WesWorld

The Marinha Imperial has issued a design study for a Light Cruiser of Class A configuration to be used for anti-aircraft duties, as well as escort ship suppression. No interested party shall be turned away and and there are no submission limits.

Requirements for the design are as follows:

Primary armament: 152mm DP or largest available DP gun.
Secondary/Tetriary/etc armament: 120mm, 76.2mm, and 13.7mm are options
Armour: Shall be armoured to withstand combat with a like armed ship
Speed: Minimum speed of 28 knots
Range: Minimum 8,000nm
Space: Hull space and accommodation are to be rated as adequate, minimum

Probably should be in the ship design forum. Not sure how many DP guns over 120mm or so there are in 1929. My largest is the 5"/38 and a 6" is still 15 years or so in the future. Something along the lines of an Atlanta would certainly be possible and could probably be done on a Class B hull since they were 6K tons.

There are some 4" guns. Two marks of 4.7" HA, the 5"/25 and thats about it.

By later eyes, they were unsuccessful, but it was pretty common at this time period to specify 6" guns with high angle capability. Some were built with it, others dropped it after it was realized that they wouldn't be able to usefully do what they were asked to do.

There's also the Japanese 5"/40 from this period, and the 5"/50 was given a high-angle capability (but was ultimately unsuccessful in the AAA role).

I do wonder at the goals desired for this cruiser, though. Why the emphasis on AA work, when there are few carriers in your region and not many more combat aircraft? A ship capable of defending itself against planes, certainly, that's just looking ahead, but one who's primary role is anti-aircraft work? That seems slightly off, both for the region (your seas are not constricted, making finding your ships more difficult) and for the period.

I moved this thread to the board it belongs to.

alt_naval has an interesting idea to sim high-angle/DP 6" guns by siming triple mounts but then changing the ship report to twins. Could be used here.

"The SAE will boycott this design study. No interest in contracts due to the political situation in South America. The naval race just started has to be stopped as soon as possible - before it reaches full speed agead."

Could always use the 8"/50 guns as fitted to the County-class. 70° elevation but extremely limited use for AA. DP 6" would be the 1930 model fitted to Richelieu but it didn't work too well.

Or the 6" mounted on the Leanders, or the 6.1" on the Mogami's. The 6.1" went up to 55 degrees, the 6" to 60, but neither one was a successful AA weapon.

[Remember guys, this is a design study. I'll accept anything you put forward.

CanisD: If you can do an Atlanta copy in a Class B hull, what's to stop you from doing it in a Class A hull? After all, the only difference between a Class A and a Class B is size. I'd think it'd actually be easier to do with a larger hull.]

Atlantis has a 5.1 DP gun, seeing as for some odd reason big gun no longer works on my computer I can't really give you stats on its performance but I doubt I could improve on any of the other designs out there.

When you're in the treaty system you think in terms of smallest hull to do the job.

http://www.panzer-war.com/Naab/NAaB.html

Wes. This is better than BigGun and doesn't involve dos.

What does everyone mean by "dual purpose"? Guns that elevate up to 80-90° to shoot down dive bombers? For level bombers 45° is more than adequate. Its simple maths, if the bombers are flying at 1000m then you can shoot at them no closer than 1000m. Well probably a bit further away than that with shell drop.

Quoted

Originally posted by thesmilingassassin
Atlantis has a 5.1 DP gun, seeing as for some odd reason big gun no longer works on my computer I can't really give you stats on its performance but I doubt I could improve on any of the other designs out there.

PM me the stats and I'll run it through BG for you.

Without the treaty, what would be built instead of a class B Atlanta?

Interesting program, looks like I have another toy to play with. Thanks RA.

Quoted

Originally posted by Fyrwulf

Quoted

Originally posted by thesmilingassassin
Atlantis has a 5.1 DP gun, seeing as for some odd reason big gun no longer works on my computer I can't really give you stats on its performance but I doubt I could improve on any of the other designs out there.

PM me the stats and I'll run it through BG for you.

Thanks for the offer Fyrwulf, I'll likely screw around with the program on RA's link and PM you later and see what we come up with.

Quoted

Without the treaty, what would be built instead of a class B Atlanta?

