[1.12.x] Anatid Robotics / MuMech - MechJeb - Autopilot - [2.14.3] [4th March 2023]

[Oaterson]

Question about function of ascent guidance.

 

is there a way for me to have it stage while there still is fuel in the bottom stage? I wanna make a reusable rocket and do propulsive landings.

[Max Headroom]

Firstly, many thanks for working on such a useful piece of kit!

Using Smart RCS, it appears clicking off the "Use RCS for rotation" button means that MJ will still turn on the yaw/pitch/roll actuation on my RCS modules, but when I hit wasdqe it temporarily turns them off.  So *my* rotation actions don't use RCS, but MJ still feels free to use RCS for rotation.  This is my experience with both dev and master.

Q: Am I understanding things correctly, the behavior I'm seeing is expected/intended?  Or is it a bug (presumably an interaction with another mod) which I should try to isolate?  I ask only because everything I find via Google suggests "turn yaw/pitch/roll actuation toggles off" should make MJ use the reaction wheels, but clearly that's not what's happening. 

Q: Assuming this is normal behavior, is there somewhere a setting for "actually leave the RCS rotation actuation toggles off, and only use the reaction wheels"?

Thanks!

Edit: This is for a 4.7-ton lander using the Munar Excursion Module, so the RCS is pretty powerful, and a bit off-center.  When I turn the RCS thrust limiter down to 15%, the problem (mostly) goes away.  Could the Attitude Adjustment module be seeing things get wildly out of envelope, and start using RCS in desperation?

Edit2: This github issue #979 being marked as a bug suggests this is not intended behavior after all?

Perhaps relatedly, I was also separately having exactly this guy's problem with the rockets stuttering and MJ firing RCS to turn off-target.  This problem also went away when I turned the RCS thrust limiter down to 15%.

The moral seems to be that very powerful unbalanced RCS thrusters, such as found on the Munar Exclusion Module, can cause problems for MechJeb.  Luckily the fix is easy - turn down the power, or balance the RCS thrusters.

If any of this is still of interest, I'm happy to supply logs, .craft file, whatever helps.  Cheers!

Edited May 28 by Max Headroom

[OrbitalManeuvers]

16 hours ago, Oaterson said:

is there a way for me to have it stage while there still is fuel in the bottom stage? I wanna make a reusable rocket and do propulsive landings.

I use SmartParts for this. Then you can stage or action group on a % of fuel left in the tank, for example. I also use SASAG which lets you control SAS settings from action groups. 

[dlrk]

Is there any way to control throttle with the Scripting Module?

Also, I tried launching to rendezvous, but it launched "backwards" in the opposite direction of target orbit. Any idea where I went wrong?

 

Edited June 2 by dlrk

[Errol]

On 6/1/2024 at 11:24 AM, dlrk said:

Is there any way to control throttle with the Scripting Module?

Also, I tried launching to rendezvous, but it launched "backwards" in the opposite direction of target orbit. Any idea where I went wrong?

 

A suggestion I have for you is to try this mod which gives you throttle setting action groups, then using the MJ scripting module's action group triggers;
 

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@sarbian A question I have about the MJ is scripting module is how the target body function is supposed to work? I can't seem to get it to do anything. I am playing with OPM, and see all the extra bodies in the list. I'm also using an MM script to further alter orbital parameters of all the bodies. Perhaps I need to test the target body scripting function in a more stripped down, clean install with just MJ and go from there.

Edited June 2 by Errol

[RunaDacino]

I've tried searching, but I found no explicit answer.

 

In the ascent profile editor, what does "Automatic altitude turn" do exactly? I finally opted to de-select it and I see it allows me to edit my final turn altitude (something I wished for a long time).

Is that all there is to it? It automatically sets altitude for horizontalizing?

[hellothere___]

whenever i use it to get to the mun, i see a periapsis until i get into the mun's sphere of influence. then it just sends me onto a trajectory that makes me crash. what do i do?
 

[GuessingEveryDay]

2 hours ago, hellothere___ said:

whenever i use it to get to the mun, i see a periapsis until i get into the mun's sphere of influence. then it just sends me onto a trajectory that makes me crash. what do i do?
 

That may have something to do with how your orbits are drawn. In the settings, under Graphics, there's an option to change "Conic Patch Draw mode". The default is Relative, which can be a little weird, I prefer to use Local to Body, as it will draw exactly what my orbits will be around a specific moon or planet, i.e. Mun or Minmus, while transferring.

[hellothere___]

 

On 6/15/2024 at 12:43 PM, GuessingEveryDay said:

That may have something to do with how your orbits are drawn. In the settings, under Graphics, there's an option to change "Conic Patch Draw mode". The default is Relative, which can be a little weird, I prefer to use Local to Body, as it will draw exactly what my orbits will be around a specific moon or planet, i.e. Mun or Minmus, while transferring.

i might have fixed it. apparently setting the orbit to 20 km around the mun was making it go 20 km away from the core and thats underground.

[Ker Ball One]

Are there any tutorial videos on MJ Landing Guidance specifically for RO/RSS RP-1 Moon landing with MechJeb?

I'm having some issues for which I want to find the cause.

1. Auto-Warp on descent has to stop and start every couple of seconds since it seems MJ isn't accounting for persistent rotation during warp. As the craft drifts X degrees from retrograde, warp stops, RCS attempts to correct, as soon as it's back on retrograde it warps again but the angular momentum just causes it to go off again... And the cycle repeats.  Is MJ expecting no rotation during auto-warp?  Making this function incompatible with  RealismOverhaul?

2.  Anyone know the optimal TWR for MJ Landing Guidance for the RSS Moon? 

3.  For ROEngines that are unthrottleable, the rapid succession of feathering the throttle insures an ignition failure will definitely happen.  For other ROEngines that have throttle but maybe take a second to spool up, MJ will misjudge the suicide burn countdown. 

 

Edited Thursday at 05:38 PM by Ker Ball One