1.1 and interplanetary travel

[Haruspex]

Since upgrade to 1.1, weird things happen to all my attempts at interplanetary flight.

In 1.0.5 and before, I'd just look up the transfer window in alexmoon.github.io/ksp/ , attain a 100x100 km orbit, wait until the prograde marker at the navball hits the target marker and burn to target. That "easy mode" burn usually ended up in an encounter or a convenient closest approach that was easily corrected mid-flight.

Now, in 1.1, the same routine with the same ship inevitably ends up in a rather awkward 800 to 350 000 km closest approach with my ship's position on it falling behind the planet, be it Duna or Eve. It can be fixed with series of radial-in and prograde or retrograde burns, but those waste a LOT of fuel.

No more easy mode :(

So, what happened?

- Is KSP Launch Window Planner outdated?

- Was there a change to navball functionality, namely the behavior of the "target" marker?

- Was there a change to orbital mechanics, orbital speeds or positions or Eve and Duna?

- Can it be a result of old 1.0.5 save converted to 1.1? Could it somehow move planets a dozen degrees forward in their orbits than where they should be?

Halp.

Edited April 25, 2016 by Haruspex

[Red Iron Crown]

I have never used the Target marker that way, and I'm surprised it worked at all. I've used the same site and made a maneuver node at the correct angle to prograde, then executed that node.

Nothing has changed regarding the orbital or physical characteristics of the celestial bodies in 1.1, so I really don't think that's the cause here.

[Haruspex]

Just now, Red Iron Crown said:

I have never used the Target marker that way, and I'm surprised it worked at all.

Probably a coincidence and totally unintended use, but it did work (to some degree), hehe. I discovered this by accident when making my first blindfolded steps in KSP (had no idea how to use maneuver nodes) and travelled to Mun, Minmus, Eve, Duna, Jool and basically everything else except Moho and Eeloo by just doing this.

[EivlEvo]

4 hours ago, Haruspex said:

Probably a coincidence and totally unintended use, but it did work (to some degree), hehe. I discovered this by accident when making my first blindfolded steps in KSP (had no idea how to use maneuver nodes) and travelled to Mun, Minmus, Eve, Duna, Jool and basically everything else except Moho and Eeloo by just doing this.

But you're probably using WAY more deltaV using this method.

I honestly don't know that it's changed, but it's worth noting that if your game has progressed, and the planetary alignment is different... perhaps you just got lucky the first time round, and now you're just unlucky?

[zarakon]

I'm gonna say that you were just getting a bit lucky before.

[Wjolcz]

7 hours ago, Haruspex said:

Probably a coincidence and totally unintended use, but it did work (to some degree), hehe. I discovered this by accident when making my first blindfolded steps in KSP (had no idea how to use maneuver nodes) and travelled to Mun, Minmus, Eve, Duna, Jool and basically everything else except Moho and Eeloo by just doing this.

This actually works with the Mun. Back before we had the manouver nodes you literally would wait until the Mun has risen above the Kerbin's horizon and start the burn until you got an encounter.

[Haruspex]

Just now, zarakon said:

I'm gonna say that you were just getting a bit lucky before.

lol, that must have been quite a bit of luck (and a lot of wasted fuel) involved. Weird. Anyway, time to start doing it properly I guess.

[LameLefty]

So, why not just wait until you're about at the "correct" (*) window and then set up a maneuver node? Back in 0.19 - .25 days, before I gave in and started letting MJ plan all my transfers, I planned EVERY interplanetary transfer and correction manually by setting nodes and tweaking them, and then throttle-jockeying the burns as precisely as possible. I made transfers to every planetary body in the system this way, and several moons. 

 

(*) "Correct" isn't really the right term - you can go anywhere in the system you want at just about any time if you're willing to waste enough dV to do it.

[CloudlessEchoes]

I too think something is different with this release.  I tried for a while to find the "perfect" transfer window to Duna using the minimum dV, and no matter what I did I was always in front of or behind it.  I ended up having to waste some fuel to intercept it properly.  Some transfer tools seem very broken too (kac was way off for instance).

One thing I noticed when doing interplanetary transfer nodes was that if I put the periapsis at Kerbin, the path seemed crooked.  In the past the most efficient burn puts the planet you are leaving at periapsis and the arrival point at apoapsis (which makes sense).  It seems "off" to me somehow.

[Haruspex]

Sorry for the necro, but it's better late than never: the mystery is solved.

The problem is, that the vanilla system map currently shows ONLY ONE of the possible closest approaches. In my case, it's usually the first and the least convenient one, on the ascending part of the trajectory, while the second, much better potential intercept after the apoapsis remains hidden unless there's some voodoo magic, camera tweaking and sacrificed chicken involved (so the first closest approach is no longer recognized by the map as Teh Closest Approach).

According to the 1.2 Dev notes, there's an incoming solution to this problem.

 

 

Edited September 13, 2016 by Haruspex

[Sneaky Bstard Sword]

On 4/25/2016 at 5:54 PM, Veeltch said:

This actually works with the Mun. Back before we had the manouver nodes you literally would wait until the Mun has risen above the Kerbin's horizon and start the burn until you got an encounter.

hell I still do this for mun encounters when i'm too lazy to make a proper maneuver node

[Sharpy]

On 25.04.2016 at 11:54 PM, Veeltch said:

This actually works with the Mun.

Zero eccentricity, zero inclination, big SoI.