How Do You Navigate My Scifi Starship?

[Spacescifi]

This a fun scifi scenario with some relation to reality:

You have a scifi starship in orbit fully fueled with propellant and cargo, using antimatter thermal rocket engines with methane propellant.

Yet to to reach planets and star systems in a reasonable amount of time you use:

Slingshot Translation (ST) drive: Which moves space past your ship, translating your ship across space without acceleration. Similar in function to a warp drive. It has two speeds only. Lightspeed and a lightyear per hour.

The catch is how the ST drive works... it will translate indefnitely without refueling UNLESS you are within a 100 kilometer range of a mass that has more mass than your vessel.

Trust me, that is generally not a good thing, since the only way to stop translating would be to leave your starship. With shuttles or escape pods, which would be stranded in deep space while the starship continues merrily chugging along translating/warping space.

If you start translation across space the direction you translate/warp to will be the same direction as your current trajectory.

In other words, if you are orbiting Earth and turn on translation then to viewers you will appear to shoot out of orbit at lightspeed, even though you are moving space... not your ship. If you went out at max translation (LY per hour) they would just see you gone in a blink.

Results: Careful planning is required, since you need to know the trajectories and speeds of target destinations BEFORE you arrive. Otherwise you will travel indefinitely at warp, leaving with you with two options:

1. Adjust your warp speed to lightspeed when passing through solar systems and hope a mass greater than your vessel's mass drops you out of warp. But space is BIG, and the radius to mass lock (drop out of warp) your warp drive is relatively small (100 kilometers).

2. Abandon ship inside a solar system while warping near a planet at lightspeed. Your starship is gone but maybe you can make it with shuttlecraft to this alien planet over there?

Main question for discussion: Without FTL sensors... how in the world do you navigate to places you have not been before? Assuming you have not sent ships to scout ahead of you. You are the scout!

Your mission, if you choose to accept it, is to seek new resources for your civilization, discover new worlds and cosmic phenomena, and boldly go where no human has gone before.

Bonus question: Where do you choose to go? You have a total of 3 solar systems to explore before returning to Earth, alternately you can trade one solar system visit to explore cosmic phenomena (black holes, novas, pulsars etc).

 

[Shpaget]

Have multiple of those highly impractical drives and dump them as needed.

[Spacescifi]

10 minutes ago, Shpaget said:

Have multiple of those highly impractical drives and dump them as needed.

 

Could work actually.

 

Warp staging... who knew LOL.

I am still wondering if any of you are witty enough to figure a way to acomplish single stage warp.

Doing it in the home solar system is straightforward enough

 

Light years away with light lag coming into play?

Hard.

Edited March 29, 2020 by Spacescifi

[Shpaget]

Detach the drive, it stops warping because the rest of the ship is bigger than the drive, the ship stops warping because it doesn't have the drive, then come back and pick it up.

[Spacescifi]

21 minutes ago, Shpaget said:

Detach the drive, it stops warping because the rest of the ship is bigger than the drive, the ship stops warping because it doesn't have the drive, then come back and pick it up.

 

Clever. Nice.

Here I thought I had a really tough scifi drive.

There is one caveat though.

 

The reason your mass lock is 100 kilometers is because that is the radius of your warp field.

 

In other words, once you drop out of warp via detachment, youe warp drive section will be 100 kilometers away... at a relative stop to you since you were traveling together at first.

 

No problem... your antimatter thermal rockets with propellant can handle that easily.

Time is all that matters really, faster recovery equals more methane propellant spent and vice a versa.

EDIT: Still... changing your trajectory using propellant alone will be costly.

The cheapest way to go would be to use mix of propellant and gravity assist, then finally engage the warp to get where you want to go.

No matter what you will need to keep an eye on how much propellant you have left, since if it is too low you would have either find a way to ISRU on some barren world or find a way back to your home system and call for help to get refueled after detaching the warp drive.

 

At the very least... it gives an opening for pirates if nearby (lightseconds away).

Edited March 29, 2020 by Spacescifi

[kerbiloid]

Use a pusher plate.

If it's enough heavy, you can detach/reattach just the pusher plate instead of the whole drive.

