~ PAGE FOUR ~
It's taken a long time and a lot of hard work in my spare time to reach this point, but the shop and storage are finally set up and work on the Nautilus Minisub is underway again. This is my new office.
Wearing it's rotary collar, the dusty sub rides on a wheeled carrier in the shop.
We've obtained the shafts, bearings, seals, couplers, through-hull, and propeller shaft for the drivetrain.
Guidance control will be achieved via medical-grade 12-volt actuators to move the rudder and planes.
As of September 17th, 2018, I've purchased this 48 volt motor and controller system (with potentiometer instead of a twist grip) rated at 6 hp continuous and 16 hp for sprints of up to one minute. I could have gone bigger and more powerful (and still can if I later want to change the motor and controller) but I don't believe we'll need it. If this boat cruises in the neighborhood of 5 to 6 mph and can sprint briefly at a top speed of, say, 10 to 12 mph; that will be about right for performance, appearance, and spectator appeal. And even by conservative calculations, this system should be able to spin a 10" diameter by 10" pitch propeller fast enough to do that and maybe more.
So, with all the major components for the drivetrain and control system upgrades either on our shelves or in the mail, here's the plan. (1) Assemble and water-tank test the propulsion system and bench-test the guidance actuators. (2) Install them in the submarine using the original through-hull stuffing boxes and shafts; repacked, of course. (3) Install all previously-removed exterior metal plating so she looks exactly like she did during the proving tests of 1991. (4) Check and dry-test weight & balance and adjust component (battery) position as necessary to achieve normal CG with pilot weight in the cockpit. (5) Launch the boat and conduct surfaced and submerged tests of the new propulsion and guidance systems. (6) Modify the hatch, foredeck and pilot house for lighter weight and greater ease of access. (7) Replace the control through-hulls with pressure-compensated units containing bearings, seals, and packing on lathe-turned stainless steel shafts.
After the boat is running properly, I'll "put the icing on the cake" with exterior detailing as seen in 20,000 Leagues Under the Sea. Rakers, headlights, gills, hatches, skiff, anchors, fairings, and about 15,000 simulated rivet heads. All that good stuff. J
Tuesday, September 18, 2018: These are the basic components for the propeller shaft. Two pillow blocks support a stainless shaft with couplers; one mates to the motor and the other to the stuffing box. My only concern is that this shaft has a key slot cut from end to end and I'm wondering what that variance in weight might do when it's rotating at high speed. Might have to swap this for a better shaft. I'll see what kind of vibration we get when there's a motor turning it and decide then if it needs to be replaced. If not; this is what we'll be running.
Here it is lined up to measure the length. For the first tests I'll leave the end of the shaft from the JS-550 as is and turn a squirt drive in the test tank because (1) that will be easiest and (2) we already have the squirt drive. All I need to do is put a hydrostatic load on the motor. The JS-550 stuffing box contains bearings and seals and is watertight at moderate depths. But after the shaft leaves the pressure hull, it will also pass through a short pressure-compensated bearing-and-seal case that I'll have to make. That will ensure no water even gets to the stuffing box, let alone inside it. So the already slim chances of a propshaft leak into the pressure hull are greatly diminished. When the tank testing is done and we have to go to a propeller for the submarine, cutting this shaft off at the start of the taper will give us the perfect length to put a prop where it should be in the tail section.
Here's the JS-550 outbox, shaft, and pump we'll be using for the first load tests of the motor. All newly rebuilt and ready go. The water-testing tank will get a hole in the side that the stuffing box bolts onto. Inside the tank, the pump will be securely bolted to a 2X6 screwed to the tank walls, thus keeping the pump submerged. A big, heavy, glass table top will cover the testing tank and we expect to see some real action in there!
The stuffing box is watertight but again; I'm backing it up with an externally-mounted pressure-compensated bearing case so water shouldn't even touch the box's aft end. Another important function this unit performs is to act like a thrust bearing. Electric motors like mine aren't made to take the axial loads usually imparted by a propeller so some kind of thrust bearing is necessary to absorb that shock. In this case, the stuffing box is bolted to the hull and will serve as a very excellent thrust bearing.
