HrMs O-13 by FreekS - 1:50 - RADIO - 1931-1940 - Last Dutch Sub “on eternal patrol”

[FreekS]

I’ve gone down a bit of a rabbit hole! Having developed the idea of the functioning front diveplanes described above - the ideas for improvement kept coming! I’ve now got a prototype ready to be built into the hull, where the two movements of the front diveplanes, the folding and unfolding of the planes flush against the hull, and the up/down movement of the diveplanes when sailing under water, are achieved with just one servo.

 

 

the up/down movement is achieved with a white gear and a white linear gear. 

 

 

 

prior to folding, the planes are rotated vertical by these white 3D printed cogs. On further movement of the servo the linear cog runs out of teeth, and the white gear contain a magnet leaving the planes in the vertical parking position. Then a brass rod pushed in parallel with the white linear gear folds the planes via the brass gears previously described. A spring made from 0,5mm brass unfolds the gears as the servo retracts both rods until the linear gear re-engages. 
 

crazy complex, but it runs with little friction, uses less than 0,1 amps on a mini servo and uses no current when not moving. Very happy - will need to program an arduino to tie the servo movement to the “dive” and “surface” commands and the diveplanes signals from the transmitter.

 

now hopefully back to some woodwork, apologies for the distraction!

[Ian_Grant]

Very cool design, and an Arduino to come. Submarines are demanding technologically.

[Jim Lad]

Marvelous. Are you by any chance an engineer by trade?

 

John

[FreekS]

4 hours ago, Jim Lad said:

Marvelous. Are you by any chance an engineer by trade?

 

John

No! A chemist!

[FreekS]

Ok, further with self-taught engineering. Many if not all concepts below are well known in the model sub world, I did not invent them! I want to have a final design of the water-tight compartment (WTC) and its connections to propellers and rudders because only then can I plan and make the required holes in the wooden hull and finish the hull.

 

The WTC will consist of three connected PVC pipes connected with 3D printed parts

- aft: 44mm ID with the motor, motor controller, and two servos for the rudders and diveplanes, 

- middle: a 69mm ID pipe with the  dive tank (a 60mm PVC tube), the receiver, the pump, a self-made valve as well as the ballast tank controller.

- bow: another 44 mm ID pipe with servo for front dive planes and the batteries.

 

These components will be housed in a techrack which is pulled out of the WTC. I’ve been designing these in Fusion360 and printing them on my 3D printer. The techrack will be mounted on four M3 rods to give it strength.

here on the left the aft WTC , connected to a printed bajonet (located on the “cut” in the boat in background), and then to the right the beginnings of the techrack and dive tank 

The dive tank (here left) has a water-in and air-out brass connection. The resistance between these is measured by the dive tank controller to determine if the tank is full. The pump is a 500ml/min gear pump, and since gear pumps are not closed, I’ve re-purposed a mini-servo to pinch the air-out tube closed so no water leaks in when pump is idle. A 40 MHz 8 channel receiver will be mounted here as well.

the rear WTC with motor axle sticking out (through a seal) and two o-ring holders for the pushrods to the planes and rudder. The motor drives a gearbox “in the wet” which drives two shafts and 30mm Raboesch props. The white printed part will be glued to the PVC pipe, but the motor can be unscrewed from the outside so that the rear techrack can be removed for maintenance. The screws must be sealed.

 

here the tank again with its controller forward. Many electrical and signal wires will pass over the tank (which will be inside the 69mm ID WTC).

 

finally, I did manage to do a little woodwork, the main rudder consists of two 0,3 mm brass sheets soldered to the 3mm shaft, and then covered with two layers of 1 mm boxwood on both sides. then sanded in shape. Also the future mount of the diveplanes is visible.

sorry for the technical stuff - subs are a technical game, but I will get to the nice part of making the conning tower later!

[FreekS]

Further with the rear of the boat. 
the rudders and diveplanes are made by soldering a 0,5mm brass plate on the shaft, then covering it with wood before sanding. Here the diveplanes were added - these are controlled through a brass rod coming vertically down from within the boat. Should be near invisible

The prop shaft is a little too low here - it is driven from the above describes brass gearbox and fixing this meant reprinting the rear bulkhead of the WTC with a small 5 degrees offset from the horizontal. 
Both propshafts are reasonably aligned and holes made in the hull. The brass fins in below picture will be soldered to a structure in which the shaft runs and to the hull. This is a quite tricky part - I have little or no room for a proper motor-shaft coupling - so alignment must be very good to avoid vibrations. 

 

[Jim Lad]

Amazing work!

 

John

[Kuparu]

Amazing and challenging model and a very bold method of making everything accessible.  Can I suggest that you double check the direction your propellers will be rotating?  It looks as though you have a port prop on the starboard shaft. I am looking forward to the completion. Rod 

[FreekS]

Thanks Ron! I will watch that! I’ve been mounting and remounting the propshafts dozens of times to correct the alignement ! I’ll be mounting the gears on the shafts today I hope!

[KeithAug]

Very interesting mechanisms. I feeling the need to unpack the lego technics.