real mistake the Admiral Hipper class and destroyers?

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Urmel
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Re: real mistake the Admiral Hipper class and destroyers?

#16

Post by Urmel » 25 Feb 2014, 18:47

LWD wrote:One thing that puzzles me is that I seem to recall that one of the reasons the S-boats were considered so good was ther diesel engine and they certainly were capable of good speeds for their type. What am I missing here? Lack of armor and light weapons?
Very simply:

S14-S-25, 39.1 HP/t displacement (115t - that's loaded, apparently)
Z51: 27.3 HP/t displacement (standard) or 24.5 HP/t displacement (loaded)

S-Boote had a 43% (vs. standard) or 60% (vs. loaded) power advantage.
The enemy had superiority in numbers, his tanks were more heavily armoured, they had larger calibre guns with nearly twice the effective range of ours, and their telescopes were superior. 5 RTR 19/11/41

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Re: real mistake the Admiral Hipper class and destroyers?

#17

Post by LWD » 25 Feb 2014, 23:28

I'm guessing they achieved this by the following:
1) No armor
2) relativly light weapons (save the torpedoes)
3) Fairly short range (compared to DDs and up)
Anything else?


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Re: real mistake the Admiral Hipper class and destroyers?

#18

Post by Urmel » 26 Feb 2014, 00:07

Much smaller size. Big engines.
The enemy had superiority in numbers, his tanks were more heavily armoured, they had larger calibre guns with nearly twice the effective range of ours, and their telescopes were superior. 5 RTR 19/11/41

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Re: real mistake the Admiral Hipper class and destroyers?

#19

Post by LWD » 26 Feb 2014, 00:57

If it was just size then it should scale. Both displacement and engine power should scale with the same factor, at least I think so. So one needs to look for areas that either didn't scale.
The S-boats didn't have any armor so there's one area. Although I'm not sure how much armor DDs had. Probably more structural steel though.
Looks like they had less than half the range of a DD so there's another area where mass/volume savings could be made.
Crew looks like about 4 per 10 tons for the E-boat and 1 per 10 tons for the DDs. However I'm not sure how that should scale. The E-boat may have not had much in the way of crew quarters either 800 miles at 30 knots isn't much over a day's journey, while 1,900 miles at 19 knots is 4 days.

I can see a number of possibilities but I'd just be guessing.

Just thought of a relevant question. I was assuming engine power scaled as the cube of the linear dimensions like volue. Does it instead scale as the square? That would explain a lot.

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Re: real mistake the Admiral Hipper class and destroyers?

#20

Post by Urmel » 26 Feb 2014, 01:29

It strikes me as a non-sensical comparison.

So Diesel engines were great for an unarmoured, lightly armed boat supposed to go out on a nightly high-speed raid and be back by morning.

It doesn't follow that they will be good for a much larger vessel that should be able to attain about the same speed, go out on months-long cruises, and carry heavy weaponry, ten times the crew, supplies, bunkerage, ammunition storage, yada yada yada. The roles are so fundamentally different, you can't compare.
The enemy had superiority in numbers, his tanks were more heavily armoured, they had larger calibre guns with nearly twice the effective range of ours, and their telescopes were superior. 5 RTR 19/11/41

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Re: real mistake the Admiral Hipper class and destroyers?

#21

Post by thaddeus_c » 26 Feb 2014, 02:50

Urmel wrote:It strikes me as a non-sensical comparison.

So Diesel engines were great for an unarmoured, lightly armed boat supposed to go out on a nightly high-speed raid and be back by morning.

It doesn't follow that they will be good for a much larger vessel that should be able to attain about the same speed, go out on months-long cruises, and carry heavy weaponry, ten times the crew, supplies, bunkerage, ammunition storage, yada yada yada. The roles are so fundamentally different, you can't compare.
so a diesel would work in a pocket battleship or e-boat but not in something in-between?

for use in something like this http://www.german-navy.de/kriegsmarine/ ... index.html

not classed a destroyer by KM but it approximates a destroyer used by other navies.

in my novice mind it would be useful to use the same fuel as u-boat and carry torpedoes so both could be resupplied by the same "milkcow?"

the surface ship able to catch ships the u-boats couldn't, serve other functions when not raiding.

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Re: real mistake the Admiral Hipper class and destroyers?

#22

Post by Urmel » 26 Feb 2014, 11:54

thaddeus_c wrote:so a diesel would work in a pocket battleship or e-boat but not in something in-between?
Well in a Panzerschiff it gave you endurance, but not very high speed, and the ability to interchange fuel with standard merchant fuel (I believe). In an S-boat it gave you speed but not endurance. In an ocean-going destroyer, you need both, so not a good choice, given the technology.
thaddeus_c wrote:for use in something like this http://www.german-navy.de/kriegsmarine/ ... index.html
And I note these were specified with steam turbines at the same time as destroyers were specified with diesels. Why?
thaddeus_c wrote:in my novice mind it would be useful to use the same fuel as u-boat and carry torpedoes so both could be resupplied by the same "milkcow?"
A single Milchkuh would not be able to completely refuel such a vessel you imagine even once. What's the point, and the advantage then?

http://www.dubm.de/typ_xiv.html
The enemy had superiority in numbers, his tanks were more heavily armoured, they had larger calibre guns with nearly twice the effective range of ours, and their telescopes were superior. 5 RTR 19/11/41

The CRUSADER Project - The Winter Battle 1941/42

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Re: real mistake the Admiral Hipper class and destroyers?

