dave@questar.questar.mn.org (David Becker) (04/28/89)
From: dave@questar.questar.mn.org (David Becker) Bill Thacker writes: : : Details of Iowa's underwater protection are very vague, but it seems : likely that four torpedo bulkheads were provided, the outer two filled : with fuel oil or water. A triple bottom was also fitted. This system : was used on the South Dakotas which immediately proceded them, and : planned for the Montanas to follow. What did the navy have in mind for the Montana class? I suppose they only wanted carriers after WWII and built those instead of any more battleships. [mod.note: Precisely. The Montanas were a logical follow-on to the South Dakota class, being relatively slow (27-knot) battleships, as opposed to the high-speed Iowas. The were to mount a fourth 16"/50 turret astern, and use the new 5"/54 dual purpose secondary battery. Otherwise, they were bloody big (58000 tons design); too big to pass the Panama Canal, but the sacrifice was considered necessary to keep even with the next generation of battleships (which was expected to evolve internationally). Orders were placed for 5 ships: Montana (BB 67), Ohio, Maine, New Hampshire, and Louisiana, but work never started. - Bill ] : Tim McDaniel writes: : >- Armor is "expensive" in weight, leading to a deeper draft, thus less : >fuel efficiency and less maximum speed (any other costs?). : : This is essentially it. In WWII and before, the "big three" items : in warship design were armor, propulsion, and armament; a gain in one : could only be achieved to the detriment of the others, unless you : could increase displacement (which was limited by docking considerations : and, at the time, the Panama Canal). : How would fission reactor affect this tradeoff? How would a fission powered Iowa compare to the fossil ones? I believe a couple large carriers are fossil powered(JFK or America?) while most are fission(Nimitz, Enterprise). Did their designers throw out armor totally in favor of armament(aircraft). -- David Becker and another bug bites, and another bug bites another bug bites the dust db@kolonel.MN.ORG
henry@zoo.toronto.edu (Henry Spencer) (05/02/89)
From: henry@zoo.toronto.edu (Henry Spencer) >: This is essentially it. In WWII and before, the "big three" items >: in warship design were armor, propulsion, and armament; a gain in one >: could only be achieved to the detriment of the others... > >How would fission reactor affect this tradeoff? How would a fission >powered Iowa compare to the fossil ones? Not a lot of difference. The problem is not fuel storage, not to any great extent anyway -- fuel tanks can be used as ersatz armor on a battleship, so they aren't waste space -- but power output. Warship engines are enormous, especially on WW2-vintage ships which put a premium on speed. (The Iowas are not only the biggest non-carrier warships in the world, they are also among the fastest -- faster than many of their modern escorts.) This means they're heavy, which is where the tradeoff comes from. Nuclear propulsion doesn't help the weight much (might even hurt it), although it does wonders for high-speed endurance. >I believe a couple large carriers are fossil powered(JFK or America?) >while most are fission(Nimitz, Enterprise). Did their designers throw >out armor totally in favor of armament(aircraft). Carriers generally aren't armored to speak of, unless you count the armored flight deck (which is pretty well necessary for structural strength anyway) and the limited armor around the magazines. The main penalty the non-nuclear carriers suffer (apart from reduced endurance) is less aircraft-fuel capacity, since a hull of unchanged size had to put a fair bit of ship fuel *somewhere*.
