Concepts: Today's similarities and differences to the HV

Theemile wrote:"Sonar Speed" is the result of an issue caused by the noise of water against the hull created when your ship moves too fast - the noise of the water moving past the sensors blinds them. Less of an issue in the era of digital filters and slicker hull forms, but still an issue to this day.

In the Honorverse, ships drones wouldn't have the same issue with radar and lidar until they hit a velocity .6-.8c when the particle density is too high to see through and blinds the sensors (and collapses the particle shields).

Even if the particle shielding isn't an effect, a drone moving at 0.6c isn't going to have much time looking at something close enough to resolve it and provide sufficient detail to its mothership. So drones still need to slow down to "sonar speed."

However, this is where we depart from the movie. Drones are launched in waves: a first that will not decelerate and will get the roughest but earliest data, then a second that will come slower but probably still fly past, then a third that will slow down to a relative stop to whatever was found by the first two passes and linger in stealth. That is, even though you need to slow down, you don't need all drones to slow down.

More importantly, none of this affects the mothership.

In the movie at one point the Greyhound's captain ordered the convoy to look out for surface radar. In the darkness of the night particularly doing rough seas the subs had to see as well. They had to locate their prey. But surface radar can be detected.

Fast forward to the HV. The LDs have to locate their prey. Wedges are easy to spot, but drones are not. How does an LD spot GR drones so they can steer clear of them? Any active radar could give them away. Assuming the "Spiders" can localize GR drones to steer clear or eat them.

penny wrote:In the movie at one point the Greyhound's captain ordered the convoy to look out for surface radar. In the darkness of the night particularly doing rough seas the subs had to see as well. They had to locate their prey. But surface radar can be detected.

Fast forward to the HV. The LDs have to locate their prey. Wedges are easy to spot, but drones are not. How does an LD spot GR drones so they can steer clear of them? Any active radar could give them away. Assuming the "Spiders" can localize GR drones to steer clear or eat them.

As far as we know LDs only have the same kinds of sensors as any other Honorverse warship -- and GR drones are designed to hide really well from those sensors.

The LD's advantage is that it itself is vastly harder to spot so the inverse square law works somewhat in its favor. The drones have to get closer to the LD to spot it, compared to a regular warship, and the closer they are the easier they are to spot (not easy; but easier). Though the LD might still get unlucky and a drone it hasn't spotted flies through its 'exhaust' (the directionally aimed waste heat), by pure change, which would let the drone spot the LD from much further out than from any other angle.

Still, from what little we know, it's not going to be easy for LDs to spot GR drones in order to evade them. And if the Grand Alliance gets a good feel for just how stealthy LDs are they can adjust to bring and use enough drones that there aren't LD sized holes in their drone net out to quite some significant distance. At that point the only evasion is breaking away from the fleet and its drone screen

"Look! Dicky forced her to the surface. She must be hurt!"


I suppose as far as an LD goes, forcing her to surface would be causing her spider drive to go down.

penny wrote:"Look! Dicky forced her to the surface. She must be hurt!"


I suppose as far as an LD goes, forcing her to surface would be causing her spider drive to go down.

Not really -- there isn't really an proper analogy. Though if a spider ship also carried an impeller drive bringing that drive up might be a bit closer.

A sub that surfaces is easier to see (optical and radar now also come into play; not just active/passive sonar), faster (well in the WWII era; that's switched today), can be engaged by more types of weapons (guns, rockets, regular bombs), but can also bring more weapons of its own into play (in the WWI/II era) -- deck guns, AA guns, small arms and grenades.

And LD whose spider drive goes down is harder to see, slower (well; lower acceleration), and doesn't change what weapons either side cane use. OTOH a LD that somehow brought up a wedge (or sails) is easier to see. (Though due to her size isn't any quicker, and except for being easier to see doesn't affect what weapons either side is physically capable of using)

penny wrote:I suppose as far as an LD goes, forcing her to surface would be causing her spider drive to go down.

A sub is normally forced to the surface, because it has been located and damaged. Now when a sub is forced to the surface it completely loses its stealth, but the LD's stealth does not reside solely in the spider drive. However if it lost the spider drive because it was hit by a weapon, so it was forced to deploy a spherical sidewall; then the resulting visibility to everyone could correspond to a sub being forced to the surface. Note that this assumes the LD is either within the hyper-limit or the damage was also to the hyper-generator, because otherwise the LD has another way to escape.

Jonathan_S wrote:

penny wrote:"Look! Dicky forced her to the surface. She must be hurt!"


I suppose as far as an LD goes, forcing her to surface would be causing her spider drive to go down.

Not really -- there isn't really an proper analogy. Though if a spider ship also carried an impeller drive bringing that drive up might be a bit closer.

