Ydoow Posted January 2, 2012 Share Posted January 2, 2012 Is it possible to determine the eccentricity of an orbit you\'re in?I\'m not sure how to go about it with the data available; apoapsis, periapsis, and velocity. Link to comment Share on other sites More sharing options...
Hypocee Posted January 2, 2012 Share Posted January 2, 2012 Theoretically I think it may also be necessary to know that the planet\'s radius is 600km, to translate into point-source measurements. In general form the velocity at any point can be converted to angular momentum at any point in the orbit, which is conserved, and tells you the central mass. Given the mass and the semimajor axis and...crazy math term that the periapsis is...you can calculate the semiminor axis and get your eccentricity.In terms of me actually knowing the steps? NOPEEdit: One Wikicheat later, you can do it from just periapsis and apoapsis. Huh! That does require the radius info to translate from altitudes to...distances. Link to comment Share on other sites More sharing options...
Cepheus Posted January 2, 2012 Share Posted January 2, 2012 e=(ra-rp)/(ra+rp), where ra is the radius at apoapsis, and rp is the radius at periapsis. You can also use 1-(2/((ra/rp)+1)). Link to comment Share on other sites More sharing options...
Ydoow Posted January 2, 2012 Author Share Posted January 2, 2012 e=(ra-rp)/(ra+rp), where ra is the radius at apoapsis, and rp is the radius at periapsis. You can also use 1-(2/((ra/rp)+1)).That\'s radius from the center of Kerbin? Or from the center of the two foci in an ellipse?If from the center of Kerbin, that means add in the 600km to the radius, correct (I don\'t see why not.)I have another question, sorta unrelated, sorta related.When revolving around Kerbin in an elliptical orbit, the center of Kerbin is one of the two foci present in an ellipse, yes?Just a question out of curiosity. Link to comment Share on other sites More sharing options...
RulerOfNothing Posted January 2, 2012 Share Posted January 2, 2012 I have another question, sorta unrelated, sorta related.When revolving around Kerbin in an elliptical orbit, the center of Kerbin is one of the two foci present in an ellipse, yes?Just a question out of curiosity.That is correct. Link to comment Share on other sites More sharing options...
Saaur Posted January 5, 2012 Share Posted January 5, 2012 e=SQRT(r1 x v12 / GM - 1)2 x sin2phi1 + cos2phi1) Link to comment Share on other sites More sharing options...
Recommended Posts