ballast tank equipped 1.25" SubDriver now in production

[He Who Shall Not Be Named]

A very small diameter system used to control, manage ballast water, and propel small scale r/c model submarines. Developed to animate 1/144, 1/350, and like sized scale plastic submarine models currently available on the market. We call it a 'SubDriver, or SD for short.

The availability of very small servos and other r/c devices has made the very compact 1.25" diameter SD possible. The SD can be arranged as either a static or dynamic diving type system, i.e. with or without the water ballast sub-system: For the exceptionally small model submarines, demanding a shorter SD, a dynamic type is used; larger models equipped with the static diving type SubDriver.

These and other r/c submarine products are available from http://www.sub-driver.com/

http://youtu.be/Lu6x3vI2Yek

[small sub guy]

Can you tell me on (image 4) what is the purpose tube blue in color coming out of the end cap and where does it connect?

[He Who Shall Not Be Named]

Can you tell me on (image 4) what is the purpose tube blue in color coming out of the end cap and where does it connect?

You're looking at the low pressure blower (LPB). It's the air-pump that drives air -- when commanded either from the transmitter or the fail-safe circuit -- from the surface (through the top of the sail) into the ballast tank, blowing out the ballast water, surfacing the boat. You'll note the suction hose going up (into the sail) and the horizontal discharge hose leading to the top of the ballast tank.

For the 1.25" SD's I devised this special forward bulkhead -- it houses both the LPB and attached motor pump controller. All into one very dense package. Space is at a special premium within any type SD's, but no more so than a cylinder of this diameter.

[trout]

That is so fascinating.I love the thought of adding a ballast tank. David, I think the blue tube Mark is referring to it the one between the in/out gray tubes. It is the light sky blue tube coming out of the conical end cap shooting between the gray tubes. Is it used to equalize the pressure? If so, what do you plug it with or do you simply clip it?

[He Who Shall Not Be Named]

That is so fascinating.I love the thought of adding a ballast tank. David, I think the blue tube Mark is referring to it the one between the in/out gray tubes. It is the light sky blue tube coming out of the conical end cap shooting between the gray tubes. Is it used to equalize the pressure? If so, what do you plug it with or do you simply clip it?

[ATTACH=CONFIG]29184[/ATTACH]

Thanks for the clarification, Tom. It's a short length of 3/32" round RTV rubber -- I cast these up for jobs like this. Yes, it's a plug for a hole in the forward bulkhead, used for equalization when one of the two bulkheads is installed or removed. I also use that hole as a test point when I pressurize the SD when chasing down leaks.

[trout]

More questions, in a working model, do you seal that permanently? Or do you have to remember to replace the plug before use? Hey I have forgotten to replace a screw on a sub, once and it sank my feet!
I really like the valve on this little tube. Gotta hand it to you, it is really excellent design.
Mark, you going to get one of these?

[He Who Shall Not Be Named]

More questions, in a working model, do you seal that permanently? Or do you have to remember to replace the plug before use? Hey I have forgotten to replace a screw on a sub, once and it sank my feet!
I really like the valve on this little tube. Gotta hand it to you, it is really excellent design.
Mark, you going to get one of these?

Thanks, Tom. You are a 'small submarine' nut of the first-order. I knew you would appreciate this work. So far this thread has garnered one big yawn from the community.

And talking about forgetting something and having the model sink as a consequence: The very first SD I produced for Mr. Caswell was fit into his big model representing his Dad's S-class boat. Mike installed the SD, got everything running, put the model in the water.... and the thing flooded out! I had forgotten to put the core back into the equalization valve after I had checked it out here.

He was not amused! Not a good start to what otherwise turned out to be a great business relationship.

The idea of the guillotine-valve... actually, now that I think about it, I should call it a slide-valve... came to me at the end of a long series of experiments conducted as I attempted to come up with a simple, cheap, and reliable vent valve mechanism suitable for use on this very small cylinder.

Way back when, being your typical dumb-ass, "I can't spell it, but I can lift it", Torpedoman in the navy, I had extensive experience with the big annular slide-valves at the breech end of the hydraulic type torpedo tubes. Like the ones we had on the WEBSTER. I was forever in the tubes to inspect and maintain those things. The slide-valves opened to admit the water-slug that sent a weapon on its way. When closed (the damned slide-valves would always leaked!) the slide-valve provided the two-valve safety demanded by the Navy.

Anyway. Having walked away from the 1.25" ballast tank vent valve problem for a few months, I was casually leafing through an old boat piping TAB, and the booklet flopped open to the launcher page. And there it was! All I had to do was drop the annular valve complexity, reduce it to one plane -- a machined flat atop the Lexan cylinder (which is why God gave us milling machines) -- and you have a simple valve that, with some servo push-pull, would open and close.

The last remaining issue was to work out a means to produce a tight fit of the rubber element over the vent hole in the center of the machined trough -- and to do so without introducing so much drag on the mechanism as to prevent operation. The most effective (and as it turned out, the simplest) solution was to compress the rubber element over the vent hole by magnetic attraction: A magnet atop the rubber element, set into the carriage -- a cast resin part to affix the magnet and rubber element, attached to the ballast sub-system pushrod; and a 'floating' magnet within the ballast tank. The two magnets working to squeeze the rubber element down tight upon the machined flat of the trough. This is how the thing effects a positive air-tight seal over the vent hole.

