LAC vs. Destroyer and Cruiser accelerations.

MuonNeutrino wrote:

munroburton wrote:It occurs to me that the newest all-up warships could have incorporated beta-squared nodes. Would this have improved their max accel, perhaps even closing the gap on the new LACs?

Max accel for almost all ships isn't set by nodes, it's set by the efficiency of the compensator, and it's the improvements in that piece of tech that have led to the increases in accel over the series.

The beta-squared nodes basically just let you generate a more powerful wedge with less mass invested in nodes. That's nice, but for normal warships that won't increase acceleration. The Shrike actually did get an acceleration increase from the beta-squared nodes, but that's because previous LACs didn't actually have powerful enough wedges to even max out their inertial compensators. (One example is the Grayson LACs being slower than their other ships in HotQ.) The same isn't true for regular warships.

munroburton wrote:It occurs to me that the newest all-up warships could have incorporated beta-squared nodes. Would this have improved their max accel, perhaps even closing the gap on the new LACs?

MuonNeutrino wrote:Max accel for almost all ships isn't set by nodes, it's set by the efficiency of the compensator, and it's the improvements in that piece of tech that have led to the increases in accel over the series.

The beta-squared nodes basically just let you generate a more powerful wedge with less mass invested in nodes. That's nice, but for normal warships that won't increase acceleration. The Shrike actually did get an acceleration increase from the beta-squared nodes, but that's because previous LACs didn't actually have powerful enough wedges to even max out their inertial compensators. (One example is the Grayson LACs being slower than their other ships in HotQ.) The same isn't true for regular warships.

Theemile wrote:The original LAC issue doesn't appear to be "crap" nodes, but that LACS only used beta nodes, not Alpha nodes and Beta nodes in their ringThe replacement of the alpha nodes with just beta nodes in their rings doesn't give enough power to run at full accel.

Alpha nodes are multiple times the size and mass (and cost) of the beta nodes, and since LACS don't need grav sails, it's an easy thing to negate on a LAC.

House of Steel, The Royal Manticoran Navy, Order of Battle wrote:Highlander-class light attack craft
Mass: 11,250 tons

Dimensions: 138 × 23 × 21 m

Acceleration: 409.3 G (4.014 kps²)

80% Accel: 327.5 G (3.211 kps²)

Broadside: 12MB, 1L, 3PD
Chase: 1L

Service Life: 1843–1912

The Highlander-class light attack craft was commissioned in 1843 PD as a system defense picket and customs patrol unit. It had a heavier beam armament than most contemporary classes, though contrary to typical RMN doctrine of the time, the lasers were optimized for point defense fire as well as the antiship role. The one-shot missile launch cells were built directly into the hull, allowing for system checks and routine maintenance without vacuum gear by the crew, although this increased costs and made them somewhat less suited to rapid re-arming than previous external launchers.
When the Highlander class was first placed into service, light attack craft were primarily used as home system pickets and scouts, freeing up hyper-capable hulls for interstellar deployment or for concentrated rapid reaction system defense formations. As King Roger’s naval buildup progressed, Manticore system hyper-limit picket duty was shifted to destroyers cued by reconnaissance satellites and the passive system arrays. Starting in 1887 PD, the Highlander class was retired. A number of hulls were stripped of armament, modified heavily and transferred to Astro Control Service as search and rescue platforms. An additional small number were retained purely as training craft attached to Saganami Island Naval Academy.

Series 282 light attack craft
Mass: 17,750 tons

Dimensions: 121 × 20 × 19 m

Acceleration: 573.2 G (5.621 kps²)

80% Accel: 458.6 G (4.497 kps²)

Broadside: 12MB, 1L, 1CM, 3PD

Chase: 1L, 2PD

Service Life: 1904–1918
The Series 282 light attack craft was never given a formal class name because it was a prototype LAC, designed by the Weapon Development Board for the Trojan Horse program which saw extremely limited operational service.
While the Highlander class was a typical LAC design, built to very similar standards as a conventional warship, the Series 282 took advantage of advances in both equipment miniaturization and automation to greatly decrease the volume necessary for critical systems. The result was a flattened hull that was slightly smaller than the Highlander, despite being half again the tonnage. The small size of the Series 282, along with the fact that its “on-paper” offensive capabilities were nearly identical to those of the old design, was cited numerous times by the program’s many critics.
These critics uniformly failed to recognize the qualitative improvements behind the figures. The 282s carried only twelve cell-launched missiles, but both the missiles and launch cells were far in advance of anything the Highlander mounted. Beam mounts were also more powerful, and the addition of a counter-missile launcher in each broadside more than doubled their survivability, as well as allowing them to perform an area defense mission in protection of their launch platform. Perhaps most notably, the Series 282 was the first LAC to mount an impeller ring powerful enough to accelerate it to the limits of its inertial compensator.* This class was the first to serve as testbeds for the early second generation compensator, raising its maximum acceleration to just over 600 G.
Despite the type’s clear advantages, it was never able to overcome the opposition of its critics. Regarded as suitable solely for local defense and burdened with the anti-LAC attitudes of a navy philosophically committed to projecting combat power (and vehemently opposed to attrition-based tactics), it was produced in very small numbers. The number built provided valuable experience in the new technologies and were used as test beds for many of the systems incorporated into the early Shrike-class prototypes, however, and the 282s provided a critical component in the combat power of the Trojan-class Q-ships until their final retirement in 1918.

