Concepts: Today's similarities and differences to the HV

tlb wrote:We have a couple of examples of small wedge powered anti-vehicle missiles, including the ones that downed Honor's shuttle in FiE. So a wedge will work in atmosphere, I believe the problem is that wedges big enough to move people around are destructive to everything (except air) and so too dangerous; the same way that wedges are not permitted (with very few exceptions) around the orbital platforms like Hephaestus.

Theemile wrote:I was going to mention those, but I think their "magic" is they only work for a handful of seconds at most - having a wedge work for a hour or 2 in low atmo might be... interesting.

ThinksMarkedly wrote:That's 90 km, not meters. In fact, the distance between the floor plane and the ventral side of the ship is also in the multi-km range, so the ship would need to cut its wedge while still as high as or higher than current commercial aeroplanes. So it couldn't lower itself to the ground on wedge.

The length of the spider tractor is also unknown. But given that the ship floor orientation is in the direction of travel, it could also land as a skyscraper, so the tractors would be to the side, not down.

There are two other problems with landing on a planet. First and obvious is getting back up again. Could the spider be used for this, for lifting from a standstill?

Second, does the ship's structural integrity allow for it to be immersed in a 1g gravitational field? The spider ships may allow it, because unlike a wedge, they are not in zero-g during acceleration but are instead under those 150 to 300 gravities the tractors would be pulling. I wouldn't submerge them, though - the water pressure increases by 1 atmosphere every 10 m (well, 9.81 m), and the pressure vessel may not be designed to hold that much. Then again, it's a warship and has armour. And if it is going to go down in water, it may decide to go on its side, not upright, and then people would just have to walk on the walls, with the decks becoming bulkheads, like the ships in The Expanse did (at least for the Rocinante). That way, the difference in pressure would only be around 20 atmospheres, instead of 100+. I'm trying to remember which Sci-Fi franchise landed a tall ship in water... was it a Revelation Space lighthugger?

Of course, the most important question here is: why would you do that? Is this for repairs on ground-based shipyards? Is it for hiding the ship for an ambush? Is it for disgorging an invasion force?

tlb wrote:

tlb wrote:We have a couple of examples of small wedge powered anti-vehicle missiles, including the ones that downed Honor's shuttle in FiE. So a wedge will work in atmosphere, I believe the problem is that wedges big enough to move people around are destructive to everything (except air) and so too dangerous; the same way that wedges are not permitted (with very few exceptions) around the orbital platforms like Hephaestus.

Theemile wrote:I was going to mention those, but I think their "magic" is they only work for a handful of seconds at most - having a wedge work for a hour or 2 in low atmo might be... interesting.

I do not know what atmospheric effect you believe will occur. I expect the air will get ionized, but breaking things down to the atomic level is the limit of my knowledge. Note that sidewalls work fine in atmosphere, that is what they use in firing ranges.

Theemile wrote:A wedge (in an atmosphere) is a gravity well moving through the atmosphere. Even if the wedge has no effects at a distance, it should still suck up and compress atmosphere as it passes, with inclined planes, we're talking about thousands of sq KM of frontage.

Even if we are just discussing ionization (then passing on the air) that 2000+ KM^2 wedge is (at a minimum) doubling the number of molecules as it ionizes the passing air - which will moments later recombine explosively in the ship's wake. So if this is the case, a ship entering the atmosphere is going to be a thundering fireball that cannot be hidden.

tlb wrote:PS: It is the after aspect that is wider, right? So much of the disturbance is outside the wedge.

ThinksMarkedly wrote:

Jonathan_S wrote:Handfuls of seconds and a wedge that's probably only a meter or so wide. Far different from the dozens of meters that even a pinnace wedge must be; much less then 90+ meters of a starship wedge.

That's 90 km, not meters. In fact, the distance between the floor plane and the ventral side of the ship is also in the multi-km range, so the ship would need to cut its wedge while still as high as or higher than current commercial aeroplanes. So it couldn't lower itself to the ground on wedge.

The length of the spider tractor is also unknown. But given that the ship floor orientation is in the direction of travel, it could also land as a skyscraper, so the tractors would be to the side, not down.

There are two other problems with landing on a planet. First and obvious is getting back up again. Could the spider be used for this, for lifting from a standstill?

Second, does the ship's structural integrity allow for it to be immersed in a 1g gravitational field? The spider ships may allow it, because unlike a wedge, they are not in zero-g during acceleration but are instead under those 150 to 300 gravities the tractors would be pulling. I wouldn't submerge them, though - the water pressure increases by 1 atmosphere every 10 m (well, 9.81 m), and the pressure vessel may not be designed to hold that much. Then again, it's a warship and has armour. And if it is going to go down in water, it may decide to go on its side, not upright, and then people would just have to walk on the walls, with the decks becoming bulkheads, like the ships in The Expanse did (at least for the Rocinante). That way, the difference in pressure would only be around 20 atmospheres, instead of 100+. I'm trying to remember which Sci-Fi franchise landed a tall ship in water... was it a Revelation Space lighthugger?

