capi3101

It's a good one. Not wholly foolproof but definitely useful (particularly when it comes to determining correct phase angles). It'll get you close to an intercept at the very least; I imagine it would be extraordinarily powerful if you were to team it up with Enhanced Nav Ball (that one's on my short list these days; maybe I'll grab it once I wrap up this challenge). http://kerbalspaceprogram.com/protractor-for-ksp-0-18/

I want to say no; on the other hand, it is possible to re-pack chutes for re-use, so it should be possible to reactivate an engine that's been previously activated and shut down previously via staging. You might try going ahead and setting up your new staging, switching to a different craft or getting completely out of the game, and then trying again.

Kerbin's atmosphere has a scale height of 5,000 meters, with an atmospheric pressure of 1 atmosphere at the surface. Isp in the game is setup so that its minimum level is reached at an atmospheric pressure of 1 atmosphere (so for places like Jool and Eve, which have substantially higher surface atmospheric pressures, an engine will still have the same Isp at the surface as it does on the surface of Kerbin. No, that's not how it would work on RL, but let's move on anyway. The formula for Kerbin's atmospheric pressure with height looks like this, according to the wiki: Pk = 1atm * e(-a/5000), where Pk is the atmospheric pressure, atm means "atmospheres" (=1013 millibars or 101.3 kiloPascals), a is altitude and e is the inverse natural logarithm. So atmospheric pressures on Kerbin look like this (rounded to five digits): 1,000 m: 0.81873 2,000 m: 0.67032 3,000 m: 0.54881 4,000 m: 0.44933 5,000 m: 0.36788 6,000 m: 0.30119 7,000 m: 0.2466 8,000 m: 0.2019 9,000 m: 0.1653 10,000 m: 0.13534 15,000 m: 0.04979 20,000 m: 0.01832 25,000 m: 0.00674 30,000 m: 0.00248 35,000 m: 0.00091 40,000 m: 0.00034 45,000 m: 0.00012 50,000 m: 0.00005 55,000 m: 0.00002 60,000 m: 0.00001 65,000 m: 0.00000 70,000 m: (in vacuum) Since Isp scales linearly with height, what you can do to guesstimate it at a particular altitude is take the difference between the two given Isp ratings, multiply it by one minus the atmospheric pressure at the altitude, and add that amount to the atmospheric Isp rating. As a formula, it looks like this: Isp = Isp(atm) + ((Isp(vac) - Isp(atm)) * (Pk(sfc) - Pk(current)) Let's take the Skipper for example: Isp is 300 at the surface and 350 in space. 350-300 = 50. At 3,000 meters, the atmospheric pressure is .54881 atmospheres (as per above), so we have the following: Isp(3000 m) = 300 + ((350-300) * (1-.54881) = 300 + (50*0.45119) = 300 + 22.5595 = 322.5595 If you want to know the specific altitude at which the Isp is exactly a specific amount, you have to work both the atmospheric scale formula and the formula above backwards. Like so for the Skipper: Isp = Isp(atm) + ((Isp(vac) - Isp(atm)) * (Pk(sfc) - Pk(current)) 320 = 300 + ((350-300) * (1 - Pk) 320 - 300 = 50 * (1 - Pk) 1 - Pk = 0.4 -Pk = -0.6, therefore Pk = 0.6 Pk = e(-a/5000) ln(Pk)= -a/5000 a = -5000 * ln(Pk) a = -5000 * ln(0.6) = -5000 * -.51083 = 2,554.128 meters (the answer to your original question, if I'm not mistaken) From those atmospheric scales above, you can see that by about 25,000 meters any engine is just about at its vacuum Isp. This is, incidentally, completely consistent with the structure of Earth's atmosphere; standard surface pressure is 1013 mB, at 10 kilometers - the tropopause region - it's around 10 mB.

