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SparvieroVV

Help me wrap my head around Normandie, please?

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IronMike11B4O    144
51 minutes ago, Show_Me_Your_Cits said:

They had the same problems everyone else did with direct drive turbines. Direct drive turbines were horrible, because in order to be efficient, a turbine needs to run as close to its optimal design speed as possible. This can't be done with direct drive turbines, because turbine speed = shaft speed. So when you're going slow, it's essentially lugging the turbine and you need to push a lot of steam through it to keep it turning. With the advent of geared turbines, you can run the turbines at a much higher speed than the shaft speed with reduction gears and keep them in the sweet spot between power and efficiency. A lot of older warships with DD turbines were refit at some point with geared turbines if they could be because of how much less fuel they ended up burning. 

 

Had any of the class been built, the plan was to use the recips for cruising and reversing, and the turbines for high speed. But none of these ships actually were completed or sailed in that configuration (the one that became a CV used 4x turbines and ditched the recips) 

Agreed. I'm actually IRL a Marine Propulsion technician I work on large propellers and rudders for a living doing repair and warranty work in the shipyard in Portland. The reduction gears on today's larger vessels are pretty amazing I guess 80 years ago they were still in the infancy of figuring this out. I'm taking a break under the USNS Frank Cable as we speak. LOL

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SparvieroVV    609

I don't many people would really mind mid 20s speeds. Even similar to the Italian refits. Hitting near 30 knots is a bit cheese. I'm just going to steal this and apply the comments inappropriately here. 

 

https://forum.worldofwarships.eu/topic/41130-lets-talk-french-battleships-a-bit/?do=findComment&comment=2099797

 

59dcb90e967d0_Normandie25000tdesign.thum

 

Quote

 

 

A bit late but John Jordan's French Battleships of World War One has a picture of a Normandie design more or less corresponding to WG one, including the mid turret (main differences being two funnels instead of one but that's probably a what-if engine modernization, as what was done for the Iron Duke).

 

 

Normandie 25000t design.jpg

 

 

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Lord_Slayer    87
On 11/12/2017 at 10:34 PM, Crucis said:

Seems like a very significant change between the ship in the line drawing and the WG picture.  The early version has the central turret aimed aft, without much blocking its rearward fire.  But in the modernized WG version, the turret is now normally aimed forward.

Interesting.

 

 

On 11/13/2017 at 4:38 AM, ValkyrWarframe said:

It's not unheard of to reverse turrets during a rebuild.  The Japanese did it with Yamashiro - her #3 turret faces backwards, but as-built she was just like Fuso.

 

In the line drawing, she does have two funnels, while her 'upgraded' WG pic only has the one. So, it's 'possible' that removal of the funnel clears that gun arc and allows the rotation.

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5 hours ago, IronMike11B4O said:

Agreed. I'm actually IRL a Marine Propulsion technician I work on large propellers and rudders for a living doing repair and warranty work in the shipyard in Portland. The reduction gears on today's larger vessels are pretty amazing I guess 80 years ago they were still in the infancy of figuring this out. I'm taking a break under the USNS Frank Cable as we speak. LOL

 80 years ago (1937) they actually had a pretty good grasp on steam turbines and reduction gearing... 112 years ago ( year of the Normandie designs)? Not so much. I can't remember if it was more a matter of "We don't understand turbines" or "We don't have the industrial capacity to make these ginormous gearboxes."

 

I think it was a little bit of both. The interwar period was when steamship propulsion tech really made a massive leap between superheating, oil fired boilers, and geared turbine sets.

 

And it sounds like you have a really, really cool job too! There's something fascinating about large machinery making large objects move.

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