Jump to content

-Velocity-

Members
  • Posts

    864
  • Joined

  • Last visited

Community Answers

  1. -Velocity-'s post in Not Understanding Rovers was marked as the answer   
    It's extremely easy to combine the function of rover and lander into the same vehicle.  You can even combine more than just lander and rover.  This is rover/science research base/lander/interplanetary transfer ship/ISRU base all rolled into one, for example, for use in the Duna and Kerbin systems:
    Notice I have two sets of engines- the primary engines in the back aligned axially and the landing/take-off engines in the middle pointed downward.  This was due to aerodynamic considerations within Duna's atmosphere, but honestly, it might not be worth the trade-off.  If you stay outside of atmospheres, you CERTAINLY only need a single set of engines, and if you are only landing in weak gravity (like, less than 3 m/s^2) then you are better off with LV-N nuclear engines.  In fact, the LV-Ns can be used even for Moho and Duna landing, it just gets more difficult, you start needing a lot of them to get a decent TWR.
    Here's another example that only combines the lander and rover functionalities.
    As for how to get the rovers into orbit, yes, they can be draggy.  Start a slight gravity turn almost immediately off of the pad so that you never have to make your rocket turn so much below 30 km that there is a greater than 5 or 10 degree difference in the surface prograde vector and where your rocket's nose is pointed. A lot of KSP players in my experience (based on forum surveys I read a long time ago) do not start their gravity turns early enough anyway.  So, as long as you keep your rocket pointed within like 5 to 10 degrees of where the surface velocity vector is pointing, your rocket's control system should have enough authority to overcome the inherent instability of having your center of drag too far forward.  If it DOESN'T, you need to add more control surfaces and/or fins to the back and/or add more engines with thrust vectoring capability.
    This is what my ISRU rover looks like on the pad:
    If you're wondering how that relatively small rocket gets that huge rover into orbit, it's because I'll launch big things like that with mostly empty fuel tanks and then refill them on Minimus.
    And this is that over rover I showed on the pad:
    ALSO: Do NOT try to go too fast in the lower atmosphere with that big, front-draggy rover attached to your rocket.  Keep your TWR pretty low, you should have a lift-off TWR below 2, and your TWR shouldn't get much more than 3 or MAYBE 3.5 before going second stage- and that's assuming you aren't controlling the thrust from getting too high, which you actually should, especially in this case (generally, the rule in the lower atmosphere in the stock game is to control your TWR to be around 2).  The slower you go, the easier it is for your thrust-vectoring engines to keep your rocket straight (assuming the rocket is aerodynamically unstable), and slower can also mean being more efficient in the lower atmosphere, especially with a lot of drag.
×
×
  • Create New...