.FuelNode' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

 System.TypeLoadException: Could not load type 'MuMech.MechJebModuleStagingController' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

 System.TypeLoadException: Could not load type 'MuMech.PositionTarget' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

 System.TypeLoadException: Could not load type 'MuMech.PositionTarget' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

 System.TypeLoadException: Could not load type '<SetConsumptionRates>c__AnonStorey1' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

 System.TypeLoadException: Could not load type '<CanDrawNeededResources>c__AnonStorey2' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

 System.TypeLoadException: Could not load type '<HasStayingChutes>c__AnonStorey9' from assembly 'MechJeb2, Version=2.0.9.0, Culture=neutral, PublicKeyToken=null'.

My List of Mods:

KSP: 1.0 (Win32) - Unity: 4.6.4f1 - OS: Windows 7 Service Pack 1 (6.1.7601) 64bit
USI Tools - 0.4
Community Resource Pack - 0.3.3
Contracts Window Plus - 1.0.5
DMagic Orbital Science - 1.0.2
RasterPropMonitor - 0.19.1
Kerbal Engineer Redux - 1.0.16.3
KSP-AVC Plugin - 1.1.5
RealChute - 1.3.2.1
SafeChute - 1.6
TextureReplacer - 2.4
TAC Life Support - 0.11.1.19
Freight Transport Tech - 0.4
Karbonite - 0.6
Karbonite Plus - 0.4
MKS - 0.22.8
USI Survivability Pack - 0.3
USI Alcubierre Drive - 0.2

So....any Ideas?

Thanks for any help

LG

DJ

[sarbian]

DJToxica

"D:\Steam\SteamApps\common\Kerbal Space Program\Plugins\MechJeb2.dll" " Version=2.0.9.0"

That is is a REALLY old mechjeb still installed in the old (0.19) plugin dir. Nothing should be in KSP/plugins and KSP/parts since a long time ago. You ll have to delete that.

agfutbol : that look correct but I would need to have to full log to be sure. Have a look at that post to find it

Umm... that is completely incorrect.

Yes, a proper ascent will eventually need a large AoA as it pitches over to begin building horizontal velocity. We used to be able to pitch over with impunity, but the new aerodynamic model sends the craft tumbling head over heels if you try it too low. (Below about 10-12k.)

No, that's perfectly correct. AoA is the angle between the air speed and the vessel front, not the angle between the ground and the vessel. For a proper ascent the AoA needs to stay low or your rocket will loop. The AoA limiter make that angle stay under the set value and the limit relax as you get under the specified Dynamic Pressure.

[CleverLikeMe]

So I've got the latest dev build (#438 as of this writing) and I'm getting some serious wonkiness in the dV calculations, specifically when using "asparagus" staging. For all my asparagus influenced stages, I'm getting dV calcs of zero, except for the bottom stage, which seems to be seeing only the dV of the bottom stage. Every time I stage, the dV will recalc. For example I just sent a probe up, and the bottom stage read consistently around 2k dV after each staging event, then after the final asparagus stage, it read 5k.

I'm getting the correct dV in total out of the ship, so it's not necessarily a build issue. I just have no idea what the total dV is (except my guestimate) because it seems to want to only count the bottom stage, whatever that happens to be, in the asparagus tree.

Suggestions?

[REGZZZ]

I'm having a similar problem with SRBs... the dV does not make sence? and as I stage, the dV increases... I'll try and thinker more with other designs...

[ManuxKerb]

Hi

Im intrested in the following functions. Do they work in 1.0 ksp -> 2.5 Mechjeb?

- Docking

- Rendezvous

- Landing

Thanks!

[smjjames]

Hi

Im intrested in the following functions. Do they work in 1.0 ksp -> 2.5 Mechjeb?

- Docking

- Rendezvous

- Landing

Thanks!

Landing in atmosphere is mostly working with tweaks needed, at least the land at target part is for atmosphere. Airless worlds are fine.

Haven't tried the rendezvous or docking myself, so I can't confirm, but I think they'll work.

Edited May 1, 2015 by smjjames
Less broken, more working

[sarbian]

Landing in atmosphere is broken, at least the land at target part is for atmosphere. Airless worlds are fine.

