eggrobin

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About eggrobin

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    Sr. Spacecraft Engineer

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  1. For the new moon (lunation number 249), the new release (Frenet) is out. Nothing new this time; we have been working on the preservation of angular momentum, but it is not quite ready yet. See the change log for more details. We support two sets of versions of KSP: downloads are available for 1.8.1, and for 1.5.1, 1.6.1, 1.7.x. Make sure you download the right one (if you don't, the game will crash on load). For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.
  2. Some of them will be unstable: see the orbit shown in the release announcement for Εὔδοξος for an example. There are however low lunar orbits that remain stable (so-called frozen orbits), and there is extensive literature on the subject. For instance, the figure below, from Martín Lara's 2011 paper Design of long-lifetime lunar orbits: A hybrid approach, shows the stable eccentricity corresponding to a given inclination for lunar orbits with selected semimajor axes (for a frozen orbit, the argument of periapsis ω is either 90° or 270°, so that the value plotted on the vertical axis, e sin ω, is ±e). Note that only 4 non-equatorial inclinations are permitted for stable circular (e = 0) orbits at any of these altitudes. You can use the orbit analysis tool to see the mean orbital elements of your current orbit; by aligning those with the values given by that figure, you should be able to keep your spacecraft in low lunar orbit without need for long-term stationkeeping.
  3. We have a feature request tracking that, #2348. In the meantime, I would recommend using the Orbit Analysis window, which gives you general information about your current orbit; it focuses on long-term properties (orbit size, shape, orientation, and stability) rather than the immediate "am I about to reenter?", but it should be useful nonetheless. No.
  4. For the new moon (lunation number 248), the new release (Frege) is out. Celestial histories are now displayed as far as requested in the past (if available), rather than being limited to the time of launch. Miscellaneous bugs have been fixed (perhaps most visibly, the wild camera spin in the pause menu introduced in Fréchet).  See the change log for more details. We support two sets of versions of KSP: downloads are available for 1.8.1, and for 1.5.1, 1.6.1, 1.7.x. Make sure you download the right one (if you don't, the game will crash on load). For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.
  5. It looks like it is indeed necessary for the orbits of circumbinary planets to be legible. This will be a nontrivial amount of work (both for implementing the reference frame and sorting out UI questions). I opened #2454 to track this. In the meantime, for interplanetary flights, I suggest using the reference frame centred on the target planet and fixing the direction of the Sun (the reference frame with the orange navball). This reference frame is similar to the target vessel frame (red navball) and should hopefully remain usable even with the binary star. Impressive work stabilizing the Beyond Home system by the way!
  6. For the new moon (lunation number 247), the new release (Fréchet) is out. Support for KSP 1.8.1 has been added. The camera is oriented in map view and the tracking station so that the horizontal is the reference plane of the selected plotting frame. Further, the camera rotates with the plotting frame, so that the plotted trajectories do not rotate as time passes.  See the change log for more details; note in particular the known issue with map view camera rotation when showing the menu. We support two sets of versions of KSP: downloads are available for 1.8.1, and for 1.5.1, 1.6.1, 1.7.x. Make sure you download the right one (if you don't, the game will crash on load). For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.
  7. By seeking to change the tilt of planets, you enter the realm of making your own mods, not unlike, e.g., changing other characteristics of planets with Kopernicus. The page linked by @pleroy documents the Principia-specific aspects of that. It is not intended as a general introduction to KSP configuration modding. It would be a good idea for you to become acquainted with that, and with ModuleManager patches in particular; see for instance @sarbian's ModuleManager handbook.
  8. @Delay same duration as the prediction of the active vessel, if any. In the absence of an active vessel, i.e., in the tracking station with no vessel selected, no prediction is shown, only a history going back to the beginning of the game (or less, depending on the history length setting).
  9. For the new moon (lunation number 246), the new release (פרנקל) is out. Principia now plots the trajectories of celestial bodies. This closes an ancient feature request (#942, March 2016), and builds up on a lot of intervening work; in particular, this is based on the method for trajectory plotting introduced for vessels in Чебышёв (August 2017). The history length setting now hides the history instead of forgetting it; this means that you can shorten histories when they are visually distracting, while retaining the ability to bring them back when you want an overview of your mission. It also uses the same duration format and selector used elsewhere in the Principia UI instead of seconds in scientific notation.  See the change log for more details. For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.
  10. I think so; going from J2-only to J2 through J12 (in del Ferro) reduced the error on the orbit of Io from 2″.1 per revolution to 0″.077 per revolution. What does the transit look like in-game in the 1.3.1 versions (I think Fatou is the last one of those)? It would be fun to have a visualization of the improvement.
  11. For the new moon (lunation number 245), the new release (Fourier) is out. Two crashes involving flight plan edition (one reported by @Neph) have been fixed.  See the change log for more details. For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云
  12. The documentation is here: https://github.com/mockingbirdnest/Principia/wiki/Orbit-analysis. It includes some background information on frozen orbits and ground track recurrence, as well as many examples based on real-life satellites to illustrate the underlying concepts.
  13. For the new moon (lunation number 244), the new release (Fibonacci) is out. An orbit analysis tool has been added which computes mean elements and orbit recurrence properties. This has been in the works since February; more features will be added at a later date, e.g., mean solar times of ascending nodes (for controlling sun-synchronicity). See below for a screenshot of the orbit analysis tool in action on a Молния orbit. The tool is fairly complex; documentation will be provided soon. A crash reported by @Delay has been fixed. A dependency issue that would prevent Principia from starting has been fixed.  See the change log for more details. For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云