Any way to plot out maneuvers from launch?

[Buster Charlie]

Okay, so what I would like to know if there is a mod or method of planning maneuver nodes from launch? Id like to be able to simulate direct  rendezvous or transfer a little more reliablely. Ithe wouldn't even need to be perfect, just ballpark so I could guesstimate a launch window myself without automation mods or trial and error.

[Guest]

There's MechJeb, which can show a little marker on the navball for optimal ascent trajectory that you can do yourself.

If you want to launch up and know where you are going e.g. maneuver nodes, there's no mod.

[Buster Charlie]

Yeah I use mechjeb, but I'd like to be able to show the projected gravity turn, and plot a maneuver node off of that without doing a parking orbit, so I guess I'm out of luck.

[Cloakedwand72]

20 minutes ago, spink00 said:

There's MechJeb, which can show a little marker on the navball for optimal ascent trajectory that you can do yourself.

If you want to launch up and know where you are going e.g. maneuver nodes, there's no mod.

I heard about that neat Mechjeb feature from your post.How do i use the projected gravity turn.

[Guest]

23 minutes ago, Cloakedwand72 said:

I heard about that neat Mechjeb feature from your post.How do i use the projected gravity turn.

Somewhere in the ascent trajectory editor, there is a button to show optimal ascent on the navball. You can then fly that manually.

[Cloakedwand72]

Just now, spink00 said:

Somewhere in the ascent trajectory editor, there is a button to show optimal ascent on the navball. You can then fly that manually.

Do not see it.All I see is on they ascent guidance mechjeb module it has the edit ascent path button.

[Guest]

1 hour ago, Cloakedwand72 said:

Do not see it.All I see is on they ascent guidance mechjeb module it has the edit ascent path button.

It has been a while since I've used MechJeb, but I remember that feature.

See the MechJeb thread and ask there.

[Superfluous J]

The problem is, when you're sitting on the launch pad 99% of your orbit is underground. And a burn to orbit isn't a "maneuver" in the game sense. A maneuver as described by the node is a 0-second burn at infinite TWR. Burning to space is a multi-minute burn most times.

This would require more than a simple addition of an ability to put a maneuver node on your "landed" orbit, which is why there's no mod for it. The best we have for this so far is what MechJeb does, and what GravityTurn does, which is essentially to do it for you

[tranenturm]

For transfer windows, I park something in orbit of the sun just outside of Kerbins SOI. Then I can plot it's maneuver node (regardless of available dv) to see upcoming windows. It's not exactly what you want, but does accomplish your goal of predicting windows in stock. Otherwise use Kerbal Alarm Clock. 

[KerbonautInTraining]

The only way to do this currently is to launch a dummy vessel with hyperedit. You can adjust the orbit and play with maneuver nodes until you find the most efficient parking orbit/transfer combo.

Once you do that, launch your mission into the same orbit as the dummy vessel and plot your transfer burn. 

It's not perfect but it works for mission planning.

[Warzouz]

On 9/3/2016 at 3:07 PM, tranenturm said:

For transfer windows, I park something in orbit of the sun just outside of Kerbins SOI. Then I can plot it's maneuver node (regardless of available dv) to see upcoming windows. It's not exactly what you want, but does accomplish your goal of predicting windows in stock. Otherwise use Kerbal Alarm Clock. 

I also use this technique to plot interplanetary burns (using a space station, a satellite or even a debis). But that's very little help for orbital rendez-vous.

[Nich]

launch you ship. Note the time you hit ap and its angle from ksa.  This should be the height of your rondavouz orbit.

Then figure out how long the period is of the target.

360/period*launch time - the angle from ksa will give you exactly when you should have launch. The problem is flight paths are so variable for every launch. I generally just pack 4500 dv and do an inefficient launch rondavouz.

when the target is just about to cross the ocean launch with an ok gravity turn (doesn't have to be super efficient). Get your ap to the height of the target orbit. Switch to target mode and push retrograde into the target. Then just maintain track to the target adjusting and slowing as necessary. If you want I can put together an advanced docking tutorial

[mrclucks]

I've seen videos of people almost rendezvousing from launch and have tried it a couple times myself.  Wait untill the target is roughly 5degrees from you and do a standard launch, and then once you're out of the thick atmosphere you adjust by burning more towards the horizon if its closer or away from the horizon if it's further.  

