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[1.2.2] Maneuver Node Splitter v1.7.0

nathan1

By nathan1
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nathan1

nathan1

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On 3/12/2016 at 8:52 AM, surge said:

Transfers are actually a really bad use for this, because of what you've discovered... it takes longer and longer to come around to the next orbit each time, and there's no easy way to tell the maneuvre system that you want to have a final ejection at *this* time, and on *this* orbit. It's not a fault of this mod, it's a fault of the basic system. It's much simpler to build an overpowered rocket and just do it all in one go. On the other hand, if you're doing a several million km transfer, the timing doesn't matter much, what matters most is the final velocity, so it's not entirely useless - as Lale said, you should just need a little correction burn after you've exited the original SOI.

 

Lastly, inclination changes are more efficient if you do them in one go... by ALOT, so don't use that as a yardstick. Sometimes you have to do them over multiple burns because of TWR/crashing into the planet, but just live with it, or build a bigger rocket. If you're not doing it already, do them as far away from the body as you can when your speed is the slowest (like just after you achieve initial orbit). You'll be surprised how little it costs. Then do the circularisation burn(s).

Transfers work fine with the mod: that's the use case I used when making it. You just have to make sure you set up your orbit far enough ahead of time. If you set up the maneuver far enough ahead of time (i.e. days ahead of time, not just 30 minutes) then it will automatically adjust the maneuvers so that your final ejection is around the same time as the original.

It also handles inclination changes. What is less efficient is when you do a prograde burn to change your orbit and then a separate normal burn for inclination, but there is no efficiency lost from splitting a combined prograde/normal burn into multiple burns.

I've used the maneuver splitter to convert a direct-transfer from Kerbin to Moho (which included a large inclination change). Performing the burn in multiple orbits after splitting the maneuver had almost the exact same periapsis around Moho as the original single-burn maneuver and did not cost more dV.

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maceemiller

maceemiller

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I just cannot get this to work at all. Got the latest version, created a node with 2400dv to go to Jool with, tried to split into two 700dv burns with 1400 for the final burn however it cost me 2400dv and I only ended up in an orbit as far as Duna? Is there something im missing?

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Val

Val

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6 hours ago, maceemiller said:

I just cannot get this to work at all. Got the latest version, created a node with 2400dv to go to Jool with, tried to split into two 700dv burns with 1400 for the final burn however it cost me 2400dv and I only ended up in an orbit as far as Duna? Is there something im missing?

The sum of the burns you type into the Node Splitter, have to be less than the escape velocity of the SOI you are in.

It takes only around 1000 930 m/s dV to exit Kerbin's SOI.

If I understand your question right, then your second burn would have taken you out of Kerbin SOI, which means the 3rd burn can't happen, in Kerbin orbit.

If you split it 450+500 450, it should work as you expected.

Edited by Val
Fixed bad info
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maceemiller

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Thanks @Val but Ive just tried again getting out of LKO to Jool using the splitter but it doesnt work for me :( added 450 then 500, hit apply and still end up near Duna, nowhere near Jool

 

EDIT : Please ignore me. I am a blithering idiot!! It is working however I was "in my head" expecting it to look different, hence my stupidity :P

EDIT EDIT : I am wrong again, it is not working. I can see the third burn but there is no way to get on the node. Ive been trying different tests for the last 2 hours and it will not work. Time to leave this alone I think which is a shame as it could be helpful to me, but alas, it just refuses to work.

Edited by maceemiller
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Val

Val

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4 hours ago, maceemiller said:

Thanks @Val but Ive just tried again getting out of LKO to Jool using the splitter but it doesnt work for me :( added 450 then 500, hit apply and still end up near Duna, nowhere near Jool.

Sorry, that's my bad. After a few tests, it turns out that around 930 m/s is the maximum from an 80 km orbit. Less from higher orbits.

450+450 should work.

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nathan1

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9 hours ago, maceemiller said:

I just cannot get this to work at all. Got the latest version, created a node with 2400dv to go to Jool with, tried to split into two 700dv burns with 1400 for the final burn however it cost me 2400dv and I only ended up in an orbit as far as Duna? Is there something im missing?

 

8 hours ago, Val said:

The sum of the burns you type into the Node Splitter, have to be less than the escape velocity of the SOI you are in.