Probably the Atlantas. They were to replace the Omahas rather than to be a dedicated AA cruiser. They were bad ships. Far too many guns and suffering from excessive topweight like all USN ships. Why did the follow-on designs (not Juneau) mount only 6 turrets on about 3000-4000tons more?

[Is anybody going to offer a design? Or do I have to go to Swamphen again and then hear people complain about how they weren't given the chance to participate?]

[Oh, and I'm not talking about a 1929 or 1930 design. More along the lines of '35-'40.]

Projekt Nr 1 , Brazylia Cruiser laid down 1930

Displacement:
7 290 t light; 7 627 t standard; 8 576 t normal; 9 336 t full load

Dimensions: Length overall / water x beam x draught
561,59 ft / 557,74 ft x 65,62 ft x 16,40 ft (normal load)
171,17 m / 170,00 m x 20,00 m x 5,00 m

Armament:
9 - 5,98" / 152 mm guns (3x3 guns), 107,15lbs / 48,60kg shells, 1930 Model
Dual purpose guns in turrets (on barbettes)
on centreline, all forward, 1 raised mount - superfiring
12 - 4,72" / 120 mm guns (6x2 guns), 52,72lbs / 23,92kg shells, 1930 Model
Dual purpose guns in deck mounts with hoists
on side, all amidships
4 - 4,72" / 120 mm guns (2x2 guns), 52,72lbs / 23,92kg shells, 1930 Model
Anti-aircraft guns in deck mounts with hoists
on centreline, all aft, 1 raised mount - superfiring
8 - 0,54" / 13,7 mm guns (2x4 guns), 0,08lbs / 0,04kg shells, 1930 Model
Machine guns in deck mounts
on centreline ends, evenly spread, all raised mounts
Weight of broadside 1 809 lbs / 820 kg
Shells per gun, main battery: 150
12 - 21,0" / 533 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 3,15" / 80 mm 446,19 ft / 136,00 m 9,71 ft / 2,96 m
Ends: Unarmoured
Upper: 0,79" / 20 mm 446,19 ft / 136,00 m 8,01 ft / 2,44 m
Main Belt covers 123% of normal length

- Torpedo Bulkhead:
0,79" / 20 mm 446,19 ft / 136,00 m 14,44 ft / 4,40 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2,36" / 60 mm 1,18" / 30 mm 2,36" / 60 mm
2nd: 0,79" / 20 mm 0,39" / 10 mm -
3rd: 0,79" / 20 mm 0,39" / 10 mm -

- Armour deck: 1,57" / 40 mm, Conning tower: 3,94" / 100 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 3 shafts, 54 510 shp / 40 665 Kw = 29,00 kts
Range 8 000nm at 15,00 kts
Bunker at max displacement = 1 709 tons

Complement:
445 - 579

Cost:
£2,828 million / $11,313 million

Distribution of weights at normal displacement:
Armament: 226 tons, 2,6%
Armour: 1 766 tons, 20,6%
- Belts: 670 tons, 7,8%
- Torpedo bulkhead: 188 tons, 2,2%
- Armament: 162 tons, 1,9%
- Armour Deck: 710 tons, 8,3%
- Conning Tower: 36 tons, 0,4%
Machinery: 1 652 tons, 19,3%
Hull, fittings & equipment: 3 546 tons, 41,3%
Fuel, ammunition & stores: 1 287 tons, 15,0%
Miscellaneous weights: 100 tons, 1,2%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
13 186 lbs / 5 981 Kg = 123,1 x 6,0 " / 152 mm shells or 2,4 torpedoes
Stability (Unstable if below 1.00): 1,24
Metacentric height 4,0 ft / 1,2 m
Roll period: 13,9 seconds
Steadiness - As gun platform (Average = 50 %): 67 %
- Recoil effect (Restricted arc if above 1.00): 0,32
Seaboat quality (Average = 1.00): 1,06

