Attacking Darius:

ThinksMarkedly wrote:

tlb wrote:I hope that you know that her thrusters were very visible at Hades; the Peep force was just not looking for them. Not a mistake that a recon drone would make.

That's what I would have expected, but wasn't. Those drive plumes should have been visible clear across the system from a light-hour away. There shouldn't have been a way for the sensors on any ship to fail to detect them at all, much less when they closed to a few light-seconds.

And yet they weren't.

Moreover, those were full 50-gravity burns from the thrusters, not small manoeuvring jets for positioning. This tells me that jets could be sufficiently hidden.

I'm not sure they could be detected at long range. You're thinking of a rocket engine that ejects hot plasma--but no chemical engine can achieve anything like the performance we saw. Furthermore, energetic rocket exhaust is undesirable, that's energy that's being wasted. (Exception: If your rocket hits something nearby the results will be energetic without being wasteful.)

Thus I think that the thrusters must be some sort of accelerator that's simply pushing out hydrogen. Look elsewhere in the tech base and you find gravity generators of great power--I think the thrusters are simply taking hydrogen and shoving it out at great speed using power from the reactor.

The hydrogen will not be emitting anything unless it slams into stuff in space. Of course there should be an awful lot of waste heat but we have seen that Honorverse ships simply don't produce the waste heat that thermodynamics says they must.

Furthermore, this plays in with using the sun as cover. She's in effect a small bright star transiting a larger, dimmer star. That's going to be very hard to spot other than by purpose-built instruments--and are warships going to mount substantial instruments to figure out of someone is trying to come at them from out of the sun? Especially since that would constrain them to not blocking the sun with their wedge.

Loren Pechtel wrote:I'm not sure they could be detected at long range. You're thinking of a rocket engine that ejects hot plasma--but no chemical engine can achieve anything like the performance we saw. Furthermore, energetic rocket exhaust is undesirable, that's energy that's being wasted. (Exception: If your rocket hits something nearby the results will be energetic without being wasteful.)

Thus I think that the thrusters must be some sort of accelerator that's simply pushing out hydrogen. Look elsewhere in the tech base and you find gravity generators of great power--I think the thrusters are simply taking hydrogen and shoving it out at great speed using power from the reactor.

The hydrogen will not be emitting anything unless it slams into stuff in space. Of course there should be an awful lot of waste heat but we have seen that Honorverse ships simply don't produce the waste heat that thermodynamics says they must.

Furthermore, this plays in with using the sun as cover. She's in effect a small bright star transiting a larger, dimmer star. That's going to be very hard to spot other than by purpose-built instruments--and are warships going to mount substantial instruments to figure out of someone is trying to come at them from out of the sun? Especially since that would constrain them to not blocking the sun with their wedge.

FromAshes of Victory, chapter 23:

"In line with the second weakness," the captain continued, "was the fact that even though a reaction thruster approach allowed her to avoid the enemy's gravitics, the plume of ejecta it produced must have been quite spectacular . . . and energetic, and Peep stealth fields, which were what Her Grace had to work with herself, you will recall, aren't as good as ours. Again, Her Grace had taken the precaution of placing herself with the local star at her back. Had she not possessed 'inside information' on Peep movement patterns at Cerberus, she would have been unable to do that, of course. In this case, as she mentioned, she knew her enemy's probable approach vector well in advance, which let her give herself the advantage of attacking 'out of the sun,' as it were. If the enemy had failed to appear where she anticipated him, the entire maneuver would have been out of the question, and I'm certain she had a more, ah, conventional fallback plan for that situation. As it was, however, Cerberus-A's emissions were sufficiently powerful to greatly reduce the effectiveness of any sensor looking directly at it, and by the time Her Grace's vector had moved her clear of the star, she'd shut down her thrusters and other active emissions. Nonetheless, the circumstances only made it difficult for the Peeps to have picked up her approach; they didn't make it impossible, and an alert sensor crew could have given the enemy warning in plenty of time.

Even if you were correct, the act of shoving hydrogen out with great force would turn it into a plasma just from internal friction, if nothing else; because the shove will exert enormous pressure.

tlb wrote:

Loren Pechtel wrote:Thus I think that the thrusters must be some sort of accelerator that's simply pushing out hydrogen. Look elsewhere in the tech base and you find gravity generators of great power--I think the thrusters are simply taking hydrogen and shoving it out at great speed using power from the reactor.