[K^2]

7 hours ago, Spacescifi said:

If you start translation across space the direction you translate/warp to will be the same direction as your current trajectory.

Relative to what? Lets illustrate with a simple example. Your ship is orbiting Earth prograde with Earth's rotation and is on the day side when it engages its translation engine. Relative to Earth, it's traveling at 7km's and will be translating out of Solar System going retrograde with respect to all the planets. Relative to the Sun, it's still moving at about 23km/s prograde, because of Earth's orbital velocity, and so the ship should be leaving the Solar System prograde. So which direction does it go? And relative to potential destination, it could be completely different direction of travel.

You can't say that two things are moving in the same direction but at different speeds. That only works when you're referencing anything relative to some fixed medium. So it makes sense when you talk about cars or boats. Not spaceships. And so a drive with this description isn't just non-physical, it's inherently inconsistent even as far as basic story-telling goes. As soon as your ship starts traveling between planets, let alone stars, the whole thing breaks down narratively.

There are additional concerns regarding physics of something like this, but they really stem from the same root inconsistencies. You just pick up additional baggage of conservation laws and having to make sure they are satisfied.

7 hours ago, Spacescifi said:

using antimatter thermal rocket engines

This one's just... why? You've taken one of the only two known ways to generate energy with 100% efficiency and combined it with the worst known way to generate thrust. It's like sticking a nuclear reactor core into a 19th century steam locomotive. I mean, it'll work, but if you can build a nuclear reactor in the first place, you can do better for your engine.

[Spacescifi]

9 hours ago, K^2 said:

Relative to what? Lets illustrate with a simple example. Your ship is orbiting Earth prograde with Earth's rotation and is on the day side when it engages its translation engine. Relative to Earth, it's traveling at 7km's and will be translating out of Solar System going retrograde with respect to all the planets. Relative to the Sun, it's still moving at about 23km/s prograde, because of Earth's orbital velocity, and so the ship should be leaving the Solar System prograde. So which direction does it go? And relative to potential destination, it could be completely different direction of travel.

You can't say that two things are moving in the same direction but at different speeds. That only works when you're referencing anything relative to some fixed medium. So it makes sense when you talk about cars or boats. Not spaceships. And so a drive with this description isn't just non-physical, it's inherently inconsistent even as far as basic story-telling goes. As soon as your ship starts traveling between planets, let alone stars, the whole thing breaks down narratively.

There are additional concerns regarding physics of something like this, but they really stem from the same root inconsistencies. You just pick up additional baggage of conservation laws and having to make sure they are satisfied.

This one's just... why? You've taken one of the only two known ways to generate energy with 100% efficiency and combined it with the worst known way to generate thrust. It's like sticking a nuclear reactor core into a 19th century steam locomotive. I mean, it'll work, but if you can build a nuclear reactor in the first place, you can do better for your engine.

 

Answer 1: The same direction the ship would go if it actually were accelerating as fast as it translates.

I called it a slingshot for that reason, since it is virtually the same concept, only moving space instead of actually accelerating.

Dropping out of warp puts you out at the same trajectory only at your normal speed.

For all intents and purposes, your vessel will follow a linear path during translation, so orbiting or thrusting to change trajectories just sets up your shot.

Edited March 29, 2020 by Spacescifi

[K^2]

1 hour ago, Spacescifi said:

Answer 1: The same direction the ship would go if it actually were accelerating as fast as it translates.

Acceleration is a vector. Which way is the ship accelerating? And you can't say "same direction as the ship moving." If you're riding a bike due North and I'm passing you by on a car going faster, you're going North relative to a person standing on a sidewalk, and you're moving south relative to the car. Would accelerating in the same direction be accelerating North or South? We can still talk about bike speeding up or slowing down in absolute quantities, because we take motion relative to the ground for granted. You don't have that in space. Just within Solar System the planets are moving fast enough to make that relevant as I've illustrated above. Are you accelerating in direction you're moving relative to planet you're departing or planet you're arriving at? Because that can be almost exactly opposite directions. And why should either of these matter? Any object or imaginary point is as valid a reference point as any other. So saying the ship accelerates in the same direction as it's already moving is nonsensical. Relative to the ship, the ship's never moving at all in any direction ever by definition. So which direction are you accelerating in?

