Defending a wormhole junction/terminus.

It costs too much. Take, for example, the Manticore wormhole junction. It had well over a hundred forts defending it at one time, massing two billion tons and having over a million crew.
Even with automation reducing crew requirements by 60% and even by downsizing to only three dozen forts, you still have over a half billion tons of construction and two hundred thousand crew tied there.

Can't the junction be defended in another way?


With LACs:

Suppose you build 10.000 LACs and station them at 700.000 kilometers from the junction. That's 200 million tons of construction and 100 thousand crew. Only about 2500 will be on duty at a time, with sidewalls raised and lots of stealth. Suppose 50 enemy ships get through in a mass transit. They will be in grazer range of the LACs because they will not have sidewalls raised - they'll need to reconfigure from warsawskis to wedges and then raise sidewalls - for a considerable interval. The LACs won't be in energy range because they will have sidewalls. Even taken totally by surprise as the Dreadnought Bellerophon was by battlecruisers, they can't be immediately destroyed.
Now, a mass transit is definitely not civilian transition no matter what happens. And an unannounced mass transit should always be enemy forces. Even allowing 10-15 seconds to confirm hostility, 2500 LACs will then blast each unsidewalled ship with 50 battlecruiser-sized energy mounts. That should be enough to cripple even a superdreadnought.
Even if those 50 enemy ships fire missiles (assuming Nike-class battlecruisers) they could not get more than 5000 missiles in space. The missiles will have a flight time of (at best) 30 seconds and will have a speed of 30.000 kps in final approach. The LACs have 15.000 total PDLCs of 8 emmitters each, allowing for 24 shots per enemy missile. They also have 10.000 total PDLCs and have time to fire 3 times, each missile eating 6 countermissiles.



With superdreadnoughts:

24 superdreadnoughts of a same mass as the LACs with 70.000 crew. Same conditions as the LACs, more or less. Each superdreadnought is to have the broadside towards the junction in full readiness, with the other broadside's crews resting and additional crew for an extra broadside onboard, also resting. This means 15 superdreadnought-sized energy mounts are covering each of those 50 hypothetical enemy ships and what that kind of energy firepower is going to do against unsidewalled ships is scary.
The SDs actually have only 1/5 as much point-defense as the LACs in this case. However, it still is only 200 missiles per SD and those are going to be very, very slow, unguided missiles (because their motherships will be toast)






With one big fortress:
OK, time to have fun designing crazy stuff.