A sub that surfaces is easier to see (optical and radar now also come into play; not just active/passive sonar), faster (well in the WWII era; that's switched today), can be engaged by more types of weapons (guns, rockets, regular bombs), but can also bring more weapons of its own into play (in the WWI/II era) -- deck guns, AA guns, small arms and grenades.

And LD whose spider drive goes down is harder to see, slower (well; lower acceleration), and doesn't change what weapons either side cane use. OTOH a LD that somehow brought up a wedge (or sails) is easier to see. (Though due to her size isn't any quicker, and except for being easier to see doesn't affect what weapons either side is physically capable of using)

Another analogy (Though again, not completely accurate) would be forcing the Spider unit to use it's Bubble Sidewall; it's now on the "surface" - radiating for all to see it, exposed to everyone's fire, it's primary drive system disengaged or limited. Which is not to say it's defenseless (it has the bubble sidewall) or disarmed (it can still fire weapons), but by popping the bubble, it's almost a statement that the spider was forced into a situation it was not able to handle, and "surfacing" into standard combat is a last resort for survival.

Theemile wrote:Another analogy (Though again, not completely accurate) would be forcing the Spider unit to use it's Bubble Sidewall; it's now on the "surface" - radiating for all to see it, exposed to everyone's fire, it's primary drive system disengaged or limited. Which is not to say it's defenseless (it has the bubble sidewall) or disarmed (it can still fire weapons), but by popping the bubble, it's almost a statement that the spider was forced into a situation it was not able to handle, and "surfacing" into standard combat is a last resort for survival.

I am not sure if you mean to state that the spider unit has to pop the bubble wall to fire a weapon. We know that "gunports" can be created in a bubble sidewall (the same as in a regular sidewall), because that is what forts do. They could not survive prior to pods, if a bubble wall have be dropped to fire a weapon. Ports might also need to be created to control pods or Keyhole controllers.

tlb wrote:

Theemile wrote:Another analogy (Though again, not completely accurate) would be forcing the Spider unit to use it's Bubble Sidewall; it's now on the "surface" - radiating for all to see it, exposed to everyone's fire, it's primary drive system disengaged or limited. Which is not to say it's defenseless (it has the bubble sidewall) or disarmed (it can still fire weapons), but by popping the bubble, it's almost a statement that the spider was forced into a situation it was not able to handle, and "surfacing" into standard combat is a last resort for survival.

I am not sure if you mean to state that the spider unit has to pop the bubble wall to fire a weapon. We know that "gunports" can be created in a bubble sidewall (the same as in a regular sidewall), because that is what forts do. They could not survive prior to pods, if a bubble wall have be dropped to fire a weapon. Ports might also need to be created to control pods or Keyhole controllers.

i meant "pop" as in to quickly turn it on - Like "Pop" it's there. But yes, with the word bubble, "pop" can be confusing.

I would assume that Bubble Walls have gunports, otherwise they are pointless on a fort - if you raise the defenses, all you can do is sit there and wait for someone else to save you - or for your attacker to run out of weapons.

I like your analogy. It seems perfect to me. Theemile.

And the part about not being helpless rings true in the movie as well. I dunno why it caught me off guard when the surfaced subs started shooting guns off the deck. They had some powerful weapons too. A big gun blew a hole in the hull of Hank’s destroyer, killing the messmate and several others.

That was one of the thrilling scenes. It showed some U-boat tactics I had never seen. After being forced to surface, the U-boat Captain put his boat on a course that kissed the destroyer. The sub was keeping pace with the destroyer while touching hulls. The destroyer’s big guns could not depress far enough to shoot the U-boat that was riding mere inches from its hull. The U-boat captain’s skills were amazing. Gutsy move.

If an LD got so close to a ship that it couldn’t shoot it, it’d have to be inside the wedge kissing hulls???

Talk about having to know your vector math, destroyer Captains trying to evade torpedos better have passed that course with a perfect score.

Destroyer Torpedo Evasion and Vector Math in WWII:
During WWII, destroyers relied on speed, agility, and clever maneuvering to evade incoming torpedoes. While sailors might not have consciously applied complex vector equations in the heat of battle, their maneuvers were effectively based on vector principles.

Here's how vector math played a role in torpedo evasion:

• Understanding Relative Motion: Evasion depended on understanding the relative motion between the destroyer and the torpedo. This involves considering the destroyer's velocity vector (speed and direction) and the torpedo's velocity vector.

• Aiming for an Intersection Point: Submarines or aircraft launching torpedoes needed to calculate a "firing solution" - where to aim the torpedo to intercept the target, taking into account the target's movement. This calculation inherently involved vector math to determine the intersection point of the torpedo's predicted path and the target's predicted path.

• Destroyer Maneuvers: A destroyer commander receiving a torpedo alert would quickly assess the torpedo's path and make adjustments to their own course and speed to avoid the predicted intersection point. Common maneuvers included:

• Turning Towards the Torpedo: By turning towards the incoming torpedo, a destroyer could reduce its relative speed to the torpedo, potentially crossing its path before the torpedo reached the predicted impact point.

