maltesh

Yeah, the Oberth effect makes little wiggles on your pod magnify into drastic differences in orbit at apoapsis. As a result, when I did the challenge, I never dropped below 5x time acceleration near Kerbol. On rails, ship jitters don't mess with your orbit.

Bearing 096° would do it, if Minmus' Descending node is directly above KSC on launch. Bearing 084° will do it, if Minmus's Ascending node is above KSC on launch. At any other time...Things get complicated. You won't be able to match Minmus' orbital plane until you pass through a point that's in Minmus' orbital plane. Depending on how and when you fly your ascent, this might not happen until you are already in orbit. If you decide not to match the plane, and just fly into a plane that will intersect Minmus' orbit when you get out there, you have to look ahead to figure out when you're going to be burning, and put your parking orbit into that plane, if you're going to be super-efficient about it. All told, flying out equatorially and plane-changing halfway out does cost up to several dozen meters per second more of delta-V than waiting for a node window, and launching directly in plane. However: 1. If Minmus is equatorial at your intercept point, it will cost less than matching the plane. 2. Several dozen m/s of delta V is generally chump change. Unless your ship is operating on a razor-thin fuel budget, you can easily eat that. 3. You don't have to care whether Minmus is above or below the equatorial plane when you launch equatorially. You only have to care when it's time to do that plane change, halfway out.

You're moving a lot slower at 23,500 km altitude than you are at the beginning of the transfer. At the beginning of the transfer, 100km up, you're moving at 3151 m/s. By 23,500 km, you're moving at about 395 m/s. And the slower you're going, the easier it is to deflect your direction of motion by a particular amount.

You'd have to do it in the demo version The star Kerbol has a surface in the paid version of KSP. Velocities of 200 km/s are probably only barely in the realm of the possible now.

Thinking about this a little more, I wound up postulating the following: Assuming your spacecraft is in an equatorial, circular orbit at an altitude 100 km above Kerbin's surface(700km from its center), and you burn into an equatorial transfer orbit to take you out to 46400 km altitude(47,000 km from its center). At the time you do so, Minmus will be at its maximum distance above the plane of its orbit. At some point during the orbit, you will perform a plane change to meet it. At what radial distance from Kerbin should you perform the plane change to minimize the delta-V cost ? That produced this graph Your best bet appears to be at about 23,000 km altitude for the plane change, where the required delta-V bottoms out at 81 m/s. You can save a litte more by waiting all the way out to apoapsis to do the plane change (72 m/s), but I only calculated the delta-V for the plane change itself; The savings you get by waiting that long are eaten by the extra oomph you need to reach Minmus before it leaves the vicinity. Of course, as mentioned upthread, a real space program on a tight fuel budget would probalby just wait for one of Minmus' orbital nodes to pass overhead, and launch directly into its plane. Waiting up to three hours for a window isn't all that onerous on a 54 hour trip, and the extra delta-V necessary to make orbit at a 6°-inclination angle is about 18 m/s by my reckoning. But who has time for that? LAUNCH NOW!

You need significant amounts of fuel, but if flown right, you can do it for a lot less fuel than one might think. As alluded to upthread, a bi-elliptic sundive can cut the delta-V needed to attempt a sundive from a starting point in LKO by more than half, at the cost of spending a /lot/ more time doing it. The mission in the video below took over 1200 days to fly. Things I'd do if I were flying that mission today, instead of several months ago. -- I'd pick my starting point for the burn better. Ideally, what you want to do is to aim your departure direction along the direction of travel of Kerbin if you want to push your apoapsis further out from Kerbol. I'd also not have done the wasteful attempt at trajectory correction when it became clear that I wasn't leaving on the line I'd hoped. -- I'd do all my burning for the distant apoapsis in LKO, to take advantage of the Oberth effect. In v.0.12, there were no patche3d conics, so I had to estimate how far an apoapsis I'd get -- I'd have run most of the mission at 100k time instead of 10k time, which was the highest option then. Took nearly four hours to complete back then. -- I'd have hit Kerbol at an altitude of about 4500 km instead of falling through it and being ejected at ludicrous velocities.

