RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

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RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Pokermind on Thu Jul 02, 2015 6:22 am

Dear Tabby,

Most Trippe and Double expansion engines run between 0 and 100 RPM what is the maximum revolutions of a four piper Destroyer like USS Walker to figure out how much the low RPM engine must be geared up to give proper shaft RPMS?  If the other steam/sail DDs used Walker's prop one would assume a similar gear up for them.

pirat Arrr,

Chief Pokermind


Last edited by Pokermind on Thu Jul 02, 2015 6:26 am; edited 1 time in total (Reason for editing : minor edits switched places pirate smilly and Arrr, and seperation of DDsused to DDs used)
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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Admin on Thu Jul 02, 2015 10:01 am

I've got a headache!

You don't need to explain why you edit, you're a moderator (a triple expansion moderator)

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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Pokermind on Thu Jul 02, 2015 1:51 pm

Oh-Kaay as Ruben would say Embarassed
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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Molybdenum on Wed Jul 08, 2015 3:13 am

Hey pokermind, with some quick research I didn't find anyhting on the Wickes class specifically, however HMS Wanderer, a british destroyer of the same vintage as Walker had screws that rotated at 260 RPM. Also aren't you forgetting that Walker has steam turbines, not triple or double expansion engines?

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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Pokermind on Wed Jul 08, 2015 12:28 pm

As far as we know the clones have reciprocating engines and the Steam Sale DDs do also. Indications are they are using a copy of Walker's prop on all. So about a one to three gear up.
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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Pokermind on Fri Jul 10, 2015 12:43 am

Cross post from Taylor Anderson's Tech blog:
"
On July 10, 2015 William Curry says:

Looking through “The Marine Power Plant” by Chapman (1922). It looks like most reciprocating engines were directly connected to the propeller, which ran at the same speed as the engine. Commercial ships were shown with engines running in the 75 to 100 rpm range. Presumably the maximum rpm of the screw was the same.
The highest development of the reciprocating for naval use was the 4 cylinder Triple expansion engine which had engine rpms in the range of 100 to 190. High speed stationary engines are shown running at speeds up to 250 rpm, with 17 to 85 rpm being more typical.
The section on geared turbine drive shows typically around 3500 rpm on the turbine with a 90 rpm on the screw. Turbine reduction gears between the turbine and the propeller shaft are shown with ratios in the 1/15 to 1/36 range with 1/15 to 1/20 listed as typical. Some high speed ships are show with propeller rpms around 125.
Super heat is shown between 0F and 230F. The recommended super heat for a reciprocating engine is said to be between 50F and 80F with 60F as the practical ideal. The naval engines has engine inlet pressure around 250 to 280 psig. The commercial engines were operating with inlet pressures around 175 to 200 psig.
All things considered, a Walker clone plant would be oil fired scotch marine boilers with waste heat superheaters producing 200 to 250 psig steam with around 60 degrees F of superheat and 4 cylinder triple expansion engine with 2 low pressure cylinders, directly connected to the propeller shaft running with a maximum screw Rpm of probably around 90 to 125. The condenser would probably be running around 26 to 27 inches of vacuum."

Hmm, Perhaps no gear up needed but direct connection.
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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by Dilandu on Fri Jul 24, 2015 5:07 pm

Some of my speculations about the origins of IJN "Amagi":

http://destroyermen.wikia.com/wiki/Talk:IJN_Amagi
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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

Post by donaldjj on Mon Jun 13, 2016 1:12 am

Given the state of technology in the story of Destroyermen world there is no reason not to believe that they are using turbines after all the steel in turbines and the steel in their metal plates is nearly the same quality. The only thing that might prevent this is if the oil that they have in other words the lubricants cannot handle the steam temperatures and I do not believe this is the case.

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Re: RPM of Destroyer Screws and how much a resiprocating Steam engine must be geared up?

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