takethecake

I think I get it now - it definitely helps to consider the individual steps/maneuvers, breaking it up makes it seem less complicated. I'm definitely going to try launching into LKO at the correct inclination and orientation first and then waiting for the time-of-year/plane intersection to leave the Kerbin SOI - will the relationship between my Kerbin inclination and Kerbol inclination be 1/1 if I launch at the correct orientation (or is the ratio dependent on doing the maneuver at the plane intersection)? Also, I meant to add in my first reply that in general, my philosophy on the time<->efficiency spectrum: at this point in my career I decided I'm not in a rush haha and that aiming for the most efficient maneuvers will a) make it easier to design ships and b) help me learn best practices, though I guess it leaves less room for error. I've been enjoying the challenge thus far! Oh I just added the Minmus ship as an example of my planning spreadsheet since I wasn't sure if my Comet spreadsheet would make sense on its own. Maybe that was more confusing haha. But no I haven't been trying to use any gravity assists from the Mun or Minmus or doing any refueling - I figured that would make things more complicated than they already are even if it'll save me 300-400 dV (or is it more, that's just a guess). I do have an orbital station at a 20km orbit around the Mun with 4000 units of liquid fuel (+ oxidizer) that doesn't have any plans. Would it make sense to refuel at the Mun, wait until on the opposite site of Kerbin and burn prograde to escape the Mun, then do an inclination change at the AN/DN to match the comet? If I do that do I still launch from Kerbin at the same orientation or do I have to do a maneuver somewhere to compensate? Okay 2000 m/s is a good rough reference point - that seems to match up with what I've seen on my attempts so far. And the one video I've seen so far - the guy also intercepted at apoapsis and that seems to be the right approach (I watched his maneuvers quite closely but just couldn't replicate them for anywhere near the same dV cost - now I think that's been a function of my launch/maneuver timing). But isn't it inefficient to do an inclination burn at apoapsis (instead of AN/DN)? If the inclination burn isn't done before say halfway to apoapsis it seems I'd end up far enough away from the comet that any efficiency savings would be canceled out by the dV needed to close the greater distance. Maybe I'm coming at this from the perspective of needing to adjust about 10 degrees after leaving Kerbin SOI in my attempts so far - from Wobbly Av8r's help it sounds like if I can make the right adjustments to my launch orientation/inclination and perform my burn to leave Kerbin SOI at the right time I can get that required inclination adjustment down to a few degrees? And maybe then it doesn't matter so much where the inclination adjustment happens? How much dV do you think I'd need - not the full 3400 m/s or so right? I budgeted 1000 m/s plus 15% safety factor for 1150 for launching off the comet, adjusting to intercept, and landing on Kerbin - do you think that's reasonable? I'd say I'm okay with up to 20 or so orbits around Kerbin before capture if necessary lol. Thanks guys!

Wow thank you for such a comprehensive reply so soon! This is really great feedback - I think that the biggest things that will help will be trying to time my launches better (that slice visualization makes perfect sense). The visualization for accounting for time-of-day as well as time-of-year is a little trickier for me though - "[launch when] the arc of the comet through Kerbol intercepts Kerbin's orbit." When I read that I immediately thought "but wait, isn't the comet orbit always intersecting Kerbin's orbit?", remembering that when I would set the comet as my target, the A.N. and D.N. would pop up pretty darn close to where it looked like the orbits intersected. But now that I think about that, I think there was still a "little" gap - am I interpreting it correctly that at a certain point, that "gap" will close up and the orbits will "actually" intercept? Maybe I should just get in the tracking station and play around with time warp, though I'm not sure how easy it would be to see. And a related question - I noticed in your second reply you didn't specifically mention where the comet physically is in it's orbit relative to Kerbin at a "reasonably optimal" launch time - is that because it's a function of one of the other "timing" things you've already suggested, because it doesn't matter, or something else? Thanks so much for all the help man gonna go do some followup research on timing launches. I guess I've been able to get by so far with the interplanetary transfer calculator to give me transfer angles - that tool makes going to the planets a lot easier than something like this!

