4 ms·

Is max torque on an typical nuclear submarine limited by the max reactor output, or can they rely on batteries to exceed this temporarily?

sgarland 2y ago
Generally it’s just various design parameters. Until the newest (and not-yet-built) Columbia-class, boats are all steam propulsion, and you can hit various pressure limits for components without maxing the reactor out. That said, yes, with nominal conditions generally All Ahead Flank will have the reactor output at 100%. All Back Emergency usually hits some other limit first. Columbia-class is electric drive, which is absolutely wild to me. Those are monstrous motors. Source: I ran a reactor on a Virginia-class (not USS Virginia, the subject of the article, but in the same class).
- philip1209 2y ago
  Thanks for the detailed answer!
- shadowgovt 2y ago
  My understanding is the electric motors have in general gotten scary-powerful. I know some cruise ships have switched over to them because it simplifies the overall mechanical architecture (fewer moving parts, fewer high-pressure fluid circuits). Some of the Royal Carribean fleet has "azipods" that can be angled 360 degrees to provide arbitrary thrust for simplifying docking and undocking.
  - iancmceachern 2y ago
    Totally, and the controls for the motors have to be crazy now. Imagine trying to reliably switch and vary that amount of power to turn on and off, and control speed at that level of power
- ranger207 2y ago
  Electric drives are nothing new on submarines in general; the _Gato_ class were diesel-electric, and the French and Chinese apparently prefer nuclear-electric. But I think this is the US Navy's first nuclear-electric ship
  - sgarland 2y ago
    Nah, we’ve had two nuclear-electric boats before: Tullibee and Glenard P. Lipscomb. They just weren’t successful (Tullibee was to some extent, but she was also quite small).
- AlgorithmicTime 2y ago
  [dead]
lukemercado 2y ago
From first principles I'd expect the functional limit not to be one of power generation but of energy transfer. The limit probably manifests as wiring and motors overheating in a full electric drive (I don't think any subs are...) or as sound, heat and fatigue in reduction gears and gear shafts.

sgarland 2y ago

Generally it’s just various design parameters. Until the newest (and not-yet-built) Columbia-class, boats are all steam propulsion, and you can hit various pressure limits for components without maxing the reactor out. That said, yes, with nominal conditions generally All Ahead Flank will have the reactor output at 100%. All Back Emergency usually hits some other limit first. Columbia-class is electric drive, which is absolutely wild to me. Those are monstrous motors. Source: I ran a reactor on a Virginia-class (not USS Virginia, the subject of the article, but in the same class).

philip1209 2y ago
Thanks for the detailed answer!
shadowgovt 2y ago
My understanding is the electric motors have in general gotten scary-powerful. I know some cruise ships have switched over to them because it simplifies the overall mechanical architecture (fewer moving parts, fewer high-pressure fluid circuits). Some of the Royal Carribean fleet has "azipods" that can be angled 360 degrees to provide arbitrary thrust for simplifying docking and undocking.
- iancmceachern 2y ago
  Totally, and the controls for the motors have to be crazy now. Imagine trying to reliably switch and vary that amount of power to turn on and off, and control speed at that level of power
ranger207 2y ago
Electric drives are nothing new on submarines in general; the _Gato_ class were diesel-electric, and the French and Chinese apparently prefer nuclear-electric. But I think this is the US Navy's first nuclear-electric ship
- sgarland 2y ago
  Nah, we’ve had two nuclear-electric boats before: Tullibee and Glenard P. Lipscomb. They just weren’t successful (Tullibee was to some extent, but she was also quite small).
AlgorithmicTime 2y ago
[dead]

lukemercado 2y ago

From first principles I'd expect the functional limit not to be one of power generation but of energy transfer. The limit probably manifests as wiring and motors overheating in a full electric drive (I don't think any subs are...) or as sound, heat and fatigue in reduction gears and gear shafts.