Shrike-class light attack craft
Mass: 20,250 tons

Dimensions: 71 × 20 × 20 m

Acceleration: 636 G (6.237 kps²)

80% Accel: 508.8 G (4.989 kps²)

Forward: 4M, 1G, 4CM, 6PD

Service Life: 1912–1917

The Shrike revolutionized the concept of the LAC in many ways. Far from a simple evolutionary outgrowth of the Series 282, the Shrike has virtually nothing in common with a conventional LAC. Although the Shrike carried over many of the 282’s technology innovations in terms of system miniaturization and increased automation, it represented a complete conceptual break with previous LACs. Earlier examples of the type had been seen as miniature warships equipped with traditional weapon systems; the Shrike was visualized as a single-weapon system, optimized for the sole purpose of getting its powerful graser into decisive range.
Historically, LACs have suffered from limited endurance driven by bunker space for fusion reactor hydrogen, so, unlike any warship in a millennia, the Shrike class carries a highly efficient fission pile as primary power. Inspired by Grayson developments in fission reactor technology, the fission plant means that the Shrike’s cruise endurance is limited primarily by crew support consumables. Its combat endurance remains a factor of plasma feedstock for the gravitic subsystems (mostly graser and missile launch systems), but its ability to stay on station for months if necessary is a huge advantage in the system defense role. In addition, while a Shrike masses almost twice as much as a Highlander (in a hull less than half the size), its remotes and expert systems are some of the most advanced anywhere in space, simultaneously increasing lethality while decreasing crew requirements.
The Shrike class was also the first warship to be fitted with the new “beta-squared” impeller nodes, which by 1921 PD have become standard equipment on all new Manticoran construction. In addition to the mass savings the nodes provided, they also allowed the Shrikes to transmit FTL communications while under acceleration. The vastly more powerful impeller rings, second generation inertial compensators and enhanced electronic warfare and stealth systems made the Shrikes the fastest, stealthiest, and ton-for-ton most dangerous warships in space for their time.
Among all of the other advances seen on the Shrike class, perhaps the most notable was the introduction of the all-forward armament, combining the new off-bore launch technology with a bow wall and a powerful spinal-mounted graser for close range antiship strikes, all without relying on the traditional broadside armament carried by LACs up until this point.
For a program that was nearly cancelled by Navy before it could prove itself, the Shrike-class LACs performed far above expectations during the Second Battle of Hancock. Able to approach to far closer range of an enemy under stealth than anyone had predicted, their initial attacks were devastating. While their survivability against a prepared opponent was questionable, their ability to isolate and destroy cripples and the savage damage they could do to the enemy’s screen proved their value.
Despite exceeding all expectations, the original Shrike was still a transitional design, with many flaws, some major and some minor, appearing during the early simulations, wargames, and battle experience. While the heavy demand for LACs kept many of them in service longer than expected, the last of the original production run was replaced in 1917 by the Shrike-B.

House of Steel, The Royal Manticoran Navy, Order of Battle wrote:The Shrike class was also the first warship to be fitted with the new “beta-squared” impeller nodes, which by 1921 PD have become standard equipment on all new Manticoran construction.

Vince wrote:<snip>

* As mentioned above, the Nucio LACs (15,000 tons) were able to accelerate at 500 gravities in The Shadow of Saganami. In contrast, the RMN Highlander-class LACs had a maximum (100%) acceleration of 409.3 gravities. The Highlander-class LACs are clearly using inferior beta nodes compared to the Nuncio LACs.

House of Steel only covers the RMN, GSN and Protector's Own order of battle.

Vince wrote:

munroburton wrote:It occurs to me that the newest all-up warships could have incorporated beta-squared nodes. Would this have improved their max accel, perhaps even closing the gap on the new LACs?

