herbal space program

On Kerbin, absolutely. I generally try to get it up to like 0.3 for my space planes, so that I can switch over sooner, but it's clearly the best way to get to LKO with the most possible dV and a useful TWR. On Eve however, I found that both the high gravity and the high altitude required to get the nukes to a TWR of even 1.2 made it so that I could not circularize on them without first lobbing my ship so high on regular engines that the better ISP was totally offset by the resulting gravity losses. But that's just me! Maybe I didn't try hard enough...

I'll be interested to see if you can get any value out of the nukes. I found that their <1.2 TWR in Eve gravity, even in vacuum, made them next to useless for an efficient lifter. The Wolfhound OTOH I found to be pretty useful.

I think I've done all of those things in one form or another except the Grand Tour, which I've started building for and abandoned several times, and and the 10,000-ton vessel, which would probably make my computer explode. There are also some things that I've done and consider important milestones that are not on the list, like building a large station on orbit and flying it somewhere besides LKO, and (I think most importantly) learning how to use gravity assists to get around. I would definitely put "using a single gravity assist to reach an interplanetary destination for significantly less dV than the standard Hohman transfer burn" under maybe level 4, and "using multiple gravity assists to get to one or more interplanetary destination(s) for much less dV than would otherwise be possible" under level 5. I think by far the hardest thing I ever did in the game was to do the Retro-solar Rescue challenge in a single stage, followed by getting to Moho orbit for under 3 km/s, which is still far from the record of only ~1800 m/s, using multiple gravity assists. I think the fact that those things didn't even make your list speaks to the level of specialization that often comes with being an advanced player, which makes trying to construct a linear scale of proficiency for such individuals difficult.

They call it the LT-2 landing strut!

There was a cornucopia of useful information here, but to me this seems like one of the potentially best nuggets. I'm going to see what happens if I mount my fairing base behind a service bay and in front of a pre-cooler!

Well thanks for trying anyway. I think I'm going to spend some time seeing what I can build that pushes the frontier of what's possible on Eve, and then maybe make a new challenge out of that once I've set some kind of a respectable benchmark. If nothing else, this whole conversation has definitely served to teach me all about Eve, so to speak, so it's been thoroughly worthwhile at least for me.

I'll heartily second that. The less mass you have behind you the easier it will be to slow down before you burn up. I have never actually landed a plane on Eve, but in other situations where I was coming in hot with a space plane, the ability to skate on the upper atmosphere, turning velocity into lift, seems to have made heating much less of a problem for me on final re-entry than it has been with more brick-like re-entry vehicles. I may have to try to build one just to see...

Depends on what the objective is I guess, but if it's the most science/buck, then sending one of each type of Kerbal, as well as a working rover with ISRU capability, multiple experiments, a science lab/storage units, and transmission capability, would allow you to collect surface data from multiple biomes in one mission and return it to Kerbin, and also to land at a much higher site than you ultimately collect your data from. If all of that can then be returned to Kerbin in one piece or at least staging off as little stuff as possible, you would be collecting a really large amount of science for very little money! As to a 300t ship being near-impossible to get to Eve, it's not really so hard, especially if you can land it under power and then refuel it by ISRU. Most craft that can make it off Eve will be able to SSTO on Kerbin.

Probably the best approach in terms of overall ROI anyway.

As I've been thinking about this, what interests me the most would be something along the lines of your previous Eve 3000 challenge, but with the mission being to take some significant payload from Kerbin to the shore of some sea on Eve and then return/recover it for the least total cost possible, i.e. allowing ISRU and counting recovery costs, with the provisos that (as before) you can't mine before you land on another body, and also that you can't offset costs by returning more fuel to Kerbin than you left with. That IMO would basically isolate the question of how close to making a practical SSTO for Eve can you get. Based on my experience trying to make a big low-dV lifter above, I suspect you could get very close to doing this from a high enough launch altitude, so if i were to try to relaunch my own challenge, I would allow the use of rovers to take the payload down to the water and back, as I think the challenges inherent in those on Eve and the need to bring them back to orbit for cost recovery would be balancing for those. I do think it would be something if somebody could manage to take a 15t payload from Kerbin to the shoreline on Eve and back without staging anything off, and I'm not convinced it's impossible. If you decide to take a pass, I might just give that a shot. I think what I had before was too tedious.

Right you are! I was turned around on that .

So I did some noodling around in my transfer window and resonant orbit worksheets, and here's the breakdown: The usual way, doing a Hohman transfer during the first K-D window (day 225), waiting for the next D-K window (day 1062), and then heading home (~318 days), will get you back to the KSC around 1,155 days after launch. Interestingly, the Hohman transfer orbit to Duna is also almost exactly 3:2 Kerbin resonant, so if you did this as a flyby you would end up back at Kerbin 3 years after launch, or 1,278 days later. You could however shave almost a year off of this by launching to a 2:1-resonant orbit that encounters Duna either on the way out or on the way back in. Not sure how close to the window your game is now, but you would probably have to do this at least a few weeks beforehand, actually you do it after!, h/t @Kryxal). Anyway, that would get you back to Kerbin in 852 days, which is roughly the fastest you can do it without shredding the pork chop with excessive dV. Hope that helps! PS: just for due diligence, I'll say that you could shave a few more weeks off of this by doing a retrograde DSM near your AP, that would lower your PE and cause you to re-encounter Kerbin somewhat sooner. But the price for those 4-5 weeks would be a very high-speed Kerbin re-entry, which may not be worth building for if you're trying to save money.

