Parthian Ships 1928 +

[Kaiser Kirk]

So this is a 1932.0 concept.

My posting in the Byzantine thread that I was resisting replacing the Vakharz class because lighter engines meant to hit the 50% weight, you need faster engines, which means more freeboard, which means a heavier/longer hull, which means more engine wt to hit 50%.

It's true. I rather like the Vakharz class, esp with the 1930 BR for AA.
The class does not excel in any way, but is capable, multirole and relatively cheap at 1140 tons.

However, if I want a modern 'low cost' destroyer, I should probably build one from scratch.
This is very similar to the Vakharz class, but 1270 tons. So only 130 more.
Same speed, range, Better main battery, good AA, good ASW.

It has a DP main battery with the new 115mm guns. Rounds per gun have been increased to provide stowage for AA rounds.

For light rapid fire weapons I've been going in ~7.5mm steps, so 7.5/15/23 (22.5)/30 / 37 (37.5)
It has a unified AA battery of 30mm. You will see the Parthians go back and forth on AA suites.
Large bore (115/120/130) for HA Bombers, and barrage fire vs torpedo bombers at range.
37mm preferred for high rate of fire and effect with good range vs. torpedo bombers.
23mm or 15mm for close in engagements. With the current torpedo release ranges and divebombings, both should be effective.
The 30mm is a bit of both and I expect the Parthians made the same evaluations that led the USN to the 28mm/1.1", which was optimized for Biplanes.

Typically I have been using 37&23 for ships that can afford split batteries with overlapping coverage,  and 30mm for vessels that can only afford fewer guns for 360deg coverage.

In this case, ironically a 37 & 23mm battery weights ~0.1 tons less, so it's right on that margin, but having a unified ammunition type and simplified fire control is attractive also.

USN DDs seem to have been extremely weight tight, frequently removing guns and torpedoes, or cranes and boats, to fit other gear.  So I did not leave as much misc weight reserve as I usually do,
and I expect I'll have to pull off torpedoes in the future to make any real changes.

Robah 'Fox' , Parthian Empire Destroyer laid down 1932

Displacement:
    1,270 t light; 1,362 t standard; 1,522 t normal; 1,649 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
    (316.88 ft / 311.68 ft) x 31.17 ft x (10.17 / 10.86 ft)
    (96.59 m / 95.00 m) x 9.50 m  x (3.10 / 3.31 m)

Armament:
      4 - 4.53" / 115 mm 47.0 cal guns - 55.12lbs / 25.00kg shells, 320 per gun
      Dual purpose guns in deck mounts, 1931 Model
      4 x Single mounts on centreline ends, evenly spread
        2 raised mounts - superfiring
      16 - 1.18" / 30.0 mm 80.0 cal guns - 0.95lbs / 0.43kg shells, 2,700 per gun
      Anti-air guns in deck mounts, 1932 Model
      2 x 2 row quad mounts on sides, forward deck aft
        2 raised mounts
      4 x 2-gun mounts on side ends, evenly spread
        4 raised mounts
      Weight of broadside 236 lbs / 107 kg

Armour:
  - Gun armour:    Face (max)    Other gunhouse (avg)    Barbette/hoist (max)
    Main:    0.24" / 6 mm          -                  -
    2nd:    0.24" / 6 mm          -                  -

Machinery:
    Oil fired boilers, steam turbines,
    Geared drive, 1 shaft, 32,250 shp / 24,058 Kw = 31.00 kts
    Range 4,430nm at 14.00 kts
    Bunker at max displacement = 287 tons

Complement:
    121 - 158

Cost:
    £0.739 million / $2.958 million

Distribution of weights at normal displacement:
    Armament: 47 tons, 3.1 %
      - Guns: 47 tons, 3.1 %
    Armour: 4 tons, 0.2 %
      - Armament: 4 tons, 0.2 %
    Machinery: 760 tons, 50.0 %
    Hull, fittings & equipment: 377 tons, 24.8 %
    Fuel, ammunition & stores: 252 tons, 16.5 %
    Miscellaneous weights: 82 tons, 5.4 %
      - Hull below water: 25 tons
      - Hull void weights: 5 tons
      - Hull above water: 1 tons
      - On freeboard deck: 40 tons
      - Above deck: 10 tons

