Temstar

Yes I agree this is the by far the most viable method method for launching even larger payload, however: 1. I can't design rockets and share them with this method , each one has to be a custom job 2. Really it's actually a case of "launching six rockets at the same time" sort of thing, only the six of them are stuck together with struts.

Moho does have one thing going for it though - frequent transfer window and rapid transit time. Transfer windows for Moho opens up something like every 30 days and it can take as little as 25 days to reach. So one option for manned Moho landing is just to send tanker after tanker to Moho to build up a stockpile of fuel as well as a lander. Then once you're ready just send a ship to Moho with enough delta-V (say 7000m/s) to get into Moho orbit and then reach the Moho propellant depot. Then you can transfer the crew over to the lander for the landing, then get back to the depot refuel the ship they used to reach Moho and head back to Kerbin. I did something similar with my Moho rover mission: So I went the rover/lander towards Moho and like a lot of us here in this thread I underestimated the amount of delta-V required to reach Moho. I used up all of my fuel and managed to get into a 50km x 180km elliptical near-polar orbit. So with my lander stuck in Moho orbit I decided to launch a refuel mission to Moho to salvage the situation: Upon reaching Moho I had a difference in orbit of the two craft by something like 100 degrees, so another big burn in the order of 500m/s delta-V was required to align the orbits. Upon docking I was able to deliver about 822L of bipropellent to the lander. 822L out of the original 4800L delivered, so 5/6 of the fuel was spent just to get that last 1/6 to Moho. After refuelling I undocked the tanker and set it to crash into Moho with the remaining RCS fuel. Then I managed to land the lander on Moho and release the rover. So manned mission to Moho could use a similar structure. Except instead of going first you send tankers to Moho first to build up the stockpile of fuel there 800L at a time. Only once there is enough fuel at Moho do you then send the manned craft.

So this is what I propose. First we launch this into LKO: Fill it with 134 crew, either on the ground before launch or afterwards via ships going up, depending on how realistic we want to do this. Personally I have a lot of confidence in the launch vehicle so I feel comfortable enough to load the space colony on the surface. Next we launch this space only booster: Planetary Manoeuvring Engine Colossus. Basically a PME Zeus stretched by adding a 6400L tank. We dock the two together, refuel it and it's ready to go to Laythe. The resulting ship is 187.486 tons, 60 tons of which is fuel. The ship is about 300 parts. Using Tsiolkovsky rocket equation: delta-V = Ve * ln(187.486/127.486) delta-V = 800 * 9.81 * 0.3857 delta-V = 3026.95m/s So that should be plenty to reach Laythe. TRW when fully fuelled is 0.23, which is pretty low but should be workable. Upon entering Jool I say we then suck all the remaining fuel out of Colossus and put it into the colony, then undock the Colossus and crash it into Jool to make the rest of the ship more manoeuvrable.

It's all stock, you can test it out here, that particular one is called Nova: http://forum.kerbalspaceprogram.com/showthread.php/24787-0-19-1-Zenith-rocket-family It's built using engine clustering technique. I used to have a thread explaining how to do it but it got eaten by the forum purge. I'll recreate it soon but basically you stick Cubic Octagonal Strut or Radial Attachment Point on the bottom of tanks using the symmetry tool (they're surface attachable) and then you stick engines onto those.

The challenge seems rather prescribe in terms of ship design. Why not just "the mission is to send 200 guys to Low Laythe Orbit, knock yourselves out" and let those who want to take up the challenge try to figure out the layout of the ship?

No no, I'm not proposing to land all 134 colonist, I'm proposing the following stages: 1. Get the space colony with its 134 passengers to Laythe 2. Get some surface colony stuff setup 3. Drop half of the colonist down to the surface colony To drop the people down we don't need SSTO, just one way landing pods that can land say 8 people at a time in two hitchhiker tanks. Each of these landing crafts will only need a tiny amount of fuel and two R24-77 radial engines for the small deorbit burn and then land on parachutes + landing legs. Rovers can then drive out to meet them and drive them back to the surface colony being setup. So each of these landing crafts will probably be around 8 tons (5 tons of which are hitchhiker tanks) and 9 will be used to land 72 people on the surface. Alternatively if we wait for Kerbal seats in 0.20 we can probably drop even more colonists in one load by building our own "home built" tightly packed non-pressurised passenger module. SSTOs are only needed if we need to actually send someone UP to orbit.