 

[Spacescifi]

1 hour ago, K^2 said:

Acceleration is a vector. Which way is the ship accelerating? And you can't say "same direction as the ship moving." If you're riding a bike due North and I'm passing you by on a car going faster, you're going North relative to a person standing on a sidewalk, and you're moving south relative to the car. Would accelerating in the same direction be accelerating North or South? We can still talk about bike speeding up or slowing down in absolute quantities, because we take motion relative to the ground for granted. You don't have that in space. Just within Solar System the planets are moving fast enough to make that relevant as I've illustrated above. Are you accelerating in direction you're moving relative to planet you're departing or planet you're arriving at? Because that can be almost exactly opposite directions. And why should either of these matter? Any object or imaginary point is as valid a reference point as any other. So saying the ship accelerates in the same direction as it's already moving is nonsensical. Relative to the ship, the ship's never moving at all in any direction ever by definition. So which direction are you accelerating in?

 

 

Alright... I will make it simple.

 

EDIT: Forget the trajectory thing.

Point starship's nose in the direction you want to translate and translate.

While translating you go in a linear path, lightspeed or a lightyear per hour are your options.

Unlike my first iteration, you will continue to translate forever UNLESS you come within 1 lightsecond radius of a celestial body (planets, stars, etc) with a gravity of 1g or greater.

The other option is to abandon ship while it leaves you at luminal warp.

 

Better? I like it.

So once again warp engine staging seems to be the safest way to go, at least until a star system is mapped out.

Inertial navigation can handle the rest once they have a map. Orbits are predictable.

Answer regarding methane: What other propellant would you suggest?

IRL hydrogen and oxygen is king since it requires less propellant for efficient thrust, but the massive fuel tankage and pipes required tend to negate that  at liftoff because of gravity. Methane would require more propellant burned to get the same thrust that hydrogen and oxygen does, but it is easier to store than hydrogen.

If you had a starfleet would you prefer less vessels using LH because it is difficult to handle, or more vessels using methane, which is easier to handle?

I am not arguing. I only want suggestions. Elon seems to like methane. Would you suggest RP-1?

Or better yet, just write 'Rocket propellant mix' without naming what is actually used and leave it to the reader to guess?

Slight EDIT: A bimodal propellant mix seems to work best:

was just wondering about Nuclear Methalox...

Discussion

Is this possible/worth it to use a (closed cycle) lox augmented nuclear methane engine for on-earth and off-earth missions? I know there would be political issues but how would it compare to nuclear hydrolox?

 

Reddit answer: 

You see to be talking about nuclear engine with afterburners. These engines operate in two modes, one where the propellant is heated by the reactor and expanded through a nozzle (achieves high efficiency) and one where the hot propellant has oxygen injected to burn it and provide additional thrust (higher thrust but much lower efficiency).

In general, if you increase the molecular weight of the propellant of a nuclear thermal engine, you lose efficiency but gain thrust. NERVA was an engine in the 50's that used hydrogen at ~950 Isp and had a thrust to weight ratio of 5, however a much more modern study into the technology predicted that with new methods and materials we could build hydrogen-fueled NTRs with thrust to weight ratio around 20 to 30 and slightly improved Isp compared to NERVA.

Using methane as a propellant in an NTR engine that achieves 1000 Isp using hydrogen gets you ~600 Isp, which still makes it much more efficient than a hydrolox chemical engine. It also increases the mass flow considerably, so an engine that achieves 25 TWR using hydrogen may achieve 50 TWR or more using methane. This is comparable with an average chemical engine, while still performing much better in terms of Isp.

Now, an after-burning NTR can't get as efficient as a chemical engine using the same propellants, simply because the NTR cannot achieve the same chamber pressures as a chemical engine. After-burning mode is tailored towards increasing the TWR significantly in order to get off the pad and fight gravity losses quickly, until such time in the flight profile that it can be shut off and the remainder of the delta V be supplied without using any oxidizer. Using an after-burning design makes more sense if your primary mode supplies a very low TWR, like NERVA did. However, if your NTR can achieve 20 or 30 TWR using hydrogen, and comparable TWR as a chemical engine when using methane, and the entire time gets you an Isp roughly two to three times higher, then a bimodal methane-hydrogen NTR makes more sense IMO.