Overall survivability and seakeeping ability:
    Survivability (Non-critical penetrating hits needed to sink ship):
      442 lbs / 200 Kg = 9.5 x 4.5 " / 115 mm shells or 0.3 torpedoes
    Stability (Unstable if below 1.00): 1.19
    Metacentric height 1.2 ft / 0.4 m
    Roll period: 11.9 seconds
    Steadiness    - As gun platform (Average = 50 %): 70 %
            - Recoil effect (Restricted arc if above 1.00): 0.39
    Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
    Hull has a flush deck,
      a ram bow and a cruiser stern
    Block coefficient (normal/deep): 0.539 / 0.547
    Length to Beam Ratio: 10.00 : 1
    'Natural speed' for length: 17.65 kts
    Power going to wave formation at top speed: 70 %
    Trim (Max stability = 0, Max steadiness = 100): 70
    Bow angle (Positive = bow angles forward): 15.00 degrees
    Stern overhang: 0.00 ft / 0.00 m
    Freeboard (% = length of deck as a percentage of waterline length):
                Fore end,    Aft end
      - Forecastle:    20.00 %,  19.42 ft / 5.92 m,  16.96 ft / 5.17 m
      - Forward deck:    30.00 %,  16.96 ft / 5.17 m,  14.50 ft / 4.42 m
      - Aft deck:    35.00 %,  14.50 ft / 4.42 m,  12.30 ft / 3.75 m
      - Quarter deck:    15.00 %,  12.30 ft / 3.75 m,  12.30 ft / 3.75 m
      - Average freeboard:        14.84 ft / 4.52 m

Ship space, strength and comments:
    Space    - Hull below water (magazines/engines, low = better): 174.1 %
        - Above water (accommodation/working, high = better): 148.0 %
    Waterplane Area: 6,495 Square feet or 603 Square metres
    Displacement factor (Displacement / loading): 72 %
    Structure weight / hull surface area: 30 lbs/sq ft or 148 Kg/sq metre
    Hull strength (Relative):
        - Cross-sectional: 0.50
        - Longitudinal: 2.29
        - Overall: 0.58
    Cramped machinery, storage, compartmentation space
    Excellent accommodation and workspace room
    Ship has slow, easy roll, a good, steady gun platform

With the new "Sher" class reaching 2000 tons,
a smaller vessel capable of all aspects of the destroyer role is desired

The 115mm is a good destroyer gun with decent offensive punch.

The 37mm guns are mounted 'en echelon' amid ships, on a lozenge shaped elevated platform.

The TDC is in the column holding up the platform and the torpedoes
are immediately fore and aft of that.

Basic Sonar + Enhanced Hydrophones for an ASW role

                    (1)                                      DC
A(B)          TT        TT      'Y'  (X) Y
                          (2)                                DC

Range @ Speeds :

Trial Speed is 31.74 knts
Bonus of 0.74 kts

90% power is 29025  or  30.31
75% power is 24187  or  29
50% power is 16125  or  26.36

The 4430 range with geared turbines is 5,094nm @ 14 knots
This makes the effective bunker 287 *1.15 = 330t


330 effective fuel tons
The Parthians want a reserve of 2200nm @ 10knts,
which would allow their vessels to "get to nearest base" virtually anywhere in the world.

2200nm at 10knots : 76t to "get home"

330-76 = 254

So effectively 254t are available for offensive operations,
more if "base" is close.

254t fuel with geared turbines  is good for :
415nm @ 30.31knts = 13.7 hrs / 0.5 days
686nm @ 26 knots = 26.3  hrs / 1 day
1140nm @ 22 knots = 51.8 hrs / 2 days
2030nm @ 18 knots = 112.8 hrs / 4.7 days
2780nm @ 16knots = 173.7 hrs / 7  days
All in addition to 2200nm @ 10knts

Allowing the destroyer to freely operate at higher speeds for
extended periods and safely return to base.