That's always been a concern of my regarding this project from the start. Seems too... Macross? Anyway to get a more colonising feel I have to suggest the colony idea again. How about we send 134 people to Laythe:

Oh damn, it's that old missing strut/fuel line bug with subassembly again. Yes there are three fuel lines pumping from the centre spine to the three stacks: If they're gone then they need to be recreated for the booster to work correctly. You don't have to have the exact same placement of course, just as long as you run three lines from centre to the three stacks and it will work.

Oh wait, when you say " in front" do you mean "from below the target's orbital altitude" or "from the leading edge side"? Either way you slice it though, you can get an encounter (and thus a gravitational assist) from either direction regardless of weather the target is a superior or inferior planet. Here's I'll show you both types of encounter using the Mun as an analogy: Here we have a Mun encounter from below the Mun's orbital altitude, that is at the moment my craft will enter Mun SOI it will be somewhere between the Mun and Kerbin. In this case Mun's gravity will serve to slow my craft down relative to Kerbin, although since the phase angle of this encounter is not very good I won't get the nice figure 8 free return trajectory back to Kerbin. If I were to coast on this trajectory to the Mun and then perform a Mun orbit insertion I will insert this craft into a retrograde Munar orbit. Here I've executed a tiny prograde burn, so small the fuel usage was less than 1L. By arriving at the encounter point 1 minute and 18 seconds earlier I will intercept the Mun and smash right onto its surface. Here I've excuted a further tiny prograde burn, you can see that the oxidiser and fuel gauges have gone down by 1L each. This burn allows me to arrive at the encounter point before the Mun reaches the same area, thus what happens is my spacecraft crosses Mun orbit in front of the Mun, then the Mun catches up to me from below and drags the spacecraft forward with its gravity, resulting in that huge Kerbin orbit that will send the spacecraft to near Kerbin escape velocity. If I were to perform a Mun orbit insertion following this trajectory I will insert this spacecraft into a prograde Munar orbit.

That's not true, you can approach either in front or from behind for any planets both superior and inferior, it's a simple matter of arriving at the same point in space slightly earlier vs slightly later, you can easily switch between the two types of encounter with minimal change in delta-V after Kerbin ejection. For example, here is an approach to Jool from Kerbin from behind. Jool's massive gravity then pulls the spacecraft forward for a huge increase in prograde velocity, hence a gravity assist:

It's certainly possible and if I were to guess it would be around 80 tons to Duna orbit. I did something similar with Nova where I sent 58 tons to Mun orbit instead of the 110 tons to LKO. Duna is a little bit further in terms of delta-V compared to Duna and Supernova's engines are bit less efficient so I reckon it will just about manage 80 tons. That said launch vehicles are optimised for launching payload to LKO and not interplanetary travel so I wouldn't recommend it - it's too unwieldy to fly for a long trip. 80 tons to Duna or 160 tons to LKO, you have to ask yourself: can I ditch the rocket in LKO and design a interplanetary transfer stage that can send 80 tons to Duna while weighing 80tons or less itself? I'm guessing with nuke engines the answer would be yes. Actually originally I did start with four 2.5m stacks around the 1.25m centre spine with the aim of 200 tons or more. But I find that for a payload of this size 2.5m parts no longer hold up. The combined forces of a 200ton dead weight being forced down by gravity against the 2G or more acceleration coming up from the engines is just too much for some parts to take. It took a lot of very precise strutting finally make a payload that wouldn't crush it's own 2.5m core while under acceleration so I felt that the 4x design was too unwieldy and with a margin of error for failure too small for comfort. Hence why I settled down on the 3x design.

So what's it about? Space junk taking out ISS and people trying to get back down?

