cantab

My thoughts. Lower orbits: Are easier to launch into. This can matter especially for marginal launchers. Even for typical cases, a launcher capable of getting a payload in a 100 km orbit might not loft the same payload to 300 km. Are easier to deorbit from, especially on bodies with atmosphere. Again, deorbiting from a few hundred km over Kerbin can require a non-negligible amount of fuel, especially if you plan on doing it with your RCS. Are more efficient, ground to target, as parking orbits before making interplanetary travel. May be easier to aerobrake into, since you won't have to raise periapsis so much. Higher orbits: Are easier to dock in. This is because things have less curved trajectories. Are in darkness for a smaller percentage of the time. Since docking in the dark is no fun, this can be a factor if you haven't got lights. Are easier to escape from, and for some interplanetary transfers require less fuel from that orbit. If you're using a fuel depot, reducing the fuel needed after visiting the depot may be more important than reducing the usage ground-to-target. Are easier to change inclination in, though the difference is small until you start talking about several thousand km. Can be quicker and less wasteful to rendezvous with, since you have the option of establishing a phasing orbit either below or above the target orbit. Inclined orbits: Are essential for surveying. In the stock game, this is mainly getting biome-specific science. Are easier to land on non-equatorial locations from, with patience to wait for the landing site to rotate under the orbit. If you're in an equatorial orbit and want to land significantly north or south, you'll need a major normal component to your deorbit burn. When coming into a planet or moon's SOI, are just as easy to reach as equatorial ones, you simply need a small mid-course correction on the way to line things up. Eccentric orbits: Are needed for rendezvousing. May be useful for science by getting both low and high altitude results. Are generally the easiest to get captured into on arrival at a body.

I attached struts to radial decouplers before I realised that I didn't need to.

After fixing the inclination of the transfer stages I launched last night and raising their apoapses to be tangent to the station's orbit, I set up the phasing burns only to find I didn't even need to do one for one of the stages! Was already on course for a close intersect in six orbits time. Complete blind luck there, but I'll take it.

This. My first approach to reaching orbit was to keep adding RT-10's at the bottom until I had enough to get there. This one's not as common as I might expect, but yeah, people have done it. I did this with some of my early launches. I knew I had to launch with the planet's spin to save fuel - but somehow I converted that into a heading of 270 degrees.

Well, despite the game description the LV-N *shouldn't* produce radioactive exhaust, at least no more so than the background radiation in any rocket exhaust. Personally, considering I sat a Near Future Propulsion nuclear reactor on the launchpad and took it to meltdown to see what would happen, I don't think I care about the LV-N exhaust. Still, I've not fired it in atmo except during tests because I've not built anything intended to.

Your rocket is clearly bent in that shot. Lack of rigidity will make things harder to control. You could resolve this by switching the upper stage to use Kerbodyne tanks. Even though they're less efficient in terms of tankage they may help make your rocket more manageable. Besides that, I suspect drag is the issue. The rocket will want to fly draggy end backwards, so try adding some fins at the bottom to compensate for the fairing up top.

I wondered why ions weren't allowed at first, then realised that they'd allow suborbital or orbital travel, which presumably is not the challenge intent. A restriction to direct solar power only, while it limits the minimum flight time, creates some extra challenges. If you want that three hour flight record you need to be capable of taking off when the Sun's low in the sky and panels flat on top of your wings aren't getting much sunlight. If you want to beat three hours you can do that by making a glide landing, but you're going to have to judge the speed of your whole journey such that you don't lose power too soon to make KSC. Koolkei, to quote the challenge Emphasis mine. A circuit of the airport is not a circumnavigation.

I launched ALL the transfer stages: This was not a stable payload. At around 50 km I lost control and did a full 360 spin before regaining control, and the launcher failed to put the transfer stages into orbit. On circularising, the wrong engines fired. Instead of the ones at the back, the next set up ignited, causing this to happen: The part in the background should have a docking port on the front, it got blown off by the engine exhaust. So now the biggest of my four transfer stages is a hunk of junk. I'll probably just dock it to the station and use its fuel for other stuff. Also, left lots of litter from the strutwork.

