VincentMcConnell Posted June 1, 2012 Share Posted June 1, 2012 There is literally not one single page on the internet that explains how to calculate SMA.I am in an orbit with an AP of 403 and a PE of 303. How do I calculate the SMa of that. Please explain in detail. This is the most annoying moment of my life. Link to comment Share on other sites More sharing options...
VincentMcConnell Posted June 1, 2012 Author Share Posted June 1, 2012 Wait a minute. I may have figured it out on my own. Someone please tell me if this is correct.I took my two Apsis and added them. 703 (to round). Divided by two. 351.5. Now I add 351 to the radius of Kerbin. 351.5 + 600 = 951.5KM is my SMa. MechJeb says that\'s correct, but I\'m not sure if it\'s just a crazy coincidence. Link to comment Share on other sites More sharing options...
Candre Posted June 1, 2012 Share Posted June 1, 2012 It should be half the width of the eclipse, so it would be (1200km + 403km + 303km) / 2. ~950km is correct. Link to comment Share on other sites More sharing options...
VincentMcConnell Posted June 1, 2012 Author Share Posted June 1, 2012 It should be half the width of the eclipse, so it would be (1200km + 403km + 303km) / 2. ~950km is correct.Thank you Candre. I was very frustrated. When I came up with my little plan to calculate it, I sent an email to check my calculations with my Uncle who teaches Orbital Mechanics at MIT. Looks like you beat him to it. I\'ll be doing one more Hohmann transfer just to back my calculations and then I don\'t have to go to bed annoyed. haha. Link to comment Share on other sites More sharing options...
Endeavour Posted June 1, 2012 Share Posted June 1, 2012 What is the semi major axis used for? Link to comment Share on other sites More sharing options...
Ascensiam Posted June 1, 2012 Share Posted June 1, 2012 What is the semi major axis used for?Being incredibly fancy Link to comment Share on other sites More sharing options...
VincentMcConnell Posted June 1, 2012 Author Share Posted June 1, 2012 What is the semi major axis used for?Calculating orbital period.Pi(2)(sqrt(SMA/3530.461 (Kerbin\'s Gravitational Parameter). Link to comment Share on other sites More sharing options...
UmbralRaptor Posted June 1, 2012 Share Posted June 1, 2012 Calculating orbital period.Pi(2)(sqrt(SMA/3530.461 (Kerbin\'s Gravitational Parameter).Also, it can be nice for finding other parameters (?V needed for a transfer burn, eccentricity, gravitational parameter for an unknown body, etc) Link to comment Share on other sites More sharing options...
VincentMcConnell Posted June 1, 2012 Author Share Posted June 1, 2012 What\'s the formula for calculating Delta V needed for a transfer burn, actually? I was just wondering that today. Link to comment Share on other sites More sharing options...
UmbralRaptor Posted June 1, 2012 Share Posted June 1, 2012 What\'s the formula for calculating Delta V needed for a transfer burn, actually? I was just wondering that today.I\'m not sure if there\'s a formal method. I just compare the velocity at where I want to start burning, and the velocity at that point in the transfer orbit. usually with orbital energy or the Vis-visa equation. Link to comment Share on other sites More sharing options...
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