Temstar

There's no reason why a booster has to follow a payload, and similarly there's no reason why you couldn't design a family of launch vehicles specifically targeting low cost for career mode for a wide range of different payload size. In fact that's what's done in real life - rockets are designed for a payload class, not for individual payloads. As for specific implementation of Vector based launch vehicle consider this: Nine Vectors in three winged boosters, lifting about 100 tons to LKO. Once payload is released the boosters can then make a deorbit burn and glide back to KSC. Cost per ton to orbit under $600, I don't actually use this launcher in my career game, because as it turned out Vector's bigger brother the Mammoth, with even higher TWR makes for an ever better engine for reusable launch vehicle on account of lower engine dry mass to orbit:

Those are hardly good argument for colonisation. One would think a good solution to the problem of nuclear war is disarmament (SALT, Comprehensive Test Ban, etc), and solution to running out of fossil fuel is to find alternative energy source (4th gen reactor, fusion, renewable etc). Using those problems as justification for colonisating other planets is the "all you have is hammer" school of problem solving. If you want a good reason for coloisation it has to be along the line of "we're colonising mars because we need lots of boots on mars to do *insert economic activity here*, and that will make us a shed load of money". Then that colonisation effort will really get going. Otherwise you'll never convince people to pay for colonisation in the long term, weather those people be investors or tax payers. Alternatively, if you pitch the idea to the government that we need a science station on Mars, something not unlike a more advanced version of what we have at Antarctica for the purpose of research and gain some political capital while we're at it too, and I have a way to achieve this cheaper than what we previously thought it will cost us then this might actually happen. But if you start rambling on about domed cities and terraforming and you ask for 500 billion dollar budget then you'll just have a repeat of the 90 Day Study that will hurt the credibility of the manned space flight program.

But that's trivial to design though, it's very simple to have a 2.5m or 3.75m stack decoupler at the bottom of your rocket with crossfeed enabled, then mount some number of Vector under this decoupler so that once the rocket has been deorbited you separate the engines from the rest of the stack and return all the engines in a bundle (in other words, the ULA Vulcan school of reusability) to Kerbin. Vector is even particularly suited for this purpose since it has high impact tolerance and so doesn't require landing legs. But that's never going to be the case. We don't have a lack of choice if you want an engine or combination of engines to provide 1/4 of the thrust of a Vector. Instead if you have a Vector sized or Mammoth sized launch vehicle job then those two engines are going to be the best, because have the best TWR in the game and pretty good Isp to boot. Again, if you find a Vector is providing four times too much thrust, it means you've just discovered an opportunity to build a rocket four times bigger.

But you know that's never going to be the case, since it's not like we have a lack of choice when it comes to small engines for small rockets. But go to the other end of the scale where you do need to lift large payloads then Vector and it's big brother Mammoth are king. So for a rocket that needs several thousand kN of thrust Vector and Mammoth gives you the required overall TWR with the least amount of engine. Vector stands out particularly because it packs an enormous amount of thrust into a tiny physical package, and that package is explicitly made so it can be easily clustered. For a given physical footprint Vector or Mammoth (or even better, Vector glued onto Mammoth's empty centre space) gives you the most bang for the least amount of real estate. I'm not saying Vector and Mammoth are overpowered. In fact given that the description specifically says they are technological breakthrough being the first staged combustion engines and the fact that they sit at the end of the tech tree even justifies their high thrust and relative high Isp in my mind. But calling their best in game TWR for bi-propellant engines as not an advantage is plain wrong.

No that's not quite correct either. While thrust by itself is not that useful, TWR is a critical number when it comes to engines. The fact is higher the TWR the better. There's no such thing as an engine with too high of a TWR, there's only rockets that are too small for their engines.

Would you consider a two stage craft: a SSTO to carry a manned spacecraft to LKO. The spacecraft then goes to Minmus to do crew exchange, then return to LKO to dock with the SSTO which then lands back at KSC? The reason being that taking all that wing and landing gear and jets to Minmus is a big waste of delta-V.

I did specify commercial reactor. I realize that research reactors and reactors specifically designed for breeding plutonium existed before bombs since the plutonium had to come from somewhere. The idea is that if kerbals can make reactors for NTR then their ground based reactor tech would already be fairly advanced. Certainly advanced enough to support a large bomb building program that Orion might require.

Haha, yeah ICBMs by their nature have some pretty unusual manufacturing requirement. Back in the early days of ICBM when they were still fueled by RP-1 the original specification for this fuel had looser requirement than it does now, as a result rocket engine people were complaining that if the RP-1 fuel could be refined to a higher standard (to avoid polymerization when used in regenerative cooling) the rockets will work better. The military didn't want this though because they argued that in a war situation where refinery could be targets making the fuel standard too strict will affect their ability to fuel more missiles. But then it was pointed out to them that if there ever was a situation that called for "FIRE ALL THE ICBMS", there will soon be no "refinery capacity problem" to worry about anyway.