Good news everyone, the Supernova SHLLV is released:

It's back in 0.18.4 when I first had the thought of "let's build the largest rocket possible with a single 2.5m core". The result was the Nova SHLLV capable of 110tons to LKO. From Nova then came the Zenith rocket family covering the whole spectrum between 15-110 tons. But then as with all things in engineering, when you build something really big people immediately start to wonder about how to build another one even bigger. Nova is no exception and I received quite a few messages proposing even bigger lifters. So I started seriously thinking about a Supernova. The problem is Nova was specifically designed with the goal of "largest 2.5m core possible". When you look at the back of its core stage: ...you'll see the problem of making it bigger - basically there's nowhere to put any more engines under a 2.5 stack, even after adding the tail connections to increase the area. The only option left is then to use a bigger stack. Without resorting to 3.75m mod parts the only way to get a fatter stack is to create "synthetic" stacks made up of multiple stock stacks. Thus this was my solution to the problem: A synthetic stack made up of a 1.25m stack at the centre surrounded by three 2.5m stack clustered around it, enough area for much more engine power than the 2.5m Nova core. And this is the final result: Supernova Super Heavy Lift Launch Vehicle 160.6 tons to LKO (75km x 75km) Payload fraction: 15.01% Thrust at lift off: 18,000kN Cost: $369,560 Cost/ton to LKO: $2301.12 Part count: 267 You may have noticed one other difference from the Zenith family of rockets - no 1.25m engine clusters. This was a deliberate design choice: I noticed that many 100ton+ rockets have part counts well above 300. The problem with a lifter using up that much part is that a payload that weighs more than 100 tons is itself going to take up A LOT of parts. If you're lifting 160 tons to orbit and your rocket is 350 parts and you load another 350 part of payload on top you're going to get something too laggy to fly for most people's computers. What is the point of designing and sharing a booster if it's a painful experience to fly? Engine clusters whilst highly efficient is very part heavy. The 12 engines of Nova core alone takes up 32 parts, if I put three Nove cores together that's almost 100 parts before I add struts. Mainsails bring the part count down at the cost of efficiency. Compared to the Zenith family Supernova has a lower payload fraction than all of them. However on the other hand mainsails give excellent value for money in terms of thrust/dollar. Thus being purely powered by mainsails Supernova has a lower per ton cost to LKO than all members of the Zenith family. Let's have a look a the ascent profile: Before lift off, hit action group 1 twice to turn off gimbling for all booster engines. Turn on ASAS, throttle up to max and hit ignition. At about 2600m your first set of boosters will run out, stage them. You'll notice that Supernova stages mainsail boosters in threes rather than the more conventional pairs. This is partly due to the size of the rocket and partly due to the geometry. At around 9000m your second set of boosters will run out so stage them too and then start to pitch down to 45 degrees for gravity turn. At 26000m your last set of three boosters will run out. At this altitude and without any control surface left you will usually have some roll motions. Turn off ASAS and turn on RCS to correct the roll. From this point onwards I recommend switching off ASAS and switch on RCS for all steering manoeuvres. Supernova core accelerating to high sub-orbital velocity. With the target AP reached, throttle down engines and coast to AP. I noticed one interesting thing - if you instantly turn off the throttle with X the sudden jolt can knock loose/ explode some of the nose cones on top of the 2.5m stacks. It doesn't seem to cause any damage or affect the structural integrity of the rocket so I wouldn't really worry about it, but if you want to avoid it then throttle down with Ctrl instead of X. Supernova just before throttling up for final circularisation. Payload released. As with the Zenith rocket family, Supernova is equipped with probe core, RCS system and electrical system for self-deorbiting after payload release to ensure compliance with the Clean Space Policy. Craft file: http://www./download.php?kcs8op66cpst9yc

