Need lots of help

[Guest]

Almost certainly a sealed ballast tank, so air is pressurized inside the central compartment as the bag fills with water.

[Nb1914]

thanks all i think I'm slowly getting the gist, i will over the weekend get the sub out the loft and have a proper look at all the parts i have. what i still don't understand is how would you submerge the sub to say 3 meters and hold it at that depth ? is the ballast purely to achieve neutral buoyancy then you can use the rudders to dive etc i think but not sure that the DLX2 can control pitch it has a motor connection so i wonder if that is for the ballast pump to automatically pump water in and out to stay at a certain depth. looking at the rear bulkhead with the bicycle valve i suppose you would pressure the front and rear containers to a set pressure x then if i pump up the ballet bag i should not see that pressure in the front and rear compartments change, confirming that the centre section is airtight and maintaining pressure within its own container.

[Nb1914]

I live in the UK in the forest of Dean which has a few very nice lakes so if there is anyone with experience close by that would be great. I did a bit of Physics research from what i can see:-

with the sub on the surface we pump in water to the ballast bag it starts to sink ( great ) it will continue to sink but as the depth increases we need less water in the ballast because the mass of water above the sub has increased, therefore to maintain a constant depth we pump some water out of the ballast bag to achieve neutral buoyancy at a specific depth. Neutral bouyancy then is not a constant its requirements change with depth. Am i on the right lines ? . Now how do we pump water in/out to maintain a certain depth when we cant see the sub ????? i see devices staing they are depth controllers, how do they work. My DLX2 unit says its a pitch controller and leveller does that mean it has control of the ballast pump, or do i need a specific depth controller ????.

[Nb1914]

I put the above diagram together for clarity,

[tompinnell]

Hi Nb1914 I live in Berryhill in Forest of dean, don't have a working sub still building well sort of after having them for a few years!

[tompinnell]

From RC Sub Workshop (think this is the sub you have) might help with X tail setup

[Nb1914]

Excellent Thankyou, i think i will be using a pushrod 1 to 2 instead of the joining bar seen here but this technique might be better i will see which is easiest to accomplish.

I have now put the below together very heath robinson and might only convey my insanity but this shows my thinking better than text.

1. I have a pressure switch which can be set to x mbar, the ESC to the ballast pump circuit runs through the switch. In normal use where the set mbar is not exceed the switch passing Leg#1 to the common which connects it through to the ballast motor. In this scenario everything operates as normal i.e. the ESC takes commands from the RX. If the set pressure is reached then the switch bypasses the ESC circuit and connects BATT straight through or i guess i could have another ESC after the switch for a more controlled pump action. The pressure switch would have an auto engage on pressure reached but you would have to manually reset it.

2. I have a fail safe something that can detect loss of radio signal, upon which it commands the Ballast ESC to pump out the ballast.

3. I have a depth control something that detects the depth via a pressure sensor and when there is no RX signal to either empty or fill the ballast or signal to control the rudders for nose up it maintains that last depth through the ballast pump.

[Nb1914]

I have just found a new sub tech ADC-1 unit would this work with the DLX2 APC i.e. i have seen mention that you simply wire as

RX-----ADC--------APC-------------servos

[Nb1914]

Or even better to allow static depth holding could this work

RX--------ADC--------esc------ballast pump

[Guest]

I'm in the UK, but a bit further South in London. There are quite a few active model submariners up your way. Barrow model boat club has a few model submariners, and they hold an annual open day for model subs, usually in September.

There are also some better attended events coming up at Bournville, the next one is in May. Bit of a drive, but you will get a good selection of boats to see, and you can get a lot of good advice.

I would forget about getting a submarine to hover at a specific depth, it's actually very difficult to do, and requires automation, with constant correction to the ballast system. Technical challenge aside, watching a boat hover underwater is a bit like watching paint dry. Trim the boat until it's just a few grams positively buoyant, then a whiff of throttle and it will submerge.

The depth controller is a nice little device, but I would leave it out of the boat for the time being, as the leveller is a far more useful device.

Concentrate on fixing the boat up mechanically, making sure it's fully watertight, and ballast it so you get a nice trim with just the top of the fin above the water when the tank is filled.

[Nb1914]

Good advice, if i try to summarise , get the sub ready so that with the ballet bag empty it is very positively buoyant and then when full it is only just very slightly buoyant so that slow speed forward using the rudders can dive the boat deeper upon which when releasing the up/down control on the transmitter the DLX2 pitch controller will keep it at that depth i.e. it will fight the slight positive buoyancy.

[Guest]

Yes that's correct. I would advise leaving the pitch controller disconnected for initial trials, as it can mask poor longitudinal trim. The boat should keep reasonable trim underway at low speeds without a leveller. If you can control it well at low speeds without a pitch controller, then with it in, and with the gain set correctly, the boat should run like it's on rails.

[Nb1914]

its slowly dawning, ok for my insanity how do people get their subs to a depth like 2meters and sit still neither up nor down and no forward movement as i have seen the TT neptune sb-1 perform with what looks like minimal electronics. I will certainly get the trim right without any fancy gizmos but my interest has caught fire on the technology to maintain a static depth.

[Guest]

Generally what is used is a means of measuring the pressure at a certain point you wish to remain, and then electronics sense whether the pressure is increasing or decreasing, and at what rate that change is taking place, the ballast volume is then adjusted accordingly.

You can't do it without assistance of something like that, because it's so difficult to judge using sight alone. I would expect the system to need some dialling in for individual boats. Engel offer a system, but they only claim depth accuracy to within a metre or so.

It's pretty advanced stuff, so I would concentrate on the basics first.

If you've seen a Neptune hovering, it probably isn't, what it is probably doing is either sinking very slowly, or rising very slowly. But as I said in my previous post- it's not my idea of entertainment.

[JWLaRue]

How long do you actually see the sub 'hover' with no lateral movement?

With one of my subs that uses the OTW dive module (pumps water) I can get the sub to hover for maybe a minute before currents cause it to change depth. But it takes a lot of adjustment to do it. Using a different sub that has an Engel piston in it, I can get that sub to hover more quickly due to the nature of the piston system. But we're still only talking about a minute or so.

The Neptune uses a ballast system similar to the OTW dive module in that it has a small bladder that is filled with water by a pump....so it's possible to get some short hover times if you're very good at adjusting the water in the ballast tank/bladder.

I'm told that the 1:1 scale subs don't easily hover for long periods of time and even then there's likely a lot of adjustment to the amount of water in the hard tanks to do it.

-Jeff