In the meantime, I have had some weird success mounting the puddlejumper rockets on top of the Puddlejumper SAS module.

Crap, looks like I did have a bum copy of MechJeb, there. Profuse apologies.

Ah, the Picard Maneuver. All species involved had possessed both FTL travel and FTL sensors for centuries, and yet, using FTL tactically is suprising. And for some reason, a widely-known tactic with no known defense isn't used in every single combat situation until someone comes up with a defense for it.

The circular orbit inclination formula actually works to find the minimum delta-v for any change in direction you want to make, as long as you know the angle you want to change your direction of motion by (ÃŽâ€i in the formula), and you want to have the same speed when you're done as when you started. All orbits of the same semi-major axis have the same Specific Orbital Energy. Once you know the radial distance and velocity for any point in your orbit, you can use the specific orbital energy equation to find the velocity at any other radius that your orbit reaches.

Depends where you do the plane change. Do the plane change in LKO at 100km, and it's 234 m/s to change a velocity of 2245 m/s by six degrees. Do the plane change just after you've burned for the transfer (I don't know why you'd do that, but hey), and it's 330 m/s to change a velocity of 3151 m/s by six degrees Do the plane change mid-tranfer at 30,000 km altitude, and it's 87 m/s to change a velocity of 287 m/s by 17 degrees (the maximum you'd need to change it to hit Minmus.). A significant amount, but not a huge waste.

Nice. I apologize for almost always complaining, It's just that I enjoy driving this thing so much. With regret, I point out a minor new issue, though. The rockets on the current puddlejumper pack block the airlock on the alpha. The other parts of the pack don't seem to cause problems.

Nah. If I hadn't been on my way to work when I'd first seen the post, I'd have flown this mission then. There are two big benefits of the Bi-elliptic sunscraper path. The first, as I previously mentioned, is that it takes significantly less fuel than the direct Hohmann. Almost every time I do a bi-elliptic sundive, I head for a 131Gm apoapsis. It's traditional. Anyway, 660 days later... We slow. We sundive. And 1233 days into the mission, we're sunscraping. Periapsis: 8971 km. From there, we fly out to apoapsis again, and at Day 1804, burn to raise our periapsis to Kerbin's orbit. And there, we hit the second benefit of the bi-elliptic return. At this distance, Kerbin will go around six times before we reach Periapsis. We know that Kerbin has a period of just under 106 days. And we know exactly how long it will take us to get to Periapsis. So we don't have to wait for a return window. We have a way of correcting our course with the instrumentation we have. Use tab to center on Minmus (it's the least jittery object in the Kerbin SOI under high time accelleration), and run time ahead until Kerbin crosses your periapsis. The timer uses 365-day years. So we'll get there in 656 days. Kerbin will next be there in 6*106 = 636 days. So we need to pull our periapsis 20 days backwards. To do this, we burn a little retrograde, to slow us down, then burn a little radially outward, to raise our periapsis. At this distance, it's easy and cheap to do. Then we let Kerbin go around again, and re-check, comparing our time to periapsis against five revolutions of Kerbin. If we need to push our periapsis forward in time, we burn a little prograde to go faster, and a little radially inward to pull our perapsis back down. We check each time Kerbin goes around. Since we'll be moving faster than Kerbin at intercept, it's best if we err a little towards getting to periapsis later than Kerbin, instead of getting there before. Typically, when I do this, I don't actually find an intercept until 106 days before periapsis. Whenever you do get an intercept, it's time to use the RCS system to feel around for the direction that lowers your Periapsis. Dump it in the low atmosphere for a good solid Aerobrake. Then go around again. And, bam. 2448 days after launch, I now have a new record holder for "Longest trip I've made that has successfully returned to Kerbin." And this time, I knew what the heck I was doing. For what it's worth: The stats screen. Peaked at just under 178 km/s.