bsmart@uunet.UU.NET (Bob Smart) (05/08/89)
From: vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET (Bob Smart) In article <6146@cbnews.ATT.COM>, henry@zoo.toronto.edu (Henry Spencer) writes: > > Not a lot of difference. The problem is not fuel storage, not to any > great extent anyway -- fuel tanks can be used as ersatz armor on a > battleship, so they aren't waste space -- but power output. Warship > engines are enormous, especially on WW2-vintage ships which put a > premium on speed. (The Iowas are not only the biggest non-carrier > warships in the world, they are also among the fastest -- faster than > many of their modern escorts.) This means they're heavy, which is > where the tradeoff comes from. Nuclear propulsion doesn't help the > weight much (might even hurt it), although it does wonders for high-speed > endurance. I remember reading that the Iowa can make 25-26 knots on 1/2 her power plant The other 1/2 is only required for the last 7-8 knots. this gives some idea about how expensive high speed is. There was some talk about removing 1/2 the plant and adding other capabilities if the Iowa would only be required to work with Amphibious ships (LHA,LPD,etc). In fact one problem with the MO was that it ran aground in Chesepeake bay in 1952 or 3 and after getting her off ( they used 750 lb depth charges to rock her off) She encountered very severe vibration above 25-27 knots and was limited to a max of 27 kt. I wonder if this was ever fixed? Some of this is documented in Breyer and some came from USNIP during the reactivation debate. > >I believe a couple large carriers are fossil powered(JFK or America?) > >while most are fission(Nimitz, Enterprise). Did their designers throw > >out armor totally in favor of armament(aircraft). > > Carriers generally aren't armored to speak of, unless you count the > armored flight deck (which is pretty well necessary for structural > strength anyway) and the limited armor around the magazines. The main > penalty the non-nuclear carriers suffer (apart from reduced endurance) > is less aircraft-fuel capacity, since a hull of unchanged size had to put > a fair bit of ship fuel *somewhere*. There are 8 non CV/CVAs of the Forrestal & Kitty Hawk classes. All of the carriers seem to have suffered from gradual weight increase over the 30 years since Forrestal was commisioned. There was a lot of discussion about Nuclear fuel for the Kennedy and I think in Friedmans AIRCRAFT CARRIERS A Design History there is a good discussion of the factors. Bob Smart (bsmart@verdix.com)
welty@Lewis.crd.ge.com (Richard P. Welty) (06/02/89)
From: Richard P. Welty <welty@Lewis.crd.ge.com> Bob Smart (vrdxhq!vrdxhq.verdix.com!bsmart@uunet.UU.NET writes: > In fact one problem with the >MO was that it ran aground in Chesepeake bay in 1952 or 3 and after getting >her off ( they used 750 lb depth charges to rock her off) She encountered >very severe vibration above 25-27 knots and was limited to a max of 27 kt. >I wonder if this was ever fixed? Some of this is documented in Breyer and >some came from USNIP during the reactivation debate. Summarized from _The Iowa Class Battleships_, by Malcom Muir, Blanchford Press, 1987, Dorset, England: The grounding took place on 17 January, 1950. The new captain of Missouri, William Brown, ignored the packet of navigational information he was given, and misinterpreted a set of spar buoys marking a shallow fishing channel for the buoys marking the acoustical range he had been ordered to run down on his way out to sea. Captain Brown ignored the frantic warnings of his Exec and Navigator, and ran Missouri aground on Thimble Shoals at 12 1/2 knots. all removable items and fluids were taken off, including about 8,000 tons of fuel oil. Various efforts, including dredging, high pressure air lances, and running destroyers up and down the channel at 27 knots (to stir up the water) were tried and failed (it is not clear in Muir to what extent explosives were used, but i have serious doubts about the assertion that 750 lb depth charges were used, as the only explosive damage was to the guages that measured the fuel level in the tanks.) On 1 February, Missouri floated off at high tide on her own. Missouri was certainly damaged enough to require a trip to dry dock, but many of the assertions made about her state (including those in USNIP) are categorically false. In fact, she received less damage than Iowa did in the Casco Bay incident of 16 July 1943. The following listing of damage is derived from the ship's report on the incident, dated 14 February, 1950: Grounding Damage: Strake G starboard damaged by scoring, indentation, and rupture between frames 99 and 114, including three holes: two 8-inch and one 20-inch ruptures (this was caused by an old anchor which had been buried in the mud where Missouri ran aground) Several fuel oil tank heating coils were damaged, necessitating replacement or repair A 4-inch indentation occured in the starboard keel at frame 104 NMC heads scratched, but operation not impaired [i'm not sure what the NMC heads are, actually -- rpw] paint on bottom somewhat scoured two TBM motor generator armatures burned out sand and debris plugged all injection and overboard discharges except for the after emergency generator set. Casings, rings, and bearings scored on four turbo-generator circulator pumps Packing journals, casings, and rings were scored on one bilge pump, one main drain pump, four cooling water pumps, and four fire and bilge pumps. Salvage damage: edges of propellers 2, 3, and 4 received minor damage from chain and cable passing. Salvage cables dished in the outboard sides of the rope guards of shafts 1 and 4. Explosive charges damaged 20 Tank-o-meter guages Minor damage to stanchions, scupper lips, etc., caused by salvage cables. the ship's damage report concludes: ``all damage incurred in the grounding and salvage operations has been repaired by Norfolk Naval Shipyard and by the ship's force of the vessel. On 8 February 1950, a fully successful post repair trial was conducted at sea'' One of the ships officers wrote in USNIP (June 1980) ``As auxiliary, repair, and boiler division officer of the watch, i can testify that the BB-63 made 32 knots and better on every occasion required in support of carrier launch/recovery operations during the Korean Conflict.'' (this officer served on Missouri from December 1948 to early 1952.) richard -- richard welty welty@lewis.crd.ge.com welty@algol.crd.ge.com 518-387-6346, GE R&D, K1-5C39, Niskayuna, New York ``Join the Navy, See Thimble Shoals''