Destroyers.....

[parsifal]

British DDs, even the tribals were not as competitive as many other Navies until later in the war. The RN determined that the overwhelming issue was numbers, and accordingly designed an built their DDs until the latter part of the war (1944-45), to the idea of sacrificing quality to an extent, in favour of numbers. Even the L&M class were nuilt to budgetry constraints....a limited displacement, no unit machinery arrangement SP guns. The "Z" , "Ca", "Ch', Co", Cr" classes had a superior DP weapon, a decent torpedo broadsise, but farly light LAA, they had machinery arranged in a unit style arramgment, but were about 1000 tons lighter than a Fletcher.

Battle Class (both the 1st and second groups) had standard displacements of 2400tons (compared to the fletchers 2300 tons), but a deep load displacement of 3300 tons to the Fletchers 2900 tons. This had a great impact on the stability comparisons for the two classes. There was no comparison. Ive trained with gearing classes (a close relative to the fletchers) in a Daring Class ( a bigger brother to the Battles), and in any kind of rough seas, the Gearings were quickly forced to lose speed, whereas the Darings were able to maintain close to full speed. The CG of the Darings was much lower than the Geariigs and topweight much less. There really is not any comparison in stability. Moreover the flush deck (ie lack of a raised weather forecastle) generally made the fletchers very wet in any sort of sea.

So, whilst I think the Fletcher was a heavily armed DD, that provided the weather was not too rough could do all things pretty well, it did have some limitations. Its 5/38s were an excellent all ropund general purpose weapon, but compared to more modern DPs was not as good at either the AA or the surface role. The Fletcher had great strength in the hull, but limited internal space brought about by the flush deck arrangements.

Fletchers were excellent all rounders, but this should not be confused with the idea that they were the best at everything. They were just a well balanced design

 

[Glider]

I agree with a lot of the previous statement by Parsifal. At the outbreak of war the UK dcided to build their destroyers to a standard design to help speed production. The hull was based on the JKN class and this really didn't change much until the Battle class. The guns, light AA and torpedos were modified here and there but the basic design wasn't changed much.
A similar decison was made re light cruisers where war built ships were based on the town class cruisers.

Considering the war service the RN destroyers and Light Cruisers faced in a multitude of situations the decision worked pretty well.

The Fletchers were almost certainly the best balanced destroyer design of the war but generally speaking the USN were not quite as concerned about their ships being top heavy. The massive rise in LAA and radar only added to the problem.

Fletchers were designed for 4 x 1.1in and 6 x 20mm and some ended up with 10 x 40mm and 7 x 20mm. Add the radars, extra directors, ready use ammo and I hate to think how much weight was added topside. Stability had to give

 

[vinnye]

Most of the British designs were intended for fleet protection if I remember correctly. They would screen heavier units and engage enemy destroyers - hence the heavy firepower and decreased torpedo banks?
As war broke out, it became clear that these types were often going to have to work in isolation or in small task groups - frequently coming under air attack. These showed their weakness in AA capability and hence a number of modifications taking place when possible. It is probably fair to note that several losses whilst undertaking near suicidal missions up to late 1941 may have helped to clarify both RN and other navies thinking regarding AA fitments. Maybe the USN took note of these actions and made improvements to their designs?
I have also read that the RN destroyers were capable of maintaining quite high speeds during severe weather.

 

[Glider]

The Tribal Class were designd to take on other Destroyers hence the priority given to firepower over torpedo's but it was recognised that this wasn't the correct balance. The following JKN class switched to 6 x 4.7 and 10 x TT which was a very good balance without being top heavy.

As for their AA fire British warships at the outbreak of war had better LAA guns and more of them than most if not all the major navies. The problem was that it wasn't sufficient, for the simple reason no one knew what sufficient was. The scale of air attack that warships had to face was beyond the imagination of pre war navies.

US Destroyer design did learn from the lessons of the European war plus their vessels were designed for the extra ranges involved when fighting in the Pacific. This made their warships bigger which then gave more deck space to fit additional LAA guns.

 

[davebender]

I've never understood why Britain diverted resources to development of 4.5" and 5.25" naval rifles. 4.7" (120mm) is ideal for DD use and weapons that size were mounted on RN DDs during 1918. Britain could have continued 4.7" development during 1920s and 1930s. By mid 1930 a proper 4.7" DP gun should have armed all British built destroyers as well as secondary weapon on KGV class battleships.