If you're tipping over on landing, try redesigning your lander so that you shorten and widen it - this lowers the lander's center of mass and increases the surface area around which the lander can pivot after touchdown, both of which makes the design more stable. For example - let's say your lander uses a single FL-T400 tank. If you've got access to fuel lines, change that out to four FL-T100 tanks, one in the center and three outboard. Run fuel lines from the outboard tanks to the center, and put your lander legs on the outboard tanks. You'll have successfully widened your lander without changing its mass in the process. Now, if you are just using an FL-T400 as your sole fuel tank, you need to watch your fuel level as you land. Most basic low-tech landers (a Mk16 chute, Mk1 Command Pod, FL-T400, LV-909 and 3-4 lander legs) will reach "bingo fuel" around 80 fuel units. If that's what you're using, think about heading back to Kerbin when it reaches 90, and when it gets to 80 either hit space or plan on not returning to Kerbin.

Not yet; I've been keeping myself busy between launch windows by sending probes out to the major SOIs I haven't visited yet. Giving Protractor a proper shakedown.

Sent probes to encounters with Moho and Dres. Launched another one with the intent of sending it into orbit around Gilly. Still waiting for probes to get out to Jool and Eeloo, still just killing time until the next Duna window comes up.

No problem. I have no issues with proving myself wrong mathematically aside from having to swallow my (largely non-existent) pride. It'll help me build my own craft better in the long run.

Actually, let's do one more example; we're going to reverse the delta-V targets from my last example - 2,275 m/s in the first stage, 1,517 in the second and 758 for the third. Five tonnes to orbit. Just curious. Third stage: 758 dV target, 5 tonne payload, .05 tonne decoupler. My guidelines suggest I need 167 kN of thrust, so let's say 8 24-77s. That's .72 tonnes of engines, deadmass is 5.77 tonnes. Isp is 250. M = 2.462348 tonnes, ~5 FL-T100 equivalents. 8.5825 tonnes full, 6.0825 tonnes empty, 844 m/s delta-V, 1.84 TWR. I probably could've knocked off a couple of 24-77s. Second Stage: 1517 target, 8.5825 tonne payload, .05 tonne decoupler. Guidelines suggest 286 kN of thrust, so let's say an LV-T45 and six 24-77s. That's 2.04 tonnes of engines, deadmass is 10.6225 tonnes. Isp will be 289.59 since we've got an mixed engine combo (combined thrust divided by the sum of the ratio of thrust to Isp for each engine). M = 9.249457 tonnes, ~17 FL-T100 equivalents. 20.188 tonnes full, 11.688 tonnes empty, 1,552 m/s of delta-V, 1.62 TWR. First stage: 2275 target, 20.188 tonne payload, .05 tonne decoupler. Guidelines suggest 673 kN of thrust, so let's simplify and say a Skipper. 4 tonnes of engines, 24.238 deadmass, Isp is 300. M = 37.23006 tonnes, ~67 FL-T100 equivalents. 57.8755 tonnes full, 24.2755 tonnes empty, 2,544 m/s of delta-V, 1.14 TWR (low...) Final Total Delta-V is 2544+1552+844 = 4,940 m/s delta-V. This process gave us a 57.8755 tonne rocket to lift five tonnes to orbit; final payload fraction is 8.639%, the worst of the lot. Okay - I think this whole thing has been a useful demonstration. I definitely know I learned something today... An SSTO for five tonnes, incidentally, would use a single Mainsail, have a launch TWR of 1.24, and would weigh 123.55 tonnes total - a payload fraction of 4.047%. It'd need ~200 FL-T100s equivalent (or three Jumbo 64s + one X200-8).

