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The Auxiliary cruiser thing turned out to be not so great. It can be traced back through centuries of sail. But Technology screwed thing up pretty quick. An Auxiliary cruiser can fight a another Auxiliary cruiser fairly evenly, assuming like to like armament. However they are both egg shells armed with hammers. Merchant ships have machinery that extends well above the waterline making it very vulnerable to hits. There is no armor on the hulls or decks, even splinter proof.So, Kreuzerkrieg it is. What kind of ships to build for that?
- Subs and the auxiliary cruisers (hilfkreuzer) were fairly successful, particularly earlier in the war, so build more of those.
- Evidently the big lead smelter required for submarine batteries was a bottleneck, so probably not feasible to start massively expanding sub production sooner?
- For auxiliary cruisers, should be possible to require some civilian transports and liners to be built with conversion in mind. This should allow getting more of them into service relatively quickly.
- As discussed in the CV thread, hard to see a role for them.
- Some gun equipped big ships are probably useful, for stuff like the Norway invasion, and as a kind of fleet in being, forcing the Allies to dedicate capital ships for convoy escort duty, as well as keeping heavy units in home waters in case the Germans try something.
Problem for the Germans was that for anything less than a capital ship the British were going to Graf Spee it. They were not going to go one on one with super cruiser. They were going to use 3-4 cruisers at the same time if there was no battle cruiser.
- Needs to be able to beat a treaty cruiser, to force the Allies to employ their own capital ships.
- Full battleships are perhaps a bridge too far, in the sense the Allies can always build more of them?
- But if not able to beat a battleship, need to be able to run away. So needs to be very fast, say 32 knots at least?
- So maybe something like a pocket battleship 2.0, with more speed and sufficient armor so the citadel is resistant to 8" fire?
- The 28cm guns are probably suitable, if for no other reason they already exist.
Germans often seemed to be distracted by pretty toys. The British were sort of sticks in the mud, but they needed machinery that was going to work when it was several years old and 10s of thousands of miles away from England. The US split the difference with a lot more steam pressure and temp than the British but a lot less the Germans. They got better power to weight than the British and a lot more reliability than the Germans.Maybe double down on diesel power rather than giving up after the PBB's? The pivot to high pressure steam wasn't exactly happy. And while the PBB power plants had worse power to weight than contemporary steam turbine plants, there was a lot of runway in diesel technology. Despite the drop in diesel funding after the steam pivot, by 1939 MAN had developed V24 diesel engines with much improved power to weight. MAN Double-Acting Diesel Marine Engines Of course, in retrospect we can say that double acting internal combustion engines were a mistake, oh well.
German 5in wasn't a very good DP gun. It may have been that some other countries but it wasn't as good as the US 5"/38.One thing the Germans missed was DP secondaries. Say the 5" gun they had on some destroyers could have been developed into one. Oh, and don't put 6" guns on destroyers, too top heavy.
The Auxiliary cruiser thing turned out to be not so great.
Maybe an Auxiliary cruiser can beat one in a gun fight or perhaps you need two on one, but in 10 fights out of 10 even this size cruiser is going to come out on top a very large percentage of the time. Even a large Destroyer has got better fire control than most Aux Cruisers.
Problem for the Germans was that for anything less than a capital ship the British were going to Graf Spee it. They were not going to go one on one with super cruiser. They were going to use 3-4 cruisers at the same time if there was no battle cruiser.
Highspeed and resistance to 8in shell fire both take more displacement than many people realize.
Graf Spee needed about 54,000hp to do 28kts, the Hippers needed 132,000hp to do 32 knts. You can similar bounces with the French and Italian cruisers
US 260lb 8in shells were rated at 4in at 23,600yds, 5in at 19,500yds and 6in 16,600yds. I don't have the figures for British 8in shells. Deck armor goes the other way. you want between 2 -3in depending on range.
Germans often seemed to be distracted by pretty toys. The British were sort of sticks in the mud, but they needed machinery that was going to work when it was several years old and 10s of thousands of miles away from England. The US split the difference with a lot more steam pressure and temp than the British but a lot less the Germans. They got better power to weight than the British and a lot more reliability than the Germans.
German 5in wasn't a very good DP gun. It may have been that some other countries but it wasn't as good as the US 5"/38.
Most countries biased the secondary guns too much for surface fire. If you want good AA you can't just point the guns upward. You need guns that are light and easy to aim, you need good shell supply and you need gun barrels that are not going to shoot out their rifling in a few air attacks.
It turned out that there were not very many German commercial ships suitable for conversion to Aux cruisers. You need better than average speed but you need to be economical. You have to be sizable to store food and other supplies for long periods away from supply ships. You need suitable crew space. Finding ships that checked most of the boxes was difficult.And yes, once longer ranged patrol aircraft, better radios, radars etc became more common as the war progressed, it was basically game over for them. But until then, a pretty cost effective weapon to wreak some havoc.
If Germany had kept building Graf Spee's or built several new/improved versions I imagine the treaties would have gained some amendments/exceptions. The mid 1930s saw the whole treaty thing falling apart anyway. Good naval architects knew who was cheating and who was not. maybe you could skate by with 5-10% but they knew who was cheating by by 20-30% and that wasn't going to keep going on.So in that sense there's nothing magical about a ship in the "capable of beating a treaty cruiser" size class, except that it's a kind of asymmetrical response to a navy that is constrained by the treaty system and can't afford to have real battleships lying around everywhere.