Try to practice that a few times with a few variations to develop more of a knack of how to do that. 

[GeneralVeers]

If you can't find a mod that will let you do the plan-from-launch deal, here's a cheap trick:

Launch a satellite to low Kerbin orbit and leave it there. See, pretty much everything you ever launch out of KSC is going to end up in low Kerbin orbit at some point--so, if you have a satellite on permanent station, you can simply plot the maneuvers using the satellite. You won't be able to move those maneuvers to new craft, of course, but you'll know what direction you want to fire in, when, and with what delta-V.

[severedsolo]

If you are using Mechjeb add "Phase Angle to Target" to one of your informational windows (it's under "target" I think, but not sure).

Select your target on the pad, and wait for it to pass directly overhead (0 degree phase angle). Launch as you normally would into the target orbit. When you are done, write down the number that Mechjeb is telling you for "Phase Angle to Target". If it's less than 180 then that's the amount you need to take off your phase angle at launch, if it's greater, then add it on.

Example: Mechjeb tells me my phase angle (after launch) is 15.6 degrees. - 360-15.6 = 344.4. So I launch when my target is at a phase angle of 344.4 degrees.

[surge]

Thats a horribly wasteful solution, severedsolo, at least for non-career modes. But I'm glad you mentioned that, it is an accurate way to get basically what mechjeb should be figuring out itself, given that it has an intended launch profile *before launch*. I guess the developers are a bit lazy? Dunno.

For more realistic scenarios, I tend to just set the altitude a few km lower than the target, set 'Launch to rendezvous' to 0 and press the button. The ship ends up slightly behind it, but it doesn't take long to catch up for a hohmann transfer. If the rocket is overpowered, sometimes I can cancel mechjeb after it does the initial burn and modify the orbital insertion maneuvre for direct rendevous myself. That gets old, quickly when I've launched the 20th rocket in a row trying to fine tune it, though.

[severedsolo]

11 hours ago, surge said:

Thats a horribly wasteful solution, severedsolo, at least for non-career modes.

I didn't say it was pretty but it does work.

I play with KCT, so essentialy I run these figures as a simulation before I do the real launch.

Also Mechjeb does figure it out for itself. If you fly a launch to rendevouz once, it remembers the number, and then it's automatically input when you revert. It just needs to know how your craft flies first.

Edited April 3, 2016 by severedsolo

[Buster Charlie]

Not really answering my own question, but I found the most reliable way to launch to rondevouez with mech Jeb, because it sometimes needs a few dummy launches to figure out a ships profile, is this:

Launch to rondevouez with a slightly higher orbit (say my station is 150k, I launch to 160k) then once launch guidance gets to apogee I cancel autopilot. If all goes well either the ascending intersection or the descending intersection should be close enough to engage rendezvous autopilot.

This way it directly engages fine tune closest approach and match velocities at closest approach without needing to orbit do a true Hoffman transfer.

Seems to be pretty fast and reliable.

[HebaruSan]

I like KER for this. I almost always launch things to a Pe of 72 km and Ap of 75-100 km, so adjust values to suit.

1. Set target from launch pad
2. Turn on KER rendezvous window
3. Launch when the target's phase angle is 330°, sometimes a few degrees less for bigger slower launches
4. Try to minimize relative inclination on the way up
5. Switch to map mode once Ap gets to 50 km or so
6. Should have a closest approach marker; try to bring the distance down as low as possible
7. Perform a standard rendezvous by combining target-retrograde thrusts with lateral ones that improve the alignment of the orbits

[Plusck]

7 hours ago, HebaruSan said:

I like KER for this. I almost always launch things to a Pe of 72 km and Ap of 75-100 km, so adjust values to suit.

1. Set target from launch pad
2. Turn on KER rendezvous window
3. Launch when the target's phase angle is 330°, sometimes a few degrees less for bigger slower launches
4. Try to minimize relative inclination on the way up
5. Switch to map mode once Ap gets to 50 km or so
6. Should have a closest approach marker; try to bring the distance down as low as possible
7. Perform a standard rendezvous by combining target-retrograde thrusts with lateral ones that improve the alignment of the orbits

Ok, so this is a feature of KER that I have never explored. Feeling daft and excessively eyebally.