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Re: ?
Post by Jonathan_S   » Thu Oct 15, 2020 5:32 pm

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ThinksMarkedly wrote:
tlb wrote:Thank you for the explanation, I was reading that as a 5 meter wide and 1 kilometer long graser from the way you wrote it (5M-km graser); whereas his question was actually about a graser with a range of 5 million kilometers. We have discussed before that the Rayleigh length of a meter wide graser is far beyond the effective ranges that RFC suggests, to the point that a ship has a chance to move a significant distance before the pulse propagates to where it had been.


Indeed. A quick calculation shows a ship that can accelerate at 500 gravities can move 700 km in any direction in the time it takes the beam to leave the graser mount and arrive at the intended target. You have to quadruple that because of the double time if you need to account for light-speed sensors, but we know FTL sensors already exist.

Anyway, this was pure speculation on my part because the LDs look fatally designed to me.
They do seem over-large for their apparent attack style. Though there's historic precedent for that mistake - I'm thinking of the interwar submarine cruisers like the French Surcouf with its 8" gun turret, to a lesser extent the US Narwhal-class with their two single 6" guns, or the British M-class subs with their single 12" gun!

Yes it's nice all that that you're a submarine and can sneak around largely undetected. But designing a very large one around a weapon system that require you to abandon that stealth and expose yourself to return fire - in a ship that is about the least capable of handling even small amount of damage from return fire. (Doesn't really matter how small the holes in your hull are, you're not going to survive submerging again with them). And to add to the fun Surcouf added on a floatplane - like the later Japanese I-400 class subs.

Yes torpedoes are expensive, complicated, relatively slow, and you can't carry many of them. Guns are simpler, the ammo is much smaller, and the short time of flight makes fire control easier. But at least a torpedo is relatively stealthy to fire - not like surfacing and then exposing your position with bright muzzle flashes!

Ultimately submarines with heavy guns proved to be a bad idea. Just because you can build something big and impressive doesn't mean you should. And I'm waiting to see if Lenny Dets are equally poorly suited to their mission or if there is a surprise in their capacities; or possibly they're designed for a doctrine we haven't properly visualized yet.


After all you should have an doctrine for using a weapons system before you go out and procure it. And presumably the folks in charge of MAlign naval procurement see the LD as suitable for whatever their planned doctrine is; even if we tend to see them as oversized for what looks to just be an ambush unit (Though doctrine can also be wrong, misguided, or overtaken by events)
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Re: ?
Post by tlb   » Thu Oct 15, 2020 5:44 pm

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Jonathan_S wrote:They do seem over-large for their apparent attack style. Though there's historic precedent for that mistake - I'm thinking of the interwar submarine cruisers like the French Surcouf with its 8" gun turret, to a lesser extent the US Narwhal-class with their two single 6" guns, or the British M-class subs with their single 12" gun!

The class I think is most peculiar is the British K-class, because they were steam driven. That had to be hotter than the diesel, plus they needed to raise and lower the smokestack. It took about 30 minutes to change from surface operation to submerged.
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Re: ?
Post by Jonathan_S   » Thu Oct 15, 2020 7:11 pm

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tlb wrote:
Jonathan_S wrote:They do seem over-large for their apparent attack style. Though there's historic precedent for that mistake - I'm thinking of the interwar submarine cruisers like the French Surcouf with its 8" gun turret, to a lesser extent the US Narwhal-class with their two single 6" guns, or the British M-class subs with their single 12" gun!

The class I think is most peculiar is the British K-class, because they were steam driven. That had to be hotter than the diesel, plus they needed to raise and lower the smokestack. It took about 30 minutes to change from surface operation to submerged.

Definitely another weird one.
They were chasing a goal that the technology of the day couldn't quite meet - the first true fleet submarine. A sub fast enough
on the surface to keep pace with the 23 knot battle fleet so they could be used in conjunction with it. Normally by submerging once contact with the enemy was established and acting as a somewhat mobile minefield that the enemy fleet would be lured into.

But the internal combustions engines available in the late 1910s simply didn't have the power to push a sub through the water at 24 knots. For that they needed geared steam turbines -- though as you note those had operational drawbacks bad enough to prevent them from effectively performing the desired fleet sub role.

