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Showing results for tags 'planetary transfers'.
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I just installed the Outer Planets Mod and am trying to figure out what kinds of Δv's I'll need to reach those planets. I began setting up a spreadsheet to calculate the required orbital velocities, but something's not right. The standard equations are giving me a reasonably accurate orbital velocity of 2,295 m/s at 70 km above Kerbin, escape velocity of 950.7 m/s and orbital velocity around Kerbol of 9,282 m/s. However, when I plug in the average orbital distance of Duna (2.07 × 1010 m) and try to calculate the Δv necessary to raise myself from periapsis at Kerbin orbit to apoapsis at Duna orbit, no matter which variation of the equation I use (I've found three), I keep coming up with a Δv of about 918 m/s, rather than the 130 m/s listed on the KSP Δv map. I'm getting similarly inflated Δv's for every planet in the Kerbolar system. What on earth am I doing wrong? The initial formula I used, provided by Scott Manley in one of his tutorial videos, is v2 = GM(2 / r - 1 / a). For M, I'm using the mass of Kerbol; for r, the orbital radius of Kerbin; and for a, the semimajor axis between the orbital radii of Kerbin and Duna. Variations found on Wikipedia provide the same result as the initial formula.
