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| Late 70s-80s Frigate design http://67.205.157.234/forums/viewtopic.php?f=15&t=7019 |
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| Author: | acelanceloet [ June 11th, 2016, 10:52 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
IIRC the SPS-39 is only 200 kg lighter then the SPS-48, so no. if I do an quick comparision with the other guided missile ships of about the same size, you have a lot of topweight indeed. |
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| Author: | Obsydian Shade [ June 11th, 2016, 11:00 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
Well, it's either live with topweight, or lose capability. As long as it isn't dangerous topweight, I can likely live with it. Otherwise, I can attempt to give a little more hull draft. |
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| Author: | erik_t [ June 12th, 2016, 12:06 am ] |
| Post subject: | Re: Late 70s-80s Frigate design |
SPS-52 would be more plausible for a FFG, yes. Although I think SPS-49 is probably the correct choice. |
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| Author: | r3mu511 [ June 12th, 2016, 4:07 am ] |
| Post subject: | Re: Late 70s-80s Frigate design |
fwiw, acc. to friedman's book on naval radar, the original cut-cylinder sps-39 antenna weighed around 1363 kg, while the sps-48 (non-E version) planar array antenna weighed around 2045 kg... so around 682 kg weight diff... sps-48E weighed even more, at around 2583 kg... sps-52 (as well as the sps-39 w/ the planar array spa-72 antenna) weighed around 1454 kg, per friedman's world naval weapons book... |
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| Author: | citizen lambda [ June 12th, 2016, 8:02 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
To shave off some top weight, how about re-shuffling the directors until you can put whichever air search radar on a platform at the front edge of the mack? It would end up one deck lower and closer to the center of mass. I mentioned above how you can rearrange the Fast-40 and NSSM over the hangar to move at least one director that way, maybe you can also shuffle some directors between the two masts. Or, more simply, swap the air search radar and the egg over the bridge... Just spitballing here about (again) the amount of director channels: - I mentioned before siting two STIRs side by side over the masts. That gives you two channels for the SM1, and possibly backup FC for the 76mm (depending on the FCS behind the STIRs) - These two STIRs would give double coverage on a very large front arc, being blocked only by the masts, so maybe +/- 30° from the stern - If they are configured to illuminate for the NSSM as well, they cover about 80% of the firing arc of the Mk.29 - The remaining stern 60° are covered by the stern egg as backup, which ends up handling all SHORAD weapons over the stern - As a second backup, the bridge egg can also illuminate for NSSMs fired to the sides - The second STIR has been moved from the mack to the bridge (lower), thus freeing up space to move other, heavier radars from the foremast to the stack - You keep your 4 AA FC channels, including 2 dedicated to the SM1 except in emergencies Your thoughts? |
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| Author: | Obsydian Shade [ June 13th, 2016, 2:12 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
I'm probably going to go with the non-mack version, due to Ace's comments about the powerplant and shaft arrangement. It looks like the easiest thing to do is going to be to replace the SPS-48 with the SPS-49. Since the frigates are going to be working with older DDs, I'll put the SPS-48 on the DDs, and arrange for some datalinking so that information can be shared. There will be something like the Forest Sherman Class of DD, still around in significant numbers, having been built in the 1960s, so I'll upgrade those with either SPS-48 or late (planar) version SPS-39. Otherwise, regards the remaining topweight issues, I'll likely just settle for extra ballasting to compensate. |
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| Author: | r3mu511 [ June 13th, 2016, 3:56 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
^acc. to friedman the sps-49 weighs in at around 1438 kg, w/c is pretty close to the sps-52 weight of 1454 kg... so why not just use the -52 so you get the 3d capability... w/ the 3d -52 set, the rudimentary 4-elevation band capab of the CAS search antenna is not needed anymore, and since you appear to have a surface search antenna above the main air search antenna (w/c would then make the CAS surface seach capab redundant), then why not switch out the two CAS for smaller STIRs (stir-12 or equiv perhaps)... might let you save some topweight as well... so you end up w/ sps-52 3d air search, stir-24 and stir-12 fore, and another set of stir-24 and -12 aft... so you still get your 2x SM-1 channels and 2x NSSM channels... and when not used for NSSM, the stir-12's can serve as fc for the guns (plus the surface search antenna on the foremast can also serve as a TWS gun fc for asuw work)... |
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| Author: | Obsydian Shade [ June 13th, 2016, 4:53 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
That's a very tempting arrangement, though less capable than the CAS, which even the early one will offer 2 surface engagement channels for the gun, (granted I don't require that much) 1 air engagement channel, for the gun, and 1 air engagement channel for missiles, either NSSM or SM-1. The later version would actually offer an additional missile channel, theoretically allowing me to have as many as six missiles in the air at once, without forcing directors to choose between gun or missile direction; there are situations where this might determine the survival of the vessel. I do take your point about SPS-52, and it sounds like the way to go. |
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| Author: | r3mu511 [ June 13th, 2016, 5:21 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
^hmm, I don't know of any model in the wm-20 series or any mod in the mk-92 series w/c will offer 3 missile channels w/ the CAS+STIR combo... afaik it's always been 1 channel via the CAS tracker w/ cwi injection, and 1 channel via the STIR, so a max of 2 missile channels... --- there is an extension to mk92 mod12 w/c will allow use of the sm-2 NTU x-band midcourse uplink capability so that there can be missiles in midcourse aside from those in terminal sarh homing... but any uplink is done via the tracker/illuminator itself so if ever a mcg uplink is to be performed (ie. due to a target moving out of the pre-launch seeker activation point homing basket) the tracker must point to the missile and perform the uplink... thales did this for the RAN perry class... tho I haven't read any disclosure of how many sm-2 can actually be in flight at the same time since it's not really 2 channels to 2 missiles assignment anymore, it's more like 2 channels time-shared b/w missiles in terminal and missiles in midcourse... |
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| Author: | Obsydian Shade [ June 13th, 2016, 6:46 pm ] |
| Post subject: | Re: Late 70s-80s Frigate design |
I was presuming the two Mk 92 mod 2 would offer two channels, and the pair of STIR-240s would offer one each, for 6. though I'm a bit unclear on some of the specifics. The problem appears to be, as you've pointed out, is that each CAS only contains 1 illuminator, even if two channels are offered. |
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