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Obsydian Shade
Post subject: Re: Late 70s-80s Frigate designPosted: June 15th, 2016, 7:00 pm
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citizen lambda wrote:
Obsydian Shade wrote:
I just had a thought...

Maybe instead of NSSM, Naval Crotale? That seems pretty self contained, and shouldn't break the bank, so to speak. Question is, is the original version of the missile effective enough to justify the weight?
Might be worth the change if it turns out cheaper and lighter than the NSSM. This would correct the very slight range gap between SM1 and ESSM by replacing the altter with a shorter-ranged self-defense SAM. If you stick to a 70s tech level, your Standard-MR will be either RIM-66B/E with 47km range. The early RIM-7H for NSSM has a given range of around 20km, which gives a lot of overlap.
Again, if the NSSM and Crotale are equivalent in cost and weight, go for the higher capability, since your ship is on the gold-plated side by design.
If you go for Crotale, don't forget you'll need one Castor-II designator, which appears to double as a gun director.
I thought Crotale had an on-mount designator.

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citizen lambda
Post subject: Re: Late 70s-80s Frigate designPosted: June 17th, 2016, 4:21 pm
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Obsydian Shade wrote:
I thought Crotale had an on-mount designator.
Looks like you're right, since I have found older ships carrying the Crotale without dedicated designators. I has assumed that the on-mount antenna was only for the CLOS guidance and that an external radar was needed for target acquisition and tracking, since this is what the Castor appears to do for both Crotale and guns on most ships. In that case, the question remains of the fire control for your aft 40mm.
Also there appears to be a modular Crotale version for lighter ships (down to 200t) with an external command antenna, which would double as gun fire control. That version would also make sense as a bolt-on addition on an existing larger ship. I don't think it has ever been built but it was on catalog in the late 80s.
r3mu511 wrote:
^in friedman's "world naval weapon systems" 1997 ed., he gives rim-7h range as 12 kyd or ~11 km...
On the other hand, Flight International gives 18km consistently throughout the 80s... Guess it depends on target parameters, as it always does.
Sources vary on the Crotale as well, with given range going down to 8.5km. The end-game is stil that the RIM-7 has longer range, even if it is only 25%.

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r3mu511
Post subject: Re: Late 70s-80s Frigate designPosted: June 17th, 2016, 4:37 pm
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^is that for the -7H version ?

-7H production began in 1973 (data from designation-systems.net), so if flight international is giving performance figures for the 80s, that might be a later mark perhaps ?


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citizen lambda
Post subject: Re: Late 70s-80s Frigate designPosted: June 17th, 2016, 4:52 pm
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r3mu511 wrote:
^is that for the -7H version ?

-7H production began in 1973 (data from designation-systems.net), so if flight international is giving performance figures for the 80s, that might be a later mark perhaps ?
I looked for the figure for the -7H specifically, and got that 18k figure in their World Missile Directories from 1980, 1985 and 1988.
Now you got me looking in earlier versions, and it turns out the 1974 edition gives 13+ km. That is still consistent with the 18km figure, though I must admit that the 80s editions do not give figures for later variants such as the -7M or -7P.

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r3mu511
Post subject: Re: Late 70s-80s Frigate designPosted: June 17th, 2016, 5:02 pm
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^that 13 km value seems close enough to friedman's 11 km value...

fwiw, for -7M, friedman gives ~26 km...


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Obsydian Shade
Post subject: Re: Late 70s-80s Frigate designPosted: July 2nd, 2016, 9:49 am
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citizen lambda wrote:
Obsydian Shade wrote:
I thought Crotale had an on-mount designator.
Looks like you're right, since I have found older ships carrying the Crotale without dedicated designators. I has assumed that the on-mount antenna was only for the CLOS guidance and that an external radar was needed for target acquisition and tracking, since this is what the Castor appears to do for both Crotale and guns on most ships. In that case, the question remains of the fire control for your aft 40mm.
Also there appears to be a modular Crotale version for lighter ships (down to 200t) with an external command antenna, which would double as gun fire control. That version would also make sense as a bolt-on addition on an existing larger ship. I don't think it has ever been built but it was on catalog in the late 80s.
r3mu511 wrote:
^in friedman's "world naval weapon systems" 1997 ed., he gives rim-7h range as 12 kyd or ~11 km...
On the other hand, Flight International gives 18km consistently throughout the 80s... Guess it depends on target parameters, as it always does.
Sources vary on the Crotale as well, with given range going down to 8.5km. The end-game is stil that the RIM-7 has longer range, even if it is only 25%.
[ img ]

I lost some of my earlier work and had to go back and reconstitute the drawing from earlier versions. I've tried to increase the displacement just a little bit to hopefully make it work better, though my original attempt at stretching messed up the aesthetics too much. I disliked the original Crotale launcher, which hasn't been updated in like...forever, so I did some modifications to it, and adding some capability as well, the upgrades described above. I did read there is something like an 18 round magazine underneath it. Does anyone have the deck penetetration on that? 40mm director has been added back. The 76mm might just be a placeholder--am debating a TAK-120, but need to get the missiles figured out before worrying too much about the gun, though the TAK seems to have a rather small footprint for its caliber.

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r3mu511
Post subject: Re: Late 70s-80s Frigate designPosted: July 2nd, 2016, 12:58 pm
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^doesn't the 40mm mask the crotale's firing arc towards the rear horizon? crotale's a CLOS system so it needs to point (and shoot) directly towards it's target, so it seems the 40mm would mask a low flying target in the rear arc... maybe put the croatale on a small platform so it's not masked by the 40mm ?


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Obsydian Shade
Post subject: Re: Late 70s-80s Frigate designPosted: July 2nd, 2016, 1:05 pm
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I did briefly consider that, but dismissed it on the grounds of the probable rarity in which the missiles would need to fire at that low of an angle, directly astern, though the pedestal mightn't be a bad idea just regards the magazine.

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We can't stop here--this is Bat country!

If it's close enough to cast a shadow, I think the flying house wins initiative.

Bronies are like the Forsworn. Everyone agrees that they are a problem but nobody wants to expend the energy rooting them out.

"That is a very graphic analogy which aids understanding wonderfully while being, strictly speaking, wrong in every possible way."


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citizen lambda
Post subject: Re: Late 70s-80s Frigate designPosted: July 2nd, 2016, 5:18 pm
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There is no direct mechanical reload for the Crotale, but some assisted hoist system for manual reload (30 minutes, no less...), where the missiles are stowed horizontally.
French sources are not that expensive on the topic, but this is what came up in discussions about the Lafayette frigate class:
- Missiles are stowed below-deck (hangar roof in this case) and reloaded to the launcher via trapdoors on the roof
- This view of the Lafayette shows the missile insertion portholes for dockside replenishment of the magazine in the side of the superstructure (You'll have to zoom a bit). This gives you an idea of the height of the magazine in this configuration.
- Note that the launcher points to 3 o'clock for reloading. The layout of other classes equipped with Crotale shows that other configurations are possible, with the magazine e.g. forward of the launcher on the F70 frigates.
- The same source gives the overall height to ~2.75-3m, with a gangway below, which constrains the over height of the superstructure
- Chinese ships apparently use a more direct mechanical loader for their HHQ-7 version, but since the launch unit is different from the French original, the loader could be a local design too.

In the end, the length/width of the system looks more important than the height, and might force the position of your launcher on the hangar roof.
Edit: found a top view where the trapdoor for the loader is clearly visible (stbd from the launcher), which shows the space taken:
[ img ]

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