A Report to the Cabal:
Yesterday the customer returned with the NAUTILUS kit and the items needed for me to convert this 31" static display into a practical r/c submarine -- a Futaba four-channel r/c system on 27mH (wow, Citizen's Band - I didn't know they still made radios on that once crowded 'toy' frequency!), three mini-servos, and a SubTech speed controller and angle keeper.
And I'll make a correction here. In the previous piece I miss-stated the WTC diameter as 2" In fact the WTC's, used aboard the 1/144 KILO and this NAUTILUS projects, are of 2.5" diameter.
I spent yesterday working to develop the propeller shaft gimbal, which will be mounted in the extreme aft end of the hull. This will permit deflection of the propeller shaft about the pitch and yaw axis. It's my intent to achieve control of the submarines through thrust vectoring -- as the planes on this design are not at all practical units in the 'real world.' Additionally, reports of the poor rudder performance from other modeler's who operate this type fictional craft persuaded me to employ not only the rudder, but the propeller, to effect the yaw forces needed to achieve reasonable turning rates.
Examination of the tight confines, where the gimbal would go, forced a discussion to employ a simple ball-in-socket type unit: I would turn a brass ball, its center bored hole to friction fit an Oilite bearing, that bearing with a bore diameter of 1/8" to pass the short propeller shaft. The propeller shaft would terminate at the after end of the ball at the propeller hub. At the forward end of the propeller shaft would be fit a Dumas type universal coupler, that coupler making up the an intermediate drive shaft, that makes up to the motor of the WTC.
The means of displacing the propeller shaft will likely be two teeter-totter arms, operated by the 'stern plane' and 'rudder' servos. The teeter-totter arms will push against an Oilite bearing around the shaft, mounted between the gimbal ball and Dumas coupler. Today's work will revolve around manufacture and setup of the two teeter-totter arms and creation of a NAUTILUS propeller -- an interesting, 'Tomahawk' bladed affair.
The kit is produced by an outfit called Totalimmersion, owned and operated by Lee Seiler. A well engineered and nearly flawless resin kit. Though of nearly 1/4" thick wall, the hull parts are hollow and do afford plenty of room for a 2.5" WTC and battery. A simply gorgeous kit, has to be seen to be believed!
This kit retails for $375. Mailing address is: Lee Seiler, P.O. Box 26, Swisshome, OR 97480. He'll take personal or business checks or money order. Lee makes these on a per order bases, so expect a substantial interval between your order and delivery of the kit.
The WTC-2.5/NAUTILUS is the designation I've assigned for this specialized cylinder. The cylinder features an aft mounted, coup shaped, 'motor bulkhead' which houses the servos, motor, push rod and watertight seals, external battery connection lugs, and receiver antenna. At the forward face of the motor bulkhead --and extending into the after portion of the clear Lexan cylinder -- are mounted the receiver, APC, and fail-safe. The internal 'ballast bulkhead' mounts the gas type ballast system actuation servo and watertight seal between the servo push rod and wet space forward of the bulkhead. The portion of clear Lexan tube between the ballast bulkhead and forward bulkhead comprises the ballast tank. I've test fit, in this shot, a 1500Ah gel-cell battery that will operate 'in the wet.' This is a free-flooding, or 'wet' type r/c submarine. Only those spaces within the motor bulkhead and cylinder will be dry The gimbal is a simple ball-and-socket type. No room for concentric rings and perpendicular axis pins here! The interior of the resin hull halves, in this area, were ground down to a nominal wall thickness of 1/16" to make room for the ball and its tight fitting socket (not yet formed in this shot). a 1/8" bore Oilite bearing has been press-fit into a hole that was bored into the brass ball - that drilling done on the lathe before the machine brass rod was machined to a ball. I've already fit an 1/8" stainless shaft into the forward end of the ball as I went about the task of using the ball to give form to the Milliput socket elements of the gimbal.
After I greased the ball element with silicon mold-release, I mixed up a small quantity of Milliput two-part epoxy filler and pressed amounts of this slow curing material into the stern sections of the upper and lower NAUTILUS hulls. I then pressed the ball unit half way in half of Milliput, giving form to the socket element of the ball-in-socket gimbal that will later permit three-axis motion of the propeller.
And here we have the two Milliput sockets. When these harden I will cup-out the forward portions of the Milliput to prevent interference with the propeller shaft as it is swung up and down and left and right, or any combination thereof.
Two plastic WTC foundations will attach permanently to the bottom of the lower hull. Hooks atop the foundations will permit me to attache the WTC in place. Registration between WTC and hull will be insured through use of a registration pin that projects from the forward foundation into a hole in the bottom of the ballast tank section of the WTC's cylinder.