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  • 85 gt kid
    replied
    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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  • ArmorPiercing88
    replied
    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?

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  • RustyBattleship
    replied
    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; 11 Dec 16,, 00:01.

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  • SharkPilot
    replied
    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.

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  • RustyBattleship
    replied
    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.

    THAT WAS FUN.

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  • Ken_NJ
    replied
    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?

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  • RustyBattleship
    replied
    Originally posted by bigjimslade View Post
    This has kept me up for nights: Does anyone know why the Iowa's have 2 different propellers? (Ok, it's really 4 but for our purposes it's 2).
    The propeller shafts are four different lengths and each one has a slight angle downwards as the go aft -- one shaft per engine room. Shafts 1 & 4 (the outboard shafts) are a bit shorter and can come out through the diaper plates in the hull higher above the keel than shafts 2 & 3 which go through the twin keels and come out lower.

    So shafts 1 & 4 cab take the larger diameter 4-bladed propeller where as then inboard shafts need the smaller diameter 5-bladed propeller so they don't dig into the harbor bottom.

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  • SW4U
    replied
    Originally posted by bigjimslade View Post
    This is the version on the Iowas (Mod 2). There are several variants used on other ships.
    [ATTACH]42791[/ATTACH]
    OP-1112 of course !!!

    Thanks a lot for your help. :-)
    Last edited by SW4U; 07 Dec 16,, 21:54.

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  • bigjimslade
    replied
    This is the version on the Iowas (Mod 2). There are several variants used on other ships.
    Click image for larger version

Name:	cat-0252 IOWA.jpg
Views:	2
Size:	148.4 KB
ID:	1469963

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  • SW4U
    replied
    Originally posted by bigjimslade View Post
    This has kept me up for nights: Does anyone know why the Iowa's have 2 different propellers? (Ok, it's really 4 but for our purposes it's 2).
    I suppose you're referring to the differences in diameter and number of blades between the inboard propellers (17' diameter, five-bladed) and the outboard propellers (18' 3" diameter, four-bladed) ?

    In case I'm not misinterpreting your question, these differences are meant to avoid (as much as possible) the severe longitudinal vibrations experienced on the North Carolina-class BBs (and the Atlanta-class CLs).

    PS 1 : I'm sure I have a sketch of the Phalanx CIWS together with various dimensions somewhere on a disc drive, but I haven't been able to locate it so far.

    PS 2 : Would you happen to have a sketch of the 5"/38 Mark-28 twin mount showing the same details as what's below for the 5"/38 Mark-30 single mount ?

    Last edited by SW4U; 07 Dec 16,, 13:55.

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  • bigjimslade
    replied
    This has kept me up for nights: Does anyone know why the Iowa's have 2 different propellers? (Ok, it's really 4 but for our purposes it's 2).

    Leave a comment:


  • RustyBattleship
    replied
    Originally posted by bigjimslade View Post
    I am amazed at how you guys (and the original builders) did this at all in the days before widespread 3D CAD programs.
    Like you, I am amazed that the design of the Iowa Class Battleships were done with just a slide rule and perhaps an electro-mechanical Marchant calculator that spun a dozen or so numbered wheels around faster than a Vulcan Phalanx Gatling gun.

    But we are professional draftsmen, we think in 3 dimensions already, most of us started in the shops (I was a ship fitter aka steel worker), and having copies of Rourke's Formulas for Stress and Strain as well as a couple of other manuals listing sizes and grades of metal (steel or aluminum) beams also helps.

    Besides, the US Navy is VERY safety oriented and duplicates lots of systems within their ships so if the port side fire and flushing system gets knocked out the starboard system will take over.

    I recall a young engineer (just out of college) reporting for work and a few weeks later he was really bitching and complaining of how we over design the mast of a Destroyer he was assigned to work on. I merely explained that the mast isn't going to set out in the middle of Death Valley where air barely moves. This mast must stay totally intact when the ship does a 30 degree roll with a 15 degree pitch in a 100 knot wind, punch its way through a Typhoon, slug it out with some shore batteries and go back through that same Typhoon again.

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  • bigjimslade
    replied
    ABL Dimensions

    I'm still looking for ABL dimensions. I have found these metric dimensions

    http://www.shipbucket.com/forums/vie....php?f=5&t=319

    but I don't know what is being measured. For example, going vertically, the ABLs on the IOWA have 3 tiers. I would guess at least one of these tiers is not included in the height.

    If anyone has some information here, it would be appreciaed.

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  • bigjimslade
    replied
    I am amazed at how you guys (and the original builders) did this at all in the days before widespread 3D CAD programs.

    Leave a comment:


  • RustyBattleship
    replied
    Slight correction to my above answer. The booklet was drawn up based upon the first issue of the plans. Then Earl Naval Weapons Center in Colt's Neck, N.J. had to ADD on extra width and length to those platforms. That required a revision to the original plans. Apparently you were not given the REVISED drawings. Then the booklet was revised to fit the larger platforms.

    Actually I think the additional deck area was a SEPARATE drawing done between TWO Design Sections (250.11 Fittings & 250.i2 Structural). But that's stretching my memory back an awful long ways back.

    Believe me, it was a confusing time as I was the Structural Project Leader for all structural modifications and placement of extra armor. Then later after being promoted (temporarily) as Configuration Manager for all four ships of the class and observed a test of loading a Tomahawk using a rolling A-frame, even I have to scratch my head as to what ship had what on it.

    Hmmm. Maybe that's why my hair is so thin now.
    Last edited by RustyBattleship; 05 Nov 16,, 22:06.

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