OK KZT: What's wrong with AAC?

tlb wrote:But wouldn't it just waste missiles if the fort were to shoot at a foe far enough out, so that it can transit to hyperspace and back multiple times to avoid being hit? Wouldn't it take actually sending ships with the idea of moving into energy range to prevent them from returning to the same place in normal space?

My mistake -- I hadn't realized how far out they were from the Junction.

I had thought that the recharge time on their hyper generators would let accurate long ranged MDMs chase them off (unless they were suicidal) -- because after each jump I figured even something as small as a BC would have a minimum of 16+1 minutes before they could hyper out again (need to recharge their hyper generators plus some time between hitting the button and hypering out). Which means if they hypered in to within 8 lightminutes of Apollo they literally physically couldn't have hypered out before being hit.

OTOH what I'd missed until I rechecked the text is that they probably never got within 30 light minutes of the Junction. AAC never gives an exact range for them - but we know the Junction is 7 light hours from the primary; and AAC does say Diamato's BC originally hypered in at "only six light-hours from the primary" -- meaning a minimum of 1 light hour from the Junction. However since it also says they stayed off to the side of the RZ they're not in a straight line between the Junction and the primary; hence are a bit more than 60 light minutes from it. And even at that range, a hair more than a billion km, we're told "Just getting this close to the Junction made Diamato's skin crawl" -- so I doubt they closed their range all that much; just hung back surveilled it from range and sent recon drones forward.

At a billion km (1 light hour) it'd take 3-drive MDMs nearly 2 hours to get there -- so you're right; that's more than enough time to make a microjump to a distant part of the notional sphere defined by their current range and still be ready to microjump again long, long, before any new missiles from the Junction could catch them. (Even if the Junction had the 4-drive system defense versions a billion km would still be nearly an 80 minute flight time)


So never mind - we can't make any assumptions about whether or not the Junction had Apollo based on their lack of engagement against Diamato's BCs.

Loren Pechtel wrote:I'm not saying the fort is easy to kill, I'm saying it can be killed from beyond it's effective range unless it's armed with missiles that can go ballistic.

You go outside it's range, build up velocity towards it, fire and turn back. Your missile will still have a tiny bit left on it's drive when it arrives, the fort's missile shooting back will have run out.

All is relative. The geometry of a set of ships accelerating towards a stationary target is the exact same as those targets accelerating at the exact rate but in the opposite direction against stationary ships. This is to say that if the ships at high velocity have the forts in range, then the forts have those ships in range too. Moreover, RMN missiles are better at long range than RHN ones, so the forts could shoot (and hit) first. And forts are much tougher than ships, even superdreadnoughts.

The ships can't stop and turn on a dime. They have to accelerate in a different direction, either fully backwards or to a side. Full reverse is actually the worst, since they'd be presenting the kilt to the forts and it's the geometry that brings them to the closest distance to the forts (assuming they can even reverse in time). Acceleration at a right angle to the planet would cause the ships to describe a parabola away from it, but they'd still be closing to the planet for a long while.

This is very different from an attack on the Junction's forts because the ships could conceivably transition to hyper before crossing the Junction's hyperlimit of just 1 million km. This is also why Sphinx is much tougher to protect because, similarly, it would be possible for an attacker to shoot from outside the hyperlimit and still have time in the drive missiles. But firing at the general direction of an inhabited planet and not sticking around to control your missiles would be at a minimum irresponsible.

Jonathan_S wrote:that's more than enough time to make a microjump to a distant part of the notional sphere defined by their current range and still be ready to microjump again

A question occurred to me about micro-jumps (not sure that it is worth starting a thread). They are said to be bad because they are hard to do accurately and can cause ships to scatter. I understand the part about problems with accuracy, but wonder about the scatter. Points in the hyper bands are one for one with points in normal space (correct?); so if a fleet is stationary when making a jump, then the ships will still be in the same formation after arriving. That also would be true if the ships had the same velocity (so relatively stationary to each other) and made the jump at the same time. So it seems to me that the only causes of scatter are that the ships are moving relative to each other or that the jumps are not simultaneous or that the ships are of greatly different tonnage so that the time to make the jump is different. Does that sound right?

It seems to me that even if they have relative movement, but jump at the same time; then they will still arrive in formation, but with different headings. Also if they are stationary, then the timing of the jump will not cause scatter.

So I conclude that scatter can only occur when ships are moving (with or without acceleration) and cannot make a simultaneous jump.

