1/32 Scale Balao Class Sub

hey guys I am starting my design of a Balao Class sub. I was going to do a german type VIID but my drawings were really bad when zoomed in to see the dimensions so I went with the USS Pompanito a Balao class sub which is currently in drydock for refurbishment and normally posted in san franciso fishermans warf as a museum. I have gotten over 1000 shipyard blueprints fairly good quality so have decided to use it as my first sub design which I am doing in solidworks 2016

Ok so tonight was able to get all the planes located for all the bulkheads. tomorrow night after work I will work on drawing out the bulkheads and getting them onto the planes ready for surface lofting my hull shape

the bulkhead planes are all scale locations as shown on the blueprints. I will be using scale locations and station numbers for the design, then after I am finished with modeling the sub, i will work on the R/C stuff and working bits. Once that is all finished I will get rid of the unnecessary stations for the Model.

The reason I design this way is so I have plenty of stations to attach what I may need for R/C to without having to add more in later if I need one in a specific spot. I do this on my aircraft all the time and it saves me a ton of headaches when i add my working bits since I have the structure already there to work with. I know subs are different as the shapes arent quite as bad as an aircraft but this is a proven workflow for me that I will always use whenever possible

Tonight when I get home from work I will start tracing stations. the one problem I am having is finding the overall shape of the hull without the decks on top. i dont know how to explain what im trying to say as im not up on the terminology, but the tube part of the hull i need to figure out the proper outlines so I can get the height and width correct for my loft.

now I am just showing the bow section but it has a weird look (to me) being stair stepped instead of a smooth flow like i was figuring would be there for the hull tube. something else I will have to figure out, however it may be more apparent when I get the stations in place.

well I started tracing lines and was going to try and trace them and just go for it but my problem is lines run together and some hard to discern so i think I will try to find a good top view and profile view and loft it with minimal lines then use the loft for my intermediates. dont know how it will work but will try as this is getting frustrating as i am used to cleaner top and profile outlines and not compound shapes on the hulls because of a second part of the hull like subs have

well right now i jumped back to my 1/6th scale higgins landing craft while i try to figure out how to get the dimensions and outlines i need for lofting the hull for the sub. like I said the bulges on the side and the flat deck on top the sub hides the true outlines of the main sub body which is making it impossible to get the info I need to loft the hull

I was just messing around adding the TOO for my Higgins LCVP and it dawned on me maybe I can find the TOO for a sub. I have one for the Pompanito but the stern numbers are all covered with garbage from when the microfilm was copied. so maybe I can find some TOO for it online thats cleaner

I'm following this thread with great interest.
Further to our pm's here is the link for your drawings:

https://www.maritime.org/tech/drawings/index.htm

Sorry that new members are "locked- out" of posting links for 7 days. (An "unlisted-feature" I confess I didn't know about!)

David

thanks for posting that for me David. Last night i had got frustrated and had decided that for now just to get me a cool sub designed and not worry abt accuracy. to solve this I had decided to do something I havent seen before (but is probably out there somewhere) and do a Steampunk or Dieselpunk sub. would be cool with all kinds of gears and tubes on it. I still might but last night I had an epiphany and that is I need to trace the top view and profile view, then use those and the body plan drawings and enlarge them to match the top and profile view at the highest an widest part of the boat. doing this should get me close to the ballpark, and then with so many bulkheads along the length it will naturally give me the shape of the pressure hull. at least that is the theory.

I know most of this sounds like blubbering nonsense these posts, however there is a method to my madness. by posting my thought processes now as a totally lost noob, maybe others in my same predicament that are also lost but do not want to post admitting it may learn. also as you just noticed above, by rambling along i may have just found the solution to my problem. I do stuff for the movies, museums, and military bases with my planes so they have to be as accurate as possible, and over the years I got very good at finding the info I needed and drawing them up. So I am very Anal when it comes to designing as I need it to be almost perfect. I am new to this and having a lot of problems with finding my info and unlike in the plane world not a lot of people share what they have collected, or just that the info isnt out there. so if this works out for my hull design it will be a major milestone for me and i will just have to accept it as the best I can do for now until I can find some sub drawings with tables of offsets for the boat. once I have TOO and decent number of drawings I can just make an excel sheet and import the curve files into my cad program.

so bear with me as i blubber my way into something here soon as this has been mainly my research and learning and once i get going it will become more interesting. in the meantime as I work out the kinks in my theory I think I will do something steampunk and see if I cannot design a sub that will blow people away.

Well tonight started working on a second steampunk design as the first one is going to take a while to get all the proportions figured out. so this one will start with a basic cigar shape then add to it. will be much simpler for me for a first sub.

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

well I got the walkway and tower sorta fleshed out. I am using a 3D model image I came across as a base starting Point then will revamp a lot of stuff once I get the basic proportions fleshed out.

I tried to find a decent sized fiberglass hull or decent plans but man everything costs more than it cost me to do a 1/4 scale aircraft. weird how something like a simple fiberglass hull with nothing else runs over 1200 bucks. I used to be in the fiberglass boating industry so I know costs etc and there would be maybe a pint of resin in a hull and thats at todays rates of 35 bucks a gallon way less that 1200 bucks i mean they have like a 2k% or more markup

I still wished I could loft my own Balao hull but like said before I need to figure out a way to get the hull outlines

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.

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.

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

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.

Ok so we see where I converted the waterlines into inches.

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.

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

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

Proflooney wrote:

I know  most of this sounds like blubbering nonsense these posts ...

so bear with me as i blubber my way into something here soon as this has been mainly my research and learning and once i get going it will become more interesting. in the meantime as I work out the kinks in my theory I think I will do something steampunk and see if I cannot design a sub that will blow people away.

Looking forward to watching this project develop in whatever direction you choose to take it.

well working slowly adding offsets. atm with the holidays working lot of hours since i am in retail business so will be little slow til after xmas

Proflooney wrote:well working slowly adding offsets. atm with the holidays working lot of hours since i am in retail business so will be little slow til after xmas

Mo worries. Slow and steady is still progress. Happy holidays!