VoidFoo

Both you guys' explanations help out a bunch. Thanks! I switched the calculation to two stages: - SRBs running: mass 41.53 -> 31.23, Isp 187.24 --> 522.95 m/s DV - SRBs empty: mass 31.23 -> 25.1, Isp 265 --> 567.97 m/s DV ------- 1090.92 m/s DV Used the fuel consumption rate on the wiki, which matches your in-game fuel consumption test. Working backwards that would give a total average Isp of 220.84 s I suppose? Yet another value for the Isp collection Inspired by your in-game test I put a probe core on it, hyperedited it into Kerbol orbit and burned prograde. Payload now 20.92t and the rest now using vacuum values, the calculated DV matched the orbital velocity increase exactly (1255.2 m/s DV). So it all seems good! Did not know about that built-in KSP indicator btw, TIL...

Looking for some help. I'm getting a different result for my Isp calculation than KSP / KER, and I can't figure out why. My dummy test rocket has a single stage: - 1 Reliant engine and two FL-T800 tanks - 3 Hammer SRBs - Dummy 20.6t payload - Atmosphere, not vacuum My calculation is giving me and Isp of 187s (and therefore 924 m/s DV), KER is saying 224s (and therefore 1109 m/s DV). Wiki says sum of thrust of each engine, divided by sum of (thrust / Isp). ( https://wiki.kerbalspaceprogram.com/wiki/Specific_impulse#Multiple_engines ) 3 * 197.9 + 205.161 Isp = ----------------------------------- = 187.23 (3 * 197.9 / 170) + (205.161 / 265) What am I doing wrong? Forum won't let me insert image, but here is the screenshot: https://imgur.com/a/IGwdTuW

When choosing what orbit to start out with when doing a rendevous coming from interplanetary transfer, is it better to do a lower orbit or higher orbit than the target? For example, I have a refueling station in circular orbit around Duna. I send a ship to Duna, and when arriving I burn retrograde to go into a circular orbit around Duna, but at a different altitude than the station. Then I can do an easy rendevous by dragging around a maneuver node until I get a close separation. So is there a rule of thumb as to what starting orbit is more efficient, delta-v wise, when coming in from an interplanetary transfer orbit? - If I go for a low orbit, I get good Oberth Effect, but it feels weird because I cross the target orbit to get into the lower orbit, then during rendevous go back up. - If I go for a high orbit, it feels like I haven't "wasted" anything because I don't cross the target orbit.

You're right, I had that option activated. When I turn that option off, I don't see a closest approach at all, because there wasn't any encounter with Moho. This clarifies it a bit for me. When the option is turned on, it shows the closest approach but not when using maneuver nodes, unless you actually have an encouter. I think before I was always encountering the Mun / Minmus / Duna which usually do have an encouter after the Kerbin escape burn, and then it was a matter of tweaking the encounter, but the maneuver nodes would work then of course. Now when trying to encounter Moho I was close but no actual encounter -> therefore no closest approach when using nodes. For now I fixed my encounter by turning the option back on, and experimentally burning in different directions to decrease the closest approach until an encounter is reached, after which the maneuver nodes work again so I can tweak the encounter periapsis. Thanks for the tip!

Sometimes when trying to set up interplanetary encounters, the 'closest approach' marker seems bugged. It shows the correct closest approach, but as soon as I place a maneuver node anywhere it moves the closest approach marker directly on top of the node. For example, here I'm trying to get to Moho: You can see the closest approach seems correct, 80,310.6km from Moho right near where my orbit and Moho's orbit intersect. Then I place a maneuver node at a random place: As you see it moves the closest approach marker onto the maneuver node, now showing 17+ million km. If I move the maneuver node, the closest approach marker happily moves along with the node, making it seem like the closest approach is always going to be exactly at the node position. It does not matter what dV values I give the node, it always shows the closest approach as being at the node. I tried reinstalling my mods, uninstalling maneuver node mods, restarting KSP... same behaviour. Using the latest KSP 1.4.3.2152 Windows x64. I've run into frustrating issues like this with the closest approach marker a number of times now. Anybody have a fix or workaround?