You are not logged in.

1

Monday, October 25th 2004, 2:51pm

1925 Destroyer Leader - Powys Class

8 units of two different sub-classes will be laid down during 1925. The only difference between both is their main armament. While one of the classes has a somewhat classic 4,7in (3x2) /4in (1x2) AA layout, the other version introduces a new 4,5in DP gun.

The ships are named after ancient british kingdoms.

[SIZE=3]Type A[/SIZE]


HMS Powys
HMS Cerin
HMS Dyfed
HMS Dummonia
HMS Deira

Powys Class Tipe A, British Destroyer Leader laid down 1925

Displacement:
1.921 t light; 2.000 t standard; 2.231 t normal; 2.407 t full load

Dimensions: Length overall / water x beam x draught
359,19 ft / 348,00 ft x 34,00 ft x 15,00 ft (normal load)
109,48 m / 106,07 m x 10,36 m x 4,57 m

Armament:
6 - 4,70" / 119 mm guns (3x2 guns), 51,91lbs / 23,55kg shells, 1925 Model
Breech loading guns in deck mounts
on centreline ends, majority forward, 1 raised mount - superfiring
2 - 4,00" / 102 mm guns (1x2 guns), 32,00lbs / 14,51kg shells, 1925 Model
Anti-aircraft guns in deck mount
on centreline aft, all raised guns - superfiring
8 - 1,57" / 40,0 mm guns (2x4 guns), 1,95lbs / 0,88kg shells, 1925 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
12 - 0,79" / 20,0 mm guns (6x2 guns), 0,24lbs / 0,11kg shells, 1925 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 394 lbs / 179 kg
Shells per gun, main battery: 145
8 - 21,0" / 533,4 mm above water torpedoes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1,00" / 25 mm - -
2nd: 1,00" / 25 mm - -
3rd: 0,50" / 13 mm - -
4th: 0,50" / 13 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 53.852 shp / 40.173 Kw = 34,00 kts
Range 4.090nm at 15,00 kts (Bunkerage = 416 tons)

Complement:
162 - 211

Cost:
£0,941 million / $3,765 million

Distribution of weights at normal displacement:
Armament: 49 tons, 2,2 %
Armour: 16 tons, 0,7 %
- Belts: 0 tons, 0,0 %
- Torpedo bulkhead: 0 tons, 0,0 %
- Armament: 16 tons, 0,7 %
- Armour Deck: 0 tons, 0,0 %
- Conning Tower: 0 tons, 0,0 %
Machinery: 1.278 tons, 57,3 %
Hull, fittings & equipment: 557 tons, 25,0 %
Fuel, ammunition & stores: 310 tons, 13,9 %
Miscellaneous weights: 20 tons, 0,9 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
415 lbs / 188 Kg = 8,0 x 4,7 " / 119 mm shells or 0,2 torpedoes
Stability (Unstable if below 1.00): 1,46
Metacentric height 1,9 ft / 0,6 m
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0,24
Seaboat quality (Average = 1.00): 1,01

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0,440
Length to Beam Ratio: 10,24 : 1
'Natural speed' for length: 18,65 kts
Power going to wave formation at top speed: 69 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 25,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 24,00 ft / 7,32 m
- Forecastle (30 %): 21,00 ft / 6,40 m (13,00 ft / 3,96 m aft of break)
- Mid (50 %): 13,00 ft / 3,96 m
- Quarterdeck (15 %): 13,00 ft / 3,96 m
- Stern: 13,00 ft / 3,96 m
- Average freeboard: 15,76 ft / 4,80 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 202,6 %
- Above water (accommodation/working, high = better): 58,1 %
Waterplane Area: 7.121 Square feet or 662 Square metres
Displacement factor (Displacement / loading): 57 %
Structure weight / hull surface area: 34 lbs/sq ft or 167 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,50
- Longitudinal: 2,36
- Overall: 0,58
Hull space for machinery, storage, compartmentation is extremely poor
Room for accommodation and workspaces is cramped

[SIZE=3]Type B[/SIZE]

(Same as above)

HMS Gwynedd
HMS Luitcoyt
HMS Rheged

Powys Class Type B, British Destroyer Leader laid down 1925

Displacement:
1.925 t light; 2.000 t standard; 2.231 t normal; 2.407 t full load

Dimensions: Length overall / water x beam x draught
359,19 ft / 348,00 ft x 34,00 ft x 15,00 ft (normal load)
109,48 m / 106,07 m x 10,36 m x 4,57 m

Armament:
8 - 4,50" / 114 mm guns (4x2 guns), 45,56lbs / 20,67kg shells, 1925 Model
Breech loading guns in deck mounts
on centreline ends, evenly spread, 2 raised mounts - superfiring
8 - 1,57" / 40,0 mm guns (2x4 guns), 1,95lbs / 0,88kg shells, 1925 Model
Anti-aircraft guns in deck mounts
on side, all amidships
12 - 0,79" / 20,0 mm guns (6x2 guns), 0,24lbs / 0,11kg shells, 1925 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 383 lbs / 174 kg
Shells per gun, main battery: 140
8 - 21,0" / 533,4 mm above water torpedoes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1,00" / 25 mm - -
2nd: 0,50" / 13 mm - -
3rd: 0,50" / 13 mm - -

