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Cargil48
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 6:51 pm
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acelanceloet wrote: *
I am not certain a modification like this would actually work. Lenghtening the ship by about 40% without modifying the beam, hull depth and main cross section likely leads to an ship that breaks in half in the first storm. You also increase drag significantly, so all new propellers, propeller shafts, bearings and stern shape might be required. (or you'd drop speed by over 40%, as the new engines could not be anymore powerful then what was in the ship already) The larger size would also require a new rudder. You already fitted an modified bow...... all in all, building a new ship would be both faster, easier and cheaper..........
Hi. I said before the width would be altered with what I'd call a "revolutionary concept": the special 8cm thick armour against torpedos would not be welded straight against the hull's wall, but would be outward shaped, concave, like in the U-boats and would be welded in compartments and, obviously, waterproof. This way you gain a protection but also an increase in width (in total by maybe 1,5 meter). And I said also in the description made that this addition of shaped armour would have inside several walls which by themselves would add a significant amount of strength to the vessel, becauswe all would be welded to the outside shaped steel wall and on the inside against the original hull. And one could use them as ballast tanks as well, when needed. The main point is the hydrodynamics involved. It would make the old hull like a huge U-boat hull... it would add very little drag, since very streamlined fore and aft and improve stability and hull strength.

Regarding the costs: These improvements in my AU would have been made in the original Spanish shipyard right after the local civil war had ended. Spain was then more then eager to get work to do, jobs for their working population. Germany, as I said also, had its shipyards then at full capacity... The main reason for giving this work to the Spanish yard (with German technicians supervising it). And why would adding an external concave watertight shell make the total cost so much higher than building a new vessel? Compare the labor costs there with Germany's... already back then...

Another question: I don't understand the point where you say:
Quote:
You also increase drag significantly, so all new propellers, propeller shafts, bearings and stern shape might be required. (or you'd drop speed by over 40%, as the new engines could not be anymore powerful then what was in the ship already)
Did the U-boats have that amount of drag as you say? No. And yes, new engines, shafts, bearings, thrust blocks and screws would be necessary. Just like in a new project. And why couldn't they be more powerful than the original ones? Final comment: This is AU. I made this new project with discussion in mind. So please keep comments coming, I think we all enjoy the sharing of ideas and comparing points-of-view. Even weird ones, like mine here...

The finished ship, "DKM Prinz Alfons" escorting medium sized aircraft carrier:

[ img ]

And here the scheme of the propulsion on each shaft: two double acting 2-stroke Diesel engines coupled on each shaft, allowing the ship to sail with only half the power or do so with full power. Each engine has an output of 11.450 shp and drives massive four bladed screws. Total power is therefore 45.800 shp.

[ img ]

What do the experts say? Doable or not?

PS: This propulsion scheme I did does not reflect the real Diesel engines used, the ones of this project presented here are nine cylinder ones, not the massive V-12 shown in the diagram.


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acelanceloet
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 7:13 pm
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The "revolutionary concept" seems to be something that is close to bulges. That helps with stability, but none of the issues with the strength higher up in the ship are resolved by that.
The armour, similarly, would mostly be near the waterline? or would it be high up as well? if so, you would need considerably more then just 1,5 meters of bulges to offset that center of gravity height.

As for the increased drag. Drag is build up from some components. The drag from waves rises very quickly with added speed, but let's assume for a moment that your hull is after the rebuild so nicely shaped that the speed is the same and the wavemaking drag remains the same. Then you add 33% more length and the bulges. Let's say that this increases your wet surface with 40%. This means a linear increase of your drag with 40%. So, you would need AT LEAST 40% more power then the original ship to reach the same speeds, and that is if (and I consider that unlikely) the bulges, the new length etc did not increase the wavemaking drag.

My point about the cost was this: you are rebuilding the midship (new engines), adding new sections, rebuilding the bow, and rebuilding the stern, and adding bulges. All in all, you are building something very close to an all new ship without all the advantages of being an new ship from the ground up. So both from a design perspective (getting the best ship) a manhour perspective, a construction time perspective and a material cost perspective, it would be easier to build an all new ship.

