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Submersible ROV

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hanslanda

Mechanical
May 19, 2016
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Hello Gents. First off i'm new to the forums! Glad to be here, some reading through existing content tells me i'm in the right place. Next a bit about myself. I'm extremely ambitious! I live in Wisconsin. I love the outdoors i'm just afraid life doesn't allow me to experience it all that often. I'm the type that can sit in google earth for hours just exploring places i'd like to visit.

I've made a few attempts at exploring the world through remote technology recently. POV setups for the first time give the average consumer the ability to experience this. I'v always wanted to do what has not been done before and that brings me to my main topic for posting in this sub-forum.

As of recently i'v gained extreme interest in our oceans floors. The place we've only explored less than 5% of right? It's the most mysterious place on our planet. And so i would like to be able to endure a massive undertaking. I find when looking for help or guidance, its best to make your goals clear. It helps reduce guess work, assumptions, etc.

GOALS
-----


1) Engineer a submersible craft that can withstand extreme pressures of the ocean (5000+ PSi)

-I have already begun this task.

2)Be able to sustain dives for weeks or more.

-I have a clever power storage system in mind

3)Controls -Autonomous

I have a system that could do basic control via sat uplink. Also have a system that could do cellular, although cellular likely will not work in most ocean regions. My thoughts on getting the satt comm to surface is a deployable antenna. Most of the control itself would be autonomous.


4)Ballast.

This in lies most of my knowledge short-comings. I'm having a really hard time figuring out how i could design a ballast system that will fight 5000 psi water pressure. I bounced a few ideas around in my head on how this could work. I'v contemplated a mechanical advantage screw style (issue with sealing + a ball-screw strong enough) , a hydraulic powered piston (same sealing issue), a pump capable of displacing the ballast water, then simply an air tank that provides make up air to avoid vacuum build up. Last option i had was an air system strong enough to displace the water straight up. I'v done some research and it appears the technology does exist. The largest issue i have here is the volume required for displacement. Using Boyle's Law i calculated 5 gallons of displacement @ 5000 psi. IE 41~ lbs of ballast water. What I come up with is a 5 gallon cylinder filled to 5000 psi is roughly 227 cubic feet of air at atmospheric pressure.

Here is where I get lost.

Lets say i have a ballast tank that is more or less the outer hull of my craft. It has 5 gallons of storage. The outside water is a whopping 5000 psi static force. Do i understand pressure correctly when i say i need 5000 psi air pressure to defeat the water pressures? Do inlet/outlet sizes of the ballast affect the water pressure?


If i understand this correctly... psi works as a uniform static force underwater? IE if i had a plate on the hull of the craft that was 4" x 4" totaling 16 in2, @ 5000 psi the total pressure/force on that plate would be 16(5000)= 80,000 lbs of force?


Thanks for any input guys!




 
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The weight on the fiber cable I've looked at @ 12,500 ft length, would be roughly 358lbs. The cost is also roughly $4,700. None of that is out of the question when it could allow complete remote control with potentially full video.
 
On page 23 of
3. Orca - with a through-water data speed of 100 bps and a nominal range of 3km.

However, they never say what happens at depth.

I don't see anything obvious in literature about depth effects on fiber, and almost all of the current transocean communications links are done with fiber, down past 8km depths.

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529
 
-GregLocock

Thanks for the reply! That's awesome information i'm going to contact them right away on a custom solution.



Thanks again.


Also wanted to add Aquacomm got back to me today with a response on my inquiry of the depth and distance issues.

Here is the response:


"Anthony:
Thank you for your inquiry. Regarding range and depth specifically - We have a recently released commercial product with independently proven capability of 8km depth and distance that we have sold previously in the defense market but have opened up to commercial markets since January 2016. So I believe our new High Powered Modems/transducers will be suitable for your needs.
On your second question yes we have many such deployments of subsurface to buoy 2 way communication solutions that are working. The basic requirement (assuming you have your on subsea encasing and power supply is Topside/Buoy (1 modem + 1 transducer) Subsea/sensor(1 modem + 1 transducer)."


Sounds like some new defense tech is hitting the consumer market. This could be ideal. It eliminates the need for fiber altogether if a reasonable speed can be reached.
 
It's not going to be close to real-time video rates, even when compressed. Their literature indicates maybe a 10x improvement over their commercial products.

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529
 
With the transducer modems, correct. With fiber... its extremely doable. It also hinges on the Iridium network. Currently it's extremely slow. 128 kbps connection rate to be exact. Not much faster than dial up modem @ 56k but a hell of a lot faster than 480bps. They have a new network launch promising typical broadband speeds(Since satellite internet already exists at these rates... it shouldn't be a huge challenge). So i'm going to contact De Regt on the fiber cable. If it really can be of the self supporting type, and possibly even include power wires i'm looking for, a one cable solution that can provide megabytes per second over bytes per second would be an easy choice as long as the cable doesn't cost $25,000. The modem would be an excellent emergency mode in the event that the cable is severed. From what i understand, sharks love to gnaw on those intercontinental fiber optic lines on the ocean floor. Those cables by the way, are designed to withstand the pressure they are in. They are roughly 3-4" steel braided re-enforced and resin filled. A cable severe at some point is almost an eventuality. A severed cable would stop charging immediately (if it was in charge mode), kill all communications (other than a potential backup). Could even affect buoyancy unless i can figure out this ballast situation. In other words, a severed cable would put the sub in emergency mode, and depending on battery life at that time, could cause an immediate surface and ultimately it would drift, hopefully near the charging/comm pad.
 
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