Miscellaneous Weight

Reserve : 5t

AD
4.7t  FC 1930
4.7t  Night Fighting
0t    Short Range Radio
1t    Colored Beacons, flares, rockets for MTB leader role

OD
2t    Lt. Paravanes
2t    2x 'Y' Thrower
6t  18x 280kg DC

30t  2TT5  21" 3t torpedo

HAW
1.3t - CO2 compressor AC

HBW
15t - Enhanced Hydophone package
10t - Basic Sonar

[TacCovert4]

I generally agree.
I was curious as to other's opinions.

If I could field an 8x215  ship in 11,000tons, I likely would do it. However that would be 33% more firepower as well

Against the 8000t Parthian Royal Nissean 12x180 series, or the Byzantine 12x191mm equivalent, there is a chance it could stay at range and get enough hits through armor to offset the mission kill hits of the faster 180/191. Say 30rpm vs. 60rpm is substantial. Add in the greater spotting difficulties with 6 guns makes more difference at longer ranges, so the 'to hit' rate would suffer more.

However, it is hard to actually keep range in a 'sweet spot' favoring you and not them, and if the range closed to the point the 180/191s could punch through, all advantages are lost.

For that matter, to take advantage of that range, you need visibility to be very good to start, which
it should not always be. That consideration actually is discussed in the discussion of USS Brooklyn's design evolution of 6" vs 8" utility.

So far, battles have happened to occur in good weather, a side effect of fighting around landing operations. There were some near misses due to night- as it's harder to find each other in the first place. Pity, the open ocean fight between the Romans and Aztecs would have been interesting.

The issue with rate of fire vs effective range is why I've stubbornly stayed with the 180mm.  Enough firepower for the job, fast enough.  My next gun was 280, now 240, as I think going bigger needs to get enough punch to be worth the weight.  Case in point, in the pacific it was the US 6in cruisers which were particularly effective in cruiser fighting.

[Jefgte]

The issue with rate of fire vs effective range is why I've stubbornly stayed with the 180mm.  Enough firepower for the job, fast enough.  My next gun was 280, now 240, as I think going bigger needs to get enough punch to be worth the weight.  Case in point, in the pacific it was the US 6in cruisers which were particularly effective in cruiser fighting.

I have the same hesitation between 6M2x191 - 8 000t and 3T3x234 - 12 340t.
The fire volume for 12x191 really appeals to me and it is less expensive.

[Kaiser Kirk]

The Pouseki class is my " 6 inch" cruiser analogue, using the heavyweight 6.5" shells.
That was the key to the USN classes, the new 6" shell was heavier with a high MV and so much better penetration, and when combined with the new guns and mounts, faster firing.

The slow turning & firing 8" mounts of the early USN Heavy Cruisers also proved limiting. My Royal Nisseans with the 180s have lighter mounts with only 2 guns, not 3, so hopefully do not experience the same problem.  I did develop 3 and 4 gun mountings, but figured testing found they did not meet specs.

In my Xiyon class the heavyweight 8.5" shell is, like the preceeding 255, expected to penetrate cruiser armor schemes at pretty much any range. The 'if I can see a cruiser, I can kill it' is the goal for the AC level ships, and wasn't really doable on a smaller gun until I had the 1925 tech.

[Kaiser Kirk]

Something of a trivial bit:
I've posted the Sher (Lion) and the Robah (Fox) Classes previously.
As a continuation of the Wolf class, a canid seemed appropriate for the Robah.
But foxes are not really pack hunters or big cats, might be a good name for a small/fast coastal destroyer. Torag (Jackle) was considered, villagers use them as guard dogs in what is Parthia.

Having done more digging,
I think I will rename the Robah to  sīāhgūš, or 'Siahgus' class, meaning Caracal. A long-legged Lynx type cat. 

Both Cheetahs (Yoz) and Caracals (Saihgus) were trained for hunting.
The Cheetahs were larger and could hunt greater games, and I'm reserving that
name for a fast offensive destroyer, but a Caracal hunted smaller game. I think that's a very apt name for a smaller destroyer hunting submarines and aircraft.

Another option would be to call it the Lynx, which I wanted, but
could be Vasag, but seems like it as Asaq or pelang-e mul 'Leopards bastard'.

Anyhow, Saihgus seems an appropriate choice.