Alrighty - my turn. 758 m/s in the first stage, 1,517 in the second and 2,275 for the third. Five tonnes to orbit. Third Stage: 2275 dV target, 5 tonne payload, .05 tonne decoupler, 1.5 LV-T45 for an LV-T45 = 6.55 tonnes. Isp is 320. y = e^(2275 / (320 * 9.81)) = 2.06413 Md = (y-1)x /(9-y) = (2.06413-1)6.55 /(9-2.06413) = 1.0049 M = 9Md = 9.0443, ~16 FL-T100 equivalents. 9 tonnes fuel => 15.55 full, 7.55 empty, 2,268 m/s delta-V, 1.31 TWR (low but acceptable) Second Stage: 1,517 dV target, 15.55 tonne payload, .05 tonne decoupler. Let's go with two LV-T45s and an LV-T30 for 615 kN thrust and 4.25 tonnes engines = 19.85 tonnes. Isp is 320. y = e^(1517 / (320 * 9.81)) = 1.62133 Md = (y-1)x /(9-y) = (1.62133-1)19.85 /(9-1.62133) = 1.67148 M = 9 Md = 15.04333, ~27 FL-T100 equivalents. 15.1875 tonnes fuel => 35.0375 full, 21.5375 empty, 1,528 m/s delta-V, 1.79 TWR (high) First Stage: 758 dV target, 35.0375 payload, .05 decoupler. Let's go with three LV-T30s and one LV-T45; that gives us 845 kN thrust and 5.25 tonnes engines = 40.3375 tonnes. Isp is 320. y = e^(758 / (320 * 9.81)) = 1.27311 Md = (y-1)x /(9-y) = (1.27311-1)40.3375 /(9-1.27311) = 1.45745 M = 9Md = 12.8317, ~23 FL-T100 equivalents. 12.9375 tonnes fuel => 53.275 full, 41.775 empty, 763 m/s delta-V, 1.62 TWR (high) Final Total Delta-V is 2,268 + 1,528 + 763 = 4,559 m/s delta-V. This process gave us a 53.275 tonne rocket to lift 5 tonnes to orbit. Final payload fraction is 9.385%. Long and the short of it: Seanner was correct - you want your delta-V roughly equal in each stage. Shows what I know......at least I hope I've shown the usefulness of being able to work Tsiolkovsky backwards. Also looks like I've got a guideline for a stage thrust guestimate now. Take your payload and divide it by .03; the result is roughly where you want to put your level of thrust. Dividing by a larger number gives you higher TWR, by a lower number gives you a lower TWR.

