Atimed Posted July 19, 2012 Share Posted July 19, 2012 Hey, fellow Kerbanauts.. Just a quick pool, I\'v been doing some last minute orbital interception, looking up tutorials and stuff..And if found that every one has got a different opinion of what is a circular orbit.. My personal preference is that the difference between the AP and PE should\'t be more than 800m,Best so far iv made a differentiation ~ 130m...What are your thoughts about the subject?And what are your best orbits? Link to comment Share on other sites More sharing options...
Kosmo-not Posted July 19, 2012 Share Posted July 19, 2012 I would base my judgement of a circular orbit on the eccentricity. Link to comment Share on other sites More sharing options...
Atimed Posted July 19, 2012 Author Share Posted July 19, 2012 'eccentricity' Could you elaborate? Link to comment Share on other sites More sharing options...
Flying Penguin Posted July 19, 2012 Share Posted July 19, 2012 Hey, fellow Kerbanauts.. Just a quick pool, I\'v been doing some last minute orbital interception, looking up tutorials and stuff.And if found that every one has got a different opinion of what is a circular orbit.. My personal preference is that the difference between the AP and PE should\'t be more than 800m,Best so far iv made a differentiation ~ 130m...What are your thoughts about the subject?And what are your best orbits?There\'s two aspects really:What is close enough that you say 'to all intents and purposes that\'s circular'?andWhat precision level do you not allow yourself to slip below?For the first, within 5 k is 'circularish', but for the second, I\'ll aim for sub 300m, but if I\'m feeling really bored I\'ll go for sub 100, but I\'m rarely doing anything that requires that level of precision!Personal best is about 80, but I was very bored.... Link to comment Share on other sites More sharing options...
Flying Penguin Posted July 19, 2012 Share Posted July 19, 2012 'eccentricity' Could you elaborate?http://en.wikipedia.org/wiki/Orbital_eccentricity Link to comment Share on other sites More sharing options...
Atimed Posted July 19, 2012 Author Share Posted July 19, 2012 'to all intents and purposes that\'s circular'What precision level do you not allow yourself to slip below? - If its just a Temporary orbit.. for instance cruising to a Munar-injection point i give my self the freedom of 800m difference.. - Everything else i aim from 150 - 200.. Doing better without Reaction Control on board seams impossible to me..http://en.wikipedia.org/wiki/Orbital_eccentricity - Now i know as much as i knew before.. - Its just a proper terminology.. Link to comment Share on other sites More sharing options...
maltesh Posted July 19, 2012 Share Posted July 19, 2012 The eccentricity of a conic section is the ratio of the distance between its foci to the length of its major axis. A circular orbit has eccentricity 0, and in-game, is only achiieved by Kerbin, Minmus, and the Mun. The best you can do with a spacecraft without persistence file editing is an extremely low-eccentricity ellipse...And yeah, I\'m fine with that definition.Though I admit, when I wrote my orbit calculator, I had it consider any orbit of a spacecraft with flight path angle of 0 degrees and velocity that matched the circular orbit velocity when both were rounded to the nearest 0.1 m/s to be circular. Link to comment Share on other sites More sharing options...
Flying Penguin Posted July 19, 2012 Share Posted July 19, 2012 - Its just a proper terminology.. Not really, it\'s a different way of describing it, based on the 'circleness' rather than heigh difference, but that\'s just semantics.Personally I think two heights (and the resulting difference) is a much easier to visualise metric to use whilst actually doing it, rather than sitting at a table with an astrophysics textbook. Link to comment Share on other sites More sharing options...
Sky Visitor Posted July 20, 2012 Share Posted July 20, 2012 Well unless your orbit satisfies the equation x^2 + y^2 = r^2, you are not in a perfectly circular orbit of eccentricity 0. But given that such is almost surely not achievable in the game, I would say a margin of error of less than 1%, calculated by |apoapsis - periapsis|/apoapsis. So, for me it depends on the height at which you desire to orbit. Link to comment Share on other sites More sharing options...