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0,500
Length to Beam Ratio: 8,50 : 1
'Natural speed' for length: 23,62 kts
Power going to wave formation at top speed: 54 %
Trim (Max stability = 0, Max steadiness = 100): 63
Bow angle (Positive = bow angles forward): 7,00 degrees
Stern overhang: 0,66 ft / 0,20 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 25,98 ft / 7,92 m
- Forecastle (10%): 16,54 ft / 5,04 m
- Mid (50%): 16,54 ft / 5,04 m
- Quarterdeck (10%): 16,54 ft / 5,04 m
- Stern: 16,54 ft / 5,04 m
- Average freeboard: 16,91 ft / 5,16 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 122,0%
- Above water (accommodation/working, high = better): 133,6%
Waterplane Area: 24 384 Square feet or 2 265 Square metres
Displacement factor (Displacement / loading): 123%
Structure weight / hull surface area: 103 lbs/sq ft or 503 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,98
- Longitudinal: 1,15
- Overall: 1,00
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent

Polish entry
Poland offers its design.Poland can bild the ship starting in 1931 or sell the ships plans for 2t Warship material

All Chile has to offer is the following Atlantean based design. While Chile can build this, it might need to talk with Atlantis before doing so...legally. Also is does not equal to an antiair design type, as it was designed more for surface work.

Atacama

[SIZE=1](Image by Wes Wilson)[/SIZE]

Chilean "Light" Cruiser laid down 1926 (Atlantis design)

Displacement:
9,747 t light; 10,105 t standard; 10,975 t normal; 11,671 t full load

Dimensions: Length overall / water x beam x draught
556.95 ft / 551.00 ft x 64.00 ft x 22.60 ft (normal load)
169.76 m / 167.94 m x 19.51 m x 6.89 m

Armament:
12 - 5.90" / 150 mm guns (4x3 guns), 102.69lbs / 46.58kg shells, 1926 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
8 - 4.33" / 110 mm guns (4x2 guns), 40.59lbs / 18.41kg shells, 1926 Model
Quick firing guns in deck mounts
on side, all aft
12 - 1.46" / 37.0 mm guns (6x2 guns), 1.54lbs / 0.70kg shells, 1926 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 1,575 lbs / 715 kg
Shells per gun, main battery: 150
12 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 4.10" / 104 mm 350.00 ft / 106.68 m 10.00 ft / 3.05 m
Ends: Unarmoured
Upper: 2.76" / 70 mm 170.00 ft / 51.82 m 5.00 ft / 1.52 m
Main Belt covers 98 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 5.50" / 140 mm 3.92" / 100 mm 3.15" / 80 mm
2nd: 1.00" / 25 mm - -

- Armour deck: 1.57" / 40 mm, Conning tower: 1.57" / 40 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 82,011 shp / 61,180 Kw = 31.00 kts
Range 10,000nm at 12.00 kts
Bunker at max displacement = 1,566 tons

Complement:
535 - 696

Cost:
£3.020 million / $12.079 million

Distribution of weights at normal displacement:
Armament: 197 tons, 1.8 %
Armour: 1,825 tons, 16.6 %
- Belts: 724 tons, 6.6 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 413 tons, 3.8 %
- Armour Deck: 671 tons, 6.1 %
- Conning Tower: 17 tons, 0.2 %
Machinery: 2,625 tons, 23.9 %
Hull, fittings & equipment: 4,950 tons, 45.1 %
Fuel, ammunition & stores: 1,228 tons, 11.2 %
Miscellaneous weights: 150 tons, 1.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
14,422 lbs / 6,542 Kg = 140.4 x 5.9 " / 150 mm shells or 1.8 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 2.9 ft / 0.9 m
Roll period: 15.7 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.45
Seaboat quality (Average = 1.00): 1.26

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.482
Length to Beam Ratio: 8.61 : 1
'Natural speed' for length: 23.47 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 56
Bow angle (Positive = bow angles forward): 12.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 28.00 ft / 8.53 m
- Forecastle (25 %): 27.50 ft / 8.38 m (26.00 ft / 7.92 m aft of break)
- Mid (45 %): 26.00 ft / 7.92 m
- Quarterdeck (18 %): 16.00 ft / 4.88 m
- Stern: 16.00 ft / 4.88 m
- Average freeboard: 22.78 ft / 6.94 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 93.5 %
- Above water (accommodation/working, high = better): 143.4 %
Waterplane Area: 23,118 Square feet or 2,148 Square metres
Displacement factor (Displacement / loading): 125 %
Structure weight / hull surface area: 126 lbs/sq ft or 615 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.09
- Longitudinal: 2.48
- Overall: 1.18
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily