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Author Topic: German type VIIC or VIIB Uboat  (Read 10372 times)

JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #50 on: November 06, 2016, 04:53:10 am »

Ok here is my loft right now it is 24 sided to give it a cooler look when finished.

ok i have this at 1/64th scale at 400 ft or 75" and 12" diameter. That should give me plenty of room for stuff. I will next be adding top deck and ballast tanks along the side

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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #51 on: November 08, 2016, 07:56:28 am »

Ok so I decided to give a little info on lofting hulls as I know it. Some of you may know this already some may not so will just cover the basics

I have tables of offsets for the Balao class but most are illegible but it will have some numbers that will work for this demo purpose.

first lets have a look at the TOO and explain what we are looking at.
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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #52 on: November 08, 2016, 08:07:44 am »

ok there are 3 important bits of info on the TOO

1: frame number = when we convert the TOO for useable data we need to convert the frame numbers. on most ships the length of the ship in inches divided by the number of frames gives you the number of inches between each frame as in ships the stations are equally spaced. Subs are the same, However with ships and subs there are instances where this may not always be true. You will need to look at the lines sheet of the factory drawings to see if it lists any deviation from the norm.

2: Waterline = the top row shows the waterline dimension for each offset this is shown in feet and inches and later will need to be converted to inches.

3: Offsets = for each frame and waterline there is a set of offsets they look like 3-4-5+ or even 3-4-5-
    So what do those numbers mean. they are actually feet-inches-8th of an inch. the + or- means a fudge greater or less when calculating we use 1/16th of an inch which is half an 8th and works out fine in our lofting. so we need to convert the offsets to decimal inches.
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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #53 on: November 08, 2016, 08:28:39 am »

Ok so now how do the Tables of Offsets help us.

Well think back to basic geometry class in high school. what we will do is use these dimensions to plot points like on a graph.

the frame dimension tells us how far back from the FP our plot of dots will be. then the waterline tells us the height of our point and the offset tells us how far from the centerline our point will be.

so in the pompanito there are 20 waterlines 1 ft apart. so we will have a series of dimensions to plot us each station.

I use an excel spreadsheet for this. here is a blank example of one of my sheets. the blue area is where my station dimensions will be
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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #54 on: November 08, 2016, 08:43:00 am »

ok I will try to add my excel for a Fletcher class destroyer I did so that you can use it as a template and see how I arranged it.

I uploaded it to my website in case you would like to download it and use it for a template and to see how I set it up.

http://www.proflooney.net/FletcherOffsets.rar


Here is a screen shot of how I set the results up so I could copy them and make a txt file so that I could import the txt file or what is called a curve generation table into solidworks and have it generate the correct station shape for me.


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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #55 on: November 08, 2016, 08:56:40 am »

for each point we need to list in a separate line in this order (at least for Solidworks) Frame Dimension - Waterline Dimension - Offset Dimension

we do this for each offset listed. if there is no offset for a waterline we do not use it or it will draw a silly line we don't want.

so with the Balao in the middle we will use all 20 waterlines so there should be 20 lines for each table. unfortunately with Solidworks you will need to create a txt file for each station. Some programs like autocad you can use a comma or semicolon at the end of each table (don't know for sure what it is as I don't use autocad) and you can just use 1 txt file to generate all the curves.

Here is an example of my Fletcher class hull once i put all the curve files into it and it generated them. there will be some missing lines to the curves in the pictures but the keel and other parts are separate offsets that at the time of the photos I hadn't added yet.


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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #56 on: November 08, 2016, 09:12:19 am »

in conclusion not all tables of offsets will be accurate. you may find a weird bulge or inset in your curve. this was common at the shipyards and usually they adjusted their curves at the site and made notes on their floor plans but they didn't get added to the original plans. it is trial and error depending on the size of the bulge, but try adjusting the 8ths of an inch if that doesn't work reset the 8ths and adjust the inches.

the other thing is that there are several lines in the table you will have to figure out which line is the bad one. once you play around a few times you will get to knowing about which line the problem lies. and be sure once you fix the error to adjust it also in your excel file and save it so if you share it or redraw later you wont have to mess around.

