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Resurrecting the dead Gato project

R/C Submarine modelers

Re: Resurrecting the dead Gato project

Postby Stevolution » Fri Mar 02, 2012 1:47 pm

OK... First ever submerge today

Not bad... looks like I can shave 60mm off the length of my ballast tank, which is good news, as that leaves me more room for floatation and access.

Needs a proper balance and setup once the WTC is finished. I basically bunged everything in + a little lead for the support frame. Just to get an idea.

In an ideal world, I suppose the ballast tank wants to be in the centre of the point of balance, but I expect that is pretty hard to achieve.

Only slight issues was a very tiny amount of water in the WTC. But I noticed air bubbles coming out of the connection to my ballast balloon as it inflated, so I am hoping the water got in by it being sucked back into the WTC as the balloon deflated.
And my WTC seems to be slightly heavier on one side than the other (I know why). I can trim that out with ballast.

Also amazes me how little air it actually takes to either float or sink it. 4 seconds of inflation is all it took to start her upwards.

Anyway, its getting chopped in length and then I will have another go.
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Re: Resurrecting the dead Gato project

Postby Stevolution » Mon Mar 05, 2012 1:55 pm

Floaty stuff help...

What are people using for floatation? I have seen people using foam. I was thinking of thin polystyrene sheet. I assume it has about the same buoyancy.
I don't have a lot of room around the edges of me WTC, so I think getting enough buoyancy inside the hull is going to be an issue.

My only other thought was to place inside the sub a cardboard tube covered in plastic - the same diameter + a little as my WTC. Then fill around it with expanding foam.
When set, I can carve it out where needed and then remove the cardboard tube.
That way, I will achieve maximum buoyancy and then hopefully I can dial it backwards from there using either lead ballast or by cutting some away.

Does sound risky however.... expanding foam can go badly wrong!

Steve
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Re: Resurrecting the dead Gato project

Postby JWLaRue » Mon Mar 05, 2012 2:08 pm

Steve,

Sounds like some good progress. Got any photos to share :)

For floatation a lot of us use that sheet insulation material sold at places like Home Depot. Easy to cut and shape as needed. As long as you are using a closed-cell foam you'll be okay.

Interesting thought with the expanding foam. I'd do a test with the same plastic as your dive module is made out of just to be sure that the chemicals in the foam don't attack the plastic.

A basic rule of thumb for trimming the boat is to start with zero foam and lead and only add as necessary. Otherwise you could be attempting to compensate for having too much foam/weight. Makes for a vicious cycle.

-Jeff
Rohr 1.....Los!
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Re: Resurrecting the dead Gato project

Postby Stevolution » Wed Mar 07, 2012 4:30 am

M WTC is pretty heavy, and the sub is nose heavy too. When she is in the water with no floatation but some lead in the keel - she sits about half an inch too low in the water. Hopefully not too much floatation material needed.
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Re: Resurrecting the dead Gato project

Postby Stevolution » Wed Mar 14, 2012 12:52 pm

Oh yea.... that's why I stopped building this thing... :x

I have a huge workshop full of drawers of everything.. except what you need.

Been HOURS trying to join a 2.3mm motor shaft to a 2.38mm prop shaft. Can find any small springs that fit, can't find any rubber tube that fits.
Local model shops are useless. Only thing I have is a universal joint that takes up far too much room. Need a simple - grub screw connector.
Oh for a milling machine.

Patience (and funds) are running low. This may soon be a static model
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Re: Resurrecting the dead Gato project

Postby Stevolution » Sun Mar 18, 2012 5:45 pm

OK. Finally got some pics together.

Really wish I could start this whole project again, as I would approach it differently. But hey... its something to do.

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As you can see.. WAY more complicated than it needs to be (but I build everything like that!)

Few notes.
There are a pair of clear pipes running outside the WTC. The one front the front of the WTC to the rear feeds the ballast balloon (temp green balloon at moment).
The other clear pipe links the front of the WTC (Pump and radio room) to the rear WTC (Engine room). Just to give me some more volume of air.
I will change these pipes to R/C fuel line (and shorten them) later as its much more flexible.

The link pipe from the radio room to the engine room, could in theory, be my vent pipe when I charge my 7.2v battery in the Radio room. If I just remove the pipe, then I have a vent.
Therefore, I will fit a waterproof charging socket somewhere along the main battery feed (large cable running outside the WTC).

The reason the pipes and main battery lead run outside, is it made breaking the WTC in half a lot easier. But that was when I fitted it through the top of the sub.
That turned out to be a pain in the backside, so I have now made the rear of the sub come off instead.

The three servo brass rods (currently folded back above the radio room) control the front planes up/down, fold the front planes and open/close the torpedo doors.

At the rear of the sub are the usual 2 servo rods for rudder and rear planes + 2x prop shafts.

There is a large blank PCB board in the engine room. Ignore the mess of wires everywhere... nothing is connected yet.
This is where my custom PIC chip ADC+APC module will go. I have written the software for my own one. Also, I will put the magnetic on/off switch here.
The circuit includes a battery changeover circuit that will feed the radio gear from the 7.2v battery, if the receiver battery dies. It will also trigger an emergency surface.

The cables hanging out in the midships go to the conning tower for some 'effects' .... snigger. They come much later on!

The whole thing seems to float fine and the ballast system works well.
My only concern is if I have room to get enough buoyancy around the WTC. There is room, but I don't really know how much I will need (but I have done some trials). Plenty of room under the WTC for lead ballast.

Like I said. If I started again (which ain't happening)... it would have no external pipes or wiring. I hate untidy builds.
Steve
Last edited by Stevolution on Sun Mar 18, 2012 8:05 pm, edited 1 time in total.
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Re: Resurrecting the dead Gato project

Postby salmon » Sun Mar 18, 2012 6:05 pm

What type of battery are you putting in? LiPo, NiMh, LiFe?
If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.
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Re: Resurrecting the dead Gato project

Postby Stevolution » Sun Mar 18, 2012 6:09 pm

NiMh - 7.2v for the motors. NiMh for the radio receiver.
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Re: Resurrecting the dead Gato project

Postby Stevolution » Wed May 02, 2012 10:53 am

Hi all

Project is going well, and I am in the middle of writing the software to control the ADC and APC.

My question is, what are the pressures in fresh water? I am not going that deep, but when I google for an answer the findings vary wildly.

Then I can find a suitable pressure sensor for the module.

Thanks
Steve
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