Well, how about an example? Let's take five tonnes and get it into orbit with a three serial stage booster. Let's further stay we want the third stage to have an initial TWR of 1.6, the second stage to have an initial WR of 1.4 and the first stage to have a launch TWR of 1.2. If we want to divide the delta-V evenly among the stages, that's 1,517 m/s of delta-V per stage (assuming 4,550 to orbit like the delta-V map indicates on the wiki). My divisions for three stages would be 1/6, 1/3 and 1/2 (actually 1/6, 2/6 and 3/6 but I'm simplifying here), so that would be 758 m/s in the first stage, 1,517 in the second and 2,275 in the third. In both cases, I'll be using the Tsiolkovsky equation backwards to calculate fuel requirements and the assumption that M=9Md. Tsiolkovsky: dV = ln(M/Md) * Isp * g dv / * Isp * g = ln((M + x)/(Md + x)) = ln((9Md+x)/(Md+x)), where x is the dead mass. e^(dv / (Isp * g)) = (9Md+x)/(Md+x), set y = e^(dv / (Isp * g)) y = (9Md+x)/(Md+x) y(Md+x) = 9Md+x yMd + yx = 9Md + x yx - x = 9Md - yMd (y-1)x = (9-y)Md Md = (y-1)x /(9-y) Okay, so three stages at equal amounts (1,517). Five tonnes, plus a stack decoupler (0.05 tonnes for the TR-18A), plus an engine. We're shooting for 1.6 TWR and we have no idea what our final weight will be, so let's just use an LV-T45 engine for this stage; that'll add 1.5 tonnes to our mass so far. So we have 5 + 0.05 + 1.5 = 6.55 tonnes for the third stage, which has a delta-V target of 1,517 m/s. We don't know if we'll be out of atmosphere when we light the stage, so you plan for full atmo and use the 320 Isp for the engine. Plug in the values: e^(dv / (Isp * g)) = y, y = e^(1517 / (320 * 9.81)) = 1.62133 x = 6.55, Md = (y-1)x /(9-y) = (1.62133-1)6.55 /(9-1.62133) Md = 0.55155 M = 9Md = 4.96396 tonnes. So the third stage would need 4.96396 tonnes of fuel mass to produce 1,517 m/s of of fuel. There's not a clean way of getting exactly that much fuel in the stage, but we can go with an equivalent of 9 FL-T100s for 5.0625 tonnes of fuel, giving the stage (working Tsiolkovsky forwards now) 11.6125 tonnes full, 7.1125 tonnes empty, a delta-V of 1,538.92 m/s and a TWR of 1.76. So far so good. Second stage - same delta-V target, we've got 11.6125 + 0.05 of deadmass so far (the third stage and payload, plus the decoupler). Let's try a pair of LV-T45s on this stage, use BZ-52s to attach them and then a long girder to attach the assembly to the first stage. 0.6+1.5+1.5 = 3.6 tonnes of mass, so the deadmass is 15.2625 tonnes. Atmo Isp is 320. Plug everything in: y = e^(1517 / (320 * 9.81)) = 1.62133 Md = (y-1)x /(9-y) = (1.62133-1)15.2625 /(9-1.62133) = 1.285198 M = 9Md = 11.56678 tonnes, + 15.2625 = 26.82933 tonnes (TWR = 400 / (26.82933 * 9.81) = 1.52; we overshot the TWR target, but not by much. You may question the engine configuration here; I actually did this equation first with a Skipper and wound up with a TWR of 2.31 - way too high. A single LV-T45 wouldn't cut it, though. As for fuel configuration, you want 21 FL-T100 equivalents - say five FL-T400s with an extra FL-T100 in the center stack. 11.8125 tonnes of fuel gives us 27.025 tonnes full, 16.575 empty, a delta-V of 1,534 m/s and a TWR of 1.51. Still cool. First stage - same delta-V target. 27.025 + 0.05 tonnes deadmass, let's try a Skipper for this stage, so 4 tonnes of engine gives us 31.075 tonnes deadweight. Isp is 300. y = e^(1517 / (300 * 9.81)) = 1.674409 Md = (y-1)x /(9-y) = (1.674409-1)27.025 /(9-1.674409) Md = 2.487978, M = 9Md = 22.39180 tonnes + 27.025 = 49.4168, 650 / (49.4168 * 9.81) = 1.34, so TWR is good. Closest fuel configuration is 40 FL-T100s equivalent, or five X200-8s (one X200-8 and one X200-32). 22.5 tonnes fuel, 49.525 tonnes full, 29.525 empty, delta-V = 1,522, TWR = 1.34. Final total delta-V is 1,522 + 1,534 + 1,539 = 4,595 m/s of delta-V. This process gave us a 49.525 tonne rocket to lift 5 tonnes to orbit, a final payload fraction of 10.096%. Not bad. I'll need to make my example next; this post has taken a while to type so I'll get back to it when I can.

Redesigned my Sandstone series probes; next time I try to go to Jool, I might actually have enough delta-V to stick around for a bit. I haven't given up on my goal of putting a probe around every moon in the Joolian system, but I'm pretty sure the planned atmospheric dive is scrubbed. Got a similar probe to a confirmed 700 klick encounter with Eeloo in a game year from now. Next up is to send a probe out to Dres, then a pair for Gilly and Eve. Basically just killing time until the next Duna window comes up and I can get the Constellation Program back on the road. Alarm Clock is making that easier; I feel like I've got an actual space program going on now. Missed a Moho window; kind of annoyed at Alarm Clock for that one.

