COL_Tatticky

"Kerbin Slingshots"? I had been lead to believe that passive gravity assists were impossible when starting from inside the gravity well? That doesn't account for the possibility of dropping to a highly elliptical orbit first which is exactly what I was suggesting. I've seen that video; in fact that's exactly what inspired me to look at the Mun slingshot possibility in the first place: making it pay is a challenge. What he was talking about is a completely different thing from what I am talking about. What I am talking about here either doesn't need the Oberth Effect (the Mun is doing the hard work for us) or has a very strong Oberth Effect (the final ejection burn is done at <100km). The most useful responce thus far has been this one: So what I'm looking at now is setting up the capability to choose between entering HEO directly, or using Mun to break; and in either case burning near Kerbin to eject. So, let's assume that I decide to brake using Mun to enter HEO as described in option B of the OP. Suppose I burn to escape Minmus directly from a low circular orbit. What's the delta-V cost to do this, the angles/altitude of the launch window, (this should work similar to interplanetary launch windows) how can Icalculate the orbit after the grav assist, and (most importantly) what will the escape trajectory be?

Hm... I hadn't thought of that one. Unfortunately it applies to all Minmus embarkations, Mun slingshot or no; but hopefully I should be able to correct for it. I've no idea how to calculate the delta-V needed for that, though...

So, I got the Kethane mod and designed a really nice mosquito to siphon it from Minmus in hefty 192 tonne chunks. Now I want to expand this into some full-blown orbital infrastructure and launch all interplanetary missions from Minmus in the future (if possible). I was wondering if I could use a gravity assist off Mun to aid in the escape from Kerbin's gravity well. At first glance, I see two options: Pass behind Mun (more than once if necessary) to increase orbital velocity directly. Pass ahead of Mun to enter a highly eccentric orbit, then make good use of the Oberth Effect with a direct escape burn <100km above Kerbin. Option B looks like it might use more delta-V, but it also looks a whole lot easier (indeed, I'm not sure that A is even possible). The two would additionally have wildly different ejection vectors to consider (although that might be a good thing to keep my options open within individual launch windows). I've calculated (you might want to check my math) that Mun passes directly between Kerbin and Minmus every 159570.67 seconds (1 day 20 hours 19 minutes 30.7 seconds), so that's the period for launch windows. Minmus's rotation only takes it 0.8217243 rad (relative to Kerbol) in this time, though, so that may limit which interplanetary launch windows can be accessed through this method. Other questions I have involve how best to embark from Minmus itself, including which direction to rotate around the planet, whether it would be better to start from low orbit or a high orbit resonant with the launch window, and (if I start from high orbit) whether it would be better to burn inwards first to use the Oberth Effect or to just escape Minmus directly.