I’m a fan of the Near-Future and interstellar mods, and while reading about the proposed second generation EMdrives, my thoughts turned to a re-usable craft, taking advantage of existing and emerging technologies. With KSP, you are effectively limited to rockets and spaceplanes, although, should certain techs evolve, then there is a strong argument for a saucer.
The saucer shape accommodates a centrifuge quite nicely in a SSTO form factor, and whilst our Kerbals don’t care about the long-term effects of zero-g, it would surely be a concern of any future astronauts.
I’ve started to conceptualise then a craft that would utilise emerging technologies to see what the art of the soon to be feasible is and pugged them together into a build. These technologies should mature over the next few decades, justifying the use of optimistic values.
As KSP doesn’t model saucers well, this will probably end up as a more or less prebuilt craft, with maybe a few connections for things like docking ports, a hanger space and surface mount equipment.
I will share the .blend file if anyone wants to have their own take on this or move it forward.
Primary Propulsion System
Four second generation EMDrives housed in gimbled mounts provides the primary thrust for the craft. Shawyer claims the second-generation drive, using super conducting microwave cavities should be able to produce 30kN/kW, or 1KW of power would produce 3 tonnes of thrust.
Assuming the flyer weighs around 100 tonnes, 70Kw of power would be ample to accelerate the craft at around twice gravity. If 25KW was provided to each gimbled mount
Direct Nuclear Turbojet
The basic principle of the nuclear turbojet is that intake air is taken in, and instead of being mixed with fuel and ignited, its simply superheated by a nuclear reaction, excited and exhausted out the back of the craft. Our craft uses a fusion reactor, who’s operating temperature is north of 100 million degrees Celsius, giving us the opportunity for some cheap thrust where its most needed; with the atmosphere.
Without traditional control surfaces, RCS will be needed for all phases of the mission. The gimbled main drives will of course provide a lot of the manoeuvrability needed.
Extended missions in zero gravity lead to muscle and bone wastage, along with a host of other health issues, so providing simulated gravity in any craft designed for prolonged endurance is advantageous. As real gravity would require so much mass that the TWR would be somewhat adversely affected, other than constant acceleration the only current option available is a centrifuge. The saucer shape is to accommodate a 10M radius torus, which contains the main quarters of the craft which can not only rotate around the centre at a steady 9RPM to simulate 1g, but can also be stopped and rotated by 90 degrees in the transverse access to that when operating in normal gravities the crew can walk around normally.
The gravity wheel will use magnetic suspension to reduce friction and in turn the power and heat generation as a result of rotating the cabins.
A small Nuclear Fusion Tokamak reactor producing around 500MWh will provide power to the craft,
Essentially, there are two competing designs for fusion generators; Stellerators and Tokamaks. Whether Stellerators or Tokamaks become the preferred mechanism for fusion, the process and output will be similar. Tokamaks require super conducting magnets, and as we are banking on that technology for our primary propulsion system, we will plump for this option.
Current achievements in fusion use two isotopes of hydrogen; Deuterium; a naturally occurring isotope found in 0.0115% of natural hydrogen and tritium, which is virtually non-existent in the natural world because it is unstable and decays with a half-life of 12.3 years. Whilst Tritium can be created from lithium, for this process we will assume that advances are made and Deuterium- Deuterium fusion is achievable within our reactor. Per Kilogram, Deuterium produces 8.42 × 1014 joules considering the efficiency of the reactor, the consumption rates specified by the team working on the ITEL Tokamak reactor, running at 500KWh would take around 125Kgs of fuel a year.
Thermal control systems are one of the more challenging aspects of the craft. Cooling is not just required for running the propulsion systems and reactor; both of which requiring lower temperatures associated with super conductivity, but also if maximum reuse is to be desired, ablation is not a suitable mechanism for re-entry heat control.
Current active cooling systems pump ammonia around conditioned systems and utilizing radiators to dump the heat into space. Essentially, other than refinements such as piezoelectric pumps, and designs to reduce re-entry thermal effects are only paths currently open to us.
To create oxygen from carbon dioxide you need photosynthesis which needs trees, however its often said that while the last 50 years have been the period of progress for computing and electronics, the next 50 will be for genetic engineering. Craig Ventnor has proposed genetically engineering bacteria to be super-efficient at this process, and given the proposed timeline of the flyer it would be fair to assume that, along with other duration extending systems like water purification, this technology would be incorporated into the design – with used air being pumped through tanks of algae-like genetically engineered protozoa, and producing nice clean breathable.
The following mission profiles would fit our craft.
The movement of people and materials to and between bodies
· Resource Gathering
Collection of rare and desirable resources from Space or from other astral bodies
Travel to distant bodies, and utilizing scientific equipment or launching probes to this effect.
All essentially require the use of a cargo bay, so we will incorporate one into the centre of our craft, which could contain raw materials, a rover for surface ISRU\G or other payload.
So I've started the model, with the saucer shape and nacelles for the EMDrives and shock cone at the top for the turbojet, leaving a large area underneath for the rover hanger.