In short, after-burning NTRs are an old idea brought about to give nuclear thermal engines a high enough thrust to weight ratio that they could be useful during all phases of launch, and not only as upper stages. However, improvements in materials and nuclear science in the decades since NERVA suggest that nuclear thermal engines can achieve useful thrust-to-weight ratio for launch without afterburners, and that a bimodal engine that can switch in flight from using methane to using hydrogen would be superior to any after-burning NTR of any propellant combination.

 

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Edited March 30, 2020 by Spacescifi

[K^2]

1 hour ago, Spacescifi said:

Forget the trajectory thing.

Point starship's nose in the direction you want to translate and translate.

While translating you go in a linear path, lightspeed or a lightyear per hour are your options.

That works. Of course, now orbital maneuvers are irrelevant. You just have to make it far enough out from gravity sources to engage the translation.

1 hour ago, Spacescifi said:

Answer regarding methane: What other propellant would you suggest?

I wasn't complaining about propellant. I was complaining about it being a thermal rocket. With thermal rocket, you always use hydrogen, because that's the lightest stuff we have that's electrically neutral and stable, and the only two factors determining efficiency of a thermal rocket are melting points of components and how light your propellant is. NTRs already have about as high of an efficiency as you can get. By switching to antimatter as energy source in a thermal rocket, all you're ditching is the fuel core, and that's not even the heaviest part of NTR. All of the heat exchangers are, and you have to keep them for any thermal rocket. At this point, you might as well just go conventional NTR.

If you insist on burning antimatter for energy, the most efficient propellant is light. You have pure energy from your fuel - there's no reason to dilute it with anything. But that assumes you can bring all of your fuel mass as equal parts matter and antimatter. If you are limited in how much antimatter you can bring, either due to costs or because there are technological limitations, then you start thinking about what propellant to use. Again, if you're trying to do a lot better than an NTR, we're talking about energies that will turn any propellant you use into fine plasma. Since nothing can contain these sort of temperatures mechanically, that becomes a moot point, and you either go for magnetic nozzles or use ablative dampers, or whatever you need to do to protect your ship. Since temperature is no longer a factor, neither is the mass or composition of your propellant. You can literally use anything. If you are trying to reduce space, you probably want dense propellant. If you want it to flow, maybe mercury will do! Or maybe you want it to be cheap, abundant, safe to handle, and easy to transport. Then why not just use water? There are a lot of good options that depend entirely on what kind of rocket you're trying to build here.

[Spacescifi]

38 minutes ago, K^2 said:

That works. Of course, now orbital maneuvers are irrelevant. You just have to make it far enough out from gravity sources to engage the translation.

I wasn't complaining about propellant. I was complaining about it being a thermal rocket. With thermal rocket, you always use hydrogen, because that's the lightest stuff we have that's electrically neutral and stable, and the only two factors determining efficiency of a thermal rocket are melting points of components and how light your propellant is. NTRs already have about as high of an efficiency as you can get. By switching to antimatter as energy source in a thermal rocket, all you're ditching is the fuel core, and that's not even the heaviest part of NTR. All of the heat exchangers are, and you have to keep them for any thermal rocket. At this point, you might as well just go conventional NTR.

If you insist on burning antimatter for energy, the most efficient propellant is light. You have pure energy from your fuel - there's no reason to dilute it with anything. But that assumes you can bring all of your fuel mass as equal parts matter and antimatter. If you are limited in how much antimatter you can bring, either due to costs or because there are technological limitations, then you start thinking about what propellant to use. Again, if you're trying to do a lot better than an NTR, we're talking about energies that will turn any propellant you use into fine plasma. Since nothing can contain these sort of temperatures mechanically, that becomes a moot point, and you either go for magnetic nozzles or use ablative dampers, or whatever you need to do to protect your ship. Since temperature is no longer a factor, neither is the mass or composition of your propellant. You can literally use anything. If you are trying to reduce space, you probably want dense propellant. If you want it to flow, maybe mercury will do! Or maybe you want it to be cheap, abundant, safe to handle, and easy to transport. Then why not just use water? There are a lot of good options that depend entirely on what kind of rocket you're trying to build here.