Also, take a note that U-boats were very specific ships for a very specific task (you know, submerging and stuff). So if you say "Did the U-boats have that amount of drag as you say? No." I want to hit my desk with my head, to be honest.

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Cargil48
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 7:42 pm
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Okay, I want to spare you hitting the desk with your head because of me. It would cause pain. And that is not the aim of being in Shipbucket. While your technical talk was very useful and instructive, your last comment is offensive, to say the least. I don't need that, I dispise to be honest anyone who throws such arrogant talk at my face. Goodbye and be happy.


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acelanceloet
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 7:51 pm
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Sorry for being so blunt. What I meant to say, u-boats are shaped like that for a very specific reason. I got a bit annoyed by the assumption 'it works for a u-boat, so it should work for a liner/carrier' (I can guarantee you I didn't actually hurt my head hitting the desk, that might have come across stronger than intended ;) ) (I might have gotten annoyed because the sentence of yours came across as a bit arrogant, so maybe we just came across too strongly against each other)

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Cargil48
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 8:42 pm
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acelanceloet wrote: *
Sorry for being so blunt. (I might have gotten annoyed because the sentence of yours came across as a bit arrogant, so maybe we just came across too strongly against each other)
My sentence? Which sentence?


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acelanceloet
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 8:46 pm
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"Did the U-boats have that amount of drag as you say? No. And yes, new engines, shafts, bearings, thrust blocks and screws would be necessary. Just like in a new project. And why couldn't they be more powerful than the original ones? Final comment: This is AU. "
Probably you didn't meant it that way, but this came across a bit as 'it is AU so it doesn't matter if it would work or not, and this works on u-boats so it works on my ship as well, I am certain'

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Ultraking101
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 10:14 pm
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Just to add a comment about the carrier,
1. there seems to be a shading issue with the propeller as it currently looks to have been copied from elsewhere as noted by the different colours.
2. Also the planes seem to be outdated, I’d visit Cascadia’s collection of AU German aircraft in the plane bucket discussion thread that provides a multitude of up to date aircraft (just remember to cite him)
3. At the bow region I noticed 2 issues, 1 being that their is a multitude of overlapping lines that create the “Heavy corner effect” (see rule 2.1 in the style guide), I also note that several lines are not connecting with one another such as the lines at the bottom corner of the bow at the end of the shading region and near the deck where there is a point missing.
4. (Take with a heavy grain of salt, as it’s my opinion) check out some other ships in the forum, I’d recommend the Spanish cruiser design by dalamace in “Never Built” and try out using those porthole colours instead of the older blues on your current carrier, for my ships I use them on it helps them look a bit more realistic.

On another note, it’s a splendid design and a nice concept, all that needs to be done now is some good ole touch up on the design and some shading adjustments and you will be good

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BB1987
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 10:50 pm
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My apologies for joning this nitpicking bandwagon, but I noticed a few things worth of mention as well:
-the gun mount at midship just below the island is a Japanese twin 127mm DP gun, which is a bit weird to see on aGerman ship (other than that, the caliber is also odd for Germans which used 105mm guns more often).
-it seems that most of the flight deck grider and supporting structure, plus a sizable portion of the superstructure aft of the island comes from Charybdis USS Langley drawing.
[ img ]
-also, forward of the island there are a lot of small platforms, small ventilation hatches for the hangar and portholes that seem to match the very front part of PomboCZ IJN Hiryuu drawing.
[ img ]
As for the latter two cases, the amount of elements used from other people's work is enough to warrant them a name in the credit line.

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emperor_andreas
Post subject: Re: AU WWII scenarioPosted: August 6th, 2020, 11:01 pm
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I like the carrier...even noticed the nod to the Yamato-class by having the bridge structure exactly amidships. :D Nice work!

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Ultraking101
Post subject: Re: AU WWII scenarioPosted: August 7th, 2020, 5:02 am
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Here are a few issues that me and BB1987 where able to find. Pointed to the locations to help you edit
[ img ]

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