I hope this helps people understand a little more about tables of offsets and maybe people have some in their reference along with the hull lines from factory drawings and wouldn't mind sharing with the rest of us and we can maybe come up with a series of excel files so people can more easily design some subs.

BTW sometimes tables of offsets are called lofting tables
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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #57 on: November 10, 2016, 05:54:05 am »

Well couple days ago i came across some fairly decent drawings for a German type VIID Minlayer sub. it has 5 banks of 3 mines on it and is something usually not done as most do the B or C model.

so looking them over and doing my research I have been doing I think I can possibly get this thing lofted up so will give it a try while i take a break from the steam punk sub so i can get some ideas for it as i got the outlines figured out but didnt figure any more on the design yet.

yesterday I got the top view traced and now i am home from work and off tomorrow will try to get the profile view traced then I can start working the loft.

so ifn I can get this lofted up this one will be 72" as a prototype boat I want to do a 1/32 scale which would be 94.875"
one thing i need to figure out is how I can split the sub in the middle to have a front and rear half for easier transport.

now for the items I want to have on the sub (some may not be feasible as this first sub so not sure what can and cannot be done)

1: working periscope
2: dunno which type ballast system is best yet still researching
3: front and rear firing torpedos
4: launchable Mines in a sequence not to have them all just pop out at one time
5: Possibly on the larger version moveable deck gun and possibly firing 22 blanks

will post pictures soon as everything is traced

since these drawings seem to show the pressure hull outlines to a point it may help me figure out how to draw the Balao. I need to get into the Balao drawings deeper as they may have offsets listed somewhere for the pressure hull top and bottom guide lines.

finally seems the more I play around bouncing along different types of subs I am learning more and more to where soon I hope to be able to draw up many different types of subs. I do have a future project as I found a really nice solidworks model of a deep sea rescue sub, so it will just be getting the parts made to kit it up.
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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #58 on: November 12, 2016, 12:45:53 am »

thanks i been there havent joined yet but I did work on a nuke sub like I said they are bland and boring looking but it will be something to start with to get the internals and WTC understanding going. like said have to do the designing solo as havent found ppl really into scratch designing to learn from. there is one site that mentioned some sub designing guru I have messaged him with a couple rookie questions but no response in a couple weeks.
here are a couple picks. I work the next 4 days in a row but will be working on the framing etc. will be approx 1/96 scale at 72" long

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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #59 on: November 15, 2016, 02:41:22 am »

well guys been silent for a few days I was studying plans for michael Bays new transformers movie there is a manned submersible in it and we  are bidding on the job to make the filming model so I was busy figuring costs, and design time,  machining time, building time, etc to reach the deadline.

due to certain issues that I cant share certain photos I can post one that isnt stamped private the rest are secret files which basically show detailed drawings and other stuff film doesnt want in public yet
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JosephHuntley

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Re: German type VIIC or VIIB Uboat
« Reply #60 on: November 20, 2016, 03:18:47 am »

well with the holidays been putting in overtime at work so not much chance to do a lot. however I have created an excel file for the Balao TOO and been putting them in. the offsets are a real PIA to read but I got  stations 70-137 entered now am going to guess at 1-70 stations since that sheet is really horrible to read.
 
 I also am still setting up the formulas for conversions and most of them are complete, and the second sheet which has the tables with all the final results for importing into cad to generate the stations is going well. the biggest hurdle of all is trying to just read the offsets. wished i had better tables like I had when I did my fletcher Hull but these were the only ones i could find and that was the ones from the Pompanito Museum site. hoping by maybe next weekend having a few of the curves generated in solidworks. If I can get several of the 1-70 lines generated mainly in the bow area I will be able to loft up the pressure hull decently
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