[trout]

David,
I would not say that this "thread has garnered one big yawn from the community". If you use that as a yard stick then this season has been a yawn for our hobby. There is not a ton going on around different sites as a whole, from what I see.
Just my two cents....

[Subculture]

Small stuff will always be highly niche.

One of the problems with producing something small is that customers expect to pay smaller prices for it. For the supplier that presents an issue- developing and tooling up for a small kit takes pretty much the same time as a bigger model, but you can charge a lot more for the latter as basic psychology dictates you are getting more for your money, even though material cost is usually a much smaller factor influencing the cost of the product.

[He Who Shall Not Be Named]

Tom: You super-sized, practical, wet-blanket you! And, of course, you're right. Putting things in context like you did, helps explain.

I blame Oboma!

Andy: Don't I know it! On more than one occasion I've had to listen to people spout off about what a crook I am for charging so much for so little. You're observation is spot on. In fact, I would argue that the cost/size rule is more insidious than the inverse square law. When you tip-toe into pricing of very small things, you are stepping into Heisenberg land.

Ah! .... **** it!

Bottom line on the small stuff: You either do it for personal gratification, or you should not bother with it at all. Yes. A niche activity, indeed!

[vital.spark]

David,

I'd love one but there are no more funds available! My fleet now is 4 finished subs with your sud-drivers installed and one under construction with a sub-driver that will go into it!

I would like to make a sugestion. If you make the ballast tank replaceable with O-rings, one sub-driver could be used in different small subs by using the correct ballast tank. This would allow someone with limited funds to build several boats and when and if funds were availabe move on to bigger and better sub projects!

Don't even think about calling me a cheapscape or I'll stop sending you Christmas Cards!!!!!!!! Did you get this years?

Myron

[He Who Shall Not Be Named]

David,

I'd love one but there are no more funds available! My fleet now is 4 finished subs with your sud-drivers installed and one under construction with a sub-driver that will go into it!

I would like to make a sugestion. If you make the ballast tank replaceable with O-rings, one sub-driver could be used in different small subs by using the correct ballast tank. This would allow someone with limited funds to build several boats and when and if funds were availabe move on to bigger and better sub projects!

Don't even think about calling me a cheapscape or I'll stop sending you Christmas Cards!!!!!!!! Did you get this years?

Myron

Christmas Card received and most appreciated, Myron.

The design of the ballast tank equipped SD permits a quick removal of the ballast section and substitution of a simple cylinder without the ballast tank and associated elements.

M

[vital.spark]

David,

What I mean is, to make the balast tank the 3rd removable lexan tube. Then for a boat with higher freeboard the balast tank will be longer and for a boat with low freeboard the balast tank will be shorter. I have 6 smaller subs that I could use the same battery and pump compartment and motor/electronic compartment along with the servo box for all the subs!

[trout]

Myron,
do you mean making the ballast tank or third tube an accessory that can be purchased? Add it to a standard tube to make a dynamic tube into a more static type tube or to lift those subs with a higher freeboard. Great idea!
To make it work, the owner would need to add a third servo and figure out how to plug in the extension and get signal and power to the pump.
In the kit or add-on, would be a bulkhead that fits inserted into the ballast tube to form a female connection to receive the male connection from the servo portion of the original sub-driver and on the other end of the ballast tube is a bulkhead that offers a male connection to fit the original battery portion of the sub-driver. Also included is the pump end piece.
i kind like the idea, but I am not the expert.

[He Who Shall Not Be Named]

Tom helped crystallize Myron's proposal in my mind. You two are saying (without yet saying it) that I provide three lengths of 1.25" Lexan cylinder in with the 'big' static diving 1.25 SD; one of the lengths in reserve so the end-user can either configure the SD as a static (with ballast sub-system) or dynamic (no ballast sub-system) type SD?

I can do that -- the cost to me of that extra length of Lexan is a non-issue, so no sweat off my balls. And if doing so is useful to the end-user, then great. A win-win. I'll do it.

However, you guys will not have an easy time of it converting the SD from one mode to the other -- there are plugs to pull pins out of, and wires to de-solder and re-solder with each transition -- doing so would be a total PITA!

Device location within the two cylinders is driven pretty much by the very tight confine within the 1/4" conduit tube. After A LOT of mock-up work I settled on this current arrangement for the statically diving type 1.25" SD: At the extreme after end of the after cylinder is the motor; then the ESC (Kevin McLeod is working up a flush-fitting ESC that conforms to the back plate of the motor, which will greatly reduce the ESC's footprint); the after ballast tank bulkhead; ballast tank proper (with center running conduit); and after face of the servo box which provides watertight unions between the forward ends of the conduit and after cylinder section. I minimized the runs through the conduit to only the power cables to the ESC and ESC lead to the receiver.

Study the block-diagram of device placement within the SD -- can any of you brainiac's come up with an arrangement that has fewer wires running through the conduit?

M