The hydrogen will not be emitting anything unless it slams into stuff in space. Of course there should be an awful lot of waste heat but we have seen that Honorverse ships simply don't produce the waste heat that thermodynamics says they must.

FromAshes of Victory, chapter 23:

the plume of ejecta it produced must have been quite spectacular . . . and energetic

Even if you were correct, the act of shoving hydrogen out with great force would turn it into a plasma just from internal friction, if nothing else; because the shove will exert enormous pressure.

I'd certainly assumed that the reaction thrusters where themselves fusing in order to get the velocity necessary for the stated thrust. (Though of course they're highly variable in power output, and the use at Cerberus had them cranked up to full emergency output levels -- and at more conventional power levels they're safe enough to use to dock and undock from stations)

But looking through the books I'm not seeing anything all that specific:
* "(21) Vectored Thrust Auxiliary Fusion Reactor Thruster" HMS Minotaur labeled sketch [EoH & AoV]
* "main fusion-powered reaction thrusters" [CoG]
* "the shuttle's fusion-powered thrusters" [SftS]
* "without the pyrotechnics of her normal fusion-powered thrusters" [SftS]

Those are are vague enough they could apply to something like an ion drive or gravity accelerator powered from the ship's fusion reaction.

Though you've got a good point that the pressure necessary to generate that kind of acceleration from any reasonable rocket throat size is going to make the exhaust all kinds of energetic (even if it might be below the threshold to self-initiate fusion).


We do know that the Shrikes kept a (smaller) hydrogen bunkerage for their reaction thrusters, despite deleting their fusion reactor. But none of the references to thrusters being "fusion-powered" are specific to the fission powered LACs - if we'd gotten a "fusion-powered thruster" mention about a fission powered LAC then that'd be a pretty good clue that the thruster itself is fusing. Unfortunately we can't read much, if anything, into the lack of that mention because most references to reaction thrusters don't mention them being fusion powered -- even on ships we know have fusion reactors)

Jonathan_S wrote:Those are are vague enough they could apply to something like an ion drive or gravity accelerator powered from the ship's fusion reaction.

A gravity-accelerated exhaust is probably the actual technology. An ion drive is a known technology and works by magnetically accelerating ions, and that magnetic field is produced by electricity. So we know roughly the inefficiencies in those systems. If we talk about a gravity accelerator, which we know nothing about, there may be ways for the energy from the fusion bottle (which itself is a gravity technology) to transfer its energy to kinetic energy of the exhaust with much higher efficiencies.

That's still something we can calculate. Let's approximate a Mars-D class heavy cruiser to 509 858 kg in mass, because that makes a 50 gravity acceleration equal to exactly 250 MN of force pushing it. If it accelerates for 1 hour at that acceleration, its delta-v will be
1765.2 km/s, which is low enough we can ignore relativistic effects. But its kinetic energy gain will be 1588.7 petajoules or 441.3 TWh. That's equivalent to 17.7 kg of matter in E=mc², which would be a 100% efficient conversion of half of matter and anti-matter to kinetic energy. Nuclear fusion of hydrogen is estimated to be about 1% as efficient as matter-antimatter would be, and if efficiency of converting that to kinetic 88%, that gives an overall efficiency of 0.88%. So this ship would need to fuse 17.7 / 0.0088 = 2008 kg per hour.

On the momentum transfer side, in one hour, that ship gained 900 billion kg m/s of momentum. If the hydrogen was expelled out at 0.1c relative, then the ship must have pushed out 30 tonnes in one hour. I suppose it can send 28 t of hydrogen and 2 tonnes of helium that is the product of fusion, so it keeps its bunkerage expenditure at 30 t/hour. Those are belieavable numbers.

The problem is that if the efficiency is 88%, then 12% of that energy is going to waste heat and we're talking about 53 terawatts of thermal energy that must go somewhere! Even at 99.9% efficiency it's 442 GW of thermal energy. Most of it must be going out with the hydrogen being accelerated out, otherwise the ship would simply melt in the first few seconds.