Ah, the demo...I cut my teeth on the demo. Your final design is what I rather crudely call a "Phallus 7", a tall, narrow lander that does the job but has a tendency to tip over if you land on a grade. Bingo fuel level on a Phallus 7 is 80 liquid fuel units. Once you get down that far, either get back into orbit or plan on not coming back. Start thinking about an abort when you get to 90. Now, I know that the smallest tank in the demo is the FL-T400, so I'll forgo my usual advice of "use four tanks to shorten and widen the stack", because I know you're already doing the best you can with what you got. That said, three FL-T400s set radially outboard, with fuel lines going from the outboard tanks to the center and your lander legs attached to those outboard tanks will improve the lander's stability. Just saying. Do not switch to an FL-T800 just for the sake of having more fuel. Trust me on this one...I didn't name that ship the "Flying Death Trap 7" for no reason... You need to use your radar altimeter when you're landing; it's a gauge that looks like this: You can get to it via IVA ("C" key, "C" key to get back) and it is present in the Mk1 Command Pod in the demo. Use it to gauge the altitude of the surface. Starting from a 14k orbit, give yourself a quick puff on the thrusters to bring your periapsis to about 5,000 over your target zone. When you almost get to periapsis, do a hard burn retrograde (make sure your speed gauge is set to "Surface" first) to bring that retrograde marker to vertically up (i.e. you want to kill your horizontal velocity as much as possible). Then kill your burn and go IVA, and watch the radar altimeter. When it starts to twitch downward and gets to an easy mark (say 2,000 or so), switch back to staging view and compare it to the altimeter; you know the surface is 2,000 meters below (so if the altimeter says 4800 when you switch back, you know the surface is at 2800). The rule for the Phallus 7 is that you don't want to be going much faster than 1 m/s per 10 m above the surface if you want to avoid lithobraking. Wait until you're about to that point of no return, then burn; don't burn the whole time, or you'll waste fuel. Watch your fuel level as you descend; I've already told you what to do if it gets to bingo fuel. If you do happen to add those extra tanks like I mentioned, start burning sooner. Your lander should have enough fuel to get you back to Kerbin without problems but your craft will also decelerate slower. Good luck.

You're calculating payload fraction correctly - in the case of my earlier post, payload mass/total mass = 0.04, thus payload/0.04 = total mass. I use a low TWR because I fly SSTO rockets a fair amount. To fly them, you want to the same thing you'd do with asparagus staging and shuck off thrust as it's no longer needed. With an SSTO, you can't shuck off thrusters, so what you have to do is use the throttle. In general, by the time of the gravity turn at 10k, an SSTO rocket that started with a 1.2 launch TWR is close to 2.0 TWR - you start that low so you don't have to muck with the throttle during that lowest 10k, when the thrust is needed the most. SSTO rockets are inefficient - I'll just say that outright; you can lift the same payload with substantially less fuel on an asparagus or even an onion design. The sole advantage is ease of construction. I came up with those fractions largely through observation. I use KER for construction and flight, and I noticed with people's asparagus designs that it's the later stages that carry the bulk of the design's delta-V. You think about it and an asparagus-staged rocket is actually pretty much the same as a serial staged rocket, it's just that you can use the engines in those later stages while the "lowest stage" is still on going. Anyway, I applied the same principles to serial stage rockets for a number of forum challenges I was involved in, and they worked as anticipated. As far as payload fractions are concerned, I only concern myself with the final payload - the bit that I want to put into space - and treat the booster as one big piece. I don't have a hard and fast rule for payload fractions for each stage, because I mainly concern myself with "how much fuel do I need, given the mass of everything else in this stage, to give it the amount of delta-V that I want?". That sometimes means that I have to adjust the engine combination I'm using to make sure I've got enough thrust and recalculate (another reason why I prefer to do it all in one stage if I can). I should probably develop guidelines for multi-stage rocket payload fractions per stage; it would make that initial stage engine selection so much easier...