Even so, Buran can loft 30 tons to LEO compared to shuttle at 25 tons. One of the reason why is because it doesn't try to return any big heavy (and expensive due to reusability) main engines back to the ground. Energia is a fully functional rocket by itself without Buran and can loft 100 tons to LEO. It demonstrated this capability once by lofting Polyus (a 80 ton Soviet death star, no seriously it had a laser cannon and everything) into orbit: Energia had an interesting story. Just like lots of us in this thread Glushko looked at the NASA shuttle and told everyone it was a really bad idea. But his bosses insist that America built the shuttle to drop nukes on the USSR from orbit and they had to have one too. Now Glushko had this obsession with building a base on the Moon and he knew that to do that he first needed a Saturn V sized rocket. So instead of simply copying the shuttle like his bosses wanted he put all the big engines on the "External Tank" instead of the orbiter and used two liquid fuel boosters instead of SRBs. The result was a moonshot sized rocket that vaguely looked like the NASA shuttle's ET+SRB that could loft 100 ton of dead weight (eg, Buran which didn't have any engines) to LEO. Of course since none of the thrust actually came from Buran the Energia doesn't actually care what that 100 ton of payload is, thus instead of Buran you could put any thing else on there (say, parts for a moon base?). Glushko was gambling that once the bosses see that Buran didn't actually have much purpose they would switch focus back to the moon and he can then jump up and say "oh hey, we just happen to have this 100 ton to LEO rocket in production to send stuff to the moon, isn't that convenient!" And it probably would have worked too, if it wasn't for the fact that Soviet Union fall apart.

The shape of the Proton was selected to facilitate rail transport. Since the rockets are going to be built in Moscow and transported to Baikonur by rail for finally assembly each individual piece much fit within existing railway wagons and platforms. What Chelomei did was he built a centre core with a single large tank used for oxidiser. This tank was designed with the largest possible diameter that could be transported by rail. Then once it arrived at Baikonur it's mated with a ring of segments each holding a smaller fuel tank and engine. Thus you then have a large first stage with all components rail-portable yet require only minimal assembly at Baikonur. And yes if you're think Proton kind of looks a bit like the UR-700 I posted above, pat yourself on the shoulder - Proton is actually UR-500. Chelomei designed his rockets so that both UR-500 and UR-700 shared the "maximum railway diameter" tanks. Only difference is UR-500 would use one in its first stage while UR-700 would use 18 of those tanks in the first two asparagus stages and a UR-500 first stage as its third stage.

Fuel crossfeeding is a very old concept, in fact Mikhail Tikhonravov first came up and wrote about the idea in 1947. The concept is pretty simple though and many people since Tikhonravov have interdependently rediscovered the idea. For example Chelomei came upon the idea again when he designed the UR-700 rocket as an alternative to the N1 moonshot: (on the top left is UR-700 at lift off, in the middle is it again with the outer ring of asparagus boosters jettisoned) but it's never been put into practice at this point, though as others have mentioned Falcon Heavy will have a go at it. The thing that makes it so overwhelming popular is because the engines in KSP are at least 4 times heavier than real life rocket engines for the same thrust, and fuel tanks in KSP are 10 times heavier than real life tanks for the same capacity. Because engines and tanks are so heavy in KSP the advantage of getting rid of them early becomes huge. In real life rocket hardware make up a tiny fraction of the fully fuelled weight of the rocket so the benefit of getting rid of them early is not nearly as pronounced.

You can construction multi-part ships in space currently, in the sense that you can build each section of the ship on the ground and launch them, then join them up in orbit. This however doesn't really require an orbital shipyard. You're suggesting building of an entire ship from raw materials on a orbital facility. In the sense that the sections are not joined by docking port but regular part to part connection with struts and everything. This isn't possible in the game yet though I have seen one rather buggy orbital construction mod that simulates this by teleporting a ship directly from the launch pad into orbit and deducts the parts needed in it's construction out of a parts cache in orbit.

I find docking quad docking ports not particularly difficult. But then again I always leave ASAS on during my docking procedure so I can concentrate only on translation after lining up the docking ports. Apparently my way of docking is very unusual given the amount of complaints I see around here with docking with ASAS, docking with unbalanced RCS and docking with unbalanced RCS with ASAS. But NERVA is solid core? I thought the whole point of a solid core is that the working fluid is not in direct contact with the fission fuel and so is clean?

