WIP - HSK Kormoran

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 From:  Mark Brown (MABROWN)
3130.1 
Hi Everybody,

I have started the third of five ship models, the German armed auxiliary cruiser HSK Kormoran. This model can be considered the companion piece to the model of HMAS Sydney II. I hope to do some renders of the two ships in battle.

Kormoran is a famous ship, at least to Australians, made even more so by the recent discovery of her wreck. She was responsible for what must be one of the most remarkable of naval victories when she sank the vastly superior HMAS Sydney II. The two ships fought a point blank gun battle leading to their mutual destruction and for Sydney the loss of her entire crew of 645. Kormoran's success seemed so unlikely that doubt has been cast on the legality of the Kormoran's actions ever since. It can be safely said I think, that at 1000m Sydney had little advantage over Kormoran and in fact, in the opening salvos was disadvantaged by reliance on those "advantages". In something of a pub brawl, she was king hit at the outset and it is amazing to me that she managed to hit back at all.

Kormoran is a difficult ship to research. There seem to be few photos of the ship, perhaps because of the secretive nature of her war service and the lack of glamour attached to it. Thanks to Jean-Paul I have a set of Russian hull curves and profile to use (which look simple but are quite nicely drawn). I also have another profile drawing for reference and a handful of useful Wikipedia photos. Finally there is an NNT model of the ship for which I have found a useful review and a very nice completed model. Link to the scale model for anyone who wants to know what this 3D version should probably look like: http://www.modellversium.de/galerie/5-schiffe-militaer/1998-hilfskreuzer-kormoran-nnt-modell+buch.html

I have rambled on! Shots of the start of the model....

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  Mark Brown (MABROWN)
3130.2 In reply to 3130.1 
Deck trimmed and hull halves blended.
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 From:  JPBWEB
3130.3 In reply to 3130.2 
Hi Mark,

Nice start! What technique did you use for shaping the hull?

It is hard to say from your screen captures, but did you take into account that Kormoran was a twin screw ship?

Keep up the good work!

Jean-Paul
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 From:  Mark Brown (MABROWN)
3130.4 In reply to 3130.3 
Hi Jean-Paul,

Thanks for taking a look. Yes, I realised that she is twin screw but have to admit, I find the design a little strange. The cutout in the hull is what I would have expected for a single screw (assuming of course I'm looking at the plan correctly). Perhaps the hole through there was simply to leave enough room for closely placed propellers? Let me know if this is wrong (I hope it isn't because I found it devilishly hard to do).

I basically used your network technique but did it in halves and mirrored. I blended the two halves. Stern around rudder/prop area required a lot of point manipulation. Even then I didn't notice that my stern had a couple of substantial undercuts. I'm attempting a cut & shut now which looks like it will work. These are not easy things to model!

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  JPBWEB
3130.5 In reply to 3130.4 
Indeed, that screw thing got me puzzled too. It seems that the cut-out in the stern was because the two screws were very close to each other. I could not find any photo of that feature anywhere on the web. The other possibility would be that the blueprints are wrong. The good thing about lack of documentation is that you can go either way and nobody will be able to prove you wrong.

Nonetheless, modelling an obscure ship brings some serious challenges, as there are features of this ship that are not common, such as the collapsible gun platforms, the hatches concealing the guns in the hull etc.

Here is an interesting photo of the gun emplacements in the bow of the HSK Atlantis. I guess that Kormoran’s would have been similar with different guns though as these were WWI vintage while Atlantis had received modern 150mm quick firing guns.


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 From:  JPBWEB
3130.6 In reply to 3130.5 
There is a thread that you might find interesting and inspiring at http://www.shipmodels.info/mws_forum/viewtopic.php?f=13&t=45785

It is a relation of scratchbuilding a 1/400 replica of HSK Penguin, Kormoran's little brother.
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 From:  Jamie (FUTUREPROOF)
3130.7 
Hi

Saw this on a rhino site thought it might be interesting for you guys. A way of hull building, probably already known to you but thought id post it in case.

http://rhinocentre.blogspot.com/2009/11/rhino-rapid-hull-modeling-methodology.html

Regards

Jamie

edit: Forgot to say great work and I enjoy following the building process.
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 From:  Mark Brown (MABROWN)
3130.8 In reply to 3130.7 
Sorry for the slow reply guys. I couldn't live with the hull and started again. I have saved 59 times as I've attempted to create a fully one piece hull. In the end I couldn't achieve it and the very tail of the rudder section is a separate network. I persisted with it more as an exercise to see if I could do it one piece rather than any particular need for it to be one piece. At least this way the undercuts have gone.

