The maximum acceleration the new technology could theoretically have attained was vastly lower than the acceleration theoretically attainable under impeller drive. After all, in theory an impeller wedge could be accelerated instantaneously to the speed of light. There were, however, a few shortcomings to that sort of acceleration, which was why theoretical acceleration rates had always been of far less interest to practical ship designers than the maximum rates which could be compensated for with sufficient efficiency to allow mere humans to survive without being turned into extremely thin layers of paste on the bulkheads.
And in that respect, even the spider drive's lower theoretical maximum acceleration presented a definite challenge, given the fact that it produced no impeller wedge. Without a wedge, it also produced no convenient "sump" for an inertial compensator, and that meant 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. Worse, smaller spider-drive ships had no acceleration advantage over larger ones. And the need to stabilize the ship relative to the hyper wall required at least three sets of "spider legs," which led directly to the "triple skeg" hull form which had been adopted. Which, in turn, meant that instead of two broadsides, a spider-drive ship had three . . . none of which could be protected by the impenetrable barrier of an impeller wedge. That meant both that areas no impeller-drive ship had to armor did require massive armor protection aboard a spider-drive warship and that there was no wedge floor and roof for a side wall to stitch together. And just to make matters even more interesting, the spider drive could not be used through a spherical sidewall like the ones fortresses generated.
All of that was true,and all of it constituted indisputably significant disadvantages. But the spider also had one overwhelming ad vantage: it was effectively undetectable by any sensor system deployed by any navy (including the MAN itself) at any range much beyond a single light-second. Even for the MAN, it was damnably hard to detect; for someone who didn't even know what to look for, the task was about as close to outright impossible as challenges came. For all intents and purposes, a spider-drive ship's drive field was invisible, and it was actually the drive signature of a ship for which virtually all long-range passive sensors searched.
Which explained how Admiral Frederick Topolev's and Rear Admiral Lydia Papnikitas' strike forces had been able to deploy their missile pods without anyone's ever noticing they were there. And it also explained how Commodore Karol Шstby's and Commodore Milena Omelchenko's scouting forces had been able to prowl undetected about both components of the Manticore Binary System for over two months, while Commodore Roderick Sung's scouts and Admiral Jennifer Colenso's strike ships had done exactly the same things at Yeltsin's Star.
And no one knew a thing about it or even suspected what was about to happen.
* * *
Now the Mesan attack came sweeping in out of the darkness. The incoming weapons had extraordinarily low radar signatures, and they were coming in at barely 60,000 KPS. Even if some of them had been detected, their velocity was so low it was unlikely to pop through the defenders' threat filters. As it happened, however, none of them were picked up as they sliced deeper and deeper in-system, unseen and undetected, like the talons of some huge, lethal, invisible bird of prey.
There were actually six separate attacks on the Manticore Binary System itself, one for each inhabited planet's infrastructure and each divided into two separate waves, although they'd been carefully synchronized to form a single, devastating sledgehammer of a blow.
The first wave of each attack consisted of a weapon which was as much a fundamental breakthrough, in its own way, as the Manticoran introduction of the multidrive missile: a graser torpedo which used its own variant of the spider drive. It was a large and cumbersome weapon, with the same trilateral symmetry as the Shark -class ships which had launched it, and for the same reasons.
The torpedo's size made fitting it into magazines and actually firing it awkward, to say the least, and the Sharks had never been intended to deploy it operationally. For that matter, the Sharks themselves had never been supposed to be deployed "operationally." The Leonard Detweiler class, which had been intended to carry out this operation, had been designed with magazines and launch tubes which would make it possible to stow and fire torpedoes internally, but none of the Detweilers were even close to completion, and it had required the development of an ingenious external rack system to allow the Sharks to use it for Oyster Bay.
For all its size, it was also a slow weapon. It was simply impossible to fit a spider drive capable of more than a few hundred gravities' acceleration into something small enough to make a practical weapon. As compensation, however, its drive had almost as much endurance as most of the galaxy's recon drones, which gave it an impressive absolute range. And a large percentage of the torpedo's volume had been reserved for systems which had nothing at all to do with propulsion. Whereas the Royal Manticoran Navy had concentrated on improving the efficiency of its standard laser heads, Daniel Detweiler's R&D staff had taken another approach. They'd figured out how to squeeze what amounted to a cruiser-grade graser projector into something small enough to deploy independently.