It will be a flop, there's just no business case for it. Yes I know, all eggs in one basket etc etc and I agree, having human presence all over the solar system is great insurance against being wiped out by another dinosaur killer rock. But still, money talks and b......t walks. If there's no economy reason to go to Mars then the money will not be forth coming and nothing will get done. I've yet to see one decent economic reason why we should go to Mars. All that "let's mine precious metals and trade with Earth" type talk are rubbish when you consider the vast cost of sending up spacecrafts to do the mining and then return your produce to Earth. It would be cheaper to just mine ore on earth, even at lower concentrations. On that note He3 mining on the Moon is a rubbish proposal too. Never mind the huge infrastructure you need in place to process vast amount of regolith needed to collect the He3, the fact that we can't even get D-T fusion to work means we're very far away from needing He3 for fusion power plants. The only plausible commercial exploration of space that I've seen is something like this: It's a robotic craft that goes to a NEO with ice. Grapple it, drill down into it, pipe some hot steam into it to melt the ice, suck up the resulting water and bring it back to propellant depot to be cracked into hydrogen and oxygen. We all know how useful a propellant depot is, and given the cost of lifting propellant out of Earth's gravity well this source of water could be very competitive against tanker rockets from earth. Unfortunately it doesn't help Mars. Although we now know there's lots of water on mars, some of it even liquid it's sitting at the bottom of a planet sized gravity well and is unlikely to be economical against NEOs and even water from moon's poles. That said a propellant depot filled by cheap source of water would make missions to Mars cheaper, even if you're going there "just because".

So I was on that atomic rocket site doing research to attempt to answer the question of "what's the Isp of an Orion drive" when an interesting thought occurred to me. The existence of LV-N means Kerbals have probably mastered all the related technologies like enrichment of fuel, breeding of fissile material and controlling sustained chain reaction. On the other hand, on earth we managed to make things that use uncontrolled chain reaction (read, bombs) first before we could make practical commercial reactors. Even if we factor in the fact that Kerbals might be more peace-loving than us humans it seems unavoidable that at some point a Kerbal would have arrived at the idea of squeezing a sphere of Blutonium-238 to make an atomic bomb. And given their fascination with rockets someone would have made the connection between bombs and rocketry as soon as they saw one go off. Since Kerbals don't have Orion drive I suppose this actually says something about Kerbal's attitude to nuclear power. Either they never made the leap between reactors and bombs which seems unlikely, or they deliberately choose not to make bombs, despite its potential usefulness for space exploration. So I think if you pull a random Kerbal off the street and asked about their view, they would be pro-nuclear but against bomb making. What do you think?

Yes it's true, from a pure aerodynamic pespective you want higher TWR as your climb, however that's not the whole story. Higher TWR is not free, it costs you dry mass to achieve higher TWR because you need to carry more engines. Once you are above say 20km you are already above most of the atmosphere, and at this altitude your gravity turn would have placed your rocket to pretty close to horizontal. So in this phase of the flight you suffer very little aerodynamic drag (since there's little air) and very little gravity drag (since you're nearly horizontal) and almost all of the kinetic energy your engine is putting out goes into building up your horizontal velocity. Because you are suffering little drag there's no reason to punch through this phase of the flight to reach the coasting phase in a big hurry by having a high TWR. You can accelerate at a leisurely pace and enjoy the higher delta-V here by carrying up less engines provided that you can keep your time to AP around 30 seconds ahead of you while you keep thrusting at prograde. I find that a TWR of around one Kerbin G is enough at this phase of the flight.

What's your liftoff TWR?

For decoupling really heavy radial boosters you generally need sepratron anyway, so the higher ejection force is moot.

Here's my entry:

g0 = 9.82 m/s2 was experimentally determined in KSP, based on the quoted Isp in seconds figure.

Let me show you my intention: Aurora Winged Booster This launch vehicle was specifically designed with large payload like single piece space stations in mind. The idea is that each winged booster is rated to put 50 ton or so of payload into orbit and you just cluster as many of these as you need radially around your large payload to lift them. Then you don't have to build an unique big asparagus launcher for each large payload you need and as a bonus most of the rocket will be reusable. Hurricane launch vehicles are just one specific implementation of Aurora Winged Booster where the "half-stage" of multiple Aurora are clustered into a single large ET that is also reusable. If I were to design a 300 ton space station I would just cluster six Auroras around the payload (probably in two rings of 3) and add a big ET tank sized for six somewhere. If you really insist no spaceplanes I could just take off the wings, but I don't see how this limitation makes the challenge better as surely, building creative launch vehicles is a critical aspect of a challenge to launch giant one piece stations.