Though you've got a good point that the pressure necessary to generate that kind of acceleration from any reasonable rocket throat size is going to make the exhaust all kinds of energetic (even if it might be below the threshold to self-initiate fusion).

Also, the exhaust is slamming into the interplanetary medium, which is not a vacuum. And in the inner system, it's denser and more energetic.

tlb wrote:For KZT's example I will need to reread the relevant text. I am guessing it is in A Rising Thunder, as part of Admiral Filareta's attack on Manticore? It is possible to be overly terse.

kzt wrote:No. UH

"Aside from the two squadrons of Agamemnon-class BC(P)s of the ready response force, Third Fleet’s hyper generators were powered completely down". "It would take a Saganami-class cruiser thirty-seven minutes—and an SD like Lysander or a CLAC like her own Fafnir over forty—to bring up their generators and translate. For that matter, except for the ready response squadrons, every ship would have to bring her impeller nodes up from scratch at the same time, and that alone would take forty minutes, so not even the Saganami was getting into hyper any sooner than Fafnir."

ThinksMarkedly wrote:Even though this passage talks about "impeller nodes up from scratch," it's talking about hyper translation to alpha. We know that the generators can be cold, ready and translating. The latter is when you press the button to translate from ready and takes up to 3 and a half minutes for an SD.

I'm trying to understand the linkage between that and the conclusion of translating. There's something there. Why couldn't a Saganami translate sonner than Fafnir?

kzt wrote:Because translating without a working impeller drive or sidewall isn't a very good idea?

The point is that the ENTIRE FLEET was parked with their impellers cold. They has two BC(P) squadrons with warm drives, everyone else was cold.

What would have happened to them if 200 graser torps swept on it? "Commander Jones, you are the highest ranking officer left from 3rd fleet. Can you explain to the court of inquiry what happened to the rest of the fleet?"

Hence I find it feasible that the RMN still has no clue what the hell really happened to the orbital platforms. This wasn't just something David stuck in the last book like the planet, he's been showing that the RMN either doesn't understand the threat or refuses to believe what they know.

The quotes are from pages 265 and 266 of UH (hardback), just ahead of the section headed "Private Yacht Anachronism Beowulf System". So Operation Fabius is just about attack the Sigma Draconis System.

I have finished rereading Uncompromising Honor, a task slowed by the basketball tournaments, and am finally ready to comment.

I will begin with what I think was learned from the Yawata Strike. The authorities have no clear idea how the weapons were initially delivered to the Manticore and Yeltsin systems, so they might not have considered freighters dropping them close in (I am not sure how much this will change when they analyze the coming Silver Bullet attack). It is possible that they believe the weapons were dropped far outside the system and came in ballistically, for the most part. But even if they suspect a nearer start, they still believe that the weapons took several days to get into position (this will not be changed by the Silver Bullet attack). If they arrive at that conclusion, then it follows that the preferred targets are those that are relatively immobile: such as munitions factories and shipyards. Individual ships or even fleets of ships may be targets of opportunity, but normally will not be the primary aim of an attack.

So Truman and Holman-Sanders were not ignoring the results of the Yawata Strike analysis; it is true that they would have been in massive trouble if 200 graser torpedoes had come their way, but that was a low probability event. However they were very complacent and negligent by not being ready for the event that had a much higher probability at the time; a strike by the Solarian Navy at facilities of Beowulf (Operation Fabius). The complacency derives entirely on their faith in Mycroft and here is where one implication of the Yawata Strike was missed by the authorities, because they were about to find out that endurance and stealth made Mycroft vulnerable. The destruction of Mycroft did not help the attacking Navy, since only about ten percent of the battlecruisers survived. Because of their negligence, they could not participate in the fight; if they had been ready, then perhaps the Solarians might have captured, instead of escaping.

Was RFC trying to highlight the incomplete understanding of the implications of Oyster Bay or was he just trying to set up a situation where a Solarian Navy was ravaged by system defense missiles without any Grand Alliance ship involvement?

tlb wrote:Was RFC trying to highlight the incomplete understanding of the implications of Oyster Bay or was he just trying to set up a situation where a Solarian Navy was ravaged by system defense missiles without any Grand Alliance ship involvement?