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 53.852 shp / 40.173 Kw = 34,00 kts
Range 4.090nm at 15,00 kts (Bunkerage = 416 tons)

Complement:
162 - 211

Cost:
£0,939 million / $3,754 million

Distribution of weights at normal displacement:
Armament: 48 tons, 2,1 %
Armour: 18 tons, 0,8 %
- Belts: 0 tons, 0,0 %
- Torpedo bulkhead: 0 tons, 0,0 %
- Armament: 18 tons, 0,8 %
- Armour Deck: 0 tons, 0,0 %
- Conning Tower: 0 tons, 0,0 %
Machinery: 1.280 tons, 57,4 %
Hull, fittings & equipment: 558 tons, 25,0 %
Fuel, ammunition & stores: 307 tons, 13,7 %
Miscellaneous weights: 20 tons, 0,9 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
416 lbs / 189 Kg = 9,1 x 4,5 " / 114 mm shells or 0,2 torpedoes
Stability (Unstable if below 1.00): 1,45
Metacentric height 1,9 ft / 0,6 m
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0,24
Seaboat quality (Average = 1.00): 1,01

Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0,440
Length to Beam Ratio: 10,24 : 1
'Natural speed' for length: 18,65 kts
Power going to wave formation at top speed: 69 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 25,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 24,00 ft / 7,32 m
- Forecastle (30 %): 21,00 ft / 6,40 m (13,00 ft / 3,96 m aft of break)
- Mid (50 %): 13,00 ft / 3,96 m
- Quarterdeck (15 %): 13,00 ft / 3,96 m
- Stern: 13,00 ft / 3,96 m
- Average freeboard: 15,76 ft / 4,80 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 202,3 %
- Above water (accommodation/working, high = better): 58,1 %
Waterplane Area: 7.121 Square feet or 662 Square metres
Displacement factor (Displacement / loading): 57 %
Structure weight / hull surface area: 34 lbs/sq ft or 168 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,50
- Longitudinal: 2,35
- Overall: 0,58
Hull space for machinery, storage, compartmentation is extremely poor
Room for accommodation and workspaces is cramped

2

Monday, October 25th 2004, 5:24pm

Whether or not a DP gun is available in 1925 is debatable, but more to the point:

Why build three different types of destroyer leaders at the same time?

3

Monday, October 25th 2004, 5:56pm

I never said It was a fully functional DP, just a first attemp. Hopefully more refined versions and mounts of the gun will be avaliable in the next 10 years.

As for the DL question, the Dianas can act as DLs, but also in a more traditional role as cruisers. And if you take a look at the RN organization as it´s right now you´ll see that some of the flotilllas are composed of 15 DDs and a leader, they´re way too big, my idea is to have more practical flotillas (1DL and 6-10 DDs), and for that I need more DLs, as I don´t want to use CLs as leaders if posible.

HoOmAn

Keeper of the Sacred Block Coefficient

  • Send private message

4

Thursday, October 28th 2004, 4:02pm

Looks like you´ve a lot of spare time...

Nice drawing (including top view ;o)!

I just wonder why you have placed it above Typ A while the drawing is showing a Typ B?

5

Thursday, October 28th 2004, 4:39pm

In fact this is going to be my last drawing for a few days, glad you like her in any case.

I know she depicts a Type B, anyway Type A is almost identical, the only difference is the aft superfiring mount (I was getting tired of messing around with the drawing and just didn´t wanted to draw another different mount, sometimes I´m lazy...)

6

Thursday, October 28th 2004, 5:29pm

You know... I was wondering about one thing:
If the 'A' type uses "a somewhat classic 4,7in (3x2) /4in (1x2) AA layout," then why did you sim it as: 6 - 4,70" / 119 mm guns (4 mounts)and 2 - 4,00" / 102 mm guns in single mounts.
The SS data suggests something like a 2x2 and 2x1 layout for the 4.7 inch guns and a 2x1 layout for the 4 inch guns.

Looking at the data for both types, it looks like you created the 'B' type first and then the 'A' type.
I assume that the 2pdrs on the 'A' type should be in two mounts of four rather than 6 mounts and that the 20mm guns should be in six mounts of 2 rather than 12 single ones.
Could be wrong. You know the designs better than me.

7

Thursday, October 28th 2004, 8:03pm

My mistake... Yes, I simmed first the type B... and it seems that I got everything grown when I posted... I´ll correct it right now.

HoOmAn

Keeper of the Sacred Block Coefficient

  • Send private message

8

Friday, October 29th 2004, 9:08am

Gravina - I can´t help but think your Type B is somewhat influenced by the british TRIBAL-class leaders. Am I right?

9

Saturday, October 30th 2004, 5:45pm

Yes, to a point. I´ve always liked the Tribals, they had very nice looks and a powerful punch, however they also had a couple weak but important points.

They only had 4TTs, and for a DD that´s not really too much, and they lacked an adequate AA defense. I´ve tried to design a ship type similar to the Tribal´s but avoiding those weaknesses.

10

Saturday, October 30th 2004, 5:55pm

Nice-looking, and potent.

Neat.