For interplanetary flight, you're going to want to be using the LV-N Atomic Rocket Engine; only reason why you wouldn't want to use it is if you're doing something for a challenge. It's an efficient engine (800 Isp) that produces a reasonable amount of thrust. Build your transfer stage like this: This way you avoid having to deal with those pesky LV-N shrouds that knock off pieces of your rocket when you activate the stupid things. The delta-V map that Vanamonde posted in the first page of this thread is your friend; use that to plan, and add more than what it says because unless you're using flight assistance mods you're going to muck it up. Go with 125% of the values listed. And plan your mission backwards. Let's say you want to do a Duna landing. So you need to design a lander that can go down and come back up again, minimum. Will it need also need to transfer back to Kerbin, or are you going to include a dedicated tug that does the transfer that the lander will dock to? You pick out the pieces of what you're going to need for the craft - command part, chutes for return, panels/batteries or RTGs, lights, lander legs, decouplers, engines, RCS and docking ports if you're going to dock it to the transfer stage - add sum up the mass of all that, everything but the fuel tanks. You've got a delta-V target for your craft, and you've got a "deadmass" of all the necessary equipment. You then work Tsiolkovsky backwards, adding that dead mass to both mass terms in the equation. You can make the assumption that M=9Md, because the way all but two of the liquid fuel tanks in KSP are designed (the exceptions being the Oscar B and the Round 8), the full-to-dry ratio is 9:1. Solve the equation for dry mass, then use that same relationship (M=9Md) to determine how much fuel you need to include for the delta-V you want that part of the mission to have. And then you pick out a combination of tanks that gives you roughly that amount. Just keep on doing that for each stage. If and if that sounds like too much mass, wing it; many KSP players just do it and pray for the best. Sometimes they get lucky, other times they don't. You might also want to check this out; its a discussion on the merits and proper use of asparagus staging. For now, it remains the most efficient way of lifting payloads in KSP. And if all else fails, there's these.

Sorry to hear that. I'll add my two cents on the thread you've got going.

And that point where gravity drag and air drag balance one another out is generally somewhere around a TWR of 2.2 while you're still in atmo. Consider then that atmo goes up to 70,000 meters... That same drag force in the lower atmosphere, incidentally, is probably what's causing your stack to disintegrate when you go full burn. Between the thrust and the drag there's more dynamic pressure being placed upon your rocket than it an handle. Solution's the same either way - either change the design to generate less thrust, or throttle back. Next question: why do most folks say "shoot for 1.6 or 1.7 at launch" with asparagus? It's so they can average out their ascent somewhere around that magic 2.2 TWR mark without having to adjust the throttle.

Lose those forward winglets, unless you want to see this thing flip over mid-launch.

Definitely too much thrust at launch then. For an 1184.5 tonne rocket, an optimal amount of thrust is somewhere between 18,592 and 19,754 kN. You need to bring it down almost by half. Or just use 1/2 throttle.

