Spider drive ships and impeller drives and alpha nodes

tlb wrote:He was looking at the Sharks on their way to carry out Oyster Bay. In Storm from the Shadows:

Chapter 40 wrote:Albrecht wasn't the military specialist Benjamin was, but even he could tell the Sharks looked subtly wrong. They were too far away for the naked eye to see, but the view screen's magnification brought them to what seemed like arm's-length and made it obvious that all of them lacked the traditional "hammerhead" design of a military starship. Indeed, the lines of their hulls were all wrong, in one way or another, as if their designers had been working to a completely different set of constraints from anyone else in the galaxy.

Which was precisely what they had been doing.

The strike ships turned slowly, and then, as one unit, they went loping away into the trackless depths of space. And that, too, was wrong. The light-warping power of a starship's impeller drive made the ship within it impossible to see, except from exactly the right angle. But there was no gravitic distortion around these ships, nothing to bend and blur light waves, because they didn't use impeller wedges.

ThinksMarkedly wrote:First, the Sharks don't have a hammerhead. So wherever they mount their nodes, it isn't on the hammerhead. Presumably there's a ring somewhere.

Second, it only says they didn't use a wedge... not that they couldn't use one. That only means that at the time he looked at them, they weren't using impellers. Though coupled with the former point, it probably does mean they can't generate an impeller.

tlb wrote:

ThinksMarkedly wrote:First, the Sharks don't have a hammerhead. So wherever they mount their nodes, it isn't on the hammerhead. Presumably there's a ring somewhere.

Second, it only says they didn't use a wedge... not that they couldn't use one. That only means that at the time he looked at them, they weren't using impellers. Though coupled with the former point, it probably does mean they can't generate an impeller.

The hammerhead is not required by the wedge, freighters do not have them. They exist on warships as a place to mount sensors and weapons.

Mycall4me wrote:Well, that's encouraging, that they DON'T have impeller drive that is. One of the things that struck me as a signicant disadvantage in a spider drive ship was it's (relatively) low acceleration bc of the lack of the grav sump for an inertial compensator to take advantage of.IIRC (There's that pesky IIRC thing again) (I'm confident that someone will let me know if I didn't) They had a max accelleration of 300 G's (?) which would make it a less than stellar time to build any decent speed in normal or hyper space. Would that also mean the same thing in a grav wave with their Warshawski sails too?

Another thing that occurs to me (IIRC × 2) is that the interior configuration of a spider drive ship required the deck layout had to be configured out differently from the standard layout of an impeller drive ship. This could cause all sorts of design compromises and limitations to things like missile tubes and decks, and ammo storage/handling systems among other things.

Yay, more problems that those pesky MAlign ship's architects have to overcome. And hopefully require some less than optimum designs to work around those limitations

Mission of Honor wrote:the maximum survivable normal-space acceleration for a spider drive-equipped ship was limited by the ability of currently available grav plate technology to offset the consequences of acceleration. Unfortunately, grav plates were far less capable in that respect than inertial compensators, which had an inevitable effect on the maximum accleration a spider-drive ship could attain. It also meant that unlike impeller-drive vessels, a spider-drive ship’s decks had to be aligned perpendicular to its axis of movement rather than parallel, which was a large part of what produced its shorter, “squatter” hull form, not to mention requiring some significant rethinks about the way spacecraft designers had been arranging ship interiors literally for centuries.
Although the Alignment’s physicists had been inspired to push grav plate technology harder than anyone else, there were still limits. Up to an actual acceleration of one hundred and fifty gravities, it could achieve an efficiency of over ninety-nine percent, producing a “felt” acceleration of only one gravity. Above that level, however, the plates’ efficiency fell off dramatically. The physical plant itself grew larger and more massive on a steeply climbing curve, which cut into internal volume, and even then, each additional gravity of actual acceleration produced a “felt” increase of approximately .05 g. That didn’t sound too terrible, but what it meant was that fifty additional gravities produced an apparent increase of two and a half gravities, which raised the ship’s internal gravity to 3.5 g, at which point the crew’s ability to move about and perform even routine duties began to become . . . ​impaired. And it also meant that grav plates powerful enough to produce that effect required almost twice the volume required to produce the 150:1 ratio.
After considering the situation carefully, the architects had designed and stressed the ship structures and control stations to permit effective maneuvering and combat at up to four gravities, but combat efficiency began to decline noticeably at that rate of acceleration due to the physiological limitations of the crew. Moreover, that still equated to an actual acceleration of only two hundred and ten gravities, which was pathetic by the standards of any impeller-drive warship. Actual acceleration could be pushed—in emergencies, and briefly, at least—to almost three hundred and ten gravities, but that produced a “felt” gravity of 9 g. Crew acceleration couches were provided for just that contingency, yet three hundred and ten gravities was still barely half of the acceleration which the RMN’s biggest superdreadnought could currently attain, and even with the best acceleration couches in the universe, no one could stand nine gravities for long

