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I am trying to write-gineer a realistic, far-future (hundreds of years), spaceplane capable of landing on and taking off of, most surfaces (planets, space stations, asteroids, etc.). To that end, I ask for the community's help in making it as believable as possible. It must be a single-stage-to-orbit craft carrying a small crew ~6 and several tonnes of cargo for trips that could last up to two months.

Why does this ship exist? To exchange cargo with distant colonies that do not have the infrastructure for more efficient systems.

Assume the following engineering marvels have been packed into one, C-5 sized, spaceplane: Power and thrust is provided by an anti-matter reactor. A Harrier-esque VTOL gets the plane off and on the ground from anywhere (without killing everyone below it). A SABRE (Synergetic Air Breathing Rocket Engine) inspired engine gets it into space. Can carry a cargo of about 80,000 kgs. Has enough food and water for 6 people to last 2 months (~800 kg of food plus ~1,400 liters of water). Has quarters and support facilities for up to 6 people. Re-entry is protected by ceramic composite skin. Has laser point-defense systems and mass driver (coilgun) armaments. An Event Horizon-ish jump drive is used for interplanetary and interstellar travel (this is the only piece of ‘space magic’ I would like to use).

Artificial gravity is not necessary as trips between colonies would take, at most, a few months (and usually only a day or two between close systems), but if there is a way to theoretically produce uniform artificial gravity by rotating a spaceplane, that would be a great bonus.

What am I missing and is it realistically possible so far?

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    $\begingroup$ The purpose of space planes is to be able to land from orbit without using engine power, because real-life rockets are subject to the rocket equation which severaly limits the amount of fuel they can carry. Since this vehicle has basically unlimited power, what does it need the aeroplane aspect? It seems to be an enormous complication wihtout any immediately visible benefit. $\endgroup$
    – AlexP
    Jun 9, 2023 at 15:23
  • $\begingroup$ It would still need to ascend and descend from orbit in a variety of atmospheres and navigate potential hazards. Wouldn't an aeroplane design give it the ability to navigate said atmospheres? $\endgroup$ Jun 9, 2023 at 15:39
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    $\begingroup$ A rocket gets out of the atmosphere in a minute or two. What hazards? A SpaceX Falcon 9 booster lands in about six minutes from the de-orbit burn; 99% of this time it is unpowered. $\endgroup$
    – AlexP
    Jun 9, 2023 at 15:43
  • $\begingroup$ Reliance on wings would make it more sensitive to differences in atmospheres. Also, a SABRE engine is dependent on being chemically fueled with liquid hydrogen and a high-oxygen atmosphere, and actually requires more liquid hydrogen for cooling than it can burn as fuel. If you've got antimatter-powered VTOL jets, it's just a massively complex and fragile pile of unnecessary machinery. $\endgroup$ Jun 9, 2023 at 16:20
  • $\begingroup$ Understood. So it sounds like I added a problem to something that was already solved. If a ship has an anti-matter reactor (and thus excessive amounts of energy), than it no longer needs an aerodynamic design to help stay aloft. That is very helpful and frees up design options. The jump drive takes it most of the way and the VTOL engines do the rest. $\endgroup$ Jun 9, 2023 at 16:30

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I will start with the fact that whilst such an ssto (single-stage-to-orbit vehicle) does not exist your parameters seem realistic enough that it is easily believable in a few hundred years for the most part. If your writing about the future and have a space magic jump drive I don't think it will be hard to convince people they worked out things like graphene.

With that said, let's start with the guns. Lasers as asteroid protection make sense but I would advise seriously considering why a transport ship has guns at all, what do you intend to shoot at during a cargo run? You already mentioned lasers to deal with asteroids. Self defence also doesn't make much sense, I will skip most of it but space is big, coil guns are dumb fire, you will rarely be in a situation where they could hit in hard sci-fi unless you put yourself there, in which case what is a transport ship doing in combat.

If you have antimatter your energy needs are a non issue. Just keep in mind that fast acceleration could cause issues for antimatter containment, unlikely to come up in a cargo ship though.

Lastly you asked about artificial gravity, this is pretty simple and is not expected to change with future tech so you should be able to look at current science explanations of how it works like this answer. If you don't want to add complexity of extending spinning habitats your c-5 wingspan seems to be 67.89 m, full living quarters on the end of wings would likely make it useless in atmosphere but you could have basic bunks down there to let them sleep in gravity. Toilets are also weirdly complex in zero g so they may be another good thing to put in your limited spin gravity space.

