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Subject: pump jet propulsion
markrigh    12/14/2007 4:30:31 PM
Ohio class submarines were refitted with pump-jet propulsion which wasn't part of the original design, but does this still make ohio sub quieter than Vanguards or Le Triomphant class subs which implemented this feature during the design process? And with the Borei class sub coming, maybe the Navy should urge for a new class of boomer?
 
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dwightlooi       12/17/2007 9:36:25 PM

Ohio class submarines were refitted with pump-jet propulsion which wasn't part of the original design, but does this still make ohio sub quieter than Vanguards or Le Triomphant class subs which implemented this feature during the design process? And with the Borei class sub coming, maybe the Navy should urge for a new class of boomer?

A pumpjet does two things...

It funnels water through a lampshade causing an increase in pressure at the locations where the blades slices through the fluid media. This increase in pressure delays the onset of cavitation. Cavitation happens when vaccuum "bubbles" form at the trailing edges of the blades when they travel through the liquid faster than the water can rush back in to fill the void they leave as they pass. As pressures increase, the propeller at which the onset of cavitation occurs also increases. This is why subs are "silent" up to a higher speeds as they dive deeper.

The lamp shade also shields the sound made by the propeller in most of the lateral directions. This makes the sub quieter laterally but may increase their sound signature longtidually -- especially dead astern.

The Ohios are very quiet with or without a pumpjet propulsor. They are quiet enough that the soviets are said to have never tracked one after it dives in deep water. One of the features of the submarine is that at slow speeds (low reactor output) the coolants are circulated through the core through natural convection without any pumps being used. The Ohios spent most their time at very slow speeds while on patrol. At 3~5 knots, it is doubtful if a pumpjet makes a difference.
 
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Herald12345       12/18/2007 12:01:44 AM

Ohio class submarines were refitted with pump-jet propulsion which wasn't part of the original design, but does this still make ohio sub quieter than Vanguards or Le Triomphant class subs which implemented this feature during the design process? And with the Borei class sub coming, maybe the Navy should urge for a new class of boomer?

Nobody is going to tell you the answer to the bolded part.  A better answer to the second question is to ask if the mission  the boats perform requires a replacement platform. You never match a new enemy build with one of your own. You build to your requirements, not his.

Herald
 
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gf0012-aust       12/18/2007 12:36:06 AM

Ohio class submarines were refitted with pump-jet propulsion which wasn't part of the original design, but does this still make ohio sub quieter than Vanguards or Le Triomphant class subs which implemented this feature during the design process?

Nobody is going to tell you the answer to the bolded part. 

nice try though! 
 
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earlm       12/20/2007 12:33:43 AM



Ohio class submarines were refitted with pump-jet propulsion which wasn't part of the original design, but does this still make ohio sub quieter than Vanguards or Le Triomphant class subs which implemented this feature during the design process? And with the Borei class sub coming, maybe the Navy should urge for a new class of boomer?


Nobody is going to tell you the answer to the bolded part.  A better answer to the second question is to ask if the mission  the boats perform requires a replacement platform. You never match a new enemy build with one of your own. You build to your requirements, not his.

Herald


Actually, it seems that the Russians built to match the US a lot.  Ended the Cold War a lot sooner since they ran out of money faster.  Also, the Nelson class BBs were built with the rotten 16" triple rather than the 15"/42 because the US and Japan had 16", another mistake.
 
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Herald12345    Earl reply   12/21/2007 11:51:07 AM
Yeah, the Mig 25. Look at what happened? The Valkyrie went away and the Russians built the bird anyway. We built the Eagle and they wound up building the Flanker.

We canceled a turkey, they built a turkey, we built a genuine air superiority fighter to our own mission requirements to counter the turkey, and what happened? They still had to build Flankers to counter our Eagles.

BUILD TO MISSION REQUIREMENTS.

Herald
 
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keensetofpeepers    bullshit   1/3/2008 7:12:05 PM
uh, ohios were refitted with pumpjet? this is news to me
 
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Yimmy       1/3/2008 7:58:25 PM
Herald, since when was the Mig 25 a "turkey"?

It certainly was not as technologically advanced as the West feared it was, however I would rank it among the most successful and potent aircraft which the Soviets designed and fielded in the Cold War.  It was an excellent interceptor (in the age where speed meant stealth and just about everything else) and an excellent recce platform, as Israel found out.

It was certainly far more useful in reality than the far more popular Mig 29.

Yeah, the Mig 25. Look at what happened? The Valkyrie went away and the Russians built the bird anyway. We built the Eagle and they wound up building the Flanker.

We canceled a turkey, they built a turkey, we built a genuine air superiority fighter to our own mission requirements to counter the turkey, and what happened? They still had to build Flankers to counter our Eagles.

BUILD TO MISSION REQUIREMENTS.

Herald
 
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keensetofpeepers    Ohios still have good ol' props   1/3/2008 9:00:01 PM
as this controversial photo from earlier this year attests
 
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keensetofpeepers    Ohios still have good ol' props   1/3/2008 9:00:37 PM
as this controversial photo from earlier this year attests

link

 
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keensetofpeepers    Ohios still have good ol' props   1/3/2008 9:02:10 PM
link

 
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gf0012-aust       1/3/2008 9:06:43 PM
there aren't too many nukes with pump jets - but Ohios aren't one of them.
 
has anyone come across any updated photos of the Kilo with a pumpjet?  (first spotted about 12 months ago in dry dock)
 
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keensetofpeepers    kilo sub with ukrainian navy   1/3/2008 11:05:06 PM
links here

link

link

 
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Herald12345    Die by the numbers. Yimmy   1/4/2008 12:29:11 AM
Eagles 3, Mig 25s 0

Herald
 
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gf0012-aust       1/4/2008 1:14:12 AM

links here
http://submarine.id.ru/galery/t269.shtml"" target="_blank">link href_cetemp=" link" target="_blank">link

http://www.alrosa.net/eng/photos/"" target="_blank">link href_cetemp=" link" target="_blank">link




ah, stealth links..... 
 
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Herald12345    Need a better sonar.   1/4/2008 1:38:43 AM
Kilo 1.

Kilo 2.

Herald
 
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