A "ship" with twice the dimensions of a superdreadnought is 3,2 kilometers long with ~400 meters max beam. Its broadside space usable for weapons would be 1500 meters x 150 meters.
Armament:
# Take a Shrike-B. Remove compensator, impeller drive, power plant, shipkiller armament, rear countermissile launchers and a few other useless things. Replace its total of 12 PDLCs with only 3 bigger ones with 25 emmiters each (instead of 8) you put up front. That that leaves you is a defense station with 1 battlecruiser grazer, 3 really big PDLCs, 4 CM tubes with 25 missiles each and four sidewall generators. The station is 10 meters wide, 10 meters thick, 100 meters long and weighs around 10 kilotons, so we should be able to fit... 2250 in our big ship's broadside. For the interest of saving space, let's only put 2000.
# In 160 more ten by ten positions we didn't fill, we fit the forty biggest, more powerful grazer mounts we can fit. Each one is twice as wide/long and eight times as massive (and powerful) as a superdreadnought grazer. Those mounts are meant for obliterating little things like superdreadnoughts that make mass transits and do manage to raise sidewalls (somehow) before the fortress reacts.
# In the last 90 ten by ten positions we didn't fill in the weapons deck, we put 22 lauch tubes / modified pod rails. Those should be big enough to fire entire pods of missiles. Those are meant only for long-range combat just in case. In the big ship's inner core, there are 4400 missile pods meant for a 25-minute engagement time in max rate of fire.
Propulsion:
Standard wedge, hyperspace generator, thrusters with hour-long fuel supply at max accel. The fortress is too big for a compensator but can make 120-150 gravities or so using gravity plates without strain (depending on available tech). The impeller nodes are designed to be retractable so they can hide behind armor when the ship is fighting on thrusters+bubble sidewall so as to avoid damage in, say, a confrontation in hyper or energy range duel.
Sidewalls:
We know that big ships have multiple sidewall generators to generate their sidewall for various reasons. Going just with the generators the LACs came with, the fortress has 8000 generators per broadside, plus a couple more to cover the larger weapons mounts. That is both for redundancy and for making a strong sidewall but also to avoid weakening the sidewall's strength from the number of weapons we put. Each generator not only corresponds to a single gunport, the same way LACs get so strong bow walls, but also has to cover a much smaller area, resulting in even stronger sidewalls.
Also, the ship has a big bubble sidewall generator for use in hyperspace or when it's fighting under thrusters.
Armor:
So far, the ship should weigh around 100 megatons or so, already being denser than the same volume of SDs. This is roughly 50 megatons from all the systems and weapons the same volume of SDs would have (except for armor) plus another 50 megatons for the broadside defense stations, extra fuel and assorted odds and ends. Since we want it capable of passing through the junction, we can't make it heavier than 170 megatons, which leaves "only" 70 megatons for armor. The same volume of SDs would only have about 16 megatons... but would have to armor twice the surface. Let's go distribute that armor.
# First of all, the ex-LAC defense stations need to be armored. Their outer surface should have armor as thick as an SDs (several meters thick), only interrupted by the grazer mount. In addition, each station should have at least some armor in its inner surfaces to contain damage from expanding sideways or inwards so that each hit could take out only one station at a time, unless the hit is extremely powerful. In fact, each station should be made as removable so if it is damaged/destroyed, it could be plugged out and replaced by a new station very quickly. That ought to take up about 16 megatons of our armor allotment despite the very small outer surface.
# The main armor of the fortress should weigh around 32 megatons. That's twice the armor mass for less than half the surface in comparison to 8 superdreadnoughts, so we got 4-5 times as tough armor. This armor is built similar to the layers of armor in an SD, only individual layers are thicker, and curves to include the large energy mounts. The only thing that can't be thus armored is the long pod-launching tubes/rails.
# 16 more megatons of armor go to armoring the back and belly of the fortress. Unlike an SD, there could conceivably be times the fortress takes hits there and thus armor is needed. This area is again about half as large as the armored surfaces of an SD so given the armor allotment, it should have armor 2x as tough as an SDs stronger points.
# The last thing to be armored is the ship's inner core. The core has about the surface of an entire superdreadnought and we got 6 megatons of mass to spare, leading to armor 2x as tough as an SDs, minimum.

Use:
This is basically a fortress, but also a ship as slow as a merchanter. Its very powerful energy batteries allow it to obliterate any enemy force forced into an energy engagement -such as someone doing mass transit on the junction it's defending- and its very heavy armor, compartmentalization and very powerful sidewalls virtually guarantee the enemy won't be able to deal much damage in the few seconds they got left.
Its 40 giant grazers are meant to destroy even enemy SDs after they've raised sidewalls at the kind of ranges they'll be at after they exit the junction.
Its 2000 battlecruiser-sized grazers are meant to engage multiple targets in case of a mass transit of smaller ships and engage faster targets at close ranges in normal engagements (i.e. swarming LACs). In the case of missiles fired from enemy forces in a mass translation they should also be usable; those missiles will start at practically 0 speed from within the energy envelope and need 30 seconds to accelerate at their final speed of only 0,1 c.
Its 6000 PDLCs (150.000 emitters total) have their usual purpose, augmented by 8000 CM launch tubes - those can't fire all at once if they want to avoid wedge fratricide but are meant to fire at one second intervals, all of them firing within 8 seconds. The Keyhole II platforms are responsible for countermissile control.
Its long-range missile capacity is roughly comparable to that of 8 normal podnoughts, except that it has a pod supply only for a quick engagement. It is generally not meant for extended missile engagements, at least not in the rapid-fire mode.

Belial666 wrote:It costs too much. Take, for example, the Manticore wormhole junction. It had well over a hundred forts defending it at one

Please give text-evidence.