For additions the only one that comes to mind would be a radiation shield, space is full of radiation and you need proper shielding if you don't want your crew full of cancer. With antimatter fuel you could just add a conventional lead shield but this is wasteful, consider real world techniques. They may even make a decent plot device real world approach.

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  • $\begingroup$ Thank you. I can't believe I forgot about radiation shielding. However, an anti-matter reactor could solve the radiation shielding problem and possibly the artificial gravity problem. With that much energy it wouldn't be that detrimental to slap some high-density armor on the ship to deflect SEPs and cosmic rays. And if the ship does not need an aerodynamic design for lift, than if could be designed like a thick rocket. In that case, could thrust provide the necessary gravity? $\endgroup$ Jun 9, 2023 at 16:37
  • $\begingroup$ As far as the weapon systems go, this ship (and ships like it) will be expected to deliver cargo to the outer edges of colonized space. In those areas piracy is common. Also, a very long (and enormously destructive) war has recently ended. The Total War mentality is still very pervasive. The coilgun is an 'after market' addition to this particular ship, and it has an overclocked (illegal) AI to help with targeting. $\endgroup$ Jun 9, 2023 at 16:46
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    $\begingroup$ if its got a story justifcation thats fine but ai is unlikely to be much help for targeting, the issue is distance, if i fire my projectile at point blank range it hits, if there is a bit of distance then ai will make it hit sure the problem is when you get the sort of distance common in space, travel time is just too long so ships can just move out of the way, i believe the expanse does this well where railguns are only usually used in there hammerlock range where there is no time to dodge and missiles are used at longer ranges because they can track a target $\endgroup$
    – aork 123
    Jun 10, 2023 at 17:27
  • $\begingroup$ Yeah, ability to hit a target with a projectile is constrained by sensors and ability to accurately throw the projectile, not by any sort of processing complexity. Aiming isn't something that requires a brilliant intellect, or even a great deal of raw number-crunching power. $\endgroup$ Jun 11, 2023 at 0:56
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How about a Nuclear ramjet? This isn't futuristic - they had them in the 1950's: see Project_Pluto. You might replace their power source with something a little less scary so it can power a craft with people in. One of these will work with most atmospheres. It does not care what the atmosphere is made from: it just heats the gases up it and squirts it out the back for the reaction. As you leave the planet, you might scoop up more gas for travelling in space.

The best protection from the radiation of the engine would be distance. Getting out of the atmosphere might take you tens of minutes. When in space, you could separate the crew quarters from the engine. The engine would be then using its gas store. If energy is not a limiting factor, then it would want to get the gas as hot as it can, which might mean passing it through the engine more slowly, so it behaves more like an ion drive than a ramjet. This would give a small acceleration but might last for days or weeks. We could separate the engine from the crew quarters by some telescoping body that could resist the light thrust. Finally, once you are in free flight through space, you could separate the craft into two halves, connected by a cable. The two halves could spin about the centre, giving artificial gravity.

On re-entry, the craft will have to shed all the potential and kinetic energy. A Hohmann transfer is the most economic route for impulse, but it is not quick. If you are taking a faster route, then you will need a reverse burn to match the speed of the planet you are approaching. If you can match this, then why not match it very closely so there is much less re-entry heating, and you do not need a sophisticated ceramic coating. If you are low on gas for the engine, you could lose momentum by aerobraking. This is probably best done by lowering the tether you had for gravity rather than putting the whole craft into the atmosphere.

A few km of cable could also be used as a space elevator when visiting asteroids. String is always handy.

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Frame Challenge.

Aircraft cycle count is better indicator of long term stress over operational hours.

This will apply to surface to space vehicles more so. So there is substantially more wear and tear on a surface to space over a space-space vehicle. increasing odds of failure.

Since anti-matter is on the energetic side and failures will happen, rare as they might be will be extremely catastrophic.

This will result on two major points:

  • Insurers: No surface / space transfer of antimatter.
  • Governments: No surface / space transfer of antimatter.

Space only cargo ship with space-plane shuttles.