Thanks JP for the photo and particularly the link to that scale model build. What an amazing model it is. I wish it was Kormoran he was doing. I'd have all the references I would need then. How is your model coming along?

Thanks Jamie for your kind words and interest in the model. Yes, I did know about the Rhino tutorial. We went through a lengthy post here throwing around ways of doing these hulls with MoI. In the end it was Jean-Paul's network method which has worked best for me. Normal and loose loft both had disadvantages I found, with loose loft creating a really nice smooth hull but one that wasn't close enough to the shape I needed at the deck line. I got a nice hull once lofting by waterlines rather than stations as shown by Burr but then couldn't replicate it a second time. Perhaps I'm missing a crucial point in that Rhino method. Perhaps it is those angled stations? One of the things that limits the way my hulls are done is lack of available info. I'm almost always limited to stations in the plans I have. Also, looking at the Rhino loose loft, it is too loose for my liking and wouldn't be accurate enough to represent a real world ship. A loose loft which could smooth out the inaccuracies in my station curves while at the same time maintaining that line at the deck would probably be ideal. That said, I think network largely achieves this in MoI with the waterlines seeming to direct the network somehow.

One thing though is that I'm still using more stations than Jean-Paul, particularly on this hull. I have found I need them to get the shape I want.

I'm rambling again so a couple of progress shots...

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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 From:  JPBWEB
3130.9 
Hello Mark,

Well, like you, I did not like the hull I got, and I rebuilt it sooo many times. The rudder area is troublesome because it changes shapes so radically in a small area. This is probably a limitation of NURBS. It think it best to append a separate rudder area and blend it to the hull. This is a challenge of its own though because of continuity issues, hence the effort to generate a one-piece hull in the first place. MoI (like Rhino, to be fair) does not have the sort of continuity tools that high-end 3D design products offer. I have become less obsessed with continuity but there still needs to be a reasonably smooth connection between hull parts.

Another area of frustration was that there are a few parts of the hull that need to get depth (at the bow mostly). This should be an easy case of using the Shell command, but for some reason, those parts when given depth, will not merge with the body of the ship (using Boolean). I suppose it is because there are tiny areas that are empty spaces where the parts do not overlap. I have resorted to giving the entire hull the required depth and then build up the enclosed space that forms the biggest part of the hull.

On the hull generation matters, I would suggest the following guidelines that come from long and painful experience:

• Try to generate your hull in one go inasmuch as it does not interfere with making a hull with the correct shape.
• Do not fiddle with curves manually. Use blend (with “vanilla settings” i.e. bulge=1) as much as possible. Often, Tangency is more than good enough. Resort to G2 and G3 only in case of dire need.
• Only use as few stations as possible. More is definitely less
• Use as few different shapes of stations as possible. Much of a ship hull is a variation of the master frame. Often, transition between different shapes is best left to MoI. Sometimes, an intermediary station might be useful though.
• Remember that most plans are second or third hand information and might not be accurate at all. If a hull “looks” right and is smooth, nobody will be able to prove you wrong.
• Disregard plan lines for building the hull if you need to, but check your work by projecting verticals that should match the plan reasonably and give you a body plan that “feels” OK.
• If you need to, make some parts of the hull as a separate fixture, but use the best blend you can. MoI does not have analysis tools, but Rhino has pretty good ones.
• Render your hull frequently while in WiP. MoI surfaces often look wonderfully clean, but are not, and sometimes the engine shows kinks etc. that are not really there. Rendering is the best way to “see” for yourself.

I will post some WiP shots as soon as I get the chance.
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 From:  BurrMan
3130.10 In reply to 3130.9 
Remember to incorporate the "Coninc Curve" tool when you need to add on the small piece in the rudder area. If you can get your trig points, it will do a great job of keeping continuity in your curve drawing attachment points. You can always cut it in half after if you are working in section mode.

FYI.
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 From:  Mark Brown (MABROWN)
3130.11 In reply to 3130.9 
Many thanks for those tips Jean-Paul. I do a number of them now and definitely agree with the render often one (btw, what do you use for rendering?).

