tavert

There are a few things you can do to manipulate how fuel drains. If fuel tanks are mounted inline with "fuel cross-feed capable" parts between them, then those tanks get treated as one unit and drain starting with the furthest tank away from the engines. If tanks are placed radially, side-to-side, then they don't get drained unless you start connecting fuel lines to them. Decouplers are one of the few things I know of that aren't fuel cross-feed capable, so for inline tanks you can try putting decouplers between your fuel tanks and routing fuel lines around them to manually control fuel feed order, but it would make your plane less rigid. CoD = center of drag

SkyRender, do you have a single central thread for your system map? Some of your numbers need revision. Dres takes closer to 600 m/s more than Kerbin escape to transfer to, and about 1500 m/s to capture at. And if you can capture into a circular low Mun orbit for only 210 m/s from a LKO Hohmann transfer, I'd like to see how. It's usually closer to 260-280 for me. Protractor and alarm clock might be using different methods to calculate the windows, not sure. I think the phase angles were added to MechJeb2 somewhat recently, you might have to select the target planet first and make a custom info window. The numbers there aren't in countdown form, but you can easily determine the number you're waiting for from ksp.olex.biz. All of these methods are really only good for near-circular and low-inclination planets. For Moho, Dres, and Eeloo especially, phase angles are going to be a ways off. In the MechJeb2 maneuver planner, select the planet as a target then make maneuvers for "transfer to another planet" then "fine-tune closest approach" and you should get much closer, as it's using the actual elliptic trajectory, the real minimum distance, and a real Lambert solver for the fine-tune option.

Another thing to note is the manned aircraft cockpits have less drag than most other parts in KSP. Due to the way KSP's drag model currently works, for the best stability you want low-drag parts up front, and high-drag parts (ram & circular intakes, SRB's, and oddly some of the nosecones, tricoupler, etc) towards the back. Your planes look very cool, but having the cockpit in the back like that hurts your stability. Also aerospikes are low-drag parts as well, so you may find replacing them with one of the conventional rockets will be more stable (just be careful you don't hit the nozzle on takeoffs/landings).

You're not interjecting when the conversation started and ended 8 months ago. Mind the old threads, eh?

Lots of useful math here: http://en.wikipedia.org/wiki/Kepler_orbit And when you change sphere of influence, the game is using the patched conic approximation

Ooh, gorgeous! Nicely done.

Breaks down completely without FAR I assume? And what's the takeoff mass? Inquiring minds and all...

Okay sadly the delta-V maps lie, it took 1500 m/s to capture in Dres orbit which is almost twice what I was expecting. The takeoff took about 130 m/s less than the map indicated, but I was still a fair bit short of being able to get back to Kerbin, much less be able to do a powered landing when I got there since I specifically chose not to bring a parachute. I may try the landing again, this time going straight from a grazing hyperbolic trajectory into a landing instead of capturing into low Dres orbit, but I don't think it'll save me enough to make it back home.

Cache found: http://webcache.googleusercontent.com/search?q=cache:4JS6md32-fAJ:forum.kerbalspaceprogram.com/archive/index.php/t-37071.html+&cd=1&hl=en&ct=clnk&gl=us It was nhnifong. I like how the forum purge has turned us all semi-senile.

Your airbreathing code has been unbelievably useful, thanks for contributing that! I found a strange quirk with intake management that probably stems from KSP's general bugginess when it comes to nested symmetry, I have an issue filed on Github but it's minor since you can workaround it by rebuilding with symmetry arranged differently... I've also been playing with your KSP-scripts a bit, some good stuff in there. Back to the topic at hand, I've developed a gut feeling that there can be such a thing as too high a TWR on planets with atmospheres, and these tiny things get there with 20 kN of thrust as they use up fuel. I should go back and test this theory with the 1.26t SSTO, since that can be repeatably flown with MechJeb to compare settings. Oh and I realized that the MechJeb2 part provides 5 units of electric charge but doesn't draw as much power as a probe, so it's unfairly lengthening the lifetime of the probe without using any batteries or solar panels.

The 1.26 I initially had was stealing someone's design, probably yours, I forget who originally posted it in the old challenge. I seem to remember seeing the patch you refer to, but again I forget where... was it on the MechJeb 2 github? I was limiting acceleration to avoid going too ridiculously fast down low.

Going lighter can get you almost all of the way to orbit with just the jet. Here's an example I did for a different challenge a couple months ago, I think it was even my first post: http://imgur.com/a/uGXCu That had a separate tiny stage to circularize so that my Mun lander was counted as "payload" just for the rules of that old challenge. With the SRB required for this challenge, the mass budget is pretty tight if you're going to put something manned on top. You can get a slightly lighter lander, almost as capable, if you go for the small radial Rockomax engines and a drop tank design, as shown here: http://imgur.com/a/kQK17#0

Okay, since you asked (and I posted before finishing the mission), here are pictures of what I've done so far: http://imgur.com/a/RIVua#0 So superficially it looks similar to your craft, but several key differences: - To fuel the jet I used a Mk2-to-size-1 adapter and 2 round-8 toroidal tanks. This gives 100 liters of liquid fuel for 0.772t mass. The Mk1 tank that you used is small and conveniently cylindrical, but it is has a worse mass fraction than the aircraft parts. It's heavier and carries less fuel than the Mk2 fuselage (or a pair of adapters). - I have less fuel in my final stage, and less mass throughout. Your craft is so heavy (relative to what 1 jet can lift at zero speed) that a significant amount of your jet fuel fights against gravity losses, and you spend more time at low altitudes where the jet's not as efficient. I also cut down on mass as much as possible by skipping the parachute (so even if I make it back to Kerbin I'll still need to have enough fuel left for powered landing. It should only need ~200 m/s for that, and cutting out the mass of the parachute gives me some of that for free), using the tiny struts to mount my intakes instead of the larger girders, 2 tiny decouplers instead of 3 medium ones, and the aircraft landing gear (which are currently massless in flight, and can stand harder landings too) instead of legs. - Ridiculously many intakes, so the jet alone gets me past orbital speeds in the high atmosphere. I basically circularize an "orbit" at roughly 40 km altitude, then keep going even faster to get the apoapsis up into space.

I've got a manned mission heading to Dres. Started at 9.56t on the pad, and with lots of intakes and MechJeb2 controlling the jet throttle perfectly, I got up to a 45 x 158 km unstable orbit before even using the SRB. Timing your takeoff properly means there's no need to stabilize the orbit before firing the SRB to get wherever you're going. I got almost 1400 m/s delta-V from the SRB alone, it's a little less than 200 m/s more to get on a Dres encounter, and I've still got almost 3 km/s left. That should be enough to capture, land, and hopefully take back off and return to Kerbin with. I'm not sure yet, I'll post pictures after I finish up the mission. With a probe you might even be able to get a Laythe sample return? Guessing on that, haven't actually done the design or run the delta-V numbers for the mission plan.

I wonder if perfect piloting could pull it off with some number of the Round-8's replaced by Oscar-B's...

Your number got me curious, and I just proved myself wrong. I guess most of the entries in the past challenge were done in 0.18, so the lightest probe core was 0.01t heavier and this would not have been possible. Did I just fly your design? http://imgur.com/a/dqOI6#0 Because of the staging-from-the-top, I had to turn around to ditch the first 6 tanks. So I flew the ascent semi-manually. I had MechJeb doing "Show navball ascent path guidance" with gravity turn starting at 10km, ending at 50. I also had the throttle control set to limit to terminal velocity and limit acceleration to 40 m/s^2. Turned off the acceleration limit after hitting 70km apoapsis and had the maneuver planner do the circularization burn, though MJ2 doesn't get quite as perfectly circular as MJ1 did. Oh, and I got to orbit quick enough that I could've even gone without the solar panel.

Fair enough, just saying there's precedent that sets a high bar (or in this case low), which is now unfortunately much harder to reference or be aware of.