Hey guys! I'm about 200-300 hours into my first KSP career mode, and I recently got a contract to take a surface sample from a comet my Sentinels found. Like most comets (from what I gather), it's really far away and in an inclined, eccentric orbit. What I've been doing so far to plan my missions is a basic DV chart - here's an example of one that worked (just to see how it's *supposed* to work), and then my attempt for this comet mission: Minmus Ferry/Recoverer Mk1 Start End dV dV + 15% Stage Kerbin Surface Kerbin LO 3200 3680 I Kerbin Surface Kerbin LO 200 230 II Kerbin LO Minmus Apoapsis 930 1069.5 II Minmus Plane Change 300 345 II Minmus Apoapsis Minmus LO (10km) 160 184 II Rendevous & Capture 200 230 III Minmus LO Kerbin Capture 160 184 III Minmus Apoapsis Kerbin LO + Aerocapture 300 345 III Stage Totals I 3680 II 1828.5 5508.5 (I/II) III 759 Total 6267.5 Tanner Comet Lander Mk1 Start End dV dV + 15% Stage Kerbin Surface Kerbin LO 3200 3680 I Kerbin Surface Kerbin LO 200 230 II Kerbin LO Kerbol (Sun) Apoapsis 950 1092.5 II Kerbol (Sun) Apoapsis Inclination Change 250 287.5 II Comet Rendezvous & Land 2350 2702.5 II Comet Rendezvous Transfer to Kerbin LO + Aerocapture 1000 1150 III Stage Totals I 3680 II 4312.5 III 1150 Total 9142.5 Originally my stage 2 was ~2700 m/s delta-V, which I realized after a few launch attempts wasn't going to be nearly enough, so I upped it to the 4300 it's at now, but I still don't seem to have enough fuel to make the rendezvous. My biggest issue troubleshooting this is not knowing if I'm doing the maneuvers inefficiently causing me to need more fuel, or if I just need more dV. That reason is why I started doing these charts in the first place, but when I'm not navigating between bodies listed on the kerbal "cheat sheet" where the dV values are roughly known, I'm a bit lost at what dV values to put in my chart. For instance, once in a solar orbit, the inclination change takes ~1000 m/s at the AN/DN on the way to apoapsis, but only ~400 m/s if I wait all the way until I hit apoapsis and come around to the other AN/DN - which is right? If I do this sequence of burns, I run out of fuel: Leave Kerbin LO (~2000 m/s to get apoapsis near comet's), Inclination change so AN/DN=0 (~1000 m/s), then prograde/retrograde burn about halfway from last node to apoapsis (~600), gives me about 800 m/s left to rendezvous, but my relative speed is still usually 700-800 m/s, so I burn all the rest of my fuel just to stay within, say 200,000 km of the comet and can't get any closer. These dV values are from my maneuver nodes I've set up during these attempts. Is it best practice to launch into an inclined orbit from Kerbin, or just do a standard 90? When I've tried launching into an inclined orbit, I can't figure out the relationship between Kerbin LO inclination and solar inclination, so my Kerbin inclination attempts of 10-45 degrees all resulted in a solar inclination of ~5 degrees. My target comet has around a 10 degree solar inclination. Also, *when* do you launch to intercept a comet? I think I want the comet to be about 15-20 degrees behind Kerbin at launch but would appreciate some confirmation. Last, just some notes on my chart/design for the comet lander - the 3400 for Kerbin LO is split up so I dump a stage ~68km and then fully reach orbit with my second stage - not leaving junk in space is a big objective for this career. Since there isn't a planet to crash a booster stage into around here, I designed the lander to leave the second stage attached to the comet and just detach the third stage to return home (though I have absolutely no friggin idea how much dV that'll take). Also, what engines would you think to use for this mission? Thought about using six xenon engines for second stage & a single terrier for the third stage, but I couldn't really get my TWR above 0.6 with the xenon's which I figured would make a rendezvous difficult. Thanks for any help guys!