www.Robse.dk - SSBN737, R/C Submarine

The sea trail, now what?

On saturday and sunday, April 12 & 13, I went and put my 99% completed sub in the test tank. This was the first time ever that power was turned on in water, to the complete system, all at once. The seatrail was a faliure, and the boat is back in dry dock. As a result, the web site about the sub will change a hole lot shortly.

Issues:
The surfaced waterline was off by quite a bit, and it proved impossible to add enough foam inside at the stern to correct this. The sub is too heavy.

The MBT system volume is too small to fully surface the missile deck and sail. The weight of this has been re-estimated to be app. 6lbs / 3 kg, and the MBT volume is only 1.6L all together.

The sensors for ALT (Automatic Leveller Trimmer) and ASAT (Automatic Surface Alignment Trimmer) sends confusing signals to the electronics, which at random blows the tanks or dives. The sensors are gold plated, but gets covered by some strange material from the water. (Electrolyses?)

The dive pump is inefficient even after pump and hoses has been cleared for air. At the same time, the stern MBT tank is almost ignored, as it’s the furthest away, with the longest hoses.

Success:
The bow thruster worked great, especially when the sub was sailing either direction.
The prop. was perfect for the sub, and was quick and power full in moving the vessel.
Self righting of the vessel was fine.
Drain holes in the bottom of the hull was large enough to drain quickly when pulled out of the water.

Plan:
Follow the K.I.S.S rule. (Keep It Simple, Stupid.) :-)))
WTC1: I’ll remove all of the active logic electronics, including ALT, ASAT and voltage alarm. I will keep the water sensors. Air pressure alarm will remain, though modified. Removing the ALT and electronic boards allows be to shorten the WTC1 by app. 5½ inch / 14 cm. Valves (two) will be controlled directly by the rc switches.

WTC2: Then I’ll remove six of the eight valves, and convert the dive system to a single-MBT system (Need to build a new MBT, placed in the center of the vessel). Removing the six valves would allow me to shorten the WTC2 by app. 5 inches / 14 cm as well, but I’ll leave this space open for the new electronic board. Besides, this is pretty much just empty, air-filled space, thus positive buoyancy. Five of the ten hose ports will be sealed.
The new dive system will operate the top ports of the MBT only, thus leaving the bottom port open to the sea at all times (Like real subs.)

Converting the sub to a single ballast tank boat eliminates the need for automatic levelling (ALT), and I really don't need the system (ASAT) that allignes the sub with the surface when surfaced. Suppose I'd like to over-surface the sub to cross shallow water? Can't do that with an active ASAT system.
Thus: Both systems are out, and thus some sensors. Also out is the emergency surface system and voltage monitoring. Nice to have, but not essential.
A failsafe will be added to surface the sub in the event that radio is lost, as this was done by the now scrapped voltage alarm in the old days.

Also, the rudders push-rods will now go in a straight line from WTC1 and to the control surfaces, because these no longer needs to go under the stern ballast tank. This should improve the rudder function even more.

Removing compartments, and shortening one, gives me plenty of space within for the new central ballast tank (MBT), as well as foam etc. The new design lets me reuse the electric cable network installed in the sub. The 2Hz pulse generator for the nav. light must be re-build on a new PCB, and put with the three remote controlled swiches, and the bow thruster control. Five bulkheads (+ the single one for the sensors) will be removed as there will no longer be a compartment to hold.

The new design will be simple, thus reliable. Weight will go way down, and all parts needed for the new design can be taken from the present design. Parts left over will go to other projects. Of cause this was not quite the plan, having to rebuild, but at least the only cost will be time. I’m considering using the batteries for the Emma model until the sub is ready again, because these has already been on the shelf a while already.