>Another area of frustration was that there are a few parts of the hull that need to get depth (at the bow mostly). This should be an easy case of using the Shell command, but for some reason, those parts when given depth, will not merge with the body of the ship (using Boolean). I suppose it is because there are tiny areas that are empty spaces where the parts do not overlap. I have resorted to giving the entire hull the required depth and then build up the enclosed space that forms the biggest part of the hull.

I'm having trouble guessing what these parts are. Do you mean depth for decking?

I'm looking forward to those WIP shots

>Remember to incorporate the "Coninc Curve" tool when you need to add on the small piece in the rudder area. If you can get your trig points, it will do a great job of keeping continuity in your curve drawing attachment points. You can always cut it in half after if you are working in section mode.

I'm having trouble working out what this is too. Is this a script I don't know about?
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 From:  BurrMan
3130.12 In reply to 3130.11 
Mark,
Its under the points and helix tool. THe edges will remain tangent to the pick points...
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 From:  JPBWEB
3130.13 In reply to 3130.12 
BurrMan,

I am sorry, but I do not get the point. I know the Conic tool and what it does, but how do you suggest we use it in this context?
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 From:  JPBWEB
3130.14 
Mark,

For rendering, I use Flamingo, that is a plugin for my Rhino 3.0. It is a relatively rudimentary tool as renderers go, but a notch above the built-in renderer in Rhino, and the biggest advantage is that I can just copy a model in MoI, paste it into Rhino and get it rendered presto. No file saving, no export, no conversion. Just plain workflow.

For more serious rendering, I export my model to Luxology Modo. I hasten to admit that I do not fully master that beast, by far. Even lighting and displaying a simple scene seems to be soooo awkward. I suppose that I am a bit dense, as it seems that others can get wonders out of Modo, but when I read their description of how they did it, I do not even understand much of it, let alone replicate it. How frustrating! In fact, I sort of like Modo, but I wonder why. Joke apart, I just cannot get myself in the mood of subD modelling, but if I did, I am sure that Modo is a great tool.
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 From:  BurrMan
3130.15 In reply to 3130.13 
Hi JP,
I screwed up....I was in My mind and when i got to MoI and tried it, I couldnt do what I was thinking it would do for the tail sections....

My bad. Thanks for looking out for me there! Sorry to mislead.
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 From:  Denis (SPACELAND)
3130.16 In reply to 3130.8 
Wow nice tries to do that in one piece.

I know you will be able to do that one. A lot of work but practice is the best teacher to learn.
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 From:  JPBWEB
3130.17 
Hi Mark,

I have good news and bad news about Kormoran.

The bad news is that the Russian drawing you and I used as a base is probably very wrong in the rudder area. It seems that whoever drew the plan used a single screw ship setup for what is in fact a twin-screw ship. I suspected that much early on and could not find a single photo of a multiple screw ship that would have a gap in front of the rudder. This was confirmed today from knowledgeable chaps at the modelwarship.com forum.

The good news is that the proper setup is much easier to model, much like a sailing ship in fact, with a keel extending nearly to the stern but no extension.

That puts a final nail into the coffin of that nagging doubt. Now I can resume the modelling of Kormoran. Still no luck finding proper photographs of a WW1 vintage 15cm gun though. All the ones I have show only the business end of the gun into its casemate. No view of the breech whatsoever, except from a single drawing.

But I guess that a contemporary smaller gun might be similar enough for our purposes.

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 From:  JPBWEB
3130.18 
It seems that Kormoran's rudder and propellers would have been very similar to Altmark's, a contemporary ship that was used by the Kriegsmarine as a support ship for the Graf Spee. Here is a view from my friend Peter Lienau.
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 From:  Mark Brown (MABROWN)
3130.19 In reply to 3130.18 
Hi Jean-Paul,

Sorry for my slow reply. I think I mentioned that my employer was going to give me a shot at some drafting work. Unfortunately never happened (don't think it was ever really going to). Most of my time the last couple of weeks has been devoted to finding a new job.

Thanks for all the excellent info for Kormoran. I hunted down your Model Warships forum thread. Very helpful stuff. I had a devil of a time undoing the incorrect stern I already had. I had gone too far with other work on it to start from scratch. I think it has come out OK though. Some screen shots attached.

How is your Kormoran coming along?

---
Mark
http://www.homepages.ihug.com.au/~mabrown/index.html

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