ThinksMarkedly wrote:All is relative. The geometry of a set of ships accelerating towards a stationary target is the exact same as those targets accelerating at the exact rate but in the opposite direction against stationary ships. This is to say that if the ships at high velocity have the forts in range, then the forts have those ships in range too. Moreover, RMN missiles are better at long range than RHN ones, so the forts could shoot (and hit) first. And forts are much tougher than ships, even superdreadnoughts.

Yes and no. What I'm saying is that given equal ranges and a case where they can't go chasing off across the star system the guy with the acceleration advantage can always engage so the enemy is just barely within his powered envelope but the other guy is just beyond it.

The ships can't stop and turn on a dime. They have to accelerate in a different direction, either fully backwards or to a side. Full reverse is actually the worst, since they'd be presenting the kilt to the forts and it's the geometry that brings them to the closest distance to the forts (assuming they can even reverse in time). Acceleration at a right angle to the planet would cause the ships to describe a parabola away from it, but they'd still be closing to the planet for a long while.

Yes and no. Full reverse presents the kilt--but if you're doing it right the enemy missiles run out of drive time just before they engage--which means you can present just wedges to them. There's not enough advantage to just bypass them, but you can ensure very few are in a position to do anything and you can use your point defense against those few.

This is very different from an attack on the Junction's forts because the ships could conceivably transition to hyper before crossing the Junction's hyperlimit of just 1 million km. This is also why Sphinx is much tougher to protect because, similarly, it would be possible for an attacker to shoot from outside the hyperlimit and still have time in the drive missiles. But firing at the general direction of an inhabited planet and not sticking around to control your missiles would be at a minimum irresponsible.

Yeah, the junction forts are only there to engage hostiles coming through the wormhole. They can't hope to stop a well-done attack from space.

ThinksMarkedly wrote:All is relative. The geometry of a set of ships accelerating towards a stationary target is the exact same as those targets accelerating at the exact rate but in the opposite direction against stationary ships. This is to say that if the ships at high velocity have the forts in range, then the forts have those ships in range too. Moreover, RMN missiles are better at long range than RHN ones, so the forts could shoot (and hit) first. And forts are much tougher than ships, even superdreadnoughts.

The ships can't stop and turn on a dime. They have to accelerate in a different direction, either fully backwards or to a side. Full reverse is actually the worst, since they'd be presenting the kilt to the forts and it's the geometry that brings them to the closest distance to the forts (assuming they can even reverse in time). Acceleration at a right angle to the planet would cause the ships to describe a parabola away from it, but they'd still be closing to the planet for a long while.

That's not quite accurate - though depending on the geometry the differences may be only academic.

In fact against MDMs it is academic. But even with SDMs if ships are in missile range of the stationary forts then the reverse is true only if the ships maintain their speed towards the forts. But the ships can break off the moment they launch and the missile keep the range advantage granted by that base velocity while the ships start accelerating to ensure they don't slide into range of the return fire -- though the ships need to be at low velocities or very carefully chosen courses to be able to break off and stay out of SDM range.

Now MDMs make this all very messy as "within range" is really more a factor of acceptable fire control accuracy; and breaking off to keep you far enough out that their missiles aren't dangerous means you're not controlling your missiles either. The fort's missiles might need a ballistic segment that yours don't, or a longer segment than yours do, but if you're close enough to provide any usable fire control you'll still be close enough for the forts to do the same to you.



Still, for amusement let's look at a single drive missile engagement. And to keep the math easy let's take the worst case scenario -- after launching the ship is trying to come to a stop beyond the forts' missile range. As illustration I'll use a ship with 500 gees of acceleration and standard RMN single drive missiles (180 s @ 46,000 g = 7,302,960 km range). If the ship approaches the forts at a very sedate 980 km/s that base velocity extends their powered single drive missile range from 7.3 million km to over 7.5 million km; an extra 176,400 km of range. But at 500 g the ships can decelerate from 980 km/s to rest (relative to the forts) in only 200 seconds; while covering just 98,000 km -- thus bringing them to a halt 7,381,360 km from the fort; or 78,400 km beyond the forts' SDM powered range.

The math is harder but they could do the same thing at higher speed by flying a course just inside of being tangent to the sphere defined by max missile range of the forts - where their delta v was just enough to alter their trajectory remain to outside of that sphere after launching their missiles.


Still, what was a cute trick in the SDM era is basically pointless with/against MDMs.

Theemile wrote:As I mentioned above, they also built 5 of the new pre-fab forts for Medusa.