MuonNeutrino wrote:Max accel for almost all ships isn't set by nodes, it's set by the efficiency of the compensator, and it's the improvements in that piece of tech that have led to the increases in accel over the series.

The beta-squared nodes basically just let you generate a more powerful wedge with less mass invested in nodes. That's nice, but for normal warships that won't increase acceleration. The Shrike actually did get an acceleration increase from the beta-squared nodes, but that's because previous LACs didn't actually have powerful enough wedges to even max out their inertial compensators. (One example is the Grayson LACs being slower than their other ships in HotQ.) The same isn't true for regular warships.

Theemile wrote:The original LAC issue doesn't appear to be "crap" nodes, but that LACS only used beta nodes, not Alpha nodes and Beta nodes in their ringThe replacement of the alpha nodes with just beta nodes in their rings doesn't give enough power to run at full accel.

Alpha nodes are multiple times the size and mass (and cost) of the beta nodes, and since LACS don't need grav sails, it's an easy thing to negate on a LAC.

Ship acceleration in normal space is a function of both impeller wedge strength (generated by the impeller nodes to generate acceleration) and the inertial compensator efficiency (to negate felt acceleration so the crew can survive the actual acceleration).

Most (but not all) conventional LACs (all LACs without beta-squared impeller nodes) have/had beta impeller nodes that were not capable of generating an impeller wedge that would generate enough acceleration that would reach the maximum a conventional (non-Manticore improved Grayson-model) inertial compensator could dissipate.

The exceptions we have text-evidence on are the Manticoran Series-282 LAC at 17,750 tons--with a modern Grayson inertial compensator capable of 458.6g @ 80% of max & 573.2g @ 100% of max (House of Steel), and the Nuncio LACs at 15,000 tons--with conventional inertial compensators capable of 500g @ unknown % of max (The Shadow of Saganami).

Let's look at the specifications for the Manticoran Highlander (fully conventional LAC), the Series 282 (LAC with modern inertial compensator and beta nodes), and the original Shrike (LAC with modern inertial compensator and beta-squared nodes):

House of Steel, The Royal Manticoran Navy, Order of Battle wrote:Highlander-class light attack craft
Mass: 11,250 tons

Dimensions: 138 × 23 × 21 m

Acceleration: 409.3 G (4.014 kps²)

80% Accel: 327.5 G (3.211 kps²)

Broadside: 12MB, 1L, 3PD
Chase: 1L

Service Life: 1843–1912

The Highlander-class light attack craft was commissioned in 1843 PD as a system defense picket and customs patrol unit. It had a heavier beam armament than most contemporary classes, though contrary to typical RMN doctrine of the time, the lasers were optimized for point defense fire as well as the antiship role. The one-shot missile launch cells were built directly into the hull, allowing for system checks and routine maintenance without vacuum gear by the crew, although this increased costs and made them somewhat less suited to rapid re-arming than previous external launchers.
When the Highlander class was first placed into service, light attack craft were primarily used as home system pickets and scouts, freeing up hyper-capable hulls for interstellar deployment or for concentrated rapid reaction system defense formations. As King Roger’s naval buildup progressed, Manticore system hyper-limit picket duty was shifted to destroyers cued by reconnaissance satellites and the passive system arrays. Starting in 1887 PD, the Highlander class was retired. A number of hulls were stripped of armament, modified heavily and transferred to Astro Control Service as search and rescue platforms. An additional small number were retained purely as training craft attached to Saganami Island Naval Academy.

Series 282 light attack craft
Mass: 17,750 tons

Dimensions: 121 × 20 × 19 m

Acceleration: 573.2 G (5.621 kps²)

80% Accel: 458.6 G (4.497 kps²)