Honor Among Enemies wrote:"In addition to that, we have our own manpower needs. We've got roughly three hundred of the wall in commission, with an average crew of fifty-two hundred. That uses up another million and a half men and women. After that, we've got a hundred and twenty-four forts covering the Junction, with another million plus people aboard them...

That's pre-automation. With automation reducing the number of required men by 60% and by reducing the number of forts by half, we still get 992 megatons (nearly a billion tons) of fortresses and 300.000 crew. So equivalent construction and crew to 100+ superdreadnoughts.

Belial666, your first proposal only works for an attack coming through the wormhole. It is not sufficient to deal with a force coming through hyperspace, with wedges and sidewalls already up. A fleet popping into normal space outside graser range of your LACs could essentially shrug them off.

For the second proposal, what is the advantage of using superdreadnoughts instead of fortresses? Manticore evaluated the potential threat, including the threat of attack from hyperspace, and selected a certain number of fortresses as necessary for defense. So in truth, you should be looking at a mass of superdreadnoughts equal to the mass of the current fortresses. Using fortresses instead of superdreadnoughts means that you can put a larger percentage of the mass into weaponry. Superdreadnoughts do not provide any advantage over forts when defending a fixed point.

Actually, both LACs and superdreadnoughts have a major advantage over fortresses; the tactical one. In a system with a wormhole junction, you need to protect the junction, the inhabitable planet(s) and the space infrastructure that is near neither.

This requires you divide your forces in two or three separate locations. Fortresses may have more weapons per mass than SDs but due to their very low mobility, they invite a defeat in detail. SDs and LACs can join forces to deter enemy attacks, have one separate force retreat/delay till the others arrive and other tactical options.
Then it's the problem of surface. However much of a fortresse's mass is devoted to weapons, it has less surface per mass than a superdreadnought and since weapons take surface, a fortress is going to have fewer - if heavier - weapons.

Take the Shrike-B for example. A fortress weighing 16 megatons has the same mass as 800 LACs. Those 800 LACs however have 4800 point-defense clusters and 3200 countermissile tubes in their bows, plus 800 grazers. They could handle missile fire from 3 enemy SDs simultaneously with ease and once they close to energy range - which they will due to higher accel - the SDs will get to fire their energy mounts once and maybe destroy 150 assuming good hit probability. But then the remaining 650 Shrike-Bs are going to turn over 200 grazers on each SD from point-blank range and shred them to pieces.

Belial666 wrote:Actually, both LACs and superdreadnoughts have a major advantage over fortresses; the tactical one. In a system with a wormhole junction, you need to protect the junction, the inhabitable planet(s) and the space infrastructure that is near neither.

This requires you divide your forces in two or three separate locations. Fortresses may have more weapons per mass than SDs but due to their very low mobility, they invite a defeat in detail. SDs and LACs can join forces to deter enemy attacks, have one separate force retreat/delay till the others arrive and other tactical options.

Which is great when the LACs are all the way across the system at the Junction and need to get to one of the planets. Oh...wait...

Then it's the problem of surface. However much of a fortresse's mass is devoted to weapons, it has less surface per mass than a superdreadnought and since weapons take surface, a fortress is going to have fewer - if heavier - weapons.

Fortresses mount weapons in all aspects, unlike the just the broadsides of a superdreadnought. And without having to worry about little things like hyper generators or compensators, they can devote more mass to weapons than a SD.

Take the Shrike-B for example. A fortress weighing 16 megatons has the same mass as 800 LACs. Those 800 LACs however have 4800 point-defense clusters and 3200 countermissile tubes in their bows, plus 800 grazers. They could handle missile fire from 3 enemy SDs simultaneously with ease and once they close to energy range - which they will due to higher accel - the SDs will get to fire their energy mounts once and maybe destroy 150 assuming good hit probability. But then the remaining 650 Shrike-Bs are going to turn over 200 grazers on each SD from point-blank range and shred them to pieces.