Maybe. But here's another wrinkle: this is another lesson. The hot wash of this battle would have shown that the Mycroft installations were vulnerable because the enemy could sneak actively-manoeuvring weapons undetected in the system. They went for relatively or completely stationary targets like the Mycroft installations, but if a fleet stands idle for a long enough period of time, it can become a target too.

But their impellers being down does not mean that their sensors were. The Mycrofts were supposed to be stealthy, so they weren't emitting radar pulses to find what was close to them. That flight might have.

We know Oyster Bay's delivery of the Sharks was by a freighter way out and beyond almost the most tenuous edge of the Manticore System sensor net and it was investigated. The Sharks had moved away under Spider drive and fairly slowly at that.
No information about the approach to Grayson though the target was out a Blackbird and not right on top of the planet,
If you remember, at the time, nobody's freighters are just showing up and making approach to any of the habitable systems in Manticore. MMM ships perhaps and certainly Liners but I suspect the liners were Haupmann and other Manticore flagged ships. All the other traffic has to transfer cargo and people out at the Junction station and warehousing facilities.

So no freighter dropped off the g-torps at Manticore and the other two Binary System inhabited planets, unlike the situation at Beowulf- which was one or perhaps two double sized heavy shipping containers with superb stealthing and passive sensors. Same problem with the ballistics packages sent in at Oyster Bay, ejected/launched from the Sharks way out and comming in un-powered with extreme stealthing and not much going on until they get well in on their targets and then blow off (does not have to be explosive but your classic "explosive bolt" system would be enough to discard the physical partical shield on them. Nobody saw the various particle shields either- that we have been told.

20-20 hindsight talking about Beowulf. What the Silver Bullets were looking for was FTL transmissions and gathering information on where they originated and where they looked to be going.....the nexus of that were the Mycroft installations as the transceivers for contact and updating tactical data to the pods.

Brigade XO wrote:We know Oyster Bay's delivery of the Sharks was by a freighter way out and beyond almost the most tenuous edge of the Manticore System sensor net and it was investigated. The Sharks had moved away under Spider drive and fairly slowly at that.

You seem to have conflated two arrivals. The Ghosts arrived by freighter, that was scheduled to transit the Junction and just dropped out of hyper a little long and expelled them.

The (far larger) Sharks arrived under their own power and formed two tractored rings; which each make a very low speed translation out of hyper a couple light months out from the system; then split up and snuck into the Manticore A & B systems.

ThinksMarkedly wrote:They went for relatively or completely stationary targets like the Mycroft installations, but if a fleet stands idle for a long enough period of time, it can become a target too.

But their impellers being down does not mean that their sensors were. The Mycrofts were supposed to be stealthy, so they weren't emitting radar pulses to find what was close to them. That flight might have.

Yes, if a fleet is stationary long enough, then it can become a primary target.

The problem with radar is twofold: first the approaching enemy can detect outgoing radar signals long before radar echoes are detectable and second, about the point that radar return signals are detectable, you are close to graser range. Therefore a fleet had better not be counting on radar to give enough warning to get wedges up against a graser torpedo, and that is not even factoring in the various anti-radar technologies we already have in our world.

Brigade XO wrote:No information about the approach to Grayson though the target was out a Blackbird and not right on top of the planet,
If you remember, at the time, nobody's freighters are just showing up and making approach to any of the habitable systems in Manticore. MMM ships perhaps and certainly Liners but I suspect the liners were Haupmann and other Manticore flagged ships. All the other traffic has to transfer cargo and people out at the Junction station and warehousing facilities.

So no freighter dropped off the g-torps at Manticore and the other two Binary System inhabited planets, unlike the situation at Beowulf- which was one or perhaps two double sized heavy shipping containers with superb stealthing and passive sensors. Same problem with the ballistics packages sent in at Oyster Bay, ejected/launched from the Sharks way out and comming in un-powered with extreme stealthing and not much going on until they get well in on their targets and then blow off (does not have to be explosive but your classic "explosive bolt" system would be enough to discard the physical partical shield on them. Nobody saw the various particle shields either- that we have been told.

The point is that the drop-offs could have been performed by freighters on their way to the Manticore Junction, rather than at the limit of the net's detectability. That gives an enormous uncertainty in the amount of time that the weapons had to travel. In any case, while we know the method used; the authorities at Manticore and Grayson do not have a clue.