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


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Holy crap long time no see sojourner, does your first stage use clamps?

Yeah, I saw something earlier in the thread about launch clamps, so I have tried them as a separate staging event and as part of the first stage engines staging. It didn't make any difference.

ETA: Ah, now I see the issue. If the launch clamps are part of the first staging event it messes up the staging somehow. If you place them in the second staging event it seems to go away. Hmmm, odd. It's only an issue with radial decouplers.

Edited by sojourner
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Yeah, I saw something earlier in the thread about launch clamps, so I have tried them as a separate staging event and as part of the first stage engines staging. It didn't make any difference.

ETA: Ah, now I see the issue. If the launch clamps are part of the first staging event it messes up the staging somehow. If you place them in the second staging event it seems to go away. Hmmm, odd. It's only an issue with radial decouplers.

Yeah, Sarbian is working on a lot of fixes, the poor guy is busting his ass fixing this mod :)

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Yeah, Sarbian is working on a lot of fixes, the poor guy is busting his ass fixing this mod :)

Found a work-around. place the clamps in stage event two or higher, then go into action groups and add the "release clamps" function of the launch clamps into staging. The launch clamps will fire when you activate the rocket with the space bar and after that the radial decouplers will do thier job as normal when the time comes.

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Yeah, I saw something earlier in the thread about launch clamps, so I have tried them as a separate staging event and as part of the first stage engines staging. It didn't make any difference.

ETA: Ah, now I see the issue. If the launch clamps are part of the first staging event it messes up the staging somehow. If you place them in the second staging event it seems to go away. Hmmm, odd. It's only an issue with radial decouplers.

By first staging event, you mean the bottom stage right? I'm seeing this as well, except it's with launch into plane of target, not launch to rendevous. I'm also noticing that it doesn't happen when autostaging is off, so theres one workaround, turn autostaging off initially and then turn it back on after launch.

Edited by smjjames
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Hey guys... question re: the ascent autopilot on the current dev build (445)....

I'm confused as to whether the ascent profiles are working correctly or not. To make a long story short, in a career game I have an early-ish stock rocket with the basic "Swivel" engine. Ascent profile is more or less default -- 15km start, 75km end, shape is 50%ish, 100 m/s speed. Rocket is small, so fairly high TWR and fairly high COG (not high enough to cause significant instability, though).

The issue: It appears that the gravity turn starts at the lesser of the input speed or the input altitude. With this smallish rocket, speed is the first mark hit by a longshot. (The craft is at 100 m/s by about 5000m, give or take.) The gravity turn starts. The result I expected is that the gravity turn progresses based on the shape from that point until the target end altitude. What actually happens is that the turn progresses, it appears, based on something else. I can't tell if its speed, or % of desired final orbital altitude (as determined by current apoapsis), or what. I wind up with a craft that's finishing its gravity turn at about 35,000 m, and is at the desired final orbital angle -- i.e. pretty close to horizontal -- and is accelerating to hit the desired apoapsis. 35km is a low atmospheric density region... but it ain't zero. I'm getting frictional heat generation, inefficiency in the overall ascent profile, etc.

If I set the gravity turn starting speed to be something higher than what I expect to be flying at 15km altitude.... perfect gravity turns.

So tl;dr I'm not sure if this is a bug or a feature, and thought I'd report it even though I've applied my own fix.

Niether a bug or a feature. You will have to tune your ascent profile to the ship as there is no easy way to auto-tune it. If you need to start the turn at higher speed then that's what you need to do.

I do think your ship may be a little under powered. If you are only hitting 100m/s at 5km altitude, especially in the new aero, you might want to increase your first stage's twr. I haven't fiddled much with 1.0.x yet but on the old FAR 1.5 launch TWR was just about optimal. With the new ISP effects a little lower might be better now but I doubt it.

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does this mod work with the 1.0.2 KSP??? becuase mine keeps saying its outdated

Use the latest dev build. Landing AP is a bit wonky and you might have to fiddle with the ascent AP settings a bit but it's mostly working OK.

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How do you use the devbuild? Or more how do you do to use it?

Opening post, just below the link for the release build there's a link for dev builds. Go there and locate the most recent release, download it and copy it into your game data folder. Replace files as necessary.

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Use the development build for now. It won't give you the warning.

ok i installed the dev build but i cant use it is there something i have to press to make it come up on the screen?

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Is the "prevent overheats" option compatible with the new NERVA engines? I've heard stories of people's engines exploding at half throttle.

I haven't used it myself, so I can't confirm, however, it should work. Let us know if it doesn't. I see no reason why it wouldn't work anyway.

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Worked fantastic, though I don't get the menu up

If you're referring to the MJ menu with the buttons, etc. it will depend on what mode you're playing KSP in. First, the MJ part must be placed onto the vessel. In sandbox mode all MJ functionality is unlocked from the start. If playing in career or science mode you have to unlock the various MJ functions through the tech tree.

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If you're referring to the MJ menu with the buttons, etc. it will depend on what mode you're playing KSP in. First, the MJ part must be placed onto the vessel. In sandbox mode all MJ functionality is unlocked from the start. If playing in career or science mode you have to unlock the various MJ functions through the tech tree.

Except based on mine and some others' experience, career mechjeb unlocks everything from the start anyway.

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Is the "prevent overheats" option compatible with the new NERVA engines? I've heard stories of people's engines exploding at half throttle.

That was an old problem with KSP, fixed in recent versions.

From the 1.0.1 Changelog.

Lowered heat production on LV-N.

Always check the changelogs first.

Also it's not a new engine.

Edited by futrtrubl
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Parachute landing sim is back in. Still landing short but I we are more or less back to the pre 1.0 level of feature, so I ll have break now if you don't mind (end even if you do ;) )

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Parachute landing sim is back in. Still landing short but I we are more or less back to the pre 1.0 level of feature, so I ll have break now if you don't mind (end even if you do ;) )

You deserve a break today.

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Thanks for all your excellent work on MJ Sarbian many of us appreciate the effort you put in but often fail at saying it

Buy the guy a beer via PayPal, 5-10 bucks no biggie, he's earned it, just saying we all should :) not pressuring

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I'm getting some errors in the delta-v calculations. I installed kerbal engineer and it's giving me the correct delta-v. Mechjeb's expended delta-v is also correct, so if you build a ship, burn all the fuel, and then compare predicted vs spent dv, you get different numbers. However, KER's predicted dv will match mechjeb's spent dv.

I think I have a theory of what's causing it. Mechjeb is ignoring the mass of parts marked as "physics insignificant," but I think the new implementation of that in 1.0 only zeroes out their drag and not mass.

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Given that MJ uses the KER vessel simulation code to calculate deltaV and actually has a newer version of the code than the current version of KER, if this is really happening then I must have lost one of the recent fixes that Cybutek made to the KER code. I'll run some tests and see if the new code is ignoring the parts...

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Buy the guy a beer via PayPal, 5-10 bucks no biggie, he's earned it, just saying we all should :) not pressuring

No, he's French, send him a Merlot or Chardonnay or something :D

There is a chance that he actually does like and drink beer though. If he does drink liquor.

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