 

So you are saying that because of the extra mass of heat exchangers and radiators required, antimatter rockets won't be greater by a large margin compared to nuclear?

That would be funny:

 

Captain 1: My ship runs on AM and propellant.

Captain 2: Mine runs on nuclear and propellant. Let's race to the moon roundtrip to see who gets back to Earth first!

 

I have a feeling the nuclear actually has a chance of winning, since unless the stuff required to store the AM is small or lightweight, it will probably be on par with a nuclear for weight or greater.

Weight matters not in space, but weight means mass and mass does matter. Meaning more mass requires more thrust to change speed quickly.

More thrust means you run out of propellant faster, which is the difference between a controlled landing and a crash landing, depending on how much you have. Or worse yet, missing the planet entirely with zero propellant.

Edited March 30, 2020 by Spacescifi

[mikegarrison]

On 3/28/2020 at 10:33 PM, Spacescifi said:

This a fun scifi scenario with some relation to reality:

You have a scifi starship in orbit fully fueled with propellant and cargo, using antimatter thermal rocket engines with methane propellant.

I navigate it the same way you created it. I just throw a bunch of buzzwords into the hopper, put the setting on blend, and come out with something like: "Set the course to match the gravity wave potential current flux and push through the gamma barrier until I achieve singularity, allowing the ship to reintegrate at the desired galactic coordinates."

[K^2]

2 hours ago, Spacescifi said:

So you are saying that because of the extra mass of heat exchangers and radiators required, antimatter rockets won't be greater by a large margin compared to nuclear?

Well, the heat exchangers are required for both. So that's no advantage to either one. I suppose, depending on how your antimatter confinement works, it could actually be worse than an NTR overall, yes. But again, this is specific to thermal rocket, where you convert energy to heat and use it to heat up propellant. But there have been other proposals for antimatter rockets that are way, way more efficient. Including ones that can theoretically do short interstellar runs in reasonable time. Wikipedia has an article on antimatter rockets which might be a good starting point if you want something a bit more powerful than an NTR.

Of course, if you want to do practical interstellar runs with a rocket, you probably want to have a black hole drive, as that has the same 100% matter-to-energy efficiency and doesn't require antimatter confinement. A black hole drive is only practical as a torch and you can maintain a 1g proper acceleration throughout the trip for a ship in a few thousand metric tons range. Which means you can do a round trip to center of the galaxy within human lifetime of the crew. Of course, 45,000 years would pass on Earth in the mean time. Not great for interstellar commerce, but if your goal is to seed the galaxy with life, quite doable. If you can figure out how to deal with drag, radiation, etc.

If that's not good enough, and you want to actually be making interstellar round trips in reasonable time in Earth years, then you do have to go FTL, and some variant on warp drive is probably the best bet for that. That's the place where math of General Relativity gives us some idea of what is and isn't inherently possible, but beyond that, completely unknown area as we lack all kinds of basic requirements to conduct the most rudimentary experiments. So at that point, we're dealing with pretty much pure fiction.

[Spacescifi]

6 hours ago, K^2 said:

Well, the heat exchangers are required for both. So that's no advantage to either one. I suppose, depending on how your antimatter confinement works, it could actually be worse than an NTR overall, yes. But again, this is specific to thermal rocket, where you convert energy to heat and use it to heat up propellant. But there have been other proposals for antimatter rockets that are way, way more efficient. Including ones that can theoretically do short interstellar runs in reasonable time. Wikipedia has an article on antimatter rockets which might be a good starting point if you want something a bit more powerful than an NTR.

Of course, if you want to do practical interstellar runs with a rocket, you probably want to have a black hole drive, as that has the same 100% matter-to-energy efficiency and doesn't require antimatter confinement. A black hole drive is only practical as a torch and you can maintain a 1g proper acceleration throughout the trip for a ship in a few thousand metric tons range. Which means you can do a round trip to center of the galaxy within human lifetime of the crew. Of course, 45,000 years would pass on Earth in the mean time. Not great for interstellar commerce, but if your goal is to seed the galaxy with life, quite doable. If you can figure out how to deal with drag, radiation, etc.