NERVA is closed cycle solid core. They wouldn't be able to do this while the engine is running if it's open cycle: My own rule for LV-N is simple - no destructive re-entry on Kerbin, Duna and Laythe. I tend to mostly design reusable crafts using the LV-N (Mun surface-orbit taxi, interplanetary motherships). Alternatively I would crash them into places where radiation wouldn't matter such as surface of the Mun or Eve. On rare occasions I would also design recovery rigs for LV-N tugs:

Hindsight is 20/20, so some leeway should be given to the original decision to go for the shuttle. The unfortunate thing is after NASA decided to go for the shuttle and proved that spaceplane technology could work (per launch cost not withstanding) everyone and his mother caught onto the spaceplane fad and it resulted in a long string of dead ends for other space programs trying to imitate: Buran Hermes Tianjiao HOPE In fact even in KSP, just hop on to the Spacecraft Exchange and have a look around at the ratio of spaceplanes to booster rockets. Spaceplanes are dime a dozen on there even though the majority achieves little other than getting their lone pilot to LKO and maybe dock with a station.

In that case you still should use asparagus staging, since the highest "delta-V/part" ratio parts are big orange tanks and mainsail, and the most efficient way to use these two is asparagus staging.

It's not the drag, is the TWR of the engines and the dry weight of the tanks. In the real world: engines have TWR approaching 100 (94 for F-1, 137 for NK-33, 160 for Merlin 1D) dense fuel tanks can have a dry weight as little as 1% of the fully fuelled tank In KSP: highest TWR liquid fuelled engine is mainsail with a TWR of 25.5 bipropellant tanks have a dry weight ratio of 11% In KSP both engines are fuel tanks are so inefficient that for the same level of thrust you need engines 4 times as heavy in KSP. And for the same amount of fuel you need fuel tanks more than 10 times as heavy. With tanks and engines so heavy the advantages of getting rid of them as early as possible becomes huge. Where as in the real world a much higher proportion of the rocket's weight are fuel. With the rocket hardware being only a tiny fraction of the fully fuelled rocket's weight there is much less incentive to ditching parts early.