Broadside: 12MB, 1L, 1CM, 3PD

Chase: 1L, 2PD

Service Life: 1904–1918
The Series 282 light attack craft was never given a formal class name because it was a prototype LAC, designed by the Weapon Development Board for the Trojan Horse program which saw extremely limited operational service.
While the Highlander class was a typical LAC design, built to very similar standards as a conventional warship, the Series 282 took advantage of advances in both equipment miniaturization and automation to greatly decrease the volume necessary for critical systems. The result was a flattened hull that was slightly smaller than the Highlander, despite being half again the tonnage. The small size of the Series 282, along with the fact that its “on-paper” offensive capabilities were nearly identical to those of the old design, was cited numerous times by the program’s many critics.
These critics uniformly failed to recognize the qualitative improvements behind the figures. The 282s carried only twelve cell-launched missiles, but both the missiles and launch cells were far in advance of anything the Highlander mounted. Beam mounts were also more powerful, and the addition of a counter-missile launcher in each broadside more than doubled their survivability, as well as allowing them to perform an area defense mission in protection of their launch platform. Perhaps most notably, the Series 282 was the first LAC to mount an impeller ring powerful enough to accelerate it to the limits of its inertial compensator.* This class was the first to serve as testbeds for the early second generation compensator, raising its maximum acceleration to just over 600 G.
Despite the type’s clear advantages, it was never able to overcome the opposition of its critics. Regarded as suitable solely for local defense and burdened with the anti-LAC attitudes of a navy philosophically committed to projecting combat power (and vehemently opposed to attrition-based tactics), it was produced in very small numbers. The number built provided valuable experience in the new technologies and were used as test beds for many of the systems incorporated into the early Shrike-class prototypes, however, and the 282s provided a critical component in the combat power of the Trojan-class Q-ships until their final retirement in 1918.

Shrike-class light attack craft
Mass: 20,250 tons

Dimensions: 71 × 20 × 20 m

Acceleration: 636 G (6.237 kps²)

80% Accel: 508.8 G (4.989 kps²)

Forward: 4M, 1G, 4CM, 6PD

Service Life: 1912–1917

The Shrike revolutionized the concept of the LAC in many ways. Far from a simple evolutionary outgrowth of the Series 282, the Shrike has virtually nothing in common with a conventional LAC. Although the Shrike carried over many of the 282’s technology innovations in terms of system miniaturization and increased automation, it represented a complete conceptual break with previous LACs. Earlier examples of the type had been seen as miniature warships equipped with traditional weapon systems; the Shrike was visualized as a single-weapon system, optimized for the sole purpose of getting its powerful graser into decisive range.
Historically, LACs have suffered from limited endurance driven by bunker space for fusion reactor hydrogen, so, unlike any warship in a millennia, the Shrike class carries a highly efficient fission pile as primary power. Inspired by Grayson developments in fission reactor technology, the fission plant means that the Shrike’s cruise endurance is limited primarily by crew support consumables. Its combat endurance remains a factor of plasma feedstock for the gravitic subsystems (mostly graser and missile launch systems), but its ability to stay on station for months if necessary is a huge advantage in the system defense role. In addition, while a Shrike masses almost twice as much as a Highlander (in a hull less than half the size), its remotes and expert systems are some of the most advanced anywhere in space, simultaneously increasing lethality while decreasing crew requirements.
The Shrike class was also the first warship to be fitted with the new “beta-squared” impeller nodes, which by 1921 PD have become standard equipment on all new Manticoran construction. In addition to the mass savings the nodes provided, they also allowed the Shrikes to transmit FTL communications while under acceleration. The vastly more powerful impeller rings, second generation inertial compensators and enhanced electronic warfare and stealth systems made the Shrikes the fastest, stealthiest, and ton-for-ton most dangerous warships in space for their time.
Among all of the other advances seen on the Shrike class, perhaps the most notable was the introduction of the all-forward armament, combining the new off-bore launch technology with a bow wall and a powerful spinal-mounted graser for close range antiship strikes, all without relying on the traditional broadside armament carried by LACs up until this point.
For a program that was nearly cancelled by Navy before it could prove itself, the Shrike-class LACs performed far above expectations during the Second Battle of Hancock. Able to approach to far closer range of an enemy under stealth than anyone had predicted, their initial attacks were devastating. While their survivability against a prepared opponent was questionable, their ability to isolate and destroy cripples and the savage damage they could do to the enemy’s screen proved their value.
Despite exceeding all expectations, the original Shrike was still a transitional design, with many flaws, some major and some minor, appearing during the early simulations, wargames, and battle experience. While the heavy demand for LACs kept many of them in service longer than expected, the last of the original production run was replaced in 1917 by the Shrike-B.

Italics are the author's, boldface and underlined text is my emphasis.

All other Manticoran (and presumably Grayson) naval warships (from DDs all the way up to SDPs and CLACs as well as subsequent LACs) and naval auxiliaries (dispatch boats, missile colliers, etc.) built on/after 1921 PD have beta-squared nodes replacing old-style beta nodes. The evidence is in the underlined text of this sentence from the description of the Shrike-class LAC in:

House of Steel, The Royal Manticoran Navy, Order of Battle wrote:The Shrike class was also the first warship to be fitted with the new “beta-squared” impeller nodes, which by 1921 PD have become standard equipment on all new Manticoran construction.

Italics are the author's, boldface and underlined text is my emphasis.