That's a disingenuous comparison at best. Those LACs aren't just going to be floating around completely unsupported. They require basing and rearming facilities. Taking the docking collar, missile magazines, maintenance facilities, spares, etc, you're looking easily at 50 or 60 thousand tons per LAC, minimum.

Duckk wrote:Which is great when the LACs are all the way across the system at the Junction and need to get to one of the planets. Oh...wait...

Except that LACs may get almost 1000 gravities of acceleration nowadays. Old-style fortresses got only 50 gravities and even a fortress with a wedge is limited to less than 150.
In the two hours of acceleration where a superdreadnought fleet pulling 700gs could move 184 million kilometers, a force of LACs could move 260 million kilometers. Since the LACs will be in-system and the enemy force will usually be out-system, the LACs can intercept in most cases.

Duckk wrote:Fortresses mount weapons in all aspects, unlike the just the broadsides of a superdreadnought. And without having to worry about little things like hyper generators or compensators, they can devote more mass to weapons than a SD.

Not really. They also need to mount armor to all aspects because they don't rely on wedge coverage. So whatever mass is gained from not having hyper generators, compensators and powerful impellers is lost on having to armor 30%-40% more of their surface.
Also, even if a fortress has twice the tonnage in weapons that a superdreadnought has spread over all aspects, it can still turn only one broadside out of four towards the enemy. This means it loses at least the far broadside's weapons entirely even with off-bore firing so it ends with only 50% more available missile power than an SD (including countermissiles) but it is also limited in close-in point defende to a single broadside out of four due to lack of wedge coverage - the missiles may go right at it from one side, ignoring the other three. Whereas the superdreadnought turns its belly towards the missiles and forces them to go around and face the point-defence of both its active broadsides as well as complicate their firing solutions. This last is fairly important; because an SD can interpose its wedge, a missile has to make a lot bigger terminal attack maneuvers to position itself. That limits missile speed to at most 0.9 c against it; if the missiles go any faster, they don't have time for said maneuvers and bypass the SD, losing their shot. Vs a fortress, the missiles can do c-fractional attacks and still expect to hit.

All in all a 16-megaton fortress can bring to bear 50% more missile power and 50% more countermissile defense than an SD (3 out of 4 broadsides), can engage with only 1/4 of its energy weapons at a time (1 broadside) and thus has 0% improvement over an SD and with the missiles focusing on a single broadside at a time and lacking wedge coverage, it only gets half the PDLCs an SD would have forced the missiles to use and is far more succeptible to c-fractional attacks.

Duckk wrote:That's a disingenuous comparison at best. Those LACs aren't just going to be floating around completely unsupported. They require basing and rearming facilities. Taking the docking collar, missile magazines, maintenance facilities, spares, etc, you're looking easily at 50 or 60 thousand tons per LAC, minimum.

Not really. Take the Aviary-class CLAC which is both a base for all its 240 LACs and a starship to boot. At 9,5 megatons for the entire starship, the total mass per LAC is less than 40 kilotons. Housing the LACs in a normal base and not a starship would reduce the mass cost to only 32 kilotons per LAC. And last but not least, maintenance, rearming and repair would only need to be done at half the LACs at a time, not all of them together (in fact, at least half would need to be active, a quarter in full readiness, the other quarter in normal patrol mode). So we're looking at an extra 6 kilotons per LAC or so for a total of 26 kilotons per LAC.

Part of the role of the forts is to provide LAC basing.
LACs require that basing and the protection of their basing. Hense the large number of forts...

If this was Starfire and you could count on only 1 threat axis - then your concept of massed LACs would still require bases to resupply, but they could be in the rear. This is not Starfire, the attack could come out of Hyper and/or through the wormhole - no secure rear area. Hense the forts to provide secure areas.

Duckk: How many Manty LACs based on the forts at the Junction?

Secure areas are provided by the hyper limit. Most inhabited planets are 10 or more light-minutes inside the limit so even MDM attacks cannot reach with any accuracy. And by the time they've done their 10-minute run to reach, the LACs will have been launched, providing at least 2000 countermissile tubes and 3000 PDLCs per enemy superdreadnought. No missile attack is getting through that.