In general, if I'm building an SSTO rocket booster, I go with a payload fraction of 4% and a launch TWR of 1.2; that becomes 8% for onion and a launch TWR of 1.5. In general serial staging is somewhere between the two. Example time: Your payload is five tonnes. Okay, with 4% payload fraction, you need a rocket that has a total mass of 125 tonnes (5/0.04=125). You therefore need a booster that has 1471.5 kN of thrust available to it (9.81*1.2*125 = 1471.5). That's a single Mainsail, of course. Mainsails weigh six tonnes, so 11 tonnes of your rocket is deadmass - the rest (114 tonnes if I'm not mistaken) is fuel. Now, I would take that much and start divvying it up to see what tank combination comes out the easiest (as it is, you've got three orange tanks plus six tonnes, and three orange tanks isn't exactly stable of course). I would set it up as a center stack with four outboard stacks, the four outboard stacks feeding into the center stack, and each stack containing an X200-32 and an X200-8 tank. If necessary, add an FL-T200 tank to the central stack or possibly two FL-T100s attached radially somewhere along the stack. The secret to serial staging: use Tsiolkovsky backwards. To both the mass and drymass portions of the equation, add the previous stage's "dead mass" (i.e its weight) as well as the dead mass of the current stage (everything but the tanks). You can also simplify things by setting M = 9Md; this is an assumption based on the fact that every liquid fuel tank in KSP with the exception of the Oscar-B and the Round-8 has a 9:1 full-to-dry mass ratio. Set delta-V goals for each stage based on the number of stages you're using, like this: 1 stage: 1/1 (all 4550 in one go) 2 stage: 1/3 for the first stage, 2/3 for the second 3 stage: 1/6 for the first stage, 1/3 for the second, 1/2 for the third 4 stage: 1/10 (455 m/s) for the first stage, 1/5 (910) for the second, 3/10 (1,365) for the third, 2/5 (1,820) for the fourth. And so on. Hope that helps. I can provide additional examples if you wish.

1) With a 1.2 TWR on liftoff and a 4% payload fraction, you can get stuff into orbit with one stage. Pretty much the same goes no matter what kind of rocket you're building - though it's 8% payload fraction and around 1.5 TWR for onion staging, 15% payload fraction and 1.6-1.7 TWR for asparagus. Basically, build your payload first, then put it put on the pad without a booster. Go to the map screen and get the mass, then go back to the VAB and start designing the booster around what you discovered. Keep the gee meter right at the top of the green meter as you go. Example - say you've got a thirty tonne payload. If you wanted to launch it on an SSTO rocket, you'd need something that had a mass of around 750 tonnes (30/.04 = 750). You know automatically that you need a launch thrust of 8829 kN or so (750 * 1.2 * 9.81 = 8829), so six Mainsails. Six mainsails weigh 36 tonnes, your payload's thirty, from 750 tonnes that leaves 684 tonnes (750-36-30 = 684), which you then divide into seven stacks (a centerline and six outboard, the engines would go outboard and you'd run fuel lines from the center to outboard); each stach would therefore need 97.7 tonnes of fuel. That's two orange tanks, an X200-32, and an X200-16 in each stack. Add whatever other accouterments you'd like (RCS and a probe core for deorbiting, winglets, nose cones, etc). Oughta do the trick. You can generally build simple SSTO boosters for payloads up to about 45 tonnes; after that they get complex. Flying them requires you to adjust the throttle downward as you go. One other thing to consider - if you want to do a staged rocket, try to have each subsequent stage up progressively add a greater fraction of the total 4550 delta-V to orbit requirement. I go with: 1 stage: 1/1 (all 4550 there) 2 stage: 1/3 in the first stage, 2/3 in the second 3 stage: 1/6 in the first stage, 1/3 in the second, 1/2 in the third 4 stage: 1/10 in the first stage, 1/5 in the second, 3/10 in the third, 2/5 in the fourth And so on. Also helps to consider for purposes of building boosters that the full mass of almost every liquid fuel tank in KSP (with the exception of the Oscar-B and Round-8) is exactly nine times its dry mass. When using Tsiolkovsky, you can add the "dead mass" to both the M and Md parts of the equation, and then substitute M=9Md and run it backwards. Be sure to add your engine mass and decoupler mass to the deadmass of any subsequent stages. 2) What's your launch TWR? If it's above 2.2 (i.e. the gee meter jumps up above the green area the moment you hit the space bar), throttle back - you've got too much thrust. You might also try putting launch clamps on the booster - they've become increasingly necessary in 0.22. And then you might also want to put your engines into the ground in the VAB; the game will automatically adjust them to ground level for the launch.