#23

Post by thaddeus_c » 26 Feb 2014, 13:19

Urmel wrote:
thaddeus_c wrote:so a diesel would work in a pocket battleship or e-boat but not in something in-between?
Well in a Panzerschiff it gave you endurance, but not very high speed, and the ability to interchange fuel with standard merchant fuel (I believe). In an S-boat it gave you speed but not endurance. In an ocean-going destroyer, you need both, so not a good choice, given the technology.

believe the projected D-class successor to the Panzerschiff was still using diesel and was faster (larger engine?) but they increased armor and armament leading to the switch to turbine engine to keep the speed?
thaddeus_c wrote:for use in something like this http://www.german-navy.de/kriegsmarine/ ... index.html
And I note these were specified with steam turbines at the same time as destroyers were specified with diesels. Why?

they built ships with both power systems, was pointing out a CANDIDATE for diesel engine SMALLER than the actual testbed the KM used http://www.german-navy.de/kriegsmarine/ ... /tech.html if you compare the test bed destroyer with the 1936 turbine version the range doubled with no (projected) reduction in speed? but IMO the boat was too big, a better choice would have been a scaled up torpedo boat.
thaddeus_c wrote:in my novice mind it would be useful to use the same fuel as u-boat and carry torpedoes so both could be resupplied by the same "milkcow?"
A single Milchkuh would not be able to completely refuel such a vessel you imagine even once. What's the point, and the advantage then?

http://www.dubm.de/typ_xiv.html
PARDON ME, was using "milkcow" in a generic sense for supply ship. the advantage would be if there is a total fuel supply in the Atlantic on a variety of vessels, both submarines and my "dreamboat" Flottentorpedoboot 1944 with a diesel engine could be supplied even if, as you note, not filled completely by the submarine supply version.

the plan is to work within existing resources that were expended 5 Ad.Hipper class (1 sold, 1 90% complete? never launched), 40+/- destroyers, and since there is considerable overlap the torpedo boats from Elbing class onward they perhaps should be included.

while I tend to agree withe the sentiment that all KM surface vessels were a waste there is considerable evidence a complete focus on submarines would produce diminishing results.

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Re: real mistake the Admiral Hipper class and destroyers?

#24

Post by Urmel » 26 Feb 2014, 14:00

If you go for a smaller vessel, how can you sustain a raiding trip? You reduce space while increasing machinery size and weight compared to turbines. So you have now reduced endurance, ability to carry additional ammunition/torpedoes, spares and supplies, which means you are extremely dependent on the supply network functioning.

The dreamboat also has smaller calibre main armament, so it is going to be outgunned even by destroyers now, let alone 6" cruisers. It'll again be like the Falklands every time they encounter a target.

I just don't see it.

You overlook that the FTB44 was supposed to work as part of the fleet, not as a single raider.
The enemy had superiority in numbers, his tanks were more heavily armoured, they had larger calibre guns with nearly twice the effective range of ours, and their telescopes were superior. 5 RTR 19/11/41

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Re: real mistake the Admiral Hipper class and destroyers?

#25

Post by mescal » 26 Feb 2014, 15:24

Urmel wrote: You overlook that the FTB44 was supposed to work as part of the fleet, not as a single raider.
And this is by itself a very strong reason to have it on steam turbine and therefore bunker oil and not diesel.
Because it enables to refuel the escorts from the heavy units.

Else you may have a fleet with battleships still with reserve, but dry escorts. Therefore you have to curtail a search for the enemy convoys to find that damned tanker, and prey hard it hadn't been caught by the Royal Navy.
Olivier

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Re: real mistake the Admiral Hipper class and destroyers?

#26

Post by Polar bear » 26 Feb 2014, 15:48

hi,
LWD wrote:I'm guessing they achieved this by the following:
1) No armor
2) relativly light weapons (save the torpedoes)
3) Fairly short range (compared to DDs and up)
Anything else?
Well, not quite.
The boats built in 1944 were fast, had bridge armor (the so-called "Kalottenbrücke", LWD is wrong there, see picture in the link) and were rather well armed for their size with one 20 mm gun forward, a twin or even triple MG 151 behind the bridge and one 37 mm or 40 mm gun aft.
Of course they did not have "oceanic" range, but they could go, e.g., with a load of six mines in one night with high speed from Dutch ports to the Humber estuary and back which isn't bad.
Anything else: yes, hull design and the "Lürssen effect" http://www.modelwarships.com/reviews/sh ... 100-p2.htm

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Re: real mistake the Admiral Hipper class and destroyers?

