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Thread: Ask An Expert- Battleships

  1. #1651
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    I take it that the inboard shafts would run at a different rpm then outboard since the thrust difference between a 4 and 5 blade prop is different. How would they gauge what the difference in rpm be?

  2. #1652
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    Quote Originally Posted by Ken_NJ View Post
    I take it that the inboard shafts would run at a different rpm then outboard since the thrust difference between a 4 and 5 blade prop is different. How would they gauge what the difference in rpm be?
    No. They all ran at the same RPM. Though the 5-bladed props (2 & 3) appeared to have more surface area of the blades, they were smaller in diameter than the 4 bladed props and turbulated the same amount of water. I've been aboard the high speed sea trials on both the New Jersey and Missouri. All shafts start off at about 100 rpm. After 5 or 10 minutes of our crew and engineers checking the vibration (if any) and change of temperature in the shaft bearings (if any) they would recomend an increase of 10 rpm. Then it was the ship's Captain to approve the recommendation. After all, we had experienced machinists and machinest mates dating back to WW II from NAVSEA, LBNSY & the old timers from the US Navy who rejoined just to run those behemoths again.

    We usually stopped at 200 RPM (212,000 hp) though our propulsion engineering super visor (Val Pena) was a bit ticked off as he said we could do at LEAST another 10 rpm if not more. Then we would hold that speed for 8 hours straight ahead (I think we passed Easter Island about then) and would then go into high speed turns at full rudders.

    Good thing I was never susceptible of motion sickness.

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  3. #1653
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    I've read in a couple places that the reason for the different screws was to hold down vibration. Having different numbers of blades on inboard and outboard shafts kept the vibrations from harmonizing. The SS United States, another powerful ship, is the same way. She also has four and five bladed screws.

  4. #1654
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    Quote Originally Posted by SharkPilot View Post
    I've read in a couple places that the reason for the different screws was to hold down vibration. Having different numbers of blades on inboard and outboard shafts kept the vibrations from harmonizing. The SS United States, another powerful ship, is the same way. She also has four and five bladed screws.
    So did Essex class Aircraft Carriers. True, that was a secondary reason for having different numbers of the blades on the "Wheels" as we sometimes called them. However, I don't know of any study done of whether that really reduced vibration or not. As far as I'm concerned, if you read chapter 27, page 216 of my book I don't think we have the instrumentation to differentiate between propeller vibration problems or the "Rooster Tail" those babies put up at 200 rpm.
    Last edited by RustyBattleship; 10 Dec 16, at 23:01.
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  5. #1655
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    Okay...I'm NOT trying to resurrect the old "should we reactive the Iowas" dead horse - BUT I have a question that is more of a fun thought experiment for the experts.

    Trump did express some interest in reactivating the Iowas (though it was just a passing comment in a speech). Say Trump decided he did want to return at least 2 of them to service, and he managed to strongarm Congress into going along with it...what would it actually take in terms of logistics to accomplish? Given that the Navy has now junked the entire supply chain for the Iowas, how would they even go about restarting it? Does the United States even have the capacity to forge new barrels if we wanted them? Has the material condition of the ships degraded to the point that it would be as unrealistic as reactivating the Texas?

    Again, NOT trying to stir the pot with the "should we" discussion...this is simply about the question of COULD we and what would that process realistically look like?

  6. #1656
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    I'm no expert, I've just read a lot but supposedly there are foundrys that could build some type of barrel but IIRC you would have to build a loose liner type like the Des Moines class. But with new technology for powder it would be awhile before they'd need barrels. Propulsion should be ok as I thought someone said all the spares are still squirreled away somewhere. Hardest thing would be to teach how to run the boilers but anything is possible with enough money.
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  7. #1657
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    If we were truly interested to bringing back the BB's and committed to doing it right and not just say, running 1 or 2 of them and scavenging the rest for parts, then it's totally possible.
    Money as usual is the limiting factor of "how far back" you bring them. Do you bring them back in their 80's config, with updated electronics? Or do you rethink their missile suite?

    As far as spares: With today's world where everyone and their uncle has a CNC machine in their garage, I don't see spares as being much of a problem. Need a valve of some sort? Make it.

    It's the big parts that would be problematic, like barrels...as mentioned. Could those still be made? I'm sure they could. To do such a task today, it might not take a foundry that's as big as a Battleship itself, like it used to. But as mentioned, the barrels have some life left still.

    Not trying to make like it's "no big deal" to reproduce some of these smaller parts....but it's not as big a deal as it might have been 30 years ago. Still, it'd be somewhat of a big undertaking if again, we truly decided that we were going to operate these ships again.

