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.

[FreekS]

The diveplanes, rudder and propshafts have been finished - meaning they are functional and firmly attached, but removable for further sanding and coating. 
one very big risk is that I lack a flexible connection between motor and shafts - the prop - shaft - gearbox - motor turns easily but I’ll have to see if vibrations don’t cause problems.

I’ve assembled the main control components, they slide onto 4 M3 wires to form the “techrack”. This assembly slides nicely into the PVC pipes that keep the water out. The home made bajonet needs some more thought - having only two bolts to connect the two halves of the boat means it rotates a bit too easily.

ive now started on the sail - which will be built of 1mm boxwood on a frame - has some acute curves through. 

[KeithAug]

The build continues to fascinate. Your workmate looks in much better condition than mine. I have the original with a cast aluminium frame. Probably 45 years old now.

Is the sub in the case a Holland?

Edited May 23 by KeithAug

[FreekS]

Hi Keith, 

 

that workmate is 37 years old! But I only started modelling in 2009 so maybe it’s had an easier life than yours!

 

yes that model is a 1:32 Holland class; its O-1, the first Dutch submarine built in 1905. It’s about 10 years old and sails well! Like O-13, it’s made of wood with a dive tank inside.

[Jim Lad]

Now she's looking like a real submarine. Hope you find a good solution to your loose joint problem.

 

John

[FreekS]

Been a while since the last update. Much time has gone into repair of other subs post sailing - either by being rammed by unobserving skippers of (surface) models, or by time causing small leaks. 

found time to continue work on O-13 too.
The joint problem seems to result from the PVC pipe not being exactly centred on the bajonet. A few wedges have improved the situation a lot!

 

The sail has been roughly built of wood - with some thoughts as to make moving periscopes, a captain on the bridge that disappears below when the boat dives, and room for LEDs. I might include one of the 40mm guns that sit in waterproof buns. I think the boat carries only one (and no deck gun) as it had chronic stability issues! Not sure about the movable persicopes, the WTC directly under the sail means they would only rise 5 or so cm, seems not worth the trouble to construct pushrods to a servo inside. 

 

the front of the boat now has the covers for the front dive planes and spaces for the anchors constructed. Needs quite a bit of fine tuning too. 

[Jim Lad]

Sorry to hear that you've had problems with surface ships attacking your subs.

 

The captain who goes below when the sub dives sounds like a great idea, but I agree with you that a periscope only moving 5cm hardly seems worth the effort.

 

John

[Mirabell61]

FreekS

Very interesting technical design and work, well done !

Just a question :

Is it realy possible  to RC-control a submerged sub, once its submerged you ca`nt see it any more ?

 

Nils

[FreekS]

@Mirabell61 yes, that is exactly the problem. Skippers of surface models don’t spot a submerged submarine! Sub skippers always keep their eye on the tip of the periscope, the periscope wave, or slight decolorations where the boat is under water. That’s why sub skippers never remember who they were talking to at the waters edge!  
Generally, you sail as deep as you can just keep track of it. In a lake that is usually at periscope depth, or with clear water and little water reflection somewhat deeper. once or twice per year some outdoor pools offer the chance to sail subs on the day before that start or end of the season. Then you can sail just above the bottom and sail all sorts of maneuvers. 
I can really recommend it as a hobby, but you need to educate the other skippers in your club…..

[Mirabell61]

Thanks,

how do you balance out at periscope depth, is there an automatic depth control, or is it to nerviously keep the eye to the periscope wave and two fingers at the hight rudder stick ?

 

Nils

[FreekS]

Mirabel,

Great question shedding light on the post-build trimming!

 

control at periscope depth typically depends on two things;

- near perfect trim. Once the boat is watertight I will trim it in a tank with lead ballast (and sometimes with pieces of foam too). One must also make sure that if the boat has a ballast tank filled with water when dived, that there is no air bubble in it that may move around. Then trim during sailing, as the shape of the hull may impart some preference for the boat to rise or sink at some speed. the position of the ballast tank relative to the center of mass, the distribution of weight must be optimized to sometimes grams. That optimization can take months after the maiden…(at least with me).