A more plausible scenario is antimatter powered cargo ship with modular add-ons. Molecularity allows for missions to go from 6 person crew, one space plane, and a few containers up to hundred of people thousands of containers and a dozen space planes. As well as allowing for much larger separation of habitat and antimatter for risk management. It also drastically increases space plane efficiency since they don't need to drop/lift dead-weight each cycle(eg FTL components).

Mission dependent addons such as:

  • Smaller VTOL fusion powered space planes capable units able to carry able to handle to carry 2-4 TEU of containers.
  • Larger non-VTOL fusion powered space planes units able to carry 8-16TEU depending on design.
  • Variable amounts of habitat.
  • Habitat shielding (debris/radiation)
  • Variable amounts of debris shields
  • Variable amounts of anti debris lasers.
  • Rotating habitat rings for artificial gravity as needed.
  • Redundancy as needed.

Container based because that simplifies logistics as compared to break bulk or weird custom stuff.

Physical description of the cargo ship would be a long spar/skeleton that components would be attached to with engines and antimatter at one far end, crew mostly away from the antimatter. ( as opposed to Star Wars like vehicles)

All in one are difficult.

All in one deigns are notoriously difficult. Consider the car+plane, or the boat+car. There are no results so far that can be broadly considered widely successful as compared to their dedicated counterparts.

Conclusion:

Having a space only cargo hauler and space-plane shuttle is more flexible easier to design, and much safer then a single vehicle that is intended to do everything.

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  • $\begingroup$ I love the concept of being officially obligated to leave the 'magic backpack' of antimatter behind for the most power-hungry aspects of the trip (ascent/descent into a gravity well (possible not THE most power-hungry, i don't know about the spacemagic jump drives)). There is great story potential in rogue actors ignoring that constraint and completely dominating the in-atmosphere game while walking on eggshells to not stir that AM-bottle too much. --- Also, somewhere in the Oort are floating all the AM-backpacks waiting for their owners to come back or some ruffian AMnapping them :) $\endgroup$
    – bukwyrm
    Jun 13, 2023 at 13:09
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A real world example of a space structure that can host a few people for months is the international space station. It weights about 450 tons and is not moving on its own. In contrast, the space shuttle could both dock on the ISS and land on Earth - but it is not designed for monthes-long interplanetary travels. The orbiter (the plane-like crewed part) weighted about 100 tons. If you add the boosters, it grows to about 1,500 tons.

But let's consider that centuries of technological progress led to a 300 tons atmospheric-capable spaceship.

The hardest part in designing your ship is to find a propulsion system that would not inflate your spaceship absurdly. Antimatter would help (1g = 20 kT, a small nuclear warhead) if you find a secure way to contain it, or even produce it onboard by transmuting matter.

Ideally, the ship would be driven by an AI, but if the crew is required to pilot the ship, they may benefit of neural implants for instantaneous command. Also, you could submerge your crew in a pool of acceleration-dampening fluid to prevent the damage caused by excessive Gs. Temperature of the fluid could be regulated so the time perception of the crew would fit the situation (slow/cold on transit, fast/hot on delicate maneuvers). The fluid could also provide shielding from particles and radiations.

Regarding atmospheric capabilities of your system, you may consider ionic propulsion. It is at its very first stages so far but has the advantage of only requiring lots of energy (that your antimatter reactor can provide) while exploiting the hull as a conductor for generating the aerodynamic forces required to lift the ship. The plasma generated by the ionocraft would absorb most of incoming radiowaves, which can help protecting from rentry and also provide stealth useful for military ships. In space or high atmosphere, you could switch on the regular antimatter thruster to escape from the planet's gravity well.

Wingspan should be adaptative to the different settings your plane will operate, from a large surface mode to enhance the ionocraft effect to a folded space mode to facilitate maneuvers and reduce chances to be hit by microasteroids or projectiles.

So regarding your 300 tons ship design, I would see something like that:

  • 10 tons - crew and anti-G chamber
  • 10 tons - additional crew support
  • 80 tons - cargo
  • 5 tons - antimatter transmuter/storage
  • 25 tons - batteries, cabling, electrical systems, telecoms
  • 40 tons - weapon systems
  • 30 tons - antimatter thrusters
  • 100 tons - hull/ionocraft structure, armour and landing gear
  • Length - 80 m
  • Width (ionocraft mode) - 120m, 6 wings
  • Width (high atmosphere) - 80m, 2 wings
  • Width (space/stored) - 50m, no wings
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