Congrats. For me landing intact and with enough fuel for the return isn't that hard. Landing upright, however, is in the lap of the krakens.

Next task: Melt down an NFP reactor in the VAB. As for LV-N fairings, my solution is to have a central structural element in the cluster. So in a group similar to the one above, I'd put a fuel tank or something down the middle and six engines around it.

Though included in your spec, bear in mind that if you're going to or from any of Jool's moons it's very wasteful to go via a low Jool orbit. Not that it makes much difference for your task since 2500 m/s or even more is plausible for a Moho capture burn. (Then again, if you use panels that's not a problem). RTGs might be viable if you compromise the overall TWR of your craft. You need 12 per ion engine, so you're effectively making the engine weigh 1.21 tons, giving it a Kerbin TWR of 0.16. So if half the mass of the craft was engines and RTGs you'd have a 0.08 TWR. This little design is something along those lines: A 1-ton payload (the pod with a chute and two mid-gain antennae), just over 10,000 m/s of total delta-V, but a Kerbin TWR of a measly 0.072. The real killer for this idea though may be the part count. Scale it up ten times and you're looking at nearly 500 parts just for the tug.

I've found the advice here useful http://wiki.kerbalspaceprogram.com/wiki/Basic_maneuvers During the vertical phase of your ascent, watch your speed against those "checkpoint" values. If you're going much faster, throttle back your engines. For solid boosters, you can right-click them in the VAB and reduce their thrust. The lower thrust will make them burn for longer so you don't lose out. If you're having to throttle way back, use smaller or fewer engines. If you're going much slower, you could add some boosters or use more or bigger engines, though a slow launch isn't all that bad IMHO. The overall method there isn't the most efficient, but it's not bad.

Being short on electric charge can cost you science, as the data gets transmitted in dribs and drabs when charge becomes available, and those dribs and drabs don't seem to add up to the full figure. A workaround is to timewarp right after starting the transmission. To avoid these issues, give ships that will be transmitting the following minimum battery capacity depending on the antennae they have. If running Atmosphere Analyses (from the sensor nosecone): Low-gain antenna: 1000 Mid-gain antenna: 1500 High-gain antenna: 2000 If not running Atmosphere Analyses: Low-gain antenna: 200 Mid-gain antenna: 450 High-gain antenna: 600

Mods like Engineer Redux, Mechjeb, or VOID will calculate delta-V for you quite easily. Except when they get it wrong. To do it yourself, the rocket equation has been mentioned, ÃŽâ€v = 9.8 × Isp × ln(m0/m1) It needs to be applied one stage at a time. Serial staging is easy enough to handle, as is crossfeed/asparagus staging though it's more tedious, but for non-crossfeed core and booster setups you'll need to separately calculate how much fuel the core has used when the boosters separate. It also assumes constant specific impulse, which won't be the case when ascending through atmosphere, but launches tend to not be perfect anyway. To get the values from the game, the simplest methods are as follows: Isp, the specific impulse, can be read off the engine info in the VAB/SPH, or when the engine is running by right-clicking it. If you have different engines, the specific impulse used needs to be a weighted average. I'm not sure if it's weighted by thrust or by fuel flow. m0, the initial mass, can be found in the map view during flight or in the tracking station. With the vessel focussed (used Backspace in the map view), open the information box on the right of the screen and you can read off the initial mass. m1, the final mass, can be found by subtracting the fuel from the initial mass. You can use the resources panel with "stage only" to read off how many units of fuel and oxidizer are available to the current stage, or if this doesn't work (or you want the delta-V you'll get from using a portion of your fuel) you can just right-click the relevant fuel tanks. Then, remember that 1 unit of either fuel or oxidizer weighs 5 kg, while 1 unit of monopropellant weighs 4 kg. Working out how much extra delta-V your RCS can give you is one of the main uses for doing the calculations manually, since most mods only consider main engines. (RCS specific impulse is 260 seconds).