Heck I took a quick look and I don't see a single US or RN submarine that ever matched the K-class's surfaced speed of 24 knots; though the RN River-class fleet sub of the early 1930s came close at 22 knots on supercharged diesels. The US fleets subs right from the beginning with the Tabor-class hovered around 20-21 knots on their diesel electric propulsion (which I guess almost kept up with the USN's slower fleet of Standard battleships :D)


After WWII powerplants had advanced to the point where it would have been possible to build a sub that ran even faster than that on the surface - but by then radar had caused the focus to shift to sustained underwater speed which requires a totally different hull form and prop optimization. So while the RN's experimental hydrogen peroxide powered Explorer-class (known as the Exploder-class thanks to their highly temperamental oxidizer) would make 24 knots submerged - matching the K-class's best speed - they'd have been much slower than the Ks if surfaced. And the same applied to the slightly later SSNs of the USN (and later still RN).
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Re: ?
Post by Brigade XO   » Thu Oct 15, 2020 7:24 pm

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How do you see a SD at 1,000,000 kilometers?
On your tactical scanners, you don't eyeball them. Shooting at them with graders means knowing where they were, where they seem to be going plus the speed and acceleration. Your shooting at where they WILL BE when the graser energy gets there.
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Re: ?
Post by tlb   » Thu Oct 15, 2020 7:34 pm

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Jonathan_S wrote:So while the RN's experimental hydrogen peroxide powered Explorer-class (known as the Exploder-class thanks to their highly temperamental oxidizer) would make 24 knots submerged - matching the K-class's best speed - they'd have been much slower than the Ks if surfaced. And the same applied to the slightly later SSNs of the USN (and later still RN).

The Germans were the first to try hydrogen peroxide in subs; from Wikipedia:
In the early 1930s Hellmuth Walter had designed a small, high-speed submarine with a streamlined form propelled by high-test peroxide (HTP) and in 1939 he was awarded a contract to build an experimental vessel, the 80 ton V-80, which achieved an underwater speed of 28.1 knots (52.0 km/h; 32.3 mph) during trials in 1940.
--- snip ---
Following the success of the V-80's trials, Walter contacted Karl Dönitz in January 1942, who enthusiastically embraced the idea and requested that these submarines be developed as quickly as possible. An initial order was placed in summer 1942 for four Type XVIIA development submarines.
--- snip ---
The U-793 achieved a submerged speed of 22 kn (41 km/h; 25 mph) in March 1944 with Admiral Dönitz aboard. In June 1944 U-792 achieved 25 kn (46 km/h; 29 mph) over a measured mile.
--- snip ---
The Royal Navy repaired U-1407 and recommissioned her on 25 September 1945 as HMS Meteorite. She served as the model for two further HTP boats, HMS Explorer and HMS Excalibur.

These would also have been slower on the surface.
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Re: ?
Post by tlb   » Thu Oct 15, 2020 7:39 pm

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Brigade XO wrote:How do you see a SD at 1,000,000 kilometers?
On your tactical scanners, you don't eyeball them. Shooting at them with grasers means knowing where they were, where they seem to be going plus the speed and acceleration. Your shooting at where they WILL BE when the graser energy gets there.

That is a major problem. If they have a wedge you can use that to fix the approximate location without the light-speed lag. But even then you do not know where they are within the wedge and you can only guess where they will be when the pulse arrives, as you said.
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Re: ?
Post by ThinksMarkedly   » Thu Oct 15, 2020 10:54 pm

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Jonathan_S wrote:After all you should have an doctrine for using a weapons system before you go out and procure it. And presumably the folks in charge of MAlign naval procurement see the LD as suitable for whatever their planned doctrine is; even if we tend to see them as oversized for what looks to just be an ambush unit (Though doctrine can also be wrong, misguided, or overtaken by events)


Quick correction: the MAN admiralty and their Detweilerships saw the LDs as suitable for their planned doctrine at the moment they were ordered, which is before Oyster Bay and the end of the Second Manticore-Haven War, before the Manticore-Solarian War started. The plan at that stage was still to pit Haven against the SL and use the LDs to wreak havoc.

The Plan is gone and the enemy is forewarned.
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Re: ?
Post by ThinksMarkedly   » Thu Oct 15, 2020 11:13 pm

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tlb wrote:
Brigade XO wrote:How do you see a SD at 1,000,000 kilometers?
On your tactical scanners, you don't eyeball them. Shooting at them with grasers means knowing where they were, where they seem to be going plus the speed and acceleration. Your shooting at where they WILL BE when the graser energy gets there.

That is a major problem. If they have a wedge you can use that to fix the approximate location without the light-speed lag. But even then you do not know where they are within the wedge and you can only guess where they will be when the pulse arrives, as you said.


