Bug #338
Escape trajectories are not shaped correctly. AKA the changing periapsis bug
100%
Description
Duna
Duna, after getting closer
Kerbin
Solar system escape at different zoom levels
(click for full size)
The strange recurve shape seems to be present for all escape trajectories. It's just more obvious when you get close to the planet. It's also very apparent on a solar system escape.
People usually complain about this at Jool, where aerobraking is the most popular and where this bug has the greatest effect. I've seen it now at Kerbin, Duna, Jool, and Bop.
People generally just wave it off as "rounding error", but the strange shape of the path and the huge changes in periapsis seem to suggest a bigger flaw. I also feel like this didn't happen in all versions of the game.
I'm attaching three save files - one for Duna, one for Kerbin, and one for a solar system escape - where the bug is reproduced. In the system escape save, turn on infinite fuel and burn a little bit retrograde to see it get really weird.
History
#1
Updated by Anonymous about 11 years ago
- Status changed from New to Confirmed
- % Done changed from 0 to 10
I have seen this many, many times. Definitely something that needs to be worked out.
#2
Updated by Ted about 11 years ago
Updated by Good bug report. Just so I'm clear on this, is it that the Pe is changing after you're coming out of warp?
#3
Updated by zarakon about 11 years ago
Updated by Yes, it seems to only change when exiting rails warp near the planet. If I stay in warp during the approach, it only changes once it's forced to exit warp. If I use physics warp, it doesn't jump around. The path still looks wrong in all cases
If I'm near the planet and go in and out of 5x warp, it will jump by a significant amount each time. On the Duna save, 100km seems to be a very distinct threshold for it. It's not about warping across that boundary, but anywhere under 100km, warping for even an instant will cause a jump.
#4
Updated by zarakon about 11 years ago
One more detail..
In the Duna example, under 100km, if I watch the navball I can actually see my prograde and retrograde markers move each time I enter timewarp
#5
Updated by Yargnit about 11 years ago
Updated by - Status changed from Confirmed to Duplicate
- % Done changed from 10 to 100
A couple of us took a look at this. It appears the wavy orbital path and the shifting PE aren't related. The wavy path you're seeing is just a result of the way the orbit happens to work out.
The shifting PE upon exiting time-wrap as far as we can tell is just a result of the way rounding errors occur, similar to how transitioning SOI's at high time-warp causes your PE to shift. If you'd like to make a bug for this portion specifically feel free, but it is known.
#6
Updated by Ted about 11 years ago
- Status changed from Duplicate to New
- % Done changed from 100 to 0
#7
Updated by Ted about 11 years ago
- Status changed from New to Closed
- % Done changed from 0 to 100