Moving the camera about when landing can help you judge the slopes. Just don't get so distracted you crash!

How far are you approaching from? If it's from several hundred metres, then remember you and the target are both in curved orbits, so the target prograde vector will drift. Just use small nudges of lateral RCS to keep it in line.

Regarding how the Kerbal's program differs from those of human nations, it can't be overlooked that the Kerbals have it easy. Even with Kerbin's soupy atmosphere to contend with, they still only need about half the delta-V, and can thus knock up their space rockets from cheap, robust, but low-performing parts.

I'm standing in the middle of a bunch of mousetraps. A helicopter comes down to pick me up. As I grab onto the rope and am winched to safety, the downdraft pushes the next poster over into the mousetraps.

Re not needing to return, you don't *need* to return Kerballed missions either. Re EVA, it's fine once you know what you're doing. Maybe it's too powerful, but then flying on the Mun with your jetpack is fun. Edit: Regarding computery stuff, look at the kOS mod.

In the event that you manage to get periapsis and apoapsis equal to within the nearest metre (which would be impressive, though I can see a technique that would make it doable), the persistence file stores the eccentricity to 15 decimal places. You won't be getting that to all zeroes.And I agree that disabled fuel tanks and zero-thrusted SRBs should be allowable payloads. Otherwise the heaviest thing you can use for payload is the 1 1/2 ton Hubmax connector, severely limiting efforts to get a high score by payload mass.

One thing you can do, if you find yourself short of delta-V for the Moho orbital insertion, is use the encounter as a gravity assist to lower your solar apoapsis, reducing the delta-V needed for capture next time around. IIRC the real MESSENGER probe made three Mercury flybys, shedding speed relative to the Sun each time, before entering orbit.

So basically it's an ion craft using battery banks to sustain it through the burns? I think you'd do well to add an RTG to "trickle charge" the batteries on the coasts, so the batteries need only run one burn at a time. Anyway, as mentioned the PB-ION uses 18 units of electricity for every 1 unit of xenon. So if you know how much xenon you need to do a such-and-such m/s burn (bear in mind it'll be less once the craft is lightened by burning some xenon off), take 18 times the units of electricity. Of course, if you use stack batteries that'll make the ship heavier, meaning you need to use more xenon to get the same delta-V, meaning you need more batteries, and so on. You may find your idea impractical if the batteries just weigh too much. If you use radial batteries you'll circumvent the problem since they're massless in .23.5, but that feels a bit exploity for me. For realistic (ie not massless) batteries, I don't think it's a simple thing to calculate except by trial and improvement. Unlike the propellant, the battery charge doesn't work properly in the rocket equation because the "tankage" has mass but the "fuel" is massless.

I'm glad it was a small bucket. Taking advantage of the fog created by the liquid nitrogen, I rush the next poster armed with a rolled-up copy of the US Constitution.

Thanks for the suggestion. In the end I plumped for a prograde burn to put apoapsis at 20,000 km at the ascending node, then a combined plane-change and circularisation burn at apoapsis. By waiting many orbits before making that first burn I can get an intersect of a few hundred km around the asteroid's periapsis, which I'll fine tune on approach. For the common target orbit of 20,000 km circular with matched inclinations, this takes around 1100 m/s of delta-V, compared to 2300 m/s for the method I showed previously, and 2800 m/s if I tried to do a single burn from LKO to put apoapsis at the asteroid periapsis. That's more like it by cantab314, on Flickr In fact it looks like in this case I've got away without too much cost from not launching directly to inclination. Considering that 18 tons of the 150 ton ship was already at the station, and I can top-off the tanks at the 255 km orbit (rather than in a lower parking orbit), I may even have saved fuel.

Having no idea who Mr Mackey is, I stick my head in the sand like an ostrich. And it works. Deprived of its sand to hide in, the ostrich goes after the next poster.