E. F. Kranz Posted July 20, 2012 Share Posted July 20, 2012 What are yall doing that requires this much precision?Typically, I eyeball it. Burning at either -apsis, I cut the engine when the apo and epi are 90 degrees opposed to my ship\'s location.If the difference is <1km, I\'m satisfied. If I\'m bored, maybe I\'ll straighten it up a little bit. Link to comment Share on other sites More sharing options...
closette Posted July 20, 2012 Share Posted July 20, 2012 I would say a margin of error of less than 1%, calculated by |apoapsis - periapsis|/apoapsis. So, for me it depends on the height at which you desire to orbit.How about calculating (apoapsis - periapsis) / (apoapsis + periapsis)? Oh wait, that is equal to the orbital eccentricity! (Yes there may be other ways of describing how out-of-round an orbit is, but this is already a well-established, scale- and unit-independent measure of what you want).I vote e < 0.1 is 'practically circular'. That only just includes Mars, but excludes Mercury and Pluto in our solar system. Calculating differences in kilometers for their apses would be silly, for instance Jupiter and Uranus have very similar orbital shapes (as given by their eccentricities) but the (apoapsis - periapsis) distances are very different since the orbits are different sizes.However (remember that Kerbin is 600 km in radius), that would mean a 100x150km altitude orbit, eccentricity 0.034, would be 'practically circular', which some may disagree with. Can we have another poll please? Link to comment Share on other sites More sharing options...
Endeavour Posted July 20, 2012 Share Posted July 20, 2012 If I\'m not doing rendezvous, I just eyeball it. If it looks like a circle from above, it\'s probably close enough. Link to comment Share on other sites More sharing options...
togfox Posted July 20, 2012 Share Posted July 20, 2012 I hit MechJeb \'circularise\' button and if I end up with a 250 x 221 orbit then it\'s circular!! ;DI jest.My parking orbit is 125km. If I can get a 125 x 123 or similar then I call that circular and get on with the real job of exploding the craft and/or Kerbals. Link to comment Share on other sites More sharing options...
Midnight Star Posted July 20, 2012 Share Posted July 20, 2012 It largely depends on how big the orbit is. I can get it down to less than 25 meters difference without using RCS for a 6km x 6km orbit. For an orbit that is 2000km, I can get it within 100 meters or so using RCS. It seems to me that the higher you go, the less accurate you can get. Link to comment Share on other sites More sharing options...
vexx32 Posted July 20, 2012 Share Posted July 20, 2012 That tends to be because the further away from the body you\'re orbiting you get, the more easily altered the Ap/Pe is from the other. Basically, it\'s easier to alter your orbit from further out than it is from close in. You can use the Fine Controls for RCS (CapsLock by default) to try to get it as accurate as possible. Link to comment Share on other sites More sharing options...
VincentMcConnell Posted July 20, 2012 Share Posted July 20, 2012 Usually circular orbits are based on visual eccentricity.I would consider anything within several KM circular. Link to comment Share on other sites More sharing options...
Atimed Posted July 20, 2012 Author Share Posted July 20, 2012 However (remember that Kerbin is 600 km in radius), that would mean a 100x150km altitude orbit, eccentricity 0.034, would be 'practically circular', which some may disagree with. Can we have another poll please? - Damn so my 100x101 are relay close.. Didn\'t thing it would be so accurate.. - What kind of pool do you propose?My parking orbit is 125km - I prefer them nice and low, 70-00 km.. High energy/speed, saves a few l while doing injections.. - More fuel bigger explosions, well about the matter iv been flying the same kerbals for the last 20+ missions..the further away from the body you\'re orbiting you get, the more easily altered the Ap/Pe is from the other. - Thx, for the info i noticed it but i never was 100% sure..What are yall doing that requires this much precision? - I practice, learning how vectors work.. - The circular it is the less loss in speed..I hit MechJeb \'circularise\' button and if I end up with a 250 x 221 orbit then it\'s circular!!starts spasming and can\'t decide exactly what my Ap and Pe are, that\'s when I\'m at circular. I don\'t know what sort of eccentricity that is. - That\'s when the Unity Engine meets its limits, well every engine, it cant compute infinity.. or some fractions.. - The freeking is inconstant if your at t-0 at app you can go to difference of ~50 without it freaking out.. - Th further you\'re away at a higher difference it frees, atm at my testing the starting points is around 300-400m.. Link to comment Share on other sites More sharing options...
Khrissetti Posted July 20, 2012 Share Posted July 20, 2012 Whenever the map view starts spasming and can\'t decide exactly what my Ap and Pe are, that\'s when I\'m at circular. I don\'t know what sort of eccentricity that is. Link to comment Share on other sites More sharing options...
Markus Reese Posted July 20, 2012 Share Posted July 20, 2012 For me, if I want circular, it is so exact that the AO and PO are in a fit on the map. Talking just metres of variation. Link to comment Share on other sites More sharing options...
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