flap Posted February 27, 2012 Share Posted February 27, 2012 Hello !Do you know if is possible to rotate the apoapsis of an orbit with an high eccentricity (That is, apopsis is at 90° from earth and move it a few degrees East or West) ? (I mean, apart from making it circular, and firing when opposite of the place that I want to turn into apoapsis) Link to comment Share on other sites More sharing options...
Alchemist Posted February 27, 2012 Share Posted February 27, 2012 Between the current apoapsis and the place it should be burn vertically. Link to comment Share on other sites More sharing options...
flap Posted February 27, 2012 Author Share Posted February 27, 2012 Hmm, it might more efficient in terms of fuel if done close to periapsis... The idea of 'vertical' is good though. I have done some tests : - when close to periapsis (but not right there) and firing perpendicular to the trajectory I could push the apoapsis opposit of me if thrusting toward the inside (inward ?) of the orbit (brown side of the ball in front)- I could have the apoapsis come closer to me when thrusting toward the outside. I don\'t really know how efficient it is in terms of fuel... and what the optimum would be (toward the planet, perpendicular of the orbit, toward the center of the orbit ? How far from periapsis...) Link to comment Share on other sites More sharing options...
shaunlake Posted February 27, 2012 Share Posted February 27, 2012 Maybe you should try to wait till you go to the opposite side of the place you want to be Apoapsis and then butn prograde?(this is just an idea) Link to comment Share on other sites More sharing options...
flap Posted February 27, 2012 Author Share Posted February 27, 2012 I had tried that close to the Mun. It mainly grew the apoapsis instead of turning it (And I ended orbiting the sun...). I feel that vertical or perpendicular to the trajectory is the key (unless making the orbit circular is more efficient... ) Link to comment Share on other sites More sharing options...
shaunlake Posted February 27, 2012 Share Posted February 27, 2012 vertical or perpendicular ...burning could probably give you unpredictable effects? Link to comment Share on other sites More sharing options...
Hypocee Posted February 27, 2012 Share Posted February 27, 2012 Yup, to purely rotate an apoapsis you burn radially (in at periapsis for greatest efficiency, or out at apoapsis) so your craft remains at a constant distance and angular velocity until you\'re at the desired angle. You could think of it as 'hovering' and 'pausing' your orbit while you rotate.This is incredibly fuel-hungry - assuming a LKO periapsis, you could need to burn for up to a half hour worst case! Link to comment Share on other sites More sharing options...
flap Posted February 27, 2012 Author Share Posted February 27, 2012 Hmm. I see the principle : at periapsis, it would behave as if we are orbiting, but a much greater speed than the attraction would allow. So we need to compensate g with thrust.That would be very expensive indeed. I suspect that the 'solution' I tried were more efficient in terms of fuel, but worked in growing the apoapsis roughly in the direction I wanted. I can\'t try again though : I am away from my Kerbal able computer for a month or so... Link to comment Share on other sites More sharing options...
Alchemist Posted February 29, 2012 Share Posted February 29, 2012 Radial burning is efficient only for moving apoapsis by several degrees (as asked in OP). It costs (delta v)=2*(vertical velocity) - you just change your vertical velocity to opposite therefore moving apoapoapsis to the other side of you. Link to comment Share on other sites More sharing options...
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