Besides, having ships and some FTL drones stationed at each hyper-band near the system guarantees you early warning against enemy ships in hyper. In fact, a megaton's worth of courier boats and drones would make an early-warning system that could detect impeller-drive ships as far as one light-hour away... in all hyperspace bands up to the theta bands.

Belial666 wrote:Except that LACs may get almost 1000 gravities of acceleration nowadays. Old-style fortresses got only 50 gravities and even a fortress with a wedge is limited to less than 150.
In the two hours of acceleration where a superdreadnought fleet pulling 700gs could move 184 million kilometers, a force of LACs could move 260 million kilometers. Since the LACs will be in-system and the enemy force will usually be out-system, the LACs can intercept in most cases.

It doesn't matter how rapidly the LACs can accelerate, the Junction is 7 light hours from Manticore-A, and even farther for Manticore-B. Any LAC force on the Junction is not going to have any impact on combat occurring elsewhere in the system.

Duckk wrote:Not really. They also need to mount armor to all aspects because they don't rely on wedge coverage. So whatever mass is gained from not having hyper generators, compensators and powerful impellers is lost on having to armor 30%-40% more of their surface.

So? They have the mass to spare. A fort doesn't care about mass, it only cares about weapons. It'll have more weapons available than a SD.

Also, even if a fortress has twice the tonnage in weapons that a superdreadnought has spread over all aspects, it can still turn only one broadside out of four towards the enemy. This means it loses at least the far broadside's weapons entirely even with off-bore firing so it ends with only 50% more available missile power than an SD (including countermissiles) but it is also limited in close-in point defende to a single broadside out of four due to lack of wedge coverage - the missiles may go right at it from one side, ignoring the other three. Whereas the superdreadnought turns its belly towards the missiles and forces them to go around and face the point-defence of both its active broadsides as well as complicate their firing solutions. This last is fairly important; because an SD can interpose its wedge, a missile has to make a lot bigger terminal attack maneuvers to position itself. That limits missile speed to at most 0.9 c against it; if the missiles go any faster, they don't have time for said maneuvers and bypass the SD, losing their shot. Vs a fortress, the missiles can do c-fractional attacks and still expect to hit.

All in all a 16-megaton fortress can bring to bear 50% more missile power and 50% more countermissile defense than an SD (3 out of 4 broadsides), can engage with only 1/4 of its energy weapons at a time (1 broadside) and thus has 0% improvement over an SD and with the missiles focusing on a single broadside at a time and lacking wedge coverage, it only gets half the PDLCs an SD would have forced the missiles to use and is far more succeptible to c-fractional attacks.

Except as explained many times in the past, fortresses 1) have wedges to move, and do move frequently; 2) c-fractional attacks go splat against sidewalls.

It should be telling that the forts at just the Lynx termnius were capable of repelling any attack, including a full reprise of Operation Beatrice, i.e. the forts at the most recently discovered terminus is capable of repelling at least 250 SD(P)s! Even with the system defense pods taken out of the equation, the combat capability of a fort is many times greater than that of a LAC or superdreadnought. And the defenses of the central junction are going to be much more capable.

Not really. Take the Aviary-class CLAC which is both a base for all its 240 LACs and a starship to boot. At 9,5 megatons for the entire starship, the total mass per LAC is less than 40 kilotons. Housing the LACs in a normal base and not a starship would reduce the mass cost to only 32 kilotons per LAC. And last but not least, maintenance, rearming and repair would only need to be done at half the LACs at a time, not all of them together (in fact, at least half would need to be active, a quarter in full readiness, the other quarter in normal patrol mode). So we're looking at an extra 6 kilotons per LAC or so for a total of 26 kilotons per LAC.

That 32 kilotons is a figure which considers the ancillary equipment aboard the CLAC only. It says nothing about missile reloads, spares, LAC sims for the crews, crew berths, and a million and one other things needed to keep LACs and their crews operational. Nor do you have LACs sitting out in space for long periods of time. LACs are meant for short to medium length deployments. They are not meant for many weeks or months out in space. Their entire doctrine is based around having them operate off of some other platform (carrier, station, whatever) to provide them the long term support and habitability.