#27

Post by LWD » 26 Feb 2014, 18:04

Polar bear wrote:...
The boats built in 1944 were fast, had bridge armor (the so-called "Kalottenbrücke", LWD is wrong there, see picture in the link)
So some of the late boats had a little armor. That doesn't invalidate my comment about the earlier boats and even the latter ones I suspect the weight of the armor compared to the vessel displacement was pretty minimal. Any idea how much this bridge armor weighed?
Polar bear wrote: and were rather well armed for their size with one 20 mm gun forward, a twin or even triple MG 151 behind the bridge and one 37 mm or 40 mm gun aft. ...
They were indeed well armed compared to other vessels of their size but that's not the question at hand. The question at hand is how heavy was their armament compared to DDs or cruisers takeing displacement into account.
Lets take a more detailed look at this.
Based on the following sites:
http://en.wikipedia.org/wiki/E-boat
http://en.wikipedia.org/wiki/Narvik_class_destroyer
The displacement ratio between a type 1936A destroyer and an E-boat (max or full displacemnt) was ~36:1. Standard displacement the ratio is ~32:1
Looking at:
http://www.navweaps.com/Weapons/WNGER_5-45_skc34.htm
http://www.navweaps.com/Weapons/WNGER_37mm-83_skc30.htm
http://www.navweaps.com/Weapons/WNGER_20mm-65_c30.htm
The destroyers armament (assuming a 4 gun version) weighed in at ~122,000 lbs and their ammo at something in excess of 43,000 lbs.
The s-boats (37mm gun for simplicity which is an over estimate) ~3,000 lbs and unfortunately no info for ammo.
and the 20mm gun (assuming a C30) ~1,100lbs for a total of 4,100 lbs
That's a ratio of ~30:1
So unless the ammo weight and or the magazines are enough to tilt the ratio it doesn't look like armament is the issue.
I don't have the weights for the torpedo mounts so it's difficult to take them into account. The torpedos themselves certainly would move the numbers in favor of the S-boats being heavily armed.
It does look like savings in armament mass won't account for the difference.

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Re: real mistake the Admiral Hipper class and destroyers?

#28

Post by Polar bear » 26 Feb 2014, 19:44

hi, LWD,

of course I can agree with your line of argument.
LWD wrote: So some of the late boats had a little armor.
Well, you have to say: most of them. All the boats in combat areas like the Channel or the Black Sea which did not have armor from the beginning got it later during 1943, or they were transferred to the training division in the Baltic.
Only the type S 30 and Type S 151 boats in the Med did not get it.

The weapons' weight were, as far as I could make ot
Torpedoes, 1,5 t each x 4 = 6 t
Bow gun 20 mm w/o ammo 0,5 t
20 mm Twin w/o ammo 3,5 t
37 or 40 mm gun aft w/o ammo 1,7 t

so you are, without artillery ammo, at roughly 12 t for a 100 t boat.

I've read somewhere, though I can't find the source in the moment, that bridge armor weight was approx. 700 kg

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Re: real mistake the Admiral Hipper class and destroyers?

#29

Post by Urmel » 26 Feb 2014, 21:20

LWD wrote:I'm guessing they achieved this by the following:
1) No armor
2) relativly light weapons (save the torpedoes)
3) Fairly short range (compared to DDs and up)
Anything else?
Again, big engines. The item you are overlooking in these questions is the ratio of engine size/weight to the hull.

I'm now making up numbers, since I actually don't know them, but let's say the S-Boot engines weighed 11.5 tons (10% of displacement), and the Z51 engines weighed 115 tons (5% of loaded displacement), then there's your answer.
The enemy had superiority in numbers, his tanks were more heavily armoured, they had larger calibre guns with nearly twice the effective range of ours, and their telescopes were superior. 5 RTR 19/11/41

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Re: real mistake the Admiral Hipper class and destroyers?

#30

Post by LWD » 26 Feb 2014, 23:27

Indeed but the question is, is that really the case? Or another way of looking at it. If the engine of the s-boat is 10% of the displacement what did they give up to get to 10% from the 5% of the DD? Structural material may be one. The S-boats may have been planeing hulls which would help as displacement hulls have a "hull speed" that's porportional to the length (or the squar root there of) so the longer the hulls the greater the hull speed. Exceeding the hull speed takes significantly more energy. However a planeing hull vessel doesn't have this problem. The hull design also seams to have been a factor but how much? The shorter range means that not as much of the displacement needs to be devoted to bunkerage and supplies or perhaps to crew quarters but that requires looking at just how much was devoted to the above. I'm sure there's a good answer it's just that I don't have a good feeling for what it is at this point.

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