WesWorld

Here's a proposed German BC/fast BB design for 1933.




DKM Mackensen, German Battlecruiser laid down 1933

Displacement:
39,921 t light; 41,985 t standard; 44,413 t normal; 46,356 t full load

Dimensions: Length overall / water x beam x draught
826.60 ft / 803.81 ft x 104.99 ft x 32.32 ft (normal load)
251.95 m / 245.00 m x 32.00 m x 9.85 m

Armament:
9 - 14.96" / 380 mm guns (3x3 guns), 1,984.16lbs / 900.00kg shells, 1933 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, majority forward, 1 raised mount - superfiring
12 - 5.91" / 150 mm guns (4x3 guns), 102.98lbs / 46.71kg shells, 1928 Model
Breech loading guns in turrets (on barbettes)
on side ends, evenly spread
2 - 4.13" / 105 mm guns (1x2 guns), 35.32lbs / 16.02kg shells, 1928 Model
Breech loading guns in a deck mount with hoist
on centreline aft, all raised guns - superfiring
16 - 4.13" / 105 mm guns (8x2 guns), 35.32lbs / 16.02kg shells, 1928 Model
Dual purpose guns in deck mounts with hoists
on side, evenly spread, 4 raised mounts
24 - 1.46" / 37.0 mm guns (12x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 8 raised mounts
Weight of broadside 19,766 lbs / 8,966 kg
Shells per gun, main battery: 105

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 15.0" / 380 mm 450.13 ft / 137.20 m 12.30 ft / 3.75 m
Ends: 2.76" / 70 mm 353.64 ft / 107.79 m 12.30 ft / 3.75 m
Main Belt covers 86 % of normal length

- Torpedo Bulkhead:
1.97" / 50 mm 450.13 ft / 137.20 m 30.02 ft / 9.15 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 16.5" / 420 mm 8.27" / 210 mm 13.8" / 350 mm
2nd: 4.72" / 120 mm 2.76" / 70 mm 4.72" / 120 mm
3rd: 1.97" / 50 mm 0.79" / 20 mm 1.97" / 50 mm
4th: 1.97" / 50 mm 0.79" / 20 mm 1.97" / 50 mm
5th: 0.79" / 20 mm 0.39" / 10 mm -

- Armour deck: 5.51" / 140 mm, Conning tower: 5.91" / 150 mm

Machinery:
Oil fired boilers, steam turbines plus diesel motors,
Electric motors, 4 shafts, 135,263 shp / 100,906 Kw = 30.00 kts
Range 8,000nm at 15.00 kts
Bunker at max displacement = 4,371 tons

Complement:
1,529 - 1,988

Cost:
£17.640 million / $70.561 million

Distribution of weights at normal displacement:
Armament: 2,122 tons, 4.8 %
Armour: 15,370 tons, 34.6 %
- Belts: 4,102 tons, 9.2 %
- Torpedo bulkhead: 984 tons, 2.2 %
- Armament: 3,751 tons, 8.4 %
- Armour Deck: 6,373 tons, 14.4 %
- Conning Tower: 160 tons, 0.4 %
Machinery: 3,941 tons, 8.9 %
Hull, fittings & equipment: 18,268 tons, 41.1 %
Fuel, ammunition & stores: 4,492 tons, 10.1 %
Miscellaneous weights: 220 tons, 0.5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
68,489 lbs / 31,066 Kg = 40.9 x 15.0 " / 380 mm shells or 10.2 torpedoes
Stability (Unstable if below 1.00): 1.09
Metacentric height 6.3 ft / 1.9 m
Roll period: 17.5 seconds
Steadiness - As gun platform (Average = 50 %): 60 %
- Recoil effect (Restricted arc if above 1.00): 0.79
Seaboat quality (Average = 1.00): 1.20

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.570
Length to Beam Ratio: 7.66 : 1
'Natural speed' for length: 32.80 kts
Power going to wave formation at top speed: 51 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 33.79 ft / 10.30 m
- Forecastle (24 %): 24.11 ft / 7.35 m
- Mid (40 %): 24.11 ft / 7.35 m
- Quarterdeck (20 %): 24.11 ft / 7.35 m
- Stern: 24.11 ft / 7.35 m
- Average freeboard: 25.04 ft / 7.63 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 81.9 %
- Above water (accommodation/working, high = better): 187.8 %
Waterplane Area: 62,503 Square feet or 5,807 Square metres
Displacement factor (Displacement / loading): 110 %
Structure weight / hull surface area: 210 lbs/sq ft or 1,024 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.96
- Longitudinal: 1.38
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

80 tons reserved for aircraft

140 tons reserved for flag accommodations and growth

Interesting... I was kind of expecting a 27-28 knot BB from you next, myself.

Seems like a solid design. Are you sticking with separate HA/LA secondaries?

There's a 28-knot design on the drawing boards as well. The armament on that design is the same, the savings in tonnage go into additional armor plate.

For now, yes, the KM is sticking with separate HA/LA batteries. Once the 12.8cm DP guns are finished, there's a possibility of going to a DP battery, but the KM's not in a hurry to go there for it's capital ships (cruisers and destroyers are a different matter). Now, if the 15cm DP project comes to fruition earlier than expected, that's different, the KM would go to a DP 15cm armament for it's capital ships in a heartbeat.

