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As time passed, the survey ships that survived had mapped out reasonably safe routes through the more heavily traveled regions of hyper space. They couldn't be entirely relied upon, for the grav waves shifted position from time to time, and sticking to the safe lanes between waves often required vector changes reaction-drive ships simply could not make. That meant hyper voyages had tended to be both indirect and lengthy, but the survival rate had gone up. And as it climbed, and as physicists went out to probe the grav waves they now knew existed with ever more sophisticated instruments, observational data increased and ever more refined theories of gravity were proposed.
It had taken just over five hundred years, but finally, in 1246 P.D., the scientists had learned enough for the planet Beowulf to perfect the impeller drive, which used what were for all intents and purposes "tame" grav waves in normal space. Yet useful as the impeller was in normal space, it was extraordinarily dangerous in hyper. If it encountered one of the enormously more powerful naturally occurring grav waves, it could vaporize an entire starship, much as Honor herself had blown the Havenite courier boat's impeller nodes with Fearless's impeller wedge.
More than thirty years had passed before Dr. Adrie
And so the grav wave, once the promise of near certain death, had become the secret to faster, cheaper, and safer hyper voyages. Captains who had avoided them like the plague now actively sought them out, cruising between them on impeller drive where necessary, and the network of surveyed grav waves had grown apace.
There had still been a few problems. The most bothersome was that grav waves were layers of focused gravity, subject to areas of reverse flow and unpredictable bouts of "turbulence" along the interfaces of opposed flows or where one wave impinged upon another. Such turbulence could destroy a ship, but it was almost more frustrating that no one could take full advantage of the potential of the Warshawski sail (or, for that matter, the impeller drive) because no human could survive the accelerations which were theoretically possible.
Improved Warshawskis had tended to offset the first difficulty by extending their detection range and warning ships of turbulence. With enough warning time, a ship could usually trim its sails to ride through turbulence by adjusting their density and "grab factor," though failure to trim in time remained deadly, which was why Sirius's claim of tuner flutter had been so serious. A captain still had to see it coming, but the latest generation detectors could detect a grav wave at as much as eight light-minutes and spot turbulence within a wave at up to half that range. The problem of acceleration tolerance, on the other hand, had remained insoluble for over a standard century, until Dr. Shigematsu Radhakrishnan, probably the greatest hyper physicist after Warshawski herself, devised the inertial compensator.
Radhakrishnan had also been the first to hypothesize the existence of wormhole junctions, but the compensator had been his greatest gift to mankind's diaspora. The compensator turned the grav wave (natural or artificial) associated with a vessel into a sump into which it could dump its inertia. Within the safety limits of its compensator, any accelerating or decelerating starship was in a condition of internal free-fall unless it generated its own gravity, but the compensator's efficiency depended on two factors: the area enclosed in its field and the strength of the grav wave serving as its sump. Thus a smaller ship, with a smaller compensator field area, could sustain a higher acceleration from a given wave strength, and the naturally-occurring and vastly more powerful grav waves of hyper space allowed for far higher accelerations under Warshawski sail than could possibly be achieved under impeller drive in normal space.
Even with the acceleration rates the compensator permitted, no ma
And that brought Honor right back to Sirius, for the ship in front of her obviously had a military-grade drive and compensator. Her sheer mass meant her compensator field was larger and thus less efficient than Fearless's, but no freighter should have been able to pull her acceleration. Even a superdreadnought, the only warship class which approached her mass, could only manage about four hundred and twenty gees, and Sirius was burning along at four hundred and ten. That left Fearless an advantage of barely a hundred and ten gees, little more than a kilometer per second squared—and Sirius had a head start of just under fifteen minutes.
It would have been worse if Fearless hadn't been at standby or Dominica Santos hadn't cut corners and chopped almost a full minute off the time it took to put her drive fully on line. As it was, Honor could still overhaul before Sirius reached the hyper limit, but not with as much margin as she might have wished. Sirius would hit the hyper limit in just under a hundred and seventy-three minutes from the time she left orbit. Honor had been in pursuit now for almost ten minutes. By cutting the safety margin on her own compensator to zero, she could match velocities with the freighter in another forty-six minutes, but it would take her over an hour just to reach effective missile range. Completely overtaking the freighter would require just over another hundred and seven minutes, leaving her less than twenty minutes before Sirius reached the hyper limit. And even if she did overtake completely, forcing the freighter to heave-to would be far from easy. Worse, momentum alone would carry Sirius beyond the hyper limit, even if she braked at max in response to Honor's demand, unless she began her deceleration within the next hour and a half, and Honor had no way of knowing just how far beyond the hyper limit a Havenite battle squadron might be lurking. No normal space sensor could see across the hyper wall. The entire Havenite Navy might lie less than a light-second beyond the limit, and no one in Basilisk would know a thing about it, so it was entirely possible Sirius needed only to break into hyper at all to accomplish her mission.