This was done pretty much to death before the forums died. The answer is 1.26 tons: http://imgur.com/a/IbXlv#0 You really only need 3 parts, a probe, an FL-T200 tank, and a single Rockomax 24-77 engine carefully rotated and mounted so the center of thrust lines up with the center of mass. The positioning is a little tricky. I added MechJeb, and 2 cubic struts at the bottom so it doesn't fall over on the pad. A launch clamp could also work for that, and you might want to add a battery and/or solar panels if you can't get to orbit in 5 and a half minutes. And here's the craft file, without MechJeb: https://dl.dropboxusercontent.com/u/8244638/MinOrb%206a%20stock.craft You'll notice if you fly it manually that the thrust is still a tiny bit off-center, but it's easy to correct for.

Have to be several times bigger than Jupiter to sustain fusion. Although the KSP planets are so tiny yet heavy relative to the real ones, their density might actually be up there...

Not if there's no oxidiser in the atmosphere... numerobis, welcome back and FYI from the middle of page 1: I was actually able to get a safe landing in Eve's ocean by using the pair of nuclear transfer engines to help slow down instead of ditching them on re-entry. I added another tiny last stage and more thrust on the penultimate stage and got to orbit successfully from sea level, but had basically no fuel left in orbit and no docking port. My last stage is so tiny that even the small docking port will cost a lot of delta-V, so I'll have to play with things a bit more to see whether I want to leave a transfer stage in Eve orbit and rendezvous with it to get back to Kerbin, or add more stages for direct-ascent return. My ascent vehicle, after dropping the transfer engines and the transfer/landing tanks and parachutes, is around 35-36 tons. It's using around 11500 m/s delta-V to get to orbit from sea level, but its TWR is lower than optimal (as can happen when you're trying to minimize total mass). More tweaking to do, I think. The mountaintop landing and rover route will definitely end up winning out here, I'm building something that works at sea level for the challenge of it.

Very cool kolt16. The low-profile look resembles real mining equipment - kinda like the debris removal trains they use with tunnel boring machines.

So I built something that weighs 63 tons at Kerbin liftoff. 6 jets for getting things into orbit, 2 LV-N's with enough fuel for the Eve transfer, then 3 aerospikes, 2 SRB's, and a little probe final stage to get back off Eve. Wasn't sure if it had enough delta-V to do the ascent from sea level or have enough left over to return to Kerbin, but I sent it off to Eve for a test anyway. When I got there I found having aerospikes and 2 full SRB's meant lots of tumbling during re-entry, standard parachutes broke off at deployment (with no hope of having the engines pointing the right way). I went in and hacked the quicksave to replace them with drogues to see if that made a difference, it did mean a lot less tumbling, but then I realized that 3 aerospikes gave a TWR less than 1 at the surface of Eve (my landing mass was about 38 tons), so there was no hope of landing safely on water (or whatever liquid Eve's oceans are made of). I think I'll go back to the drawing board, this time replacing the solids with something I can use to help with landing. I might replace aerospikes with T30's to avoid the drag tumbling, I'll have to play around some more.

The number for Dres in that diagram is at least a few hundred m/s too small.

It's also annoying to have to carry huge solar panels and make sure your apoapsis ends up on the day side. Jet ascents can cover a significant fraction of the circumference of Kerbin before getting into space. The small orange radial engines (Rockomax 24-77) are great for small maneuvers, and they don't weigh much at all.

Looks as if you got the transfer delta-V numbers from one of the existing maps, right? I don't know who originally created those, but some of the numbers (Dres especially, probably also Moho and Eeloo) need revision. They're quite a bit optimistic due to inclination and eccentricity. The real transfer numbers will depend on timing, such a simple graphical representation can't quite capture as much information as something like a full porkchop plot, but they should at least try to be close to the best-case numbers. And the Eve takeoff number is too pessimistic. Judging by successful designs, it ranges from around 8000 m/s from the highest mountain to something like 10000 m/s from sea level. That's assuming efficient TWR and trajectory.