Launch Window Planner not working for KSP2?

[KincaidFrankMF]

The longer my KSP2 campaign goes on, the less calculations from e.g. Alex Moon's excellent Launch Window Planner https://alexmoon.github.io/ksp/ seem to match reality. Have the orbits changed slightly from KSP 1, or am I missing something?

I'm currently in year 22, trying to send a mission to Duna. LWP tells me to go on Day 387, and that it'll take 1084 dv. Duna doesn't have a crazy inclination or anything, so it should be a fairly straightforward prograde burn. In reality, it's nowhere near and I'm having to mess about adding hundreds of extra dv of radial in/out before I get an encounter. A quick look at the Tracking Station confirms the phase angle is all wrong, and I actually need to wait till around Day 410+ to get an efficient transfer.

I've checked, and transfers in year 1 and year 3 both match up closely to LWP's predictions. Anyone else having the same issue? Any recommendations for a workaround?

[ncw33]

When you say "hundreds of m/s radial" presumably you mean moving the start time off the manoeuvre node? The departure burn is always 100% prograde in your kerbin orbit ... (or prograde plus a little normal).

 

I've resorted to eyeballing all the transfers, which is pretty accurate and doesn't lose much efficiency (the old alexmoon plots confirm that there is a bit of a window for departure, without much penalty).

[KincaidFrankMF]

20 hours ago, ncw33 said:

When you say "hundreds of m/s radial" presumably you mean moving the start time off the manoeuvre node? The departure burn is always 100% prograde in your kerbin orbit ... (or prograde plus a little normal).

That makes sense, I tried moving the manoeuvre start time without any luck (it just made things worse), then resorted to adding radial and reducing prograde until I eventually forced an encounter that way. I can see why that wouldn't be the most efficient approach, but it just shouldn't be necessary if the launch window is accurate.

20 hours ago, ncw33 said:

I've resorted to eyeballing all the transfers, which is pretty accurate and doesn't lose much efficiency (the old alexmoon plots confirm that there is a bit of a window for departure, without much penalty).

Yeah, looks like that will have to be the way forward. Tricky for places like Moho and Dres, though.

[byaafacehead]

I have had this too. I time warp to the suggested time and sometimes the planets are so far off (like 270° instead of 90°). I think the KSP year 1 = KSP year 0 got changed so they match, but I still check that too. I think my campaign is 100 or so years in

[Plummet]

I read elsewhere that it's an off-by-one issue: KSP1 start from year 1 but KSP2 starts from year 0.

https://alexmoon.github.io/ksp/ uses KSP1 years.

So: 

- Add a year to your KSP2 date when entering it as the earliest departure date
- Subtract a year from the calculated departure date when setting your KSP2 alarm

It's been working fine for me like that.

[KincaidFrankMF]

15 hours ago, Plummet said:

I read elsewhere that it's an off-by-one issue: KSP1 start from year 1 but KSP2 starts from year 0.

Yeah, I'm aware of that one - I think it got corrected, as byaafacehead said, but I did check. It's off by a few weeks, not a year. And gets worse over time...

[Plummet]

On 1/30/2024 at 9:41 AM, KincaidFrankMF said:

Yeah, I'm aware of that one - I think it got corrected, as byaafacehead said, but I did check. It's off by a few weeks, not a year. And gets worse over time...

Interesting, I haven't noticed that. Then again, I have started mostly using the planner in the alarm clock mod. It is more basic in that it just sets an alarm rather than giving details of the burn, but it's good enough.

[Biggen]

Here is what I use.  I just look at the transfer window angles on the left side of the image.  That seems to work.

 

Direct link: https://postimg.cc/njmWrJdz

Edited February 2 by Biggen