    Then you get into the "for how long"? Last I read about the Navy's plan for suitable fire support replacement ships, it was going to be near 2030 before they were designed and started joining the fleet. So IF the Iowas were going to be back, IMO you have to specify a service period. 10 years. 15 years. Whatever. Then back to the museum fleet for good. You do that first, then tool up your spares industry to support that time period. You don't just reactivate them with no end of service goal in mind.

  8. #1658
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    Quote Originally Posted by Pacfanweb View Post
    If we were truly interested to bringing back the BB's and committed to doing it right and not just say, running 1 or 2 of them and scavenging the rest for parts, then it's totally possible.
    Money as usual is the limiting factor of "how far back" you bring them. Do you bring them back in their 80's config, with updated electronics? Or do you rethink their missile suite?

    As far as spares: With today's world where everyone and their uncle has a CNC machine in their garage, I don't see spares as being much of a problem. Need a valve of some sort? Make it.

    It's the big parts that would be problematic, like barrels...as mentioned. Could those still be made? I'm sure they could. To do such a task today, it might not take a foundry that's as big as a Battleship itself, like it used to. But as mentioned, the barrels have some life left still.

    Not trying to make like it's "no big deal" to reproduce some of these smaller parts....but it's not as big a deal as it might have been 30 years ago. Still, it'd be somewhat of a big undertaking if again, we truly decided that we were going to operate these ships again.

    Then you get into the "for how long"? Last I read about the Navy's plan for suitable fire support replacement ships, it was going to be near 2030 before they were designed and started joining the fleet. So IF the Iowas were going to be back, IMO you have to specify a service period. 10 years. 15 years. Whatever. Then back to the museum fleet for good. You do that first, then tool up your spares industry to support that time period. You don't just reactivate them with no end of service goal in mind.
    You make a good point there and got me thinking about the whole "automation" proposal that people make. A couple years ago I'd think it would have been quite an accomplishment and quite expensive to automate the boilers, but today we have cars that can drive themselves...
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  9. #1659
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    Quote Originally Posted by Pacfanweb View Post
    If we were truly interested to bringing back the BB's and committed to doing it right and not just say, running 1 or 2 of them and scavenging the rest for parts, then it's totally possible.
    Money as usual is the limiting factor of "how far back" you bring them. Do you bring them back in their 80's config, with updated electronics? Or do you rethink their missile suite?

    As far as spares: With today's world where everyone and their uncle has a CNC machine in their garage, I don't see spares as being much of a problem. Need a valve of some sort? Make it.

    It's the big parts that would be problematic, like barrels...as mentioned. Could those still be made? I'm sure they could. To do such a task today, it might not take a foundry that's as big as a Battleship itself, like it used to. But as mentioned, the barrels have some life left still.

    Not trying to make like it's "no big deal" to reproduce some of these smaller parts....but it's not as big a deal as it might have been 30 years ago. Still, it'd be somewhat of a big undertaking if again, we truly decided that we were going to operate these ships again.

    Then you get into the "for how long"? Last I read about the Navy's plan for suitable fire support replacement ships, it was going to be near 2030 before they were designed and started joining the fleet. So IF the Iowas were going to be back, IMO you have to specify a service period. 10 years. 15 years. Whatever. Then back to the museum fleet for good. You do that first, then tool up your spares industry to support that time period. You don't just reactivate them with no end of service goal in mind.
    I posted some of my thoughts in the other thread (posts #551, 552, 553, 554, 556 & 557). To keep a long story short :

    1) Steam plant automation is feasible and has been implemented on a number of merchant vessels & naval auxiliaries. On a BB, you'd nevertheless have make sure you don't compromise on DC, which would limit the manpower savings that could be achieved through automation.

    2) As far as new 16"/50 guns are concerned, Lehigh Heavy Forge can probably provide the forgings. Machining & appropriate Heat Treatment(s) would be more problematic, so cannibalization is most likely the way to go.

    3) Without new projectiles, the 16"/50 guns are next to useless. You'd want such new projectiles to meet the USMC range requirements (i.e. at least 41 NM) and remain affordable enough to avoid the LRLAP fiasco. You'd also want them to be available yesterday, which excludes exotic R&D stuff (Ramjet, Scramjet and the likes) once promoted by the much regretted USNFSA. As a result, the best (only ?) option would be low-drag projectiles. Given the constraints imposed by the ammos handling system in terms of projectiles length, my feeling is that the best-suited projectile design would be something along the lines of HVP.