* As mentioned above, the Nucio LACs (15,000 tons) were able to accelerate at 500 gravities in The Shadow of Saganami. In contrast, the RMN Highlander-class LACs had a maximum (100%) acceleration of 409.3 gravities. The Highlander-class LACs are clearly using inferior beta nodes compared to the Nuncio LACs.

House of Steel only covers the RMN, GSN and Protector's Own order of battle.

Louis R wrote:Something to bear in mind is that, despite all the improvements in node and compensator technology, the basic equation is unchanged: LACs, of whatever design, are and always will be far smaller than any other warship. All else being equal, they will have weaker wedges, smaller inertial sumps and lower max acceleration than a destroyer built with the same tech, simply because the nodes are smaller and there are half as many of them. What has changed is that the gap is now significantly smaller than it was, since the impeller can be built with the power to max the compensator.

The numbers that surprised the OP are in the range of what I would expect. At least, they were once I took the time to think about it.

Jonathan_S wrote:

Louis R wrote:Something to bear in mind is that, despite all the improvements in node and compensator technology, the basic equation is unchanged: LACs, of whatever design, are and always will be far smaller than any other warship. All else being equal, they will have weaker wedges, smaller inertial sumps and lower max acceleration than a destroyer built with the same tech, simply because the nodes are smaller and there are half as many of them. What has changed is that the gap is now significantly smaller than it was, since the impeller can be built with the power to max the compensator.

The numbers that surprised the OP are in the range of what I would expect. At least, they were once I took the time to think about it.

I'm not sure with Beta Squared nodes that's actually true. However because of the scarcity of data points, and the way House of Steel give initial design acceleration (which because of production delays doesn't always correspond with initial service dates) it's really hard to be sure you're comparing the same 'generation' of internal compensators.
That makes it hard to make definitive conclusions.

However, its probably a good hint that LACs aren't slower anymore to look at the (apparently all 1st gen Grayson derived compensators) on the:
Series 282-class LAC [1904]- 573.2g (105.52% of pre-war accel)
Joshua-class (GSN) DD [1905]- 514.7g (105.49% of pre-war accel)
Courvosier-class (GSN) BC [1904] - 548.9g (105.50% of pre-war accel)
That seems to show that even before the full beta-squared nodes that LACs were getting their full acceleration potential.

The tricky bit is that it's hard to find other crosschecks due to limited data points. Though the Shrike [1912], Shrike-B [1914], Ferret [1914], and the Benjamin the Great-class (GSN) SD [1911] are all right around 117.2% of pre-war accel

However, to be fair, there are a couple possible counter-points. For example the later Katana [1917] is only up to 118.03% while other ships built that year are 145.09%. (But given how HoS is organized that might just mean that the Graysons did the original Katana design work 4-5 years before they felt the need to build it).
Similarly the other 1914 initial service design, the Medusa-class SD(P), was up to 125.97% (compared to the 117.27-.28% of the Shrike-B and Ferret)

So the data is suggestive, but not conclusive, that LACs of the same design and refit generation can out accelerate a DD (despite the later's Alpha nodes and more powerful wedge)

The Shadow of Saganami, Chapter 20 wrote:The small force of Nuncian vessels and their Manticoran parasites were moving towards the freighter at a relative velocity of just a hair over 17,650 KPS, and the LACs' maximum deceleration rate was five hundred gravities. It had taken them an hour of steady acceleration to reach their current velocity before shutting down their wedges to avoid detection, and it would take them another hour to kill their velocity, during which time they would cover another 31,771,000-plus kilometers. At the moment, they were about forty-two million klicks from the freighter, so to decelerate for a zero/zero intercept, they'd have to begin decelerating in no more than four minutes. The pinnaces, with their higher acceleration rate, had a bit more time to play with—they could achieve a zero/zero intercept if they began decelerating any time in the next fifteen minutes. If they didn't begin decelerating, they'd blow past Bogey Three at a range of about 67,500 kilometers and a velocity of over seventeen thousand KPS, in a shade over forty minutes.

Echoes of Honor, Chapter 36 wrote:The pinnace was running flat out, straining to catch up with HMS King William. The flagship, known affectionately to her crew as Billy Boy, was holding her accel down enough for the small craft to overhaul, and Markham watched out the port as the pinnace maneuvered to dock. He didn't think of himself as a particularly brave man, and his belly knotted with tension as he thought of what King William and the rest of his understrength force was going out to face. But heroic or not, Silas Markham was a vice admiral of the Royal Manticoran Navy, and his place was aboard his flagship when she faced the foe, not in some damned office light-minutes behind the battle.