 

[Glider]

The bit that I never understood was that pre war the RN had a DP 4.5in (on Ark Royal) and a DP 4.7in (on Nelson). Why they stop there develop one or both of these as a proper DP gun I will never know

 

[parsifal]

It does seem a bit of a mystery. I suspect that neither the 4.7DP or the 4.5DP whilst functional weapons had quite the optimal performance they were looking for. But then, one could hardly argue the 5.25" was an ideal weapin either.

In the case of the 4.7 SP weapon, I think it was simply a case of a number of factors. At the top wa cost....having developed the 4.7SP as the principal DD weapon there was probably little money for further development.

But money would have been found if true extent of threat to surface ships by a/c had been appreciated. Like a lot of contenntal Navies, the threat from a/c was grossly under-estimated. The 4.7 offered better anti-surface results over both the 4in and the US 5/38. The light AA suites were probably seen as enough protection. If so, a serious miscalculation.

The development of a good large calibre DP weapon remained problemtaic. The French had difficulties with their DP mounts, as did the italians. The Japanese DP mount was nearly useless, whilst the germans never attempted a DP mount in the interwar context. their 4.1 was an AA mount, whilst their 5.9 was an anti-surface weapon. Their 5 in DD mount was SP. I think most of the protagonisits found the development of a true DP mount a bit of a challenge. The US did develop the 5/38, and various mounting types to go with it, but while the 5/38 was an excellent gun, it did give up a lot in range and hitting power to achieve that. More than the surface battle focussed Navies of Europe and Japan were prepred to give.

 

[Shortround6]

There was a lot more to designing and working with DP guns that a few calibers of barrel length and just getting the gun to elevate. The higher velocity guns used larger propelling charges and larger (heavier) cartridge cases. Higher velocity guns could need more room for the barrel to recoil, nor a problem at 30 degrees or under but a big problem at 45 degrees and above. The trunnions need to be higher off the deck. You also need room to load, Most (all?) of these guns used fixed or semi-fixed loading, Shell and cartridge rammed as one unit. It is tough to load while kneeling. AA guns not only need to elevate they need a high rate of fire. By the time you get a high velocity gun high enough off the deck to act as an AA gun it can wind up too high to a be a good surface gun. Instead of being loaded at waist/chest height it has to be loaded at shoulder/head height.

Picture of US 5in/25 figure how high the breech would be if the gun was level or slightly depressed.

5in/38 pedestal mount

Note height and rotating platform. It is the simplest 5in/38 mount, yet is larger and more complicated than the British 4.7in single mounts. It is also about 4-5 tons heavier.

 

[Glider]

I agree with what you say but the twin 4.5 as mounted on the pre war Ark Royal weighed in at approx 30 tons, the twin 4.7 as mounted on the JKN was about 25 tons.
The hull of the standard RN destroyer was based on the JKN so you could have had 4 x 4.5in DP instead of 6 x 4.7in SP and left yourself approx 15 tons for light AA. A quad 2pd was about 10 tons. So with no additional development costs or increase in weight you could have had a standard war built destroyer in 1939 with
4 x 4.5in DP, 2 x quad 2pd, 6 x quad 0.5 and 10 x TT. Sorry but that seems like a better all round job than was built

 

[fastmongrel]

The bit that I never understood was that pre war the RN had a DP 4.5in (on Ark Royal) and a DP 4.7in (on Nelson). Why they stop there develop one or both of these as a proper DP gun I will never know

The 4.5" on Ark Royal and the 4.7" on Rodney and Nelson were pure AA guns. They could engage surface targets but that wasnt there job and the mounts were only capable of depressing -5 degrees not enough for a DP gun especially when mounted so high above the waterline on the Ark Royal.

There was an experimental 4.7" +60 to -10 degree DP mount trialled in at least 2 ships but it was a victim of early thirties defence cuts and was never developed as it probably should have been. The RN decided that it wanted lots of small destroyers around the 1400 ton mark and it wasnt possible to build a small destroyer pre war with 4 x DP guns and 10 torpedo tubes and have good seakeeping. With the benefit of hindsight the RN would have been better off mounting 3 or 4 twin 4" DP mounts as the RCN did with its later Tribal builds.