Of course, the most important question here is: why would you do that? Is this for repairs on ground-based shipyards? Is it for hiding the ship for an ambush? Is it for disgorging an invasion force?

penny wrote:I think the tactical applications would be endless to the tactical mind. I must admit, the sight of an LD disappearing into the ocean in a movie would have been awesome.

But I was thinking more like using a smaller ship like a Ghost or Shark to pull it off, like in the case of Albrecht and Evelina to hide indefinitely. Or in any case where there is not enough time for the Inner Onion to make their way to a ship in space; the ship could come to them.

It might also be an interesting tactic to hide several ships in the ocean ahead of time, like in one of the Sci-Fi movies, to activate much later, for whatever reason.

Why can’t counter-grav assist with landing and lifting the ship?


The tractors may be variable to assist with the tactic; cycling on and off, and/or shortening their range considerably.

penny wrote:I think the tactical applications would be endless to the tactical mind. I must admit, the sight of an LD disappearing into the ocean in a movie would have been awesome.

But I was thinking more like using a smaller ship like a Ghost or Shark to pull it off, like in the case of Albrecht and Evelina to hide indefinitely. Or in any case where there is not enough time for the Inner Onion to make their way to a ship in space; the ship could come to them.

It might also be an interesting tactic to hide several ships in the ocean ahead of time, like in one of the Sci-Fi movies, to activate much later, for whatever reason.

tlb wrote:

penny wrote:I think the tactical applications would be endless to the tactical mind. I must admit, the sight of an LD disappearing into the ocean in a movie would have been awesome.

But I was thinking more like using a smaller ship like a Ghost or Shark to pull it off, like in the case of Albrecht and Evelina to hide indefinitely. Or in any case where there is not enough time for the Inner Onion to make their way to a ship in space; the ship could come to them.

It might also be an interesting tactic to hide several ships in the ocean ahead of time, like in one of the Sci-Fi movies, to activate much later, for whatever reason.

A space ship is NOT a submarine, it only has to contain one atmosphere of pressure; whereas every 10.3 meters (33.8 ft) of depth adds another atmosphere of pressure. The workings of a space ship can easily handle vacuum; they would not respond well to salt water, which is both conductive and corrosive (consider a plasma conduit for example).

Theemile pointed out the problems of generating movement in air, these are compounded in water. In addition to the problem of pressure that I have repeated, ThinksMarkedly questions the orientation of a spider drive ship when laying in water.

Jonathan_S wrote:

penny wrote:I think the tactical applications would be endless to the tactical mind. I must admit, the sight of an LD disappearing into the ocean in a movie would have been awesome.

But I was thinking more like using a smaller ship like a Ghost or Shark to pull it off, like in the case of Albrecht and Evelina to hide indefinitely. Or in any case where there is not enough time for the Inner Onion to make their way to a ship in space; the ship could come to them.

It might also be an interesting tactic to hide several ships in the ocean ahead of time, like in one of the Sci-Fi movies, to activate much later, for whatever reason.

Why can’t counter-grav assist with landing and lifting the ship?


The tractors may be variable to assist with the tactic; cycling on and off, and/or shortening their range considerably.

Countergrav presumably could help -- though the largest things I think we know of that have countergrav are heavy lift shuttles which are still tiny (probably under 1500 tons; even fully loaded with their just over a thousand tons of cargo) compared to any starship. So there might be some scaling limit we haven't been told of that'd prevent you from giving such a large thing countergrav.

(And keep in mind that even a small ship like a Ghost is still about as wide as, and 25% longer than a Yamato-class, battleship (and masses about 75% as much -- so not small on any scale of ship we're used to. And around 35x the likely mass of a heavy lift shuttle. And a Shark is small only in comparison to a LennyDet; it's still about the size of an Honorverse battleship; making it around 80x the tonnage of a Ghost)

But if we assume countergrav can be scaled up to arbitrarily large vehicles it still takes volume and mass to install (quite possibly quite a lot of it to affect a ship so much larger than the largest known vehicle with countergrav). Is landing a warship on a planet a good enough trick to be worth making a larger more expensive ship just to add that one capability?
(Because outside of planetary landing countergrav isn't going to be helpful for anything else a warship does. And if you make the warship larger and more expensive you make it harder to hide and reduce the number your economy can manage to build a support. Maybe not by a lot; but warships are a compromise and I'm unconvinced the costs of enabling planetary landings are worth the advantages. (No mater how cool it might look in a movie)