With a wedge, you can use your gravitic sensors to get an FTL fix on the position of the wedge. From there, you guess where inside the wedge the ship is and you bracket those positions, as discussed upthread. The firing lag from a gigametre away is 3.3 seconds (the FTL sensor lag is just 53 milliseconds) -- and note that that's the outer edge of energy weapons. Energy duels probably happened at 2.5 light-seconds and under.

(2.5 s)² × 400 G / 2 = 12.25 km. That's less than 10 lengths of a Gryphon, at a Gryphon's max accel.

Without a wedge, you will need to add the light lag of the sensors, so 1 million km means 6.6 s lag from position fix to energy beam strike. But a ship without a wedge is also limited in acceleration. If it is just thrusters, it's not going to be above 100 gravities, so things even out: double the time, a fourth of the acceleration means equal results. With a spider at emergency acceleration of 250 gravities, the same 2.5 light-seconds away can result in position change of 30 km.

How big is the LD? If it is 2 km long, the position change is 15x its length, better than old SDs with wedge.

The problem is that if the LD has been detected, it probably has been painted by a Ghost Rider. So it's not a 5-second lag, but closer to 2.8 (2.5s beam + 0.3s FTL), which brings the position change to just 9.6 km.
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Re: ?
Post by cthia   » Fri Oct 16, 2020 12:49 am

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I'm sorry, but I just don't see the problem. Well, I can see the problem, I just don't see it being insurmountable. If point defense can hit missiles coming in at 0.9c at a 99% kill rate, then surely the same processing power can hit New York City, which is traveling much slower and is less maneuverable. Even if the LD has to fire a spread pattern with a spread that is less than the size of the targeted ship. IF, such a weapon is designed.

However, I suspect the LDs will operate like it's namesake. Firing on enemy ships which fly right into its web of influence. I also suspect the entire loadout of an LDs massive grasers will have the ability to target 50 or more ships simultaneously. Even if it has to orient itself before firing a full broadside. Plus, if you've got ten or more of these things in a system, they should use the same doctrine as the German subs. A coordinated attack, the Wolfpack. Once ten or more LDs "surround" a fleet, any vector a fleet chooses takes it right into a Spider's web.

Because the LD is so vulnerable if it is localized, it's doctrine is designed around decisive attacks. Each engagement is an At All Costs scenario. When these things ambush, they ambush. They won't be joking around. Fifty or more ships destroyed in the blink of an eye, and it still isn't localized. The M- A- N is not m-a-n-n-e-d by Sollies.

If any Navy's Home Fleet is sitting in orbit? "Clean up on Aisle 1."

Son, your mother says I have to hang you. Personally I don't think this is a capital offense. But if I don't hang you, she's gonna hang me and frankly, I'm not the one in trouble. —cthia's father. Incident in ? Axiom of Common Sense
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Re: ?
Post by tlb   » Fri Oct 16, 2020 7:00 am

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cthia wrote:I'm sorry, but I just don't see the problem. Well, I can see the problem, I just don't see it being insurmountable. If point defense can hit missiles coming in at 0.9c at a 99% kill rate, then surely the same processing power can hit New York City, which is traveling much slower and is less maneuverable. Even if the LD has to fire a spread pattern with a spread that is less than the size of the targeted ship. IF, such a weapon is designed.

However, I suspect the LDs will operate like it's namesake. Firing on enemy ships which fly right into its web of influence. I also suspect the entire loadout of an LDs massive grasers will have the ability to target 50 or more ships simultaneously. Even if it has to orient itself before firing a full broadside. Plus, if you've got ten or more of these things in a system, they should use the same doctrine as the German subs. A coordinated attack, the Wolfpack. Once ten or more LDs "surround" a fleet, any vector a fleet chooses takes it right into a Spider's web.

Because the LD is so vulnerable if it is localized, it's doctrine is designed around decisive attacks. Each engagement is an At All Costs scenario. When these things ambush, they ambush. They won't be joking around. Fifty or more ships destroyed in the blink of an eye, and it still isn't localized. The M- A- N is not m-a-n-n-e-d by Sollies.

If any Navy's Home Fleet is sitting in orbit? "Clean up on Aisle 1."

The Leonard Detweiler ships would not have this problem if they fire from closer in, since a graser beam cannot be tracked (unless the intervening space is dusty). But the target is not the size of New York City, only of the New York City Zoo in this analogy, which cannot be localized directly unless looking through the open bow or stern aspects.

PS. Is that a 99% kill rate or is it that only 1% can actually achieve a hit on the hull (with some of the others simply missing)?
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