Yes it's true, you can distribute the wet mass of the rocket outwards to the boosters if you really want to have a weaker core stage. For special cases like Eve that might even be desirable since you need much more TWR at left off, yet final climb to orbit can still be done with upper stages that have <1 Kerbin TWR. In other words for an Eve rocket the optimum TWR curve has a steeper shape than Kerbin optimum TWR curve. The fact that asparagus staging rockets jettison the first pair of boosters very early in flight is by design and intended. If you think about it, the rate that the rocket consumes fuel (ie how fast is the rocket becoming lighter) is almost linear relationship with number of engines firing (not exactly, as it's affected by atm ISP). So at the start of the flight the rocket burns through a vast amount of fuel every second, hence the engines needed to accelerate that fuel becomes rapidly redundant. Towards the end of its flight there are fewer engines so the rate that the rocket lightens is much slower, hence why you hang onto the engines for longer in later stages. With Kerbin launch vehicles, making the core stage too small has the unfortunate effect of making the core stage shorter. There's only a finite amount that you can do this before the core stage becomes shorter than the boosters and the resulting "bowl" shape means there will be form factor limitation on the payload. You will no longer be able to put very wide payload on top of the rocket because the boosters will be protruding into the wide payload.

What if the spaceplane is launched vertically like a rocket? Or in other words a winged rocket.

The point of an asparagus is to drop tanks and particularly engines as quickly as you can. If you find your asparagus lacking TWR for the payload it's suppose to be carrying then you should redesign it. Messing with fuel flow otherwise to try to keep engines with you to increase TWR is working against the very principle of asparagus staging. If you find your asparagus staging rockets having acceptable TWR at left off but too low of a TWR later on in it's burn it means the core stage is too small. You generally want something like 20-25% of the total lift off thrust coming from the core stage. If your launcher is just seven identical boosters set up in an asparagus then clearly the core stage is not up to the job as it will only be contributing 14.29% of the lift off thrust.

They have a separate engine design for sub-orbital transport called Scimitar. It's basically a SABRE minus the closed cycle mode, so hydrogen burning, precooled jet engine. Seems to me like one way around this SSTO payload fraction problem is to launch a rocket stage (or a rocket spaceplane if you really want reusable) on top of a Scimitar powered aircraft. So basically one of those many two stage spaceplane design from early shuttle proposal days, only with a more advanced air breathing stage.

It definitely is easier if they are all on one side, instead of an L shape or even worse a sandwich. I first came up with the multi-docking technique way back in beta. Back then we didn't have the large 2.5m docking port yet so assembling big structure in space that's rigid was a huge pain. To get around this I made a subassembly that's a 2.5m flat adapter with four 1.25m docking ports: Propellant depot, assembled in LKO and ready to head to Mun. Eve exploration fleet. I found it quite easy to dock and have all four connect at the same time. So this sort of multi-docking is definitely workable.

Here's a set of pictures to show my method @gilflo: Here we have a simulation of your payload inside your cargo hold. As we can see currently the top of the payload is attached to the docking port in the "cargo hold". The payload has a inline docking port facing down and there's a docking port on the "floor" of the cargo hold but they are no where near each other and not connected. Here is the same setup, but we have used the translation gizmo to closely align the inline docking port with the floor docking port of the cargo hold. They are still not connected inside the VAB and you can see a thin gap between the two Here I put the payload on the launchpad and let the physics load. You notice that the two docking ports that were connected in the VAB are still connected here and evidenced by the fact that they have the unique "Decouple Node" action that you cannot get from docking two docking ports together outside of the VAB. However the inline docking port of the payload and the floor docking port on the cargo hold has become stuck together and hard docked, as evidenced by the "Undock" function. What happened was that as soon as the physics loaded the magnetic attraction of the two docking ports glued them together. The first few times you do this you need to fiddle around with alignment to get this to work before you get the hang of it, which was why I said it can be a pain in the ass to setup. Also once you release this payload it can become very tricky to get both docking ports to dock again later.

Depends on orbit and albedo. Sputnik was tiny but it had a low orbit and a very shinny shell so it was quite visible to the naked eye despite its size.

Tractor design is used both in real life and in ksp to reduce vehicle mass, since most materials are stronger in tension than compression. Tractor design allows extremely long spacecrafts to be low mass, and one design such "waterski" crafts (eg ISV Venture Star) precisely so that the crew section can be as far away from the deadly engines as possible because of radiation. I disagree that requiring thought at design time and some careful flying at docking time is laborious. And if one is of the opinion that the radiation simulation is unnecessary then you still have the option of not using the shadow shield part, put probe core on ships, enjoy the higher TWR and just ignore the radiation sickness flag. I deliberately proposed a system to not kill crew or leave them with any permanent damage to leave that opt out option open.

That rocket stage seems so tall compare to its landing legs that if it lands on even slightly uneven terrain it's in danger of toppling. You may want to make it shorter and wider, or design some super wide landing legs using structural elements. Remember also there's lot more ocean than land, so you would want to test water landing.