It looks to me like you're watching the spacecraft more than you're watching the navball. I don't know if you're using the keyboard or a joystick, but if you're using the Keyboard, I'd recommend the following: When you start your final descent, make sure that the speed indicator is showing "Surface". On that particular design, I'd say come to as much of a stop as you can on the main engines, then lock vertical with SAS, and use your RCS thrusters to push the velocity indicator to the center of the blue hemisphere. From there down to the danger zone (which is about 3000m for moderate latitudes on the Mun), I'd stick to a descent velocity of Altitude in meters/100 (e.g, 50 m/s at 5000m). Try to find a throttle setting that will hold you there, and use the RCS to keep your descent vertical. Adjust your throttle as necessary to manage the descent rate, but most of the action should be on RCS. If you have no information about how high the local terrain is, below the danger zone, stick to <10 m/s. If you do have a general idea, stay at that velocity for the last several hundred meters at least. Watch the Navball. The spacecraft is a distraction. Keep pushing the velocity marker back into the center. When you really start to get near the surface, try to keep below 3-5 m/s. Use the RCS forward and backward controls to push downward or upward as necessary, as well as keeping the mark centered.

Depends on which world you're talking about, and what latitude, and whether or not you let the spacecraft leave rails. Over Kerbol, lowest altitude is about 4500km. Over Minmus, equatorially, you can get by with 5.6 km, and probably a little lower. Over the Mun, equatorially, you can get by with about 3 km. Over Kerbin, if the spacecraft is off-rails, going below about 69 km will cause the atmosphere to eventually deorbit your spacecraft. If the spacecraft is never allowed to leave rails while in the atmosphere, you can orbit Kerbin as low as 25 km, and possibly a bit lower. Short of persistence-file editing, though, I can't think of a good way to get a spacecraft into a 25 km altitude circular orbit, as the game won't let you save while flying in atmosphere.

Firefly also had silent space.

It should be noted that Kerbol has an invisible surface at about 4500km in v0.14-v0.16, so if you set your periapsis lower than that, you'll crash into it. Also, a Bi-elliptic sundive cuts the delta-V required from LKO almost in half.

Is it just me, or is the crew-podded Bigtrak a little harder to land in the Cuttlefish? I'm guessing it's because the pod is slightly off-center when mounted on the cuttlefish, resulting net thrust vector not going through the center of the pod. Mechjeb can't land it, and landing it manually was a bit tricky. Oh well, I've got one down now., and I imagine any further issues will be Minmal.

The Oberth Effect definitely works in Kerbal Space Program. If the Oberth Effect didn't work, the game would not be calculating kinetic energy or momentum correctly, and that would mean most of the orbital equations wouldn't work, either. It would have been impossible to write accurate orbital calculators without painstaking experimentation or access to the source code. From LKO, it requires less than 100 m/s extra delta-V to Escape Kerbin than to intercept the Mun, and less than 20 m/s extra delta-V to escape than to intercept Minmus. With the game's current instrumentation, when aiming for a specific target in interplanetary space, you're much better off burning direct from LKO; Unless you're really willing to wrangle with orbital equations and launch windows, its pretty easy to wind up with a Munar/Minmal slingshot that's a less efficient path to your interplanetary destination.

If you do the burns necessary to shift your orbit plane accordingl (I believe what you're trying to do is keep shifting your orbit so you stay over the Munar terminator here, yes?), it would be called a sun-synchronous orbit.

On the first few attempts at landing, I would recommend putting your spacecraft into a low Munar orbit first (say 10-15km or so). It's not as efficient as going straight on in, but definitely relieves the pressure on a straight-in descent My general rule-of-thumb for final descent is below 10,000 m, keep velocity at about 1/100 altitude in meters... e.g., 50 m/s at 5 km. When I hit the danger zone (about 1 km above the local altitude), it's <10 m/s all the way down, with a soft-landing at ~ 1m/s. If I'm not Mechjebbing, I typically determine the local altitude through prior knowledge (Minmal lakes are 0 altitude, Most of the Munar surface at moderate latitudses is about 1-2 km altitude), or by throwing my last pre-lander stage at the Mun and seeing how far away it is when it explodes.

