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How about an extra pipe to increase the cross section of the pipe, or use a larger hose?
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QUOTE=Subculture;n150204]How about an extra pipe to increase the cross section of the pipe, or use a larger hose?[/QUOTE]
Andy,
I like your thinking and I can see that would definitely increase the flow rate of the escaping air from the ballast tank to the vent valve. I suspect part of the problem lies more in the connections I made at the Tee fitting at the vent valve.
Allow me to explain. If the outlets from the low pressure blower as well as the outlet from the emergency gas blow were routed Instead separately from the vent valve to directly to the top of the main ballast tank top fitting, then it would not matter if their plumbing became flooded as the water would be cleared or pushed out during blowing cycles.
If the connection between the venting and blowing plumbing was split at the top ballast tank fitting this would hypothetically reduce chances of water getting into the vent plumbing circuit due to the leak by of the Diaphragm pumps.
Still other matters would need to be addressed like guaranteeing water will not enter the vent valve outlet tube and create a tension blockage.
Nick
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Quick update.
I spent a couple hours today working on the WTC project. Machined a simple part that allowed me to move the Tee fitting that was mounted on the back of the vent valve. The Tee fitting is now directly connected to the vent fitting at the top of the main tank. Same connections to the Tee fitting as before. Vent valve connection, emergency gas blow connection and low pressure blower connection.
A low pressure release one way check valve was added to the low pressure blower intake snorkel that only allows flow to occur when the pumps are drawing air in. The valve prevents any flow being pushed through the plumbing in the opposite direction.
Did some tests this evening and so far so good. I wanted to take some under water footage yesterday with the GoPro 9 I picked up recently for the Neptune sub but the digital micro servo for the ballast vent gave up the ghost yesterday from all the testing and mainly because I set the end point stop further then the vent valve could travel. Live and learn the hard way. It was replaced today and the end points set appropriately.
I did a number of quick dives and surfaces using the system in full manual mode to make sure everything was working as it should.
Decided to pull the GoPro out of its box and try it out finally. I had already charged it and downloaded the app a couple weeks ago when it showed up but I had not yet tried to actually take video with it.
I was excited because the WTC was working and hopefully the camera. So into the tub the camera went. I wasn’t even sure if I set it up correctly or if it was recording but it did record and here’s the very first video underwater from it and the WTC. Sorry it is not edited at all and the digital micro servos chattering under water are very loud so turn down your speakers a bit if you watch the video.
In the video I vent the main ballast tank then make a small adjustment to the forward piston tank. Then a quick adjustment to the aft piston tank. The static dive trim is set for about periscope depth. At the end of the video the main ballast tank is blown.
Still need to test and document the automatic functions. Haven’t even tried those yet as these in the water tests have been only the past two days. Trying to crawl before I walk. Still getting to know this contraption.
NickComment
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Good night.Comment
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That thing just looks so stable. It's gonna work great! But what challenge will you have trying to maintain PD? lolComment
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Thanks Steve,
I was surprised myself to see how stable it was too. Having the underwater camera gives a new perspective that I did not have before. Pretty cool.
As far as maintaining PD goes, that probably wouldn’t have been much of a challenge anyway with the onboard Depth Cruiser on the bow planes and the AD2 pitch controller on the aft planes with out all the complicated junk I packed into this thing! Lol !
The project was a personal learning experiment for me. As interesting as I have found it along the way, I doubt that I will build another system like it again. Too complex with too many things that could potentially go wrong. That being said, the only real advantage that I see it having is the statically adjustable trim which might come in handy for the different types of gas and electric torpedo loads and that is really the reason why I decided to go down this path. Even then, I won’t know how much those will effect the trims until I finish the type VIIC project.
I’m already looking forward to a future build of a Bronco Type XXIII that will use a 2.5” MSD which is set up with a snort system. That’s a rock solid system in my opinion. Will use a DC as well as a AD2 on that project and that will be as complex as it will get. Should be a fun boat to skipper.
NickComment
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I knew it couldn't have been the Monahan engineering!Comment
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This is impressive. Well done! Now put a hull around it!Comment
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Thank you! Believe me, I am dying to move on to putting it in the hull !!! I can’t begin to express how over it I am spending all this time on the WTC part of the project but it needs to be tested, finished and rock solid before I can confidently move on the hull build.Comment
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I'd expect a valve size of 3mm perfectly adequate to vent the tank. try it once you have the cylinder inside a hull, that may make a difference.Comment
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Andy,
You are absolutely correct that the 3mm vent at the top of the tank is perfectly adequate to vent the tank. In fact it takes 7 seconds to completely flood the main tank by uncorking the 3mm vent fitting directly at the top of the ballast tank.
The poor venting flow is due to three issues. The biggest issue of the three being the remote mounted vent valve substantially restricting the venting air flow. The flow gets worse as the tank reaches full. Takes approximately 40 seconds to completely flood the tank with the restrictive valve. Way too long.
Second issue is where the remote valve is mounted. As you’ve mentioned earlier, it is best to vent at the top of the tank. (This is the first time I’ve experimented with putting the vent valve in a remote location). Any water covering the vent valve outlet has negative effects on venting. Even with adding the vertical tube to the valve to raise the outlet above water level that I tried and found to work, there is still the risk of that tube getting enough water into it after multiple dives to have negative venting effects.
The last issue was the length of 3mm ID tubing that connected the vent fitting at the top of the tank with the remotely mounted vent valve. Flow tests showed that just adding a 12” length of tubing made the flood time for from 7 seconds to 18 seconds. Using a 12” length of tube with an ID of 3/16” had no restrictive effect on flow.
Currently, I’m making a new vent valve assembly that will be mounted on the top of the tank and have a pushrod connecting it to the ballast servo pushrod exiting the forward end cap. Was originally wanting to avoid this as it adds slightly more complexity to removing the forward end cap.
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New vent valve for the main ballast tank.
Simple sprung vent slide valve. Normally I'd like to see the sealing surface be on the pressure side which would increase sealing under pressure.
Hard to see from the photo but there is a 3/16" OD Viton ball inserted into the retracted brass vent seal cup above.
Hope to test this new vent valve in the next couple days.
NickComment
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