[PSUBS-MAILIST] auto pilot

Sun Mar 5 20:32:09 EST 2017

Al,Yikes, never thought of that, and I know Gamma rotates when descending.   Hank 

    On Sunday, March 5, 2017 6:21 PM, Al Secor via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Hank,
When we did the drop test on Persistence, we had a tether rope and another rope to release a drop weight so the sub return to thesurface.  When the sub descended, it rotated on the way down causing the two ropes to become intertwined.  It was impossible to pull the release rope for the drop weight.  Keep this in mind with the clothesline effect idea...  Al Secor

      From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Sunday, March 5, 2017 6:14 PM
 Subject: Re: [PSUBS-MAILIST] auto pilot

Hi Steve,Gamma has battery boxes in the bottom of the hull that conveniently create a water trap at the front and back of the hull.  Less than a gallon of water will trip the float switch.  The air supply actually comes from my external 122 cubic foot tank.   The other tanks I was researching are for Elementary 3000.  Unfortunately  Slocan lake is very steep on the sides, so I have to test in much deeper water with the sub suspended.  There are also sunken logs all over the lake, so I want to stay off the bottom.  Funny I was thinking today, I need to buy another roll of rope so I can have a clothesline effect.  The rope will loop through the lifting eye and back to the surface.  In a failure, I can pull a small cable down to the sub to hook it up, or get another sub out to connect it.  Actually you have an idea here, it could have a cable held up with trawl floats that can be snagged easily with a grapple hook.   Hank 

    On Sunday, March 5, 2017 3:42 PM, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Hi Hank,A pretty basic thing, but do you have enough air supply?  Ie. perhaps you will need quite a bit of water leaking in to actuate the flow switches.  Which needs quite a bit of buoyancy, and since you are at test depth you have a whole lot of extra ambient pressure to compensate for. Ie. your 10.7cu ft cylinder at 1500PSI will hold air to displace about 1000cu ft on the surface, but only 35cu ft at 300m depth.  If that's what you're using, I think you will be ok ;).
Another consideration is that for the sake of a few minutes extra before the test, it may be worth a couple of minor considerations in case the auto-surfacing method fails.  (ie. find a spot in the lake where there is a flat bottom at desired depth, leave a lifting ring attached/sticking up so that a cable could later be attached to it for lifting a fully flooded sub, etc.).
Cheers,Steve
On Sun, Mar 5, 2017 at 10:27 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Alan,Yes I have opted to exhaust my air supply into the MBT's, if I put a timer on the solenoid valves to close them, it may not lift if the sub is in a snag of some sort.  I want full lifting power.  The solenoid valves will be piped into the existing air feed for the MBT needle valves.  I will have the needle valves set to feed the air slowly.  I expect Gamma to be on the surface before the air is spent.  I am attaching a 5\16 nylon rope to the sub and lowering it 5 lbs heavy, so I could haul it up if I had to.  If my timer fails and the sub does not surface, I can also simply lower the sub another 50 feet or so and the outside  pressure valve will send power to the  solenoid valves.Hank 

    On Saturday, March 4, 2017 10:49 PM, Alan via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

 Hank,when the valve opens, is it going to stay open & continually send airin to the ballast tanks? Also you mention an external pressure sensorto avoid going too deep; are you sending it down on a rope or autonomously.Alan

Sent from my iPad
On 5/03/2017, at 2:49 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

Hi All,I am in the middle of building a remote surfacing system for my subs since I seem to be to cheap to go to a pressure chamber.  My system operates from a dual industrial timer that powers two solenoid valves, one is redundant.  The solenoid valves take regulated air to operate an air cylinder that actuates a 2,500psi ball valve.  The system also incorporates two float switches, one fore and one aft in case water gets in before the one hr test is complete.  There is also a internal pressure sensor in case there is an air leak, the sub will surface.  There is also an external pressure sensor that will prevent the sub diving past the desired pressure test depth.  Have I missed anything?Hank

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