• Turning Away from the Torpedo: Turning away could increase the time it takes for the torpedo to reach the ship, giving the destroyer more time to react and potentially increasing the turning space available.

• Changing Speed: Increasing or decreasing speed could also alter the relative motion and the time until potential impact.

• Mental Calculations and Experience: Experienced commanders developed a keen intuition for these scenarios. Through training and practice, they learned to make snap decisions based on the torpedo's bearing, speed, and the ship's capabilities.
Important Notes:

• Straight-Running Torpedoes: WWII torpedoes generally ran in a straight line after launch, making the vector analysis more straightforward than with later, homing torpedoes.

• Analog Computers: While the initial calculations for launching a torpedo might involve complex math, analog computers like the Torpedo Data Computer (TDC) were used to automate these calculations and provide the necessary gyro angle for the torpedo.

• Target Motion Analysis (TMA): The overall process of tracking a target, predicting its movement, and calculating a firing solution or evasion strategy is known as Target Motion Analysis.

In essence, a destroyer's evasive maneuvers were about altering its velocity vector (speed and direction) relative to the incoming torpedo's velocity vector, effectively creating a new "target motion analysis" that would hopefully result in a miss.

****** *

Following is a transcript of the most thrilling scene in the movie. The final battle.

[garbled radio transmission]

[Gray Wolf] Greyhound.
Guten Morgen, Greyhound.
Did you think you had slipped away from this Gray Wolf?
No, you did not. You will not.
The sea favors the Gray Wolf on the hunt,
not the hound on the run.
You and your comrades will die today.

[Charlie] Conn, Combat.
Radar showing contact at 110.
[lookout] Periscope to starboard bow.
Range is 2,100 yards and closing, sir.
[lookout] About one mile!

There, sir!
[Lopez] Fire!
The wake, sir! There!

Contact 187…
Sonar reports torpedoes, starboard beam,
bearing 187. Range 1,500, sir.
Left full rudder.

[Watson] Left full rudder.
Second torpedo to starboard beam!
Bearing 120! Range 1,000!
Right hard rudder, hard over!
Right hard rudder, hard over!

Belay that, belay that!
Meet her. Meet her!
Belay. Meet her. Meet her.

[helmsman] Aye, sir. Holding course.
[Ernie] Right hard rudder, hard over!
Starboard slow astern! Port ahead full!
[Watson] Starboard slow astern!
Port ahead full!

[Ernie] All hands, brace for collision!
Meet her! Steer straight
for that pip at 119!
119. Aye, aye, sir.
All ahead full.
All ahead full. Aye, aye, sir.
We’ll ram that U-boat if we have to!

[cannons firing]
[lookout] Torpedo off starboard bow!
Bring us full left to 100.
Aye, aye, sir.

Conning tower, dead ahead!
[Watson] We must have hit her!
Charlie! Lay a course to open the arcs of fire aft! We’ll hit ’em broadside!
Left full rudder, slow to two-thirds. After batteries, fire as you bear.
All mounts, local control!
Target will be fine on our starboard bow!
[repeating command]
Fire as they bear!

[Lopez] Weapons, Bridge. All mounts, local control. Fire as they bear.
[lookout] Second sub spotted!
Periscope, starboard bow!
[lookout] He’s got us lined up, sir!
All mounts, local control!
Get those guns around!

[lookout 2] Air cover! Air cover!
[airplane propellers whirring]
Signal Bridge reports aircraft signals. “Uncle William,” sir.

Reply, “Baker Dog.”
Right standard rudder!
Mounts 41 and 42,
open fire to mark the target
for that aircraft!
[talker] …mark target for that aircraft.

[crew cheering]
Good work.
[crew continues cheering]
[Watson] Sir, I stand relieved.
Mister Carling has the deck.
Very well.

Another tactic I’d never seen out of a sub is to line up a shot while bearing straight down the throat of the destroyer. Head on.

“He’s got us lined up, sir!”

Tom Hanks brought a lot more submarine tactics to this movie. Tom Hanks knew his vector math arithmetic very well.

“Torpedo in the water!”
“Watch your training son. What bearing?”

The captain needs those bearings, and he needs them yesterday! The final scene saw Tom Hanks going up against two subs and each sub launched a torpedo.

2 agin' 1

It was the best scene in the movie. The destroyer has two torpedos bearing down on it. The two subs launched a classic one-two punch. It was obvious that that was a classic two sub attack pattern. The way the torpedos were bearing down on him he couldn’t maneuver against the one torpedo because that maneuver would expose him fatally to the other.



Question: Could a Ghost slip inside the wedge via several gun ports that are malfunctioning?