OP: Looking at your original design, what you had going on there was a classic case of attempting to merge the stack after branching. That tends to lead to a wobbly ship (think insufficient strutting) and then if you're lucky enough to get it into orbit, something like this happens: You can get around it by placing decouplers on the bottom of the engines, then docking ports (standard Clamp-O-Trons) below that, then a second set of docking ports below that. What happens then is that your ship will "dock" to the lower stage as soon as the physics engine releases it prior to launch. You wind up with a solid connection that way. You've found a workaround though, so that's just something to file away for the future. You'll probably have to build the bottom part of your craft as a subassembly if you try the docking port trick (or at least the bottom part of the engine " sandwich"). As others have suggested, you can use I-Beams to extend your lander legs to the point where they stick out below your engines. You wind up with something that looks kinda like this: In this case I needed the extra clearance for a bottom-mounted docking port mounted on the bottom of a piece of structural fuselage. Its a design for Duna being tested on the Mün. Anyway, something like that would work with nukes. If you don't have I-beams, you can try the long girder segments that become available with Advanced MetalWorks on Tier 6 (300 pts) of the tech tree. You might also try just putting together normal girders end to end and see if that does anything for you (normal girders are, of course, Starting Tech). One more technique for you to try in the future is this: Advantage here is that you wind up without those pesky LV-N shrouds. You probably don't have BZ-52s, but Tail Connectors (available with Aerodynamics on Tier 4) can do the same job if you flip them around so the flat end is facing downward (you'll have to strut the top bit), and even girders can do the job if you turn them flat against the side of the tank (girders allow fuel flow without adding fuel lines, incidentally). You might have to turn on parts clipping to get it to work (ALT-F12 to bring up the debug menu). Anyway, there's some different techniques for you to try out. Good luck.

Well, there are advantages - the main one being that you can get away with a lighter lander (you're not hauling all that fuel you've set aside for the return trip down to the surface just to haul it back up again). It's also safer; if something goes wrong, you can still send somebody back. That was the rationale used by the Apollo program for the LM design anyway.

230 m/s by 3,000 m? Yeah, your launch TWR is too high; you want it somewhere closer to 1.6-1.7 for an asparagus-staged rocket. By 3,000 meters you only want to be going about 130 m/s or so. Looks like you've got four LV-T30s per asparagus booster - that's 860 kN of thrust. Try ramping it down to three apiece (645 kN) thrust or just use a Skipper if you have them (slightly higher thrust, lower Isp, smaller part count) and see if that helps. You want the gee meter to be right at the top of the green zone just before stage separation. Can't really tell the mass of your payload; pics are too dark. You wouldn't happen to know it, would you?

That's an impressive looking boat. Good luck, Krakens suck (got double Kraken'd last night over on the Constellation Challenge myself).

FOR IMMEDIATE RELEASE -- YEAR 1, DAY 65, 19:00:00 KST KEBSTON (AP) -- NASA has confirmed the apparent loss of the Constipation XI and Constipation XII spacecraft, blaming a phenomenon known colloquially as a "Hell Kraken". As explained by chief NASA scientific consultant Dr. Guenter F. Kerman, this form of the general Deep Space Kraken phenomenon is so named because of the effect it has on the graphical user interfaces of the controllers on the ground. "Ze navball and most of ze UI will remain, but ze rest of ze feed turns black and ze altimeter will remain at 666 666 m". NASA is already making plans to launch a second mission sometime later this year, and has vowed to work with the design team who built the Constipation craft, Crapsack Skunkworks, in order to prevent this type of disaster from occurring again. President O'Bummer Kerman, who has previously shown general apathy towards the space program, ordered a pizza after hearing the news, and was quoted as saying "Well, that kinda sucks". ### I'll be trying again when the next transfer window comes up. This sucks...I had Constipation XII set up for an aerobraking encounter (15k) with Duna just after it left Kerbin's SOI. Had too much else going on, I guess (pathfinder missions to Eeloo and Jool going on concurrently).