-a leveler like Norbert Bruggen’ Lageregler LR3. This is a piece of electronics between receiver and diveplanes. In the absence of up/down commands, it will operate the diveplanes to maintain the boat on an even keel. Commands from the transmitter are mixed with these. Levelers (or gyros) tend to work well for faster subs (like the 1:12 Delphin in the pic above). There are also subs with trim tanks fore and aft that automatically pump water around (just like real subs do) but I’ve not gone there yet… The most impressive boats tend to be the ones that can sail at periscope depth with very low speeds, when the leveler and diveplanes done do much any more.

 

finally, as boats inevitably will go out of control or get lost from view,  failsafes for loss of signal, low battery and water detected in the boat are used to force boats to rise (the 40mHz frequency used does not allow comms back to the transmitter).

 

PS, I still always have eyes on the boat and two fingers nervously on the up/down control!

Edited June 29 by FreekS

[KeithAug]

All very interesting and complex. I am glad I build floating boats!

[FreekS]

Last month or so has been the development of the arduino to control:

1. the pump pumping water in- and out of the ballast tank

2. The servo that folds/unfolds and operates the front diving planes

3. A low battery alarm and a water in the boat alarm, both resulting in surfacing the boat by emptying the ballast tank.

4. the navigation lights and alarm lights on the bridge 

 

it could get very geeky if I explain the details, but basically I’ve built a circuitboard first on a breadboard, with loose wiring to and from all components.

realising all the “mess” needs to go into a small compartment

 

next, I’ve soldered the components on a 4x6 cm circuit board (the max space available)and spent days finding soldering errors

 

at the same time I wrote the sketch or software program and tested it dry.

finally today I actually filled the tank with 570ml water before the pump shut off when the water sensors said it should, and emptied the tank again! Success! 

also did a first attempt to tidy things up so the whole assembly can slide into the waterproof PVC tube.

[Ian_Grant]

Love the electronics engineering in submarines, though I doubt I'd ever try one. 😊

 

Aren't Arduinos amazing to use!

[KeithAug]

4 hours ago, FreekS said:

I’ve soldered the components on a 4x6 cm circuit board

Too simple. I liked the rats nest of wires. I don't understand any of it but it is mightily impressive.

[Jim Lad]

It's not the 'rat's nest' that impresses me so much as the fact that it actually all fits inside the allotted space! 🙂

 

John

[FreekS]

Now that the “insides” of the sub are more or less done ( still need to make the connection from the power inside the water tight compartment to lighting on the bridge and hull), I’ve worked more on the wooden boat itself. 
 

Next major step is a wet test - so the wood needs to be impregnated. I wanted most of the remaining work on the hull finished so I don’t compromise the epoxy impregnating with future sanding and sawing. 
 

Thus I’ve made the holes to flood the hull, and the holes to let the air escape as that happens. The front dive planes are hidden behind a structured that I read was actually a set of hydrophones along the hull (in the 1930s). The bow needed a face lift. 

O-14 had a single stern tube, firing over a teakwood “deck” located over the stern rudders. Presumably to protect the torpedo from bumping into the steel hull. 

the weather was great for a photo shoot of O-13, together with her now 12 years old younger sister K-18, built to defend the Dutch East Indies from the Japanese. Both models are 1:50, O-13 was smaller as it “only” needed to cover the North Sea and the Carabean - while the K-boats defended an area as large as Europe.

the bajonet especially needs more tweaking to fit the parts better together and I’ve started on the mechanism to make the captain go below on diving.

[Ian_Grant]

"........I’ve started on the mechanism to make the captain go below on diving".   

 

??!!!!!  Wow that would be something to see. Great model!

[Jim Lad]

Can't wait to see her on the water!

 

John

[Veszett Roka]

13 hours ago, FreekS said:

mechanism to make the captain go below on diving.

That mechanism is quite simple. Are you thinking something similar, or he will be mechanized?

 

[FreekS]

That’s exactly what I’m thinking of, plus I will try to also close the hatch mechanically once the captain is down. The drawing of the actual boat gave me some idea how to do that; the hatch can also be operated by a float below the deck

Edited September 17 by FreekS