Assuming we're talking about taking off from surface or Kerbin to reach orbit, and without resorting to jet engines - yes, asparagus staging booster is ALWAYS the best staging system. See this is the issue here. If all the stacks (most importantly the centre core stack) are the same size then the TWR will progressively go down and this is a potential problem area that messes up people's asparagus staging rocket. The solution then is simple: have a centre stack that's more powerful than the boosters. Let's look at the TWR for this craft: For a payload of over 110 tons a 593 ton rocket underneath manages to deliver it to a 75km x 75km LKO with an relative consistent TWR for all stages, how do I manage this? With a very powerful core stage: Here we see the powerful double cluster of the core stage. It's powered by eight LV-T30 and four LV-T45 for a total of 2520kN of thrust, compared to the 1500kN of each of the rocket's mainsail boosters. Basically when it comes to working out TWR for an asparagus, we have to balance a number of factors. Let's see how we go about designing a well balanced and efficient asparagus staging rocket to illustrate what I'm talking about. 1. First is payload fraction. An exceptionally well engineered asparagus staging rocket can manage over 16% payload fraction, far higher than any other type of staging and thus making it unquestionably the most efficient type of staging. When efficiency is the goal you should aim for at least a payload fraction of 15%. And so given a known payload - say 44 tons. You already know how big that rocket is: 44 * 100/15 = 293 tons So for a payload of 44 tons, you should be able to lift that into orbit with a rocket weighing 249 tons for a total stack of 293 tons. 2. Second, now that we know how big of a rocket we are designing we can figure out how to engine this rocket. The number that's important here is TWR at lift off. Given that the ideal ascent profile calls for a TWR of 2 before Max Q, you want lift off TWR to be below 2 so that by the time of first staging event your rocket's TWR goes above 2 and the two ends balance each other out. I find that the ideal TWR at lift off for an asparagus is between 1.6 - 1.7. The Nova rocket above as we can see have a lift off TWR of 1.67 So, given 293 tons: 293 * 1.6 * 9.81 = 4599 kN 293 * 1.7 * 9.81 = 4886 kN Thus, we know that our rocket that can lift 44 tons need to have enough engines at the bottom for a lift off thrust of 4599kN - 4886kN 3. Last, we need to figure out exactly how we can engine this rocket to give us 4599kN - 4886kN and using an asparagus design. As we discussed above for a more consistent thrust we need the centre stage to be more powerful than the boosters. But exactly what ratio of core stage thrust vs total thrust should we use? There is no clear answer here but my own experience tells me the ideal ratio is somewhere around 22%. That is 22% of the rocket's thrust should come from its final stage while 78% comes from the asparagus staged boosters around it. So given our 4599kN - 4886kN thrust what engines should that be? well 22% of that thrust is 1012kN - 1075kN. This number clearly shows us what engine we should use: 4 x LV-T30 = 860kN 1 x LV-T45 = 200kN For a total of 1060kN which falls in our range. Thus we know for our 44 ton payload rocket, we should use a core stage powered by a five engine cluster of four LV-T30 and a centre LV-T45, which also gives us a good steering authority via vectored thrust. So now that we know our core stage, that leaves 3539kN - 3826kN of thrust that must come from the asparagus boosters around it. Exactly how many boosters is up to personal choice - the more you have the smoother your TWR curve and the closer you approach the "ideal staging rocket" that never carries any dead weight in terms of empty tanks or excess engine. On the other hand the more boosters you have the more complex the rocket becomes to engineer. I find that the ideal number for 2.5m core stage with 2.5m boosters is six. Six is the maximum number of 2.5m boosters you can cluster around a 2.5m core using standard long decouples, if you want more you have to resort to much more complex engineering for diminishing return which I find is not worth it. So say we settle on 6 boosters around our 1060kN core. This gives us 590kn - 638kN per booster. Again the choice is clear: 2 x LV-T30 = 430kN 1 x LV-T45 = 200kN For a total of 630kN per booster. Thus we now know the engine configuration of our 44ton payload rocket: a core stage of 4 LV-T30 and 1 LV-T45 for a 1060kN six boosters of 2 LV-T30 and 1 LV-T45 to give 630kN per booster The total thrust at lift off is thus 4840kN. These engines weigh a total of 30.5 tons. Our payload is 44 tons, so according to the 293 ton number we worked out in section 2 this leaves us with 218.5 tons for mostly fuel + other hardware for the rocket. Your job then as a designer is then simply work out how to distribute that 218.5 tons of mostly fuel so that each stage has reasonable TWR. The end result will look something like this: As it turned out asparagus staging is so good we didn't actually need 218.5 tons of fuel to lift 44 tons of payload into orbit. The final rocket turns out to be 234 tons including the engines for a payload fraction of 15.89%. Better than the 15% target we were aiming for and far better than what's possible with other types of staging. The above process is what I followed when I designed the Zenith rocket family:

I have some good news on the basic design of DCMS. It was based on an interplanetary ship I designed for my manned Eve landing project, Tada got an exclusive early release of it for BABYLON. The long awaited Eve transfer window has finally arrived on my save and here are some screenshots of the successful Eve transfer burn: Tanker undocking from the Eve stack Throttling up to max with phase angle and ejection angle aligned. Full thrust half way through the burn. Now obviously as you can see from just the shape of the payload docked to the interplanetary mothership the CoM is not centred. The arm with the long nuclear tug is heavier and further away than the arm with the rover and the ship has a tendency to drift right under thrust. Yet there's enough control authority to easily manually correct that drift during the burn. The DCMS has even more torque than my mothership as it uses a three man pod rather than a lander can so there should be no problem bringing asymmetrical load to Jool. Transfer burn complete, total fuel usage is about 1841L of liquid fuel and 2251L of Oxidiser. So I think we can say the general design of the mothership is validated.