I mounted four of them to the tops of empty T100 tanks, offset from the main stack using another T100 tank and a couple of small hardpoints, all offset to the max: If you attach them at the other end, as I found out and assume you did, they don't work properly. If you just want to use one, you can likely figure out a way to mount it to the bottom using various struts, etc, but if you want to flip it pointy end-up you should do it by rotating the part underneath it, so that it remains attached by the bottom.

I never had any problems with that. They didn't disappear until I stopped completely.

Drogue, drag, all I know is they work pretty well for that purpose and if you don't have them on your Duna spaceplane, good luck landing it! I'd say they're more critical to keep you pointed in the right direction than to slow you down per se, but they do that too. Since you seem knowledgeable about current bugs, is multiple Sepratrons causing everything to Kraken out on the launchpad a known thing? I was trying to build a demonstration ship consisting of a wad of Sepratrons mounted on octagonal struts behind a 2.5m fairing, by way of demonstrating their breathtaking TWR, and the second the craft went live on the launchpad there were loud explosions and it went twirling through the air, before anything had even been staged. The Sepratrons were not clipped into each other AFAICT, and making it so none of them were resting on the ground didn't help. Does this sound familiar to you or anybody else?

Thanks! I will see what I can learn using those...

All depends on what you're trying to launch! One little bit of advice I can give you is that flipping that aft heat shield is a good idea, even though it's a pain to construct it that way in the VAB, because it's very aerodynamically unstable the other way, i.e. it will try to flip you even though it's behind you. Otherwise that looks like a good re-entry package to me (from what little I can see !).

Hello all. In the process of trying to design the lowest-dV Eve lifter possible (current personal best 5,240 m/s, 28t to LEO), I've come to appreciate how useful a well-designed fairing can be for reducing drag. One thing that kind of surprised me during this exercise is that when I made my 5m fairing wider than 5m by the smallest amount possible on its first segment, with the intent of protecting more aft parts from incineration on my fiery ascent, I found that it actually seemed to reduce overall drag! I expected to pay a price for that thermal protection, but instead it actually seemed to make my lifter accelerate faster than it did with a completely flush fairing. Is that an actual thing? By which I mean, can you actually reduce surface drag on more aft rocket parts by deflecting the flow outward with a slightly higher-diameter fairing above? It sure seemed like that to me, but I have no way of proving it. Thanks!

I'm happy to take a look at it and see what advice I can offer if you're getting fed up, but I don't want to spoil it for you either

It's a great booster, especially if you're trying to save money, but if money is no object slapping multiple Vectors on a MH 2.5m engine plate is even better!

Sepratrons!

Welcome to Eve! Yeah, I pretty much never try to quicksave when I'm in any kind of highly dynamic situation, because that's what usually happens. It happens on Kerbin too if you're pushing the structural limits of an airframe, like if you save at Mach 2 and 3 km om a spaceplane ascent. But on Eve it's baked in!

I don't have any special insight into the code, but in my experience pointier is generally better. I have seen people use intakes as well though, because their drag is calculated differently. Really pointy fairings are what seems to work the very best for me.

So it looks like this whole Eve Lifter dV optimization conversation is going to get its own challenge, thanks to @Laie, but since strict lowest vacuum dV-to-orbit looks like It won't be a category and I spent a lot of time on this, I thought I'd post it here as my final entry for that criterion: This is my best ascent so far for this 650-ton, 5m-cored lifter. The part that gets to LEO weighs just over 29t. All engines are Vectors, one for the upper stage, 12 mounted on engine plates under the big tank, and 24 more on the short-burning side stacks. The smaller fairing at the front has a 2.5m heat shield behind it, and is expected to explode sacrificially on the most optimal profile, but it actually didn't on my best run so far, as can be seen by the still-intact base on the orbiting upper stage. The side stacks boosted me to 300 m/s, roughly TV for that ship, in the first 12 seconds, and from there I remained locked to prograde at full throttle from my initial ~10 degree inclination until around 20 km, where I was just south of 45 degrees. I then slowly lowered throttle until I was essentially coasting at 25km. to an AP of around 50, slowly pitching down, and opened it up again around 45km. Anyhow, total vacuum dV expended from SL to LEO: 5,258 m/s (now 5,202 on latest attempt), flown without any kind of autopilot assistance. I'm sure I can still do better than that even without an autopilot, but as it is I think this proves that large tanks are in no way inherently worse than smaller ones for this sort of thing. But we can perhaps continue that discussion in a new venue...

I don't think it's really helpful to carry that kind of TWR all the way up, but in those first few seconds I think that getting to near TV as quickly as possible does make a real difference. My biggest problem right now is that I'm having a very hard time initiating my gravity turn so that I can stay locked to prograde all the way. For me it seems like a matter of 1-2 seconds between starting too early and burning up and starting too late and hitting my 90km Ap still pitched to 45 degrees. Any deviation from dead prograde to try to correct it during that phase is prohibitively costly in terms of drag, so it seems like you just have to hit it perfectly.