Mycall4me wrote:Well, that's encouraging, that they DON'T have impeller drive that is. One of the things that struck me as a signicant disadvantage in a spider drive ship was it's (relatively) low acceleration bc of the lack of the grav sump for an inertial compensator to take advantage of.IIRC (There's that pesky IIRC thing again) (I'm confident that someone will let me know if I didn't) They had a max accelleration of 300 G's (?) which would make it a less than stellar time to build any decent speed in normal or hyper space. Would that also mean the same thing in a grav wave with their Warshawski sails too?

Another thing that occurs to me (IIRC × 2) is that the interior configuration of a spider drive ship required the deck layout had to be configured out differently from the standard layout of an impeller drive ship. This could cause all sorts of design compromises and limitations to things like missile tubes and decks, and ammo storage/handling systems among other things.

Yay, more problems that those pesky MAlign ship's architects have to overcome. And hopefully require some less than optimum designs to work around those limitations

tlb wrote:Without a compensator, they could not take advantage of the acceleration possibilities offered by a gravity wave; which is why I suggested that something as big as a Shark, might actually have one. If we further believe that a Ghost is too small to hold one; then that would help explain why the Sharks traveled to Oyster Bay using their own drives, while the Ghosts were carried by a special freighter.

The interior arrangements would still differ from a regular wedge drive; because while using the spider drive gravity plates have to cancel the force, meaning the floors are perpendicular to the direction of travel. But I am not sure whether traveling under sail can be done with floors in that arrangement (I also don't know if that is a problem).

tlb wrote:The Ghost class scouts were delivered by freighter, but it is generally assumed that they flew away under their own power (even if it was just to a meeting somewhere with another freighter). We do not have a description of how that worked at Grayson, since there is not a wormhole to serve as a fake destination.

tlb wrote:The Ghost class scouts were delivered by freighter, but it is generally assumed that they flew away under their own power (even if it was just to a meeting somewhere with another freighter). We do not have a description of how that worked at Grayson, since there is not a wormhole to serve as a fake destination.

ThinksMarkedly wrote:Actually, the Ghost's extraction need not have been stealthy. Only the insertion had to be. For leaving, they could simply go to an RV point in the outer system and await a freighter come to pick them up. The freighter's translation would be noticed, but that's not a problem so long as they're gone before the reaction force can come in.

That is, they need to be further out in light-hours than the time it takes (in minutes) to load on the freighter. If they can load minimally for translation in 2 hours, then they need to be 5 light-days out.

tlb wrote:What I find more interesting is the insertion. We know that at Manticore the freighters, which dropped them, continued on to the wormhole junction. My question is about those that dropped Ghosts at Yeltsin: did they just transit in, drop the scouts and transit out? Counting on the Ghosts' invisibility to protect them, since there is no wormhole to provide a fake destination.