It takes only around 1000 930 m/s dV to exit Kerbin's SOI.

If I understand your question right, then your second burn would have taken you out of Kerbin SOI, which means the 3rd burn can't happen, in Kerbin orbit.

If you split it 450+500 450, it should work as you expected.

The problem is as Val has described: if you perform two 700m/s prograde burns at Kerbin then you are no longer orbiting Kerbin and there's no way to wait another Kerbin-orbit and perform a third burn (you are escaping Kerbin and you're going to be orbiting the sun). There are multiple ways to deal with this:
-Use the "undo" button and keep trying different numbers until you get something that works for you.
-Specify the maneuver-splitting by apoapsis instead of by delta-v.
-Use the "repeat" option instead of specifying multiple numbers manually (the mod will figure out how many times you can split the maneuver with that amount of delta-v and add the remaining delta-v to the last maneuver).

Personally I prefer to keep my apoapsis below the Mun before the final ejection burn so that I don't get any encounters with the Mun throwing everything off. Also, if you raise your apoapsis a lot before your ejection burn then your orbital period can get really long, and your final ejection can be way later than your transfer window if you didn't plan and split the maneuver far enough ahead of time (with an apoapsis way above the Mun "far enough" could be a month ahead of time or more).

The 1.4.0 update now includes an error message when the input values cause an ejection from the body you're orbiting prior to finishing all the apoapsis-raising maneuvers. In this case it will add the remaining delta-v to the burn that causes ejection so that you will get an ejection that actually brings you out to your destination.

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maceemiller

maceemiller

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@nathan1 thanks. I wIl try this tonight. I hope I can get it working as such a useful tool. Its probably just me though! Will let you know how it goes in a few hours.

 

EDIT: Yes, it was me. Thankyou sooo much @nathan1 and @Val for perservering with me. Now, on to Jool with my seriously low TWR craft :)

Edited by maceemiller
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nathan1

nathan1

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The 1.1 version will use the stock toolbar. Make sure that you've installed it to the correct location and check the logs to see if there's anything wrong there.

I haven't downloaded the newest 1.1 pre-release build yet, so it's possible that something changed in KSP that broke the mod. I'll test it out again, but probably won't have time until Sunday.

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nathan1

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On 4/2/2016 at 11:28 PM, ddr3gamer said:

Does the 1.1 version require Toolbar or does it use the stock toolbar? I'm trying this for the first time and not seeing it in the stock toolbar, and the toolbar mod is not yet available.

I've re-tested with the latest 1.1 KSP pre-release and it's still working for me. One thing I didn't think to mention before: the button only shows up on the map view.

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nathan1

nathan1

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On 9/6/2016 at 7:42 AM, HoveringKiller said:

Is anyone else having issues with this in 1.1.3? Mine keeps freezing the game, not sure if I'm doing anything wrong or if it is just because the coding hasn't been updated yet.

I've been using it in 1.1.3 without any problems. What are you doing when the game freezes?

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nathan1

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18 hours ago, HoveringKiller said:

I think it was an issue where I was trying to split into multiple nodes but the first one that I created was not far enough in the future, causing it to want to plot nodes in the past.

If the original maneuver node isn't far enough in the future then it will just plot the new maneuver nodes in the future (making the final departure date later), so that shouldn't be an issue.

Regardless of whether it should be an issue, I tried to reproduce the freeze by splitting a maneuver node in the near future (and also by splitting a maneuver node that was already in the past), and it's not freezing for me. Is the freeze happening for you every time you try to split nodes or only sometimes? What are the specific values you're using for the split?

It's possibly input validation... if you entered something I didn't anticipate maybe it's causing the mod to go into an infinite loop. If that's the case then I can fix the input validation once I know what kinds of input are causing it.

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nathan1

nathan1

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Version 1.7.0 is now available:
-Compiled for KSP 1.2.2.
-Fix for splitting maneuvers that include a normal component.

The fix is for a bug I didn't notice before that looks like it showed up with KSP 1.2.0. Splitting maneuvers that only include a prograde component are not impacted, but in 1.2.x prior to this fix splitting a maneuver that includes any delta-v in the normal/anti-normal direction will not work correctly (the inaccuracy increased with the proportion of the burn that was included in the normal component in the original maneuver node). This build fixes that problem.

Edited by nathan1
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