For congested waters in general and the Baltic/North Sea in particular, a split battery is a Good Thing, IMHO.

Offhand, I'd go with the 28 knot version. A 30 knot version will face the same problems I'm having with the Renowns; It's not fast enough to sufficiently outrun the Fast BBs in service.

I like her, a well balanced and potent design.

Speed is a tricky issue, Memnon is slightly slower but has a slight advantage in armor at first glance while the Mackensen definately has an armament advantage over the Renowns and an armor advantage over the Hood.

New UK BB's/BC's would be fairly equal as well.

How much of a speed advantage Mackensen would have over a fast battleship depends on which BB we're talking about, and in what seas.

With that combination of Arms and Armour, is she not more BB than BC?

Probably done to confure the enemy... but I was thinking the same thing.

That depends on your definition. She doesn't look that different from the German WWI BCs of the Mackensen or Ersatz Yorck classes.

I'd say she's more of a fast BB, which is something that seems to be emerging from several nations. Technically Germany could be credited with inventing the idea, the way they armored their BC's, the Derflingers in particular.

She has radar antennas on the front plates of their rangefinders ?!?!

Hee hee, those silly Germans!

Hmmm, a 15" (380 mm) belt that's only 12.3' (3.75 m) wide and covers only 86% of normal length? Maybe a thinner but, longer and deeper belt would be better. The 15" armour thickness does sound a little excessive.

Other than that, I like her very much with that 'Bismarckian' hull and superstructure and -- the three triple turrets.

The drawing is great too.

Monty

The radar on the rangefinders is an artifact of my borrowing the base drawing from a drawing of Tirpitz at http://www.german-navy.de/. However, it's not out of the question that Mackensen would be completed with radar, after all, the historical Deutschland had a Seetact set in the fall of 1937.


As to the belt height, I just used what SS gave me as a default, it's a little taller than the 14" belt on the British Invincibles. The belt length is shorter than the "norm" probably because she's a fairly long ship with a fairly compact layout, it's again pretty similar to the Invincibles.

I'm surprised you didn't just go for a slightly modified Bismarck with triple turrets. Theres a reason why the Germans went for the incremental armourscheme and lighter shells - because they are better for their operating environment. The conning tower armour seems a little light.

The armor is a partially incremental scheme: it's ditched the upper armor, but kept the end armor. Lighter shells are only advantageous at quite short ranges, they lose their initial velocity advantages over heavy shells pretty rapidly. Also, the guns are using heavier propellant charges than the historical German 38cm guns to increase the velocity of the 900 kg shells. Barrel life won't be great, but with the chromium plating and other changes made for the Heer's 35cm guns, it won't be terrible either, probably around 180-200 shots before the barrel needs replacing.

Quoted

Lighter shells are only advantageous at quite short ranges

Its up to about 250hm which is greater than ranges you would expect to engage at. I have some nice graphs of shell velocities which i'll look out.

That armour cannot really be called incremental. 70mm is only splinter armour - the need for which has yet to arise.

No, it isn't. Take a look at the data (taken from navweaps trajectory tables).

Italian (880 kg shell, at muzzle velocity of 850 m/s)

10,936 yards (10,000 m) 2,254 fps (687 mps)
16,404 yards (15,000 m) 2,034 fps (620 mps)
21,872 yards (20,000 m) 1,847 fps (563 mps)
27,340 yards (25,000 m) 1,719 fps (524 mps)


German (800 kg shell, at muzzle velocity of 820 m/s)

10,940 yards (10,000 m) 2,103 fps (641 mps)
16,400 yards (15,000 m) 1,864 fps (568 mps)
21,870 yards (20,000 m) 1,677 fps (511 mps)
27,340 yards (25,000 m) 1,552 fps (473 mps)


French (884 kg shell, at muzzle velocity of 830 m/s)

10,936 yards (10,000 m) 2,215 fps (675 mps)
16,404 yards (15,000 m) 1,995 fps (608 mps)
21,872 yards (20,000 m) 1,785 fps (544 mps)
27,340 yards (25,000 m) 1,686 fps (514 mps)


Notice the difference particularly between the French and German shells: they start off at close to the same velocity, but the lighter shell loses velocity faster. This is normal, since the lighter projectile has less inertia. The results are exacerbated in this case because the French shells are longer (190 cm compared to 167 cm) and hence better aerodynamically


The 70mm armor is intended to keep off light and HE shells, which is the primary job of end armor. It's not going to keep off heavy shells, not even the 180mm armor on the WWI DNs would do that effectively, so there's no point in putting it on (as our friends overseas have noted to the KM designers).

The shells have different aerodynamics, thats why the mv drops above. Take the UK 16" shells from 1920/21 of 2250 and 2048lb respectively. The 2048lb shell was found to have better penetration out to 20.000yds with equality striking at about 25.000yds. Lighter shells allows higher mv for a given charge, which means a lighter gun.

The 180mm armour worked fine against HE shells. Just that now everyone has gone to using AP instead.