If that's not good enough, and you want to actually be making interstellar round trips in reasonable time in Earth years, then you do have to go FTL, and some variant on warp drive is probably the best bet for that. That's the place where math of General Relativity gives us some idea of what is and isn't inherently possible, but beyond that, completely unknown area as we lack all kinds of basic requirements to conduct the most rudimentary experiments. So at that point, we're dealing with pretty much pure fiction.

 

Yes... I knew of other antimatter schemes that are more efficient, variants of project Orion among them that combine high thrust with high efficiency of fuel (bombs).

As for AM thermal rockets, like all rockets their main limit is running out of propellant, which leads to a lot of thrust and drift. Which is not exactly good for crew health, even if you have FTL or what have you.

Somewhat off subject, but I discovered that if you had both fictional constant acceleration and warp or spatial translation, you would not need artificial gravity or spinning of the ship at all.

See, if the ship is moving space without actually moving, if you engage your engines you go nowhere,but since you're moving through space that is moving, it is like you are running on a treadmill. You feel the workout (gravity) but you go nowhere. Until you drop out of warp.

Neat little trick.

Edited March 30, 2020 by Spacescifi

[Shpaget]

I must admit this whole "ship doesn't move, it's the space that is moved" is something that doesn't sit well with me. It implies there is something beyond space that the ship references against, which while we have no indication of existing, isn't so much of a problem as long as you have only one such device in the universe. If two ships try to move space at the same time in different direction, what happens then?

[Spacescifi]

1 hour ago, Shpaget said:

 If two ships try to move space at the same time in different direction, what happens then?

We are firmly in fictional territory here.

So the easiest thing to do is ignore it and just let all ships warp anyway.

 

Now if I wanted to delve into the how's and why's of fantasy, it is utterly vain for me to do UNLESS it is a plot point or will be later.

And if it was... even then a discerning reader could pick it apart, so why bother?

I mean I could say the ship travels translates through a narrow tube of  warped space that stretches 7 lightyears in each direction. And any ship making it's own would have to not cross tubed or cancel each other out.

 

But realistically... probably would'nt be a plot point anyway... so a wast of time for me.

Making stuff plausible is a fool's errand unless we have a possible idea of how to do it.

[Dirkidirk]

3 minutes ago, Spacescifi said:

We are firmly in fictional territory here.

So the easiest thing to do is ignore it and just let all ships warp anyway.

 

Now if I wanted to delve into the how's and why's of fantasy, it is utterly vain for me to do UNLESS it is a plot point or will be later.

And if it was... even then a discerning reader could pick it apart, so why bother?

I mean I could say the ship travels translates through a narrow tube of  warped space that stretches 7 lightyears in each direction. And any ship making it's own would have to not cross tubed or cancel each other out.

 

But realistically... probably would'nt be a plot point anyway... so a wast of time for me.

Making stuff plausible is a fool's errand unless we have a possible idea of how to do it.

I read "tube of warped space" and remembered the krasnikov tube. Everything else you said however I could hardly comprehend, because my brain is square and I don't know why I posted this. 

[Hannu2]

On 3/29/2020 at 10:40 AM, Spacescifi said:

I am still wondering if any of you are witty enough to figure a way to acomplish single stage warp.

If I understood correctly, you have to achieve trajectory which goes closer than 100 km of massive body. It means  practically dwarf planets, because you probably do not want to enter into atmosphere at relativistic speed. Actually you have to assume scifi technology to handle very dilute interstellar gas.

Such predictions and targeting accuracy is as impossible as your drive. You have to invent some cool scifidevices which can handle it. All real spacecrafts measure their positions relative to targets and make several course corrections during the trip. Even in solar system when you have very good predictions of target position. Even if you target to star itself it needs impossible aiming. And you need also some nice unrealsitic tech to stop the ship at 100 km altitude over photosphere and accelerate several hundreds of kilometers per sec to normal trajectory without overheating.