Aye, that's the spirit. As rampiro's done, I'd definitely recommend doing a test flight to get an idea of just how long it's going to take you to come to a stop once you near Mimus' orbital altitude, and plan to have at least that much fuel left when you finally put the brakes on. Yep, that's basically it. The more speed you pour into your spacecraft when low, the larger the fraction of that speed you keep when high. If I'd missed Minmus, I probably would have still had over 1.5 km/s of velocity relative to kerbin when I exited Kerbin's SOI. One of the nice things that worked out, is that, when I was close to Minmus' orbit, Kerbin's gravity wasn't slowing me down much, so it got a lot easier to eyeball what I was aiming for with the intercept. I was moving about eight times Minmus' orbital velocity, so I started aiming to intercept at a point that was about eight times farther from my spacecraft than from Minmus/ I still didn't manage to find the SOI until about two hours from landing, though.

Aye, two days is basically the limit on the Hohmann transfer, so I tried the straight-on route that seemed to be so popular with the people who were hitting the Mun in under an hour (Though I didn't build a spacecraft fast enough for that, those guys were building spacecraft that hit 6km/s in transit.) I can't tell how high you are in the image, but it looks like you're moving somewhat slower than I was at that altitude. The specific orbit energy equation means small differences in velocity very close to the planet result in high velocity differences at distant points. Or you can think of it as "spending more time deep in the well gives gravity drag more time to steal your velocity." The spaceraft's Asparagus-stalk staged once the boosters go. If you want, here's the .craft file. https://dl.dropbox.com/u/4057920/KSP%20Shipshare/Minracer.craft I didn't bother getting into orbit, or doing a gravity turn (though, admittedly, that probably would have helped for more speed). My orbit was hyperbolic, basically straight up from Kerbin. I didn't try to find the SOI on launch, I figured Minmus wouldn't move too much on the ascent, and it would be easier to look for it when I was moving slower. At about 20,000 km I made the plane adjustment to try to make sure I went through Minmus orbit, but it still took a few more adjustments on the way up to find the SOI and punch straight through to the satellite. And as I said, I didn't slow down until I was only a few hundred kilometers off Minmus' surface.

Another option is the quasi-satellite orbit; In a 1:1 orbital resonance with another satellite, but sufficiently elliptical and/or out of phase so that it never enters comes under the influence of the other satellite. It's so named because, from the rotating frame of reference in the viewpoint of the other satellite, the quasi-satellite appears to trace out a weird, retrograde oblong orbit around the satellite. I was experimenting to see how little of an eccentricity I could get with synchronized quasi-satellites on the Mun and Minmus' orbits, without ever entering either body's SOI, while maintaining a synchronicity that put the Mun/Minmus directly below the quasi-sat at Apopasis, and directly above the quasi-sat at periapsis. As I recall, I was able to place a stable Mun-Synchronized quasisat with the above restrictions with an eccentricity as low as 0.25, For Minmus-syncrhonicity, I was able to go down to 0.075, and for Kerbin, managed 0.01. Though, as implied upthread, this doesn't satisfly the OP's specific request either.

All stock, no Mechjeb. 7 hours, 52 minutes, 12 seconds from launch to touchdown. I present the Minrunner. By day and just prior to launch I warped time until Minmus was practically overhead, burned down to one tank in the pre-lander stage and the lander. Finding the Minmus SOI was a bit of a bear. I figured I could land if I started braking at ~200 km up and /still/ almost crashed it. I didn't actually have a stable orbit around Minmus until I decided to see if I could return to Kerbin. And it turns out, I did have enough fuel on board for a successful return.