Thanks. I worked 2 weeks on that to get it called broken. Fix it yourself.

[Orange_Slime_]

I can never seem to build a rocket with a good enough TWR to either do a circulization on the maneuver, even with mechjeb piloting, or to be able to rendezvous...

I suck, maybe I just need a smaller rocker? I'm still used to the 0.9 pea soup

[smjjames]

Thanks. I worked 2 weeks on that to get it called broken. Fix it yourself.

Okay, how about mostly functional? I mean, how would you respond to MaunxKerbs question. I mean it works, but there are tweaks still needed to it.

Thanks for your hard work though and uh yeah, I keep putting foot in mouth here don't I without meaning to.

Look, I apologize for putting foot in mouth, but (possible more foot in mouth without meaning to) I'm trying to help you by reporting bugs and issues, really, I am trying to help, I think MJ is awesome and I'm just trying to help improve whatever issues it has.

So I've got the latest dev build (#438 as of this writing) and I'm getting some serious wonkiness in the dV calculations, specifically when using "asparagus" staging. For all my asparagus influenced stages, I'm getting dV calcs of zero, except for the bottom stage, which seems to be seeing only the dV of the bottom stage. Every time I stage, the dV will recalc. For example I just sent a probe up, and the bottom stage read consistently around 2k dV after each staging event, then after the final asparagus stage, it read 5k.

I'm getting the correct dV in total out of the ship, so it's not necessarily a build issue. I just have no idea what the total dV is (except my guestimate) because it seems to want to only count the bottom stage, whatever that happens to be, in the asparagus tree.

Suggestions?

I'm having a similar problem with SRBs... the dV does not make sence? and as I stage, the dV increases... I'll try and thinker more with other designs...

I've seen that too and posted about it.

Although, with asparagus staging (whether simple or complex), there actually is a bug with external fuel lines atm which could contribute to the problem.

Edited May 1, 2015 by smjjames

[WinkAllKerb'']

; ) how much time did it take for squad to add and adjust the new aero model ? how much time will it take to adjust mech jeb to thoose new changes ... it will take some time.

(c'est gratuit ou presque profite sarb, zen zen ; )

[CleverLikeMe]

Hi

Im intrested in the following functions. Do they work in 1.0 ksp -> 2.5 Mechjeb?

- Docking

- Rendezvous

- Landing

Thanks!

At least from my testing, those functions all work fine. Landing in atmo seems fine but I've only done it once, and didnt care where I landed as long as I landed...

Deadline - try building thin rockets and using normal old school staging (nothing fancy or asparagus-ey). A few fuel tanks below a pod, and a single engine preferably with thrust vectoring should work fine to get you into the upper atmo. From there, have your upper stage just be relatively small till you get used to flying in the new atmo. A single tank and a decent upper stage engine or whatever is unlocked. To handle the new atmo, whether you are using mechjeb ascent or not, you need to limit your angle of attack and start your gravity turns way earlier than pre 1.0. There are threads with specifics, but try a turn shape of 50 percent, and limit your angle of attack to 3 or 5 degrees. If you are flying manually, which you should to get a feel for it, start your turn as soon as you get up some speed, probably before 2km, and ease into it. just a few degrees. very slowly angle down as you get altitude.

Edited May 1, 2015 by CleverLikeMe

[smjjames]

While in the final stages of parachute descent (landing AP isn't on, but I do have show prediction with trajectory on) where my horizontal speed is in the millimeters/sec, I noticed that the trajectory shows a diagonal downwards straight forward some kilometers instead of a vertical descent. I did take screenshots to show what I mean, but can't post them right now because on iPhone.

Editwhileposting: I just realized that it may be useful to have the attitude control info open and maybe debug arrows on. I'm going to make another science collection mission (same craft) for the deserts, so I could have the info up for that one if requested sarbian.

edit: actually, now that the patch version is out and from the changelog, looks like they tweaked some aerodynamics numbers, so, I should check this out in the 1.0.1 compat version that sarbian releases.

Edited May 1, 2015 by smjjames

[Fyrem]

@Sarbian,

Thanks for all the hard work in MJ. It has always been my Go-to mod.