 

[Spacescifi]

48 minutes ago, Hannu2 said:

If I understood correctly, you have to achieve trajectory which goes closer than 100 km of massive body. It means  practically dwarf planets, because you probably do not want to enter into atmosphere at relativistic speed. Actually you have to assume scifi technology to handle very dilute interstellar gas.

Such predictions and targeting accuracy is as impossible as your drive. You have to invent some cool scifidevices which can handle it. All real spacecrafts measure their positions relative to targets and make several course corrections during the trip. Even in solar system when you have very good predictions of target position. Even if you target to star itself it needs impossible aiming. And you need also some nice unrealsitic tech to stop the ship at 100 km altitude over photosphere and accelerate several hundreds of kilometers per sec to normal trajectory without overheating.

 

You misunderstood it.

I meant that if you translate within 100 kilometers of a planet... whether that means it's atmosphere OR in the case of having none, it's crust.

Slight Edit: Really the drive is more practical for us if we forget trajectories and have ship point where it is translating.

100 kilometer lock radius is fine, since it is easy for a ship to travel 100k from a planet's atmosphere.

 

If you mess up, you lose the main ship to translation, which is why warp staging (multiple detachable vessels with warp drives) is needed.

Meaning you lose the big ship and start translating again. Can only do it so many times before ee run out of spare warp ships, and they get progressively smaller too.

Matching planet speed after translation is nothing that an antimatter upgraded pusher plate orion with airbreathing nuclear aerospike SSTO shuttles could not handle.

In other words, use the orion as as an orbit to orbit vessel. Use the airbreathing shuttles to ship payloads betwern the planet and the orion orbiter mothership.

Edited March 30, 2020 by Spacescifi

[K^2]

5 hours ago, Spacescifi said:

Somewhat off subject, but I discovered that if you had both fictional constant acceleration and warp or spatial translation, you would not need artificial gravity or spinning of the ship at all.

See, if the ship is moving space without actually moving, if you engage your engines you go nowhere,but since you're moving through space that is moving, it is like you are running on a treadmill. You feel the workout (gravity) but you go nowhere. Until you drop out of warp.

Neat little trick.

The only problem with this approach is that you continue increasing ship's momentum. First of all, it means you have to keep increasing your warp/translation speed, which might require energy or could even saturate. Second, once you drop out, you will have all that momentum, so now you're not at rest anymore, unless you spent equal amount of time "slowing down". That's inconvenient.

But there's a way to fix this. Suppose, you didn't have warp, but did have that thruster that you can burn "for free" for a constant 1g. You could put your ship into a circular trajectory, using your engines to accelerate towards the center constantly. It's just like being parked on a very large rotating station, minus the station. You're still rotating the ship, but you don't need counterweights or moving parts. But now, with warp/translation you can do even better. Using translation you can keep your ship put while it's momentum keeps turning in a circle. So effectively, instead of translating along a line, you're translating along the circle at a constant rate. It does mean that the ship still needs to rotate to point its engine in different directions, but if effective orbit you are compensating for would have been hundreds of kilometers in diameter, the rotation of the ship can be very, very slow. Say, one revolution per day.

[Spacescifi]

56 minutes ago, K^2 said:

The only problem with this approach is that you continue increasing ship's momentum.

 

Really? Why so? Conservation of momentum? Please explain.

I know if you drive a car to 100 on a treadmill and put on the ground it will still go 100 until you hit the brakes.

 

Wait... I think I just answered my own question.

Speed equals momentum. Period. The only counter to this is when speeds are matched, which is why I can walk around in a van driving 60 mph and jump up and down without being sucked into the wall. Of course if the van accelerates rapidly I will start to be pulled backward.

And your right about the constant acceleration at 1g.

That would also mean that it would help for all the RCS thrusters to have the same fictional drive.

Beats rockets soundly... just not something we can achieve IRL as of now.

Edited March 30, 2020 by Spacescifi

[kerbiloid]

13 hours ago, Shpaget said:

I must admit this whole "ship doesn't move, it's the space that is moved" is something that doesn't sit well with me. It implies there is something beyond space that the ship references against, which while we have no indication of existing, isn't so much of a problem as long as you have only one such device in the universe. If two ships try to move space at the same time in different direction, what happens then?

They tear the space apart.