Germans are in an interesting dilemma for commerce raiding. The 15cm guns are better for shooting up merchant ships with their much more destructive shells and the 15cm battery allows them to engage a 2nd or 3rd enemy warship (small) to try to push through an escort screen. Using 10.5cm guns for such work uses up a lot of shells. Where is the cross over point?Or as an alternative, use the existing 105mm heavy flak gun for surface targets as well (add a splinter proofed turret) and lose the 150mm secondaries the Germans historically had. That might have the opposite problem in that it's a bit weak for surface fire, but in retrospect I guess that might not be such a huge problem.
It turned out that there were not very many German commercial ships suitable for conversion to Aux cruisers. You need better than average speed but you need to be economical. You have to be sizable to store food and other supplies for long periods away from supply ships. You need suitable crew space. Finding ships that checked most of the boxes was difficult.
If Germany had kept building Graf Spee's or built several new/improved versions I imagine the treaties would have gained some amendments/exceptions. The mid 1930s saw the whole treaty thing falling apart anyway.
Germans are in an interesting dilemma for commerce raiding. The 15cm guns are better for shooting up merchant ships with their much more destructive shells and the 15cm battery allows them to engage a 2nd or 3rd enemy warship (small) to try to push through an escort screen. Using 10.5cm guns for such work uses up a lot of shells. Where is the cross over point?
But the 15cm guns are useless for AA work, but that is with hindsight. A lot of money and effort was put into trying to make high angle 15cm guns in several navies. It took until the USS Worcester to get it to work.
Once you are down to the 8in cruiser and smaller then the 10.5cm guns make sense although again the Germans may have tried too hard for ballistic excellence. At sea on a moving ship the extra few thousand feet of altitude doesn't make much difference. Anything flying that high can't you except by accident.
It took the Germans 6 years to build the 3 Deutschland class ships. The British already had the Renown, Repulse and Hood and the French were building the Dunkerque and Strasbourg.Maybe. However, UK would likely still want to prioritize to build modern fast battleships to counter the Italians and Japanese rather than building dedicated "PBB2 killers".
Yes the twin 15cm turrets had a lot of armor. 100-140mm depending on ship.Bigger bang delivered to a single address does have some advantages I think, however just by looking at weight of shells for installed weight the smaller gun might not be too bad. The 10.5cm twin mount was about 27 tons. Add some splinter and weather protection for the crew and we're probably looking at around 40 tons. For comparison the twin 5"/38 used on US cruisers was about 50 tons with heavier guns, so probably 40 is in the ballpark. Rof 15-18/min shooting 15 kg shells. So 12 kg shells/min/ton of turret.
The twin 15cm turrets used on German BB's was about 110 tons (though probably more armored than just splinter protection?). Rof 6-8/min, shooting 45 kg shells. So 5.7 kg shells/min/ton of turret.
Yes the twin 15cm turrets had a lot of armor. 100-140mm depending on ship.
Not sure that the German 12.7cm guns could have replied well to the Ajax and Achilles although 4 guns to 8 is a mismatch to begin with.
10.5cm would have been out of luck even with a 4 twin mounts per side.
But the Germans often did not have the magazine capacity to back up the guns. Something that is often overlooked when looking at the US 5"/38, The US ships often started with 300rpg and quickly went to around 450rpg. They were not going to run out of ammo in 8-12 minutes of fast firing.
Trouble is that the British had given up on the Leander design and laid down two Southampton's in 1934. Still with 25mm turret armor but hail of 6in shells is also going to put the 10.5cm batteries out of commission fairly quickly.The lighter DP secondaries would likely be unable to penetrate the citadels of light cruisers. However the Leanders had only 25mm turret armor, so even 10.5cm secondaries should be able to wreck them. So a hail of 10.5 cm shells would quickly mission kill it. Then again, a light cruiser would also be capable of mission killing a PBB as long as the PBB main guns are occupied elsewhere, and the UK would happily trade a mutual mission kill in the south Atlantic.
A fast "PBB2" would have the option to keep out of light battery range and rely on the main guns. However dispatching 3 cruisers at long range would run down the main battery magazines, so.. No magic solutions however you turn it.
Assumes that the German aircrew were a lot better at identifying ships than the American and Japanese aircrew wereCorrectly identifying that he was up against a York class CA and 2 Leander class CLs, not an Arethusa class CL and 2 DDs might have also changed his opinion about engaging.)
Quite right.Fire, observe shot fall, correct, and fire again - which gets firing rate down to ~2 rounds/minute at "normal" surface ranges.
Could the German commerce raiders keep a disproportionate number of ships busy looking for them?
PBB needed more aviation assets - at the very least more cylinder heads for the existing plane, preferably more airplanes.
The British were planning on having several light CVs when war broke out. Plans went to crap when they lost the Courageous and Glorious. The Hermes spent quite a bit of time in the South Atlantic and Indian Ocean as air support for convoys and anti-raider units. She wasn't much good (too small) for anything else.Even if all the above is resolved, if ammunition supply is a problem for gun based commerce raiders, I can't imagine the situation being easier for providing sufficient aviation fuel, bombs (and/or torpedoes), spare parts etc. for the baby CV. At least in the Pacific war the fleet oilers were a critical factor in being able to sustain operations.
The UK had more shipbuilding capacity than the Germans, but it wasn't infinite either. What are they going to give up to respond to German light CV's? They were already pumping out ASW escorts to counter the threat of German u-boats (which was entirely the right thing to do), are they going to sacrifice the KGV's to build more CV's? If so, what is the counter to Italian and Japanese BB's?Anything the Germans can build that can be seen building/converted in a German shipyard is going to provoke some sort of response from the British and/or French.
we can argue about if the response would work or be ready in time but the Germans are not going to expand their raiding force by much and have the British and French keep to historical building levels.