Hi all, I've been piddling around with making a destroyer using 3d modeling to layout the design and try out some different approaches to construction. Aigle just so happens to be one of my favorite DDs from World of Warships. So I figured, what the heck, let's turn this into reality. I aim to use this post as a chronicle of the design steps and changes. Please feel free to chime in with thoughts and comments. Constructive criticism is appreciated. First off, the design constraints for IRCWCC: 1. 35.17" Length , 3.25" Beam 2. Maximum weight of 5.05 lbs 3. 1.5 battle units 4. 21 sec speed Ok, now the model constraints 1. She's a twin prop boat on that narrow DD beam -> 10 pounds of flour in a 5 pound sack 2. Single rudder-> Give me 40 acres and I'll turn this rig around Given the above I expect her turning performance to be rather poor, but she'll run a straight line like a torpedo. With that in mind, I'll need to do my best in the layout and design to help offset this perceived disadvantage. Our reference photo so everyone knows what she's supposed to look like.
First, get your model or plans you want to start with. In my case, I got the STL model from gamemodels3d.com and imported the STL file into a program called netfabb to scale and pare down the model. Here's what it looks like when you first import it: And here's after it has been scaled and pared down. You have to hack off the extra details or the raw unedited STL file will eat your computer when you go to import into your 3d modeling software. Mine just happens to be Solidworks.
I did a very similar project, check out my Mogador thread. If you were interested in those files as a jump-start, let me know. -WT
FYI, if this is your first combat model, you might want to start with something a bit bigger, like one of the cruisers. If you put 5 lbs in that hull, it's not going to float. DD's are very low on the return on investment scale as it is. I ran my Le Terrible at about 3.5 lbs (on the correct waterline) and getting all the stuff in at that weight was a trick.
^This is true^ It's not easy with such a small hull, but like the title says it's for the fun of the build. I'm happy to have a tow boat if nothing else.
Per some advice of the gents above, I did cheat a bit on the depth(or draught?) of the hull. Using the scaling feature of netfabb, I added 10mm to the hull. Can you tell? Good thing about this method is that it doesn't make your hull lines look too far out of scale.
Looks pretty - just another note, you might want to check and make sure the deck step is reasonably close to correct, otherwise you might have some odd superstructure alignment issues.
Yes, as @Commodore said above, if you just warp-scaled the hull to add depth the deck step will now be too tall and the superstructure won't look right. Sure, you could skew the superstructure to match but A) that looks funky and B) you don't want to add topweight by making your superstructure bigger.
Thanks again guys for the advice. The difference in step height after scaling is only a few millimeters, so I'll shoehorn in the superstructure with a little whittling. Here's the rib lines punched out and the waterline drawn in as a plane. Should I add a little ledge above the bilge keel for the balsa sheeting to attach to?
Yes, but keep in mind that regardless of reason in order to be legal for IRCWCC the bottom of the penetrable window must be at least 1" below the waterline.
... or 45 degrees, whichever is less. Also keep in mind that certain hull features permit a stringer for balsa-gluing purposes. Review the rules, sign the wavers, and whatever you do don't feed it after midnight.
Alright, after a summer of "other" projects that life has thrown at me, I'm getting back to working on the Aigle. So, here's the drivetrain, mocked up. Not sure if I will stick with a gear drive, it's just that this DD is so tight, there's not a lot of options. Plus, have to get the props to counter-rotate to offset torque. Props will have a slight down angle and outward flair. I left extra space around the rudder servo that I can shim to take up slack in the chain drive for proper tension. I will be using that 0.1227" pitch chain from Servo City to drive the rudder. Tonight I'm printing a test run on the gear assembly to see how things work out.
You can't gear drive as drawn without universal joints. As a side note, I am interested and impressed in your netfab steps, as I haven't had a lot of success working in SolidWorks with WoW mesh files.
Yeah, I got lazy and didn't model the universals on the driveshaft. They're represented by the step at the ends. The key to get Solidworks to import the STL is to reduce the triangle count by deleting the super detail stuff in the Netfab editor. How many your Solidworks can import may depend on your computer specs. You'll have to play around with it to see what yours will handle.
Got the gearbox printed today. I must say I'm very impressed with the tolerances my 3d printer can hold. The bearings pressed in firm by hand and the gears meshed up perfectly. This one's PLA but the final version I'll probably make with PETG. I used the old offset gear trick to make the shafts counter rotate. The engagement is about 3mm overlap for them. Doesn't sound like much, but 304 stainless is pretty tough stuff. I'm confident any serious load on the shaft is going to cause the gear setscrew to slip long before the teeth give way. I still need to add retainer clips to keep the shafts moving about under forward or reverse thrust. Last pic shows the slight downward angle of the shafts and a bonus shot of the worlds smallest brushless pump.
Nice work, friendly advice would be to go with 2 gears on the port shaft to space out the pinion from the starboard shaft gear - looks like there is zero allowance for thrust motion as is, but some thrust motion should be accounted for. you could also get away with a smaller motor for a little DD
The original design did have the 2 gears on the port shaft, see above pics. However, I wanted to try this simpler arrangement, at least until I get the 3rd gear in the mail. If it don't hold up I can always go back. It will be interesting to see how much they move inder thrust. That's what the sea trials will be for!
Yes sir. I haven't even tested it yet, so it may be terrible. It does have a proper volute and impeller design, but I'll be trying several iterations to sell how things go. The hardest part is setting the clearances around the impeller. Too tight and it locks up or wastes most of its power, too loose and it loses efficiency rapidly. It's going to be tough.