 

[Glider]

I don't think that the -5 degree would be a problem as all the wartime 4.5in guns only had a depression of -5 degrees and I have never heard of an issue with this.
You are correct about the between the wars going for a 1,400 ton DD but when war broke out they went for a larger hull based on the JKN design. As shown by my previous posting I believe that we could have done better than we did with what we had available.

 

[davebender]

Germany 12.7 cm/61 (5") KM40 (Flakzwilling 40)
German 12.7cm/61 was potentially the best DP destroyer weapon of WWII yet the German Navy did not put it on a ship. It would have been a good weapon for Zerstörer 1936A class rather then historical 15cm/48 naval rifle. Would also make a good DP weapon for German battleships.

 

[parsifal]

Indeed. a formidable weapon. But too late in its navalized form to make any difference.

 

[davebender]

12.8 cm FlaK 40 - Wikipedia, the free encyclopedia

Development of the gun began in 1936

first prototype gun was delivered for testing in late 1937 and completed testing successfully.

Naval version of this weapon could have been in production by 1939 if Admiral Raeder wanted it. Early enough for Z1936A class DD and Bismarck class dreadnoughts.

 

[parsifal]

Not really. I am surprised that the gun was ready in 1937, Campbell says it did not begin naval rtrials until after 1940. In any event the 1936A (Z23-34) were already being launched in 1940, and were designed for a 5.9" main armament. The KM would have (mistakenly) considered a reversion to a 5" calibre as a backward step.

 

[DonL]

Neither the german 12.7cm/61, nor the german 12.8 cm FlaK 40 are DP weapons or to my opinion good designs for a DP weapon.
They were FLAK weapons not DP weapons.

The germans had to my opinion since 1934 a good 12,7cm DP weapon.
Germany 12.7 cm/45 (5") SK C/34

This gun had better ballistics then the USA 5"/38 (more muzzle velocity is better in the AA role), was reliable and a good gun for anti ship, which it showed on the Zerstörer 1934/34a and later Zerstörer 1936B Mob (Z35,Z36, Z43, Z44, Z45), which were back to the 12,7cm/45 sk34.

The germans totaly overslept to develop a proper turret (single or double mount), whith an elevation till 80 degrees (AA role), high training rates through motors and semi rammers, similar to the 5"/38.

From my research I have done till now, there were no technical problems to develop the 12,7cm/45 SK34 to a DP gun (with proper turrets), similar to the 10,5cm/45 C/32, which was a developed anti ship gun with AA turrets and which proved good performance at the AA role (with less good ballistics compare to the 12,7cm/45 sk34)
Germany 10.5 cm/45 (4.1") SK C/32

This gun was mounted on the Flottentorpedoboat 1939, which are to my my opinion the best german destroyers from a balanced design and seakeeping performance
Elbing-class torpedo boat - Wikipedia, the free encyclopedia

To my research Admiral Fuchs has also his hands on the not developed 12,7cm/45 sk34 in to a proper DP gun, as he has his hands on the not introduction of the Bofors 4cm AA instead of the 3,7cm/83 sk C/30 at 1936, as the major flaws of the 3,7cm were indentificated and the KM wanted an other AA in the 4cm region.

 

[davebender]

Flottentorpedoboat 1939, which are to my my opinion the best german destroyers

I agree. Germany should have built these inexpensive ships like hot roll starting in 1934 rather then building more expensive fleet destroyers.

http://www.german-navy.de/kriegsmarine/ships/index.html
RM 13 million to RM 13.7 million. German fleet destroyers.
RM 5.7million. FTB1939 class.

4 x 10.5cm DP main guns.
4 x 3.7cm AA guns.
2 to 9 20mm AA guns.
6 x 21" torpedo tubes.
50 mines.
32 knots. 2,400 miles @ 19 knots.
.....IMO exactly what you need for coast defense and the price is dirt cheap. You can build two FTB1939s for the price of one fleet destroyer and have a bit of change left over.

 

[parsifal]

They certainly look impressive, but the first was not available until the beginning of 1942.