Also today, we got a look at our new gas analyzer that will be monitoring CO2 levels in the passenger compartment. Above that are the position indicators and sensors we have for the rudder and dive planes.
Saturday, September 22, 2018: The linear actuators arrived and have bench tested OK. They are slower than I thought, though. I can use them to operate remote valves in the tailcone but for the controls I've decided to go with power window motors and regulators. The battery bears witness to how dusty it got in the shop before we did the Epoxyshield floor. Nice and clean down there, now. J
Also today, we added a controller heat sink and the Sevcon Clearview display to our motor order. The heatsink protects the controller and this readout provides necessary information if we want to alter the performance parameters of the motor. It will also come in handy when doing the wet-tank tests of the drivetrain to determine RPM under load and help us decide on the proper pitch for the propeller. Not inexpensive, but invaluable to the project so it had to be.
The company I bought my shaft couplers from only had SAE. The shaft is M18 X 1.5 so I adapted an SAE coupler to Metric. There's a rubber "spider" between couplers to absorb some shock. The only problem here is, this shaft is threaded to work with a squirt-drive that turns counter-clockwise and the Disney Nautilus prop turns standard. So after we finish the first tank-tests using the hydrojet, I'll have to modify it for a right hand propeller.The couplers come with four threaded apertures with allen-type set screws. I'll chuck it up on the drill press, drill through the coupler and shaft, and install a stainless pin as used in "pin drive" outboards; an easy fix that solves a serious coupler-mating problem.
And just for grins, I've decided to make the battery box and aft system control panel look like the ElectroVulcanic Generator described in my novel, VULCANIUM (The Secret of Captain Nemo and the Nautilus.) I recently learned there's a cool little plasma sphere device that, when combined with a battery box built like the first EVG mentioned in the book, will provide an interesting visual effect when the boat is on display. So tonight I bought one plus a USB battery pack to power it. If none of this makes sense, read the book; available at Amazon and Barns & Noble. (Shameless plug.)
My houseguest, Blackie La Goon, has been crashing in the Vette and is openly opposed to me working on it. No problemo, Blackie! I'm focused on the submarine at this time, so it's all good. Won't be long before you're gonna have to find a new place to sleep, though. And stop playing the stereo so loud at night, will ya? Sheesh! J
Monday, September 24, 2018: CONTROL ACTUATORS: The linear actuators are out! Too slow! Now, to actuate the rudder and diveplane outshafts and bellcranks, I've decided to use three of these power window motor / regulator units from a Chevy truck. I'll cut the section bordered in red away from the unnecessary metal; put a slot in the regulator blade where a ball-pin on the outshaft bellcrank will ride. Energizing the motor / regulator will move the bellcrank, outshaft, external bellcranks and connecting rods of the control surfaces themselves. Individual actuators on the dive planes allows for pitch and / or roll control via a four-way joystick switch.
I began the design work that lead to the Nautilus Minisub in the mid-1980's. I have always done my R&D with drawings like this. No CAD. This is all the visualization I need to know it will work. I save the detailed drawings until I'm making the actual part. Many guys I've seen online live to create and share pretty computer pictures of things they dream of building, and oftentimes that's as far as they ever get. (I call that"Analysis paralysis.") I'm the polar opposite of that. I develop the design in my mind by actually thinking about it, rough sketch it on paper, and build it out of steel. No time or need for anything else.
Saturday, September 29, 2018: CONTROL ACTUATORS: The power window motors work nicely! Perfect speed and plenty of torque. Checking the clearances in the tailcone near the propshaft through-hull, existing plumbing for the ballast tanks, and the location of the rudder through-hull packing gland; I might have to use a linkage (like the drawing above) for the rudder.
For the dive planes, I can turn that black regulator piece into the inner bellcrank by replacing the round pivot hinge with a square hole to fit the end of the dive plane through-hull shaft. That will apply torque directly to the outshaft without any additional bellcranks or linkages inside the hull. Simpler is betterer. J
Wednesday, October 03, 2018: PROPSHAFT: Been working on the drivetrain, minus the motor. Looking into mounting the motor as far aft as possible and measuring how that placement might conflict with the existing ballast plumbing and proposed electric guidance control mechanisms. Also seeing how that affects weight and balance. So far, it looks doable.