It was implied that the previous government was good with building forts around planets.

Loren Pechtel wrote:Yeah, the junction forts are only there to engage hostiles coming through the wormhole. They can't hope to stop a well-done attack from space.

It takes a trvial amount of firepower to stop attacks through the WH. The RMN originally had this wrong, as shown by Honors internal thoughts, but they realize now how hard an attack is, particualrly when you are using laser-head missiles. And they still built a whole bunch of forts when the built the next generation.

That's because they are to stop an attack to seize the junction from hyper. I think David explicitly explained this once upon a time here.

kzt wrote:

Loren Pechtel wrote:Yeah, the junction forts are only there to engage hostiles coming through the wormhole. They can't hope to stop a well-done attack from space.

It takes a trvial amount of firepower to stop attacks through the WH. The RMN originally had this wrong, as shown by Honors internal thoughts, but they realize now how hard an attack is, particualrly when you are using laser-head missiles. And they still built a whole bunch of forts when the built the next generation.

That's because they are to stop an attack to seize the junction from hyper. I think David explicitly explained this once upon a time here.

Or if not entire prevent such an attack slow it down and make it costly enough that it's fairly safe to use the Junction to shuttle in reinforcements. (And hopefully buy enough time for mobile forces from Manticore or the other termini to arrive and intervene)

Because I'd think that once Manticore has captured Trevor's Star the new nightmare scenario would be to trigger a case Zulu that caused the forces there to be pulled back to reinforce the home system -- then spring a lightning seizure of the Junction with no word getting through to Trevor's Star. At that point the enemy forces can defeat the transiting reinforcements in detail and then withdraw before Home Fleet can intervene.
If the Junction defenses can't buy sufficient time to prevent that from happening then the enemy could potentially inflict a very painful (and one sided) defeat that upset the balance of forces.

You might be able to eventually overcome the unsupported forts with low losses using waves of hit and run hyper tactics -- but that'll take you quite a while.

Jonathan_S wrote:Still, for amusement let's look at a single drive missile engagement. And to keep the math easy let's take the worst case scenario -- after launching the ship is trying to come to a stop beyond the forts' missile range. As illustration I'll use a ship with 500 gees of acceleration and standard RMN single drive missiles (180 s @ 46,000 g = 7,302,960 km range). If the ship approaches the forts at a very sedate 980 km/s that base velocity extends their powered single drive missile range from 7.3 million km to over 7.5 million km; an extra 176,400 km of range. But at 500 g the ships can decelerate from 980 km/s to rest (relative to the forts) in only 200 seconds; while covering just 98,000 km -- thus bringing them to a halt 7,381,360 km from the fort; or 78,400 km beyond the forts' SDM powered range.

The math is harder but they could do the same thing at higher speed by flying a course just inside of being tangent to the sphere defined by max missile range of the forts - where their delta v was just enough to alter their trajectory remain to outside of that sphere after launching their missiles.


Still, what was a cute trick in the SDM era is basically pointless with/against MDMs.

Thanks for the math, but as you conclusion says, this is unimportant now and was for AAC anyway because the Manticore forts would have had MDMs for nearly 10 years.

I considered "cutting a chord" through the sphere that the return fire would still be powered on but didn't do the math.

The other point Loren made was that forts can't chase the ships, so those would be free to interdict any shipping in the system without coming into range of the forts, and attack the asteroid mining industry

Ok, if the MBS was hit with the Author's Hammer during the BoM, which resulted in no planetary Forts, then why couldn't the RMN blunt the athor's hammer by castling?

I couldn't understand why the Forts never engaged. Tourville would have been kept off balance by the planetary Forts if there had been any. The Forts have a paltry 50g of acceleration which is much too slow for a tactical redeployment, but at an ETA of 3 days, that is plenty of time for a strategic redeployment.

That thread brought up concerns that the Forts would invite return fire that could impact with the planet, if they engage. But what are planetary forts for if not to engage the enemy? Are they simply there to bluff? Under what conditions would planetary forts engage the enemy?

Oyster Bay resulted in debris that impacted the planet, but the RMN never saw that attack coming. During the BoM, wouldn't there have been plenty of time to preposition tugs?

Also, why aren't attackers held responsible for impacts with the planet by missiles which end up far beyond the targets that they engaged? Are missiles not programmed to self-destruct beyond a certain range? IOW, I thought the planetary forts simply had to ensure that they took up position far enough from the planet.