    4) New projectiles imply new propellant, which would also have to be designed and tested. You'd have to cope with potentially conflicting requirements, e.g. IM compliance (to avoid another USS Iowa disaster), high impetus (to achieve high MV) and low erosivity / flame temperature (to preserve barrel life). The US Navy is working on various formulations colloquially known as NILE (Navy Insensitive Low Erosion), but these are not yet ready for the show (except for the M1 replacement).

    5) You'd also have to deal with such things as fuze programming (because long-range projectiles are worthless without guidance) and (perhaps) charge ignition (again, to avoid another another USS Iowa disaster).

    The bottom line is that I wouldn't even bother trying to add a fancy missile suite and would rather put the priority on rejuvenating the 16"/50 guns which are the BBs raison d'Ítre.

    And finally, I would invite those involved in such an exciting but difficult challenge to reflect on the lessons learned during the 1980s : the technical side may not be the most problematic. It's the people side that more often than not ends up being a major stumbling block.

    Steam plant automation aside, I'd for instance inactivate Turret III as part of an overall effort to avoid draining excessive resources away from the rest of the fleet and limit the number of sailors to be trained on *exotic* skills. With On The Job Training being the name of the game, this is probably the only way to keep things somewhat manageable. As a side benefit, inactivating Turret III would create a much needed source for spare parts and facilitate aviation ops.

    Just my 2 cents...

  10. #1660
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    In regards to the barrels, A few years ago I was in a discussion about 8" howitzer tubes.

    The US no longer has the capability of making anything larger than a 155mm tube at Watervliet Arsenal. The US Naval Gun Factory, where the 16" guns were manufactured, is long gone.
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  11. #1661
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    Quote Originally Posted by Gun Grape View Post
    In regards to the barrels, A few years ago I was in a discussion about 8" howitzer tubes.

    The US no longer has the capability of making anything larger than a 155mm tube at Watervliet Arsenal. The US Naval Gun Factory, where the 16" guns were manufactured, is long gone.
    1) The existing 4-hammer radial forging machine (SX-55 by GFM of Austria) and heat treatment facility at Watervliet is capable of producing M201A1 cannons (8-inch bore with 39.5-cal long barrel), as they did until the second half of the 1980s. All the necessary tooling have been kept in storage and still exists today.

    To produce these guns, you'd nevertheless have to reset the complete assembly line, which would require a significant investment.

    2) Producing brand-new 16"/50 guns at Watervliet would be a radically different story. You'd have to invest in a new radial forging machine (probably SMX-1100/200 by SMS Meer of Germany) with suitable manipulators and invest in a brand new heat treatment facility capable of accepting tubes up to 800 inches in length (about 2.5 times the current limit), not to mention all the required tooling for machining.
    Last edited by SW4U; 31 Dec 16, at 02:18.

  12. #1662
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    A novice question to the experts;

    How much more effective were the Iowa's 16 inch 50 cal as compared to the North Carolina's and South Dakota class 16 inch 45 cal? Where there any studies on this topic and was there any thought about replacing the 16 inch 45 cal on the North Carolina and South Dakota classes?

  13. #1663
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    ^Don't know about any studies to replace the 45's with the 50's, but in general: The 50's had more muzzle velocity, therefore more side armor penetration and of course, more range. The 45's were actually better deck penetrators. Both were excellent weapons.

  14. #1664
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    Quote Originally Posted by Archdude View Post
    A novice question to the experts;

    How much more effective were the Iowa's 16 inch 50 cal as compared to the North Carolina's and South Dakota class 16 inch 45 cal? Where there any studies on this topic and was there any thought about replacing the 16 inch 45 cal on the North Carolina and South Dakota classes?
    Basically the 50 caliber guns had a bit more range. Also, at the start of their tours of duty, the projectiles were heavier. The Hi-Caps were 1900 lbs (though I have seen 1,950 lb rounds also in 1968) against the original 1,720 pounders used by the 45 caliber class ships. Plus the Armor Piercing rounds were 2,700 lbs compared to the earlier 2,100 pounders.

    However, the hoist mechanisms were basically identical in all three classes of ships. So it didn't take too long for the South Dakota and North Carolina ships to load their racks with the heavier projectiles. Range might suffer a bit, but what's 3 to 5 miles between friends?
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  15. #1665
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    Hello All,

    I'm new here just signed up..
    Here is a question, does anyone know what happened to the 5" turrets that were removed from the four Iowa class Battleships when they were reactivated? were any saved or repurposed? Perhaps they are sitting in a warehouse somewhere>
    Thanks

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