In this pic, I am checking the positioning of the JS-550 propshaft and gear box inside the tailcone where they will eventually be bolted to the end cap. There will be a bearing supporting the shaft at the end of that wrap-around cylindrical motor mount where the original Minn Kota trolling motor once resided. After we've done the hydrostatic loading tests of the motor using a jetski squirt-drive; I'll cut the shaft off at the start of the taper, put a 1/4" keyway in it and thread the end for a pin-drive propeller and nut.
ELECTRIC COMPASS, CLOCK, AND TEMP GAUGE: When I bought this inexpensive electric compass, I had my doubts about it working inside an all-steel double-hulled submarine and figured I could always put it in my truck. BUT IT WORKS FINE! Accurate compass readings inside the submarine and inside the shop to boot! Didn't have this back in '91. Sure will be nice to be able to actually navigate for a change. J
SALON WINDOW FAIRINGS: Years ago, I began making and assembling the paper templates for copper pieces that would comprise the salon window fairings. Today, I'm getting ready to strip a lot of the exterior sheet metal so I can perform major surgery on the pressure hull, but I don't want to lose what I've done for the windows so far. So I'm going to replace the lost (lower) paper templates and seal the shape with sheer fiberglass cloth and resin. I might even go as far as using Bondo to refine the shapes and then glue on the cabochons as simulated rivet heads. When it's done I will build a box-frame around it and pour rubber mold-making compound into it. That way, I will have a mold for making fiberglass salon window fairings in 1:10th scale; lamp bezel, panel lines, rivets and all. I decided long ago not to make these out of copper because insulating them from the steel (to avoid electrolysis in sea water) will be very difficult to almost impossible. I'll be using fiberglass and resin castings to detail other parts of the exterior, so why not make the fairings out of the same stuff? No reason. And I'll cast an extra to make a wall clock out of, too. J
Friday, October 12, 2018: THE MOTOR HAS ARRIVED! This is the ME1117 motor and Sevcon controller system I'll be running. 48 volts equals 6 HP continuous and 19 HP for "full collision speed." Next, I will assemble a battery pack and mount the entire drivetrain on a test bench.
Tuesday, November 06, 2018: We now have the four propellers we'll test the drivetrain with. We've covered a wide range of suitable diameters and pitches and will check how the motor responds to each. I'm pretty sure we're going to want a gear reduction box but first we'll test these direct drive.
ALSO: I am building my own 5-bladed "Hammerhead" propeller (ala the Disney Nautilus) out of steel. It will be functional but the design isn't very efficient so it will mostly be for looks. When we want performace, we'll be using something like what you see above.
Sunday, December 02, 2018: This morning I ordered a 2:1 GEAR REDUCTION for the drivetrain. Now, with the motor turning at a comfortable high end of about 4,000 RPM, figuring a 2:1 reduction and a 30% slip on the 12 X 12 prop, the calculated boat speed is 15.9 MPH. In a submarine of this size, type, and purpose; that should be plenty fast enough.
And this evening I made the bushing that will adapt the splined end of our metric JS-550 drive shaft to the SAE bore of our 12 X 12" four-bladed Michigan Wheel bronze propeller. I have the parts to adapt a shortened shaft via a series of reducer couplings, but that's more complexity and weight and I really don't want to have to cut this shaft if I don't absolutely have to.
The bushing is ground to the proper ID and OD, and the ID flares to conform with the gradual shaft expansion; making for a seamless transition without a "lip" or " gap" where the coupler stops and the propshaft begins.
With the prop and coupler installed as seen in this picture, the propeller is staunchly attached and true: zero play or wobble. It's a "pin-drive" propeller so I'll drill the shaft to receive pins fore and aft. Eventually I'll trim the end of the shaft flush with the prop and install a hemispherical cap as seen on the Disney Nautilus.
Mating the SAE propeller to the Metric driveshaft was the last major engineering / fabricating obstacle to a functional drivetrain. All I need now is the hardware to bolt everything to an 8' 2X10 and then we're ready to start testing on the bench and in the water tank.
=MORE TO FOLLOW=