How do they compare to the Hunt Class? Type II appears to be the nearest equivalent with the following characterisitics


Displacement:

1,050 long tons (1,070 t) standard
1,435 long tons (1,458 t) full load
Length: 85.3 m (279 ft 10 in) o/a
Beam: 10.16 m (33 ft 4 in)
Draught: 3.51 m (11 ft 6 in)
Propulsion:2 Admiralty 3-drum boilers, 2 shaft Parsons geared turbines, 19,000 shp (14,000 kW)
Speed: 27 knots (31 mph; 50 km/h), 25.5 kn (29.3 mph; 47.2 km/h) full
Range: 2,350 nmi (4,350 km) at 20 kn (37 km/h)
Complement: 168
Armament:

• 6 × QF 4 in Mark XVI guns on twin mounts Mk. XIX
• 4 × QF 2 pdr Mk. VIII on quad mount MK.VII
• 2 × 20 mm Oerlikons on single mounts P Mk. III
• 4 × 0.5 in Vickers machine guns on twin mounts Mk. V, later replaced by 4 × 20 mm Oerlikons on twin mounts Mk. V
• 3 × 21 in (533 mm) torpedo tubes
• 40 depth charges, 2 throwers, + 1 rack


cost £352,000


By comparison, the Elbings were as follows:


Displacement: 1,295 long tons (1,316 t) (standard), 1,755 long tons (1,783 t) (maximum)
Length: 97 m (318 ft 3 in) (w/l), 102.5 m (336 ft 3 in) (o/a)
Beam: 10 m (32 ft 10 in)
Draft: 3.22 m (10 ft 7 in)
Installed power: 32,560 shp (24,280 kW)
Propulsion: 2 × Wagner geared steam turbines, 2 × shafts
Speed: 32.5 kn (60.2 km/h; 37.4 mph)
Range: 2,400 nmi (4,400 km; 2,800 mi) at 19 kn (35 km/h; 22 mph)
Complement: 205
Armament:

4 × 105 mm (4.1 in) guns
4 × 37 mm (1.46 in) anti-aircraft guns
9 × 20 mm (0.79 in) anti-aircraft cannons
6 × 533 mm (21.0 in) torpedo tubes
50 × mines


It looks to me these two classes would have been very evenly matched . The Elbing was larger, and faster, but i think the Hunt is more heavily armed, except for torpedoes. Probably the british design was a more efficient ASW platform and with slightly deeper draught may have been more stable, although not necesarily. The German design was slightly longer ranged.

An interesting match up in my opinion.

 

[DonL]

@ parsifal

The german Torpedoboats 1935 and 1937 (not E-Boats) prequels to the Flottentorpedoboat 1939, were Vessels after the London naval treaty, not larger then 600ts. To construct a Torpedoboat only with 600ts was impossible, as the Torpedoboats 1935 and 1937 has shown.

So the Flottentorpedoboat 1939 were in reality destroyers not Torpedoboats and were constructed after this worse experience with the Torpedoboats 1935and 1937 much more to destroyer standards. (So the Flottentorpedoboat 1939 was also a vialotion of the naval treatys).

The german had one realy intresting design with the training ship Bremse (1931).
German training ship Bremse - Wikipedia, the free encyclopedia
Bremse (1931)
http://www.marineoffizier.eu/KRIEGSMARINE/07-Kiel-Wiek-II/ASS_Bremse/images/hp-ass-bremse-fahrt.gif

It was a full designed destroyer without torpedo tubes (but which were planed to add later) and diesel engines.

To my opinion this design would be a realy interesting basic design for a reliable smal to mid destroyer class with very long range.
Bremse had at the beginning problems with it's seakeeping abilitys, but was rebuilt at 1934 and after that, was a realy good seaship, which could get full speed even at bad weather conditions. The diesel engines were quite interesting for the range, to escort the larger vessels.

To my opinion an improved Bremse design (with more power) would have had much more advantages to the KM then the large destroyer classes 1934/34A and Narvik class with it's unreliable powerplant and bad seakeeping performances.

 

[davebender]

Apples and oranges.

Hunt class were ASW vessels for convoy escort. FTB1939 were designed for coast defense. That's why Hunt class carry depth charges and FTB1939 class carry mines.