Up to date mechjeb information

[jbdenney]

I am trying to get some information on a couple of MechJeb functions but all the information and tutorials are from 2014 through 2016. I did find something more current but it is only in French.

I am running MechJeb 2.12.0 wiht KSP 1.11.2.3077.

There are two things I am trying to figure out.

Landing on a planet with an atmosphere - I want to land on EVE. I am running with EVE and Scatter so I can not see the surface. I have a lander that uses two sets of Inflatable heat shields, one Retrograde and one Prograde. I need both for stability and I drop them afte the parachutes open and the lander slows down. I also have fuel and engines to get back of EVE. I ony have very small engines and a little fuel to drop into the atmosphere. After that, on its way down,  it is a dead brick. I want to be able to pink a landing point in MechJeb and get reasonable close on landing.  Can MechJeb do this and if so how do I set it up. I have no issues with  a vacuum but I onoy have to deal with retros and no atmosnphere that needs chutes.

The other is can I use MechJeb to launch a space plane and get into orbit with mechJeb. ( I have no issues with vertical launch - that works great.)I understand the Autopilot where I set speed, feeding, ect,  But I cannot fly with any kind of real control so It would be helpful to use some kind of Assent Guidance to get me into the air and then into orbit. I can also use autoland to come in from a low altitude and land without an issue but can I do this from orbit,

Please don't tell me to look at the MechJeb online manual. It is way out of date and really does not help. I have looked in every forum I can find but they are so out out of date that they just say "it is buggy and does not work", but i know a lot of the bugs have been fixed and functionality has been expanded.

 

Thanks in advance.

 

Edited April 26, 2021 by jbdenney

[Guest]

The auto land in mechjeb is hit n miss. It is difficult to get consistent results with it. Try Trajectories instead.

Ascent for spaceplanes: just use the aircraft autopilot with the pitch set to 20deg.

[jbdenney]

Thanks

[jbdenney]

Ok - I cannot find where you set Pitch on MechJeb Aircraft Auto Pilot.

The entries I see are...

Altitude Hold

Vertical Speed Hold

Heading Hold

Roll Mode

There are alos PIDs but I have no clue about those.

 

[Guest]

8 minutes ago, jbdenney said:

Ok - I cannot find where you set Pitch on MechJeb Aircraft Auto Pilot.

The entries I see are...

Altitude Hold

Vertical Speed Hold

Heading Hold

Roll Mode

There are alos PIDs but I have no clue about those.

 

Ah ok sorry I forgot it's not direct setting on MJ. You can do it using the vertical speed hold and altitude I think. Set the altitude really high then adjust the vertical speed until the prograde marker on the navball is around 20 deg (or whichever angle you prefer). Obviously to maintain a certain vertical speed, the plane has to pitch at a certain angle which is how it works.

There is another plane mod actually I might be mixing it up with(!) where you can set it direct, I can't remember what it's called though. Maybe something like Airplane Autopilot. You can use it to land automatically on the runway as well for example. If I find it, I'll post link.

[jbdenney]

thanks - I just happen to be a really, realy poor pilot.

[Caerfinon]

6 minutes ago, FruitGoose said:

There is another plane mod actually I might be mixing it up with(!) where you can set it direct, I can't remember what it's called though. Maybe something like Airplane Autopilot. You can use it to land automatically on the runway as well for example. If I find it, I'll post link.

Kramax Autopilot Continued is what you were thinking of I think. Excellent mod for flying.

 

[jbdenney]

I will give it a try -thanks

[Guest]

Yes that's it, knew it was something to do with LGG!

6 minutes ago, jbdenney said:

thanks - I just happen to be a really, realy poor pilot.

Nah don't beat yourself up, the stock controls and camera hardly help when learning, it'll come with time/practice.

[jbdenney]

Well, I just discovered, the hard way, that Kramax is incompatible with my version (the latest build) of KSP. It junked my interface and I had to reload.

[camacju]

On 4/26/2021 at 11:26 PM, FruitGoose said:

Ascent for spaceplanes: just use the aircraft autopilot with the pitch set to 20deg.

This might work for some spaceplanes, but if it works, you have too much thrust, or you're losing too much fuel to cosine losses. If you are able to do a consistent 20 degree climb then you can probably cut the thrust in half and still fly it to orbit, or add a lot more fuel. Either way, you're not flying efficiently.

I prefer using Mechjeb's Smart A.S.S. for flying spaceplanes. My typical ascent profile goes like this:

When I leave the runway, I descend down to sea level to pick up speed. Then I pitch up to 7-10 degrees above horizontal to maintain level flight, and gradually relax that down to zero degrees as I pick up airspeed, while staying as close to sea level as possible. (Select the SURF mode on Smart A.S.S and set roll to be 0, heading to be 0, pitch to be 7-10, then click Execute)

When I reach 600-700 m/s I pitch up 7-10 degrees again and continue accelerating until my apoapsis reaches about 19 km, in order to take advantage of the thrust peak of the jet engines. Then I gradually pitch back down to horizontal such that I'm pointing horizontal at about 21 km altitude.

I adjust pitch up and down here to stay at 21 km while getting as much delta-v out of the jet engines as possible. I can usually reach 1650-1680 m/s here, at which point I turn on prograde hold, light the rocket engines, and let the jets run until they flame out. Then, it's a mostly hands free ascent to orbit.

There are more efficient ways to fly a spaceplane to orbit but this method is easy enough that I'm comfortable with it.

[Guest]

1 hour ago, camacju said:

This might work for some spaceplanes, but if it works, you have too much thrust, or you're losing too much fuel to cosine losses. If you are able to do a consistent 20 degree climb then you can probably cut the thrust in half and still fly it to orbit, or add a lot more fuel. Either way, you're not flying efficiently.

Fair comment and yes you are technically  right but it’s a compromise for me between efficiency and fun. I find i lack the patience to sit there climbing a few ft per minute and thus it becomes boring and unenjoyable very quickly (same with rockets doing perfect gravity turn).

The last time I flew spaceplanes properly was using OPT and some of the more ‘cheaty’ engines included which of course allows for a lot of liberty regarding fuel efficiency and time as well (the 20 deg was from that thinking about it now).

But yes with standard engines etc it fails miserably on the whole.

[Guest]

On 4/29/2021 at 12:50 AM, jbdenney said:

Well, I just discovered, the hard way, that Kramax is incompatible with my version (the latest build) of KSP. It junked my interface and I had to reload.

Just tested and it's working on mine (also 1.11.2) . Have you downloaded and installed the 2 dependencies as well (ClickThroughBlocker & ToolbarController)? Also, inside the mod folder (ie the one you put in GameData) there is a ".version" file and a "MiniAVC" file. Delete both of those or it'll tell you it's not compatible with this version etc on the load screen.

[jbdenney]

I will give that a try - thanks