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Build a WTC/Ballast/dive unit versus to buy. What?

R/C Submarine modelers

Build a WTC/Ballast/dive unit versus to buy. What?

Postby ScrumpyJack » Fri Sep 25, 2009 7:34 am

I have had serious thoughts about making my own ballast system/dive unit I have read everything I have found on the various systems. I have listened to the odd producers of systems who say don't make your own cos it won't work, buy mine its the best thing since the flushing toilet.
My problem is 'dosh' being a resident of a foreign land living on a pension thats dependant on how the Euro fairs against the Pound ie its up and down like a whores draws we have to be careful on our spend.
So tell us, please, what advice can/would you impart on the various 'units' and build or buy. I believe I have a pretty good skill base to build I just need to source 'the bits' so thats perhaps the other thing what bits?
I would like a system that is as near to the 'proper thing' as possible ie ballast tank(s) that flood on request to dive and are blown to surface. Yes I know, just and idiosyncratic thing I have being an ex submariner!! (Anorak I hear you say!). BUT I'll listen to you well established submarine modellers and bow, to your experienced, knowledge.
So please help me resolve my dilemma.
Oh perhaps I should add I am in the throes of building a Sheerline type VII
Fred
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Postby Sub culture » Fri Sep 25, 2009 10:56 am

Have you decided on a ballast system?

They all have their various pros and cons. Sounds to me like you're veering towards either a gas or some sort of compressed air system.

What I can say is that 1/48th scale Type VII, which is what the Sheerline boat is will generally require about 800-1000ml to submerge from a scale waterline.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby Sub culture » Fri Sep 25, 2009 11:43 am

I think that will be blow Fred's budget

2 x 500ml engel tanks with control board- 461.70 euro

Bayonet ring- 79 euro

540.70 euro
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby ScrumpyJack » Fri Sep 25, 2009 1:09 pm

I haven't really made my mind up.
I keep going back to a snort system ie pump in pump out. And when I have some extra cash and a gas system. But what I read this system maybe (please say I'm wrong!) not powerful enough for a largish boat!
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Postby Sub culture » Fri Sep 25, 2009 1:39 pm

The main problem with using the snort system if using the small pumps from Caswell, is that it'll take an age to pump out the tank, as the volume of air they pump is quite small.

There are larger pumps out there, but they can be tricky to get hold of.

An altogether better solution for a boat that size, is to just use an aspirated tank with a centrifugal water pump. The latter are readily available from ebay for about £10-12, search for Whale or Reich water or faucet pump. Pattern made pumps are available for a bit less

http://cgi.ebay.co.uk/CARAVAN-REICH-14L ... 286.c0.m14

http://cgi.ebay.co.uk/Caravan-submersib ... 286.c0.m14

These pumps really shift water. A litre of water will be shifted in the matter of a few seconds.

A small trim tank mounted in the centre of the main ballast tank would allow fine trim. this isn't essential, but it would add refinement at a small extra cost. The small trim tank could be a piston tank or a fixed tank fed by a peristaltic pump, etc.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby raalst » Fri Sep 25, 2009 1:48 pm

for another (not too biased) overview of systems look at this site under "technology"
http://www.heiszwolf.com/subs/

edit : that was strange : text was there just not visible...
Last edited by raalst on Fri Sep 25, 2009 2:17 pm, edited 2 times in total.
Regards,

Ronald van Aalst

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Postby ScrumpyJack » Fri Sep 25, 2009 2:12 pm

Cheers Andrew thanks.
Fred
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Re: WTC

Postby JWLaRue » Sat Sep 26, 2009 7:36 pm

sunworksco wrote:The scale size submarine that you are building needs to use Norbert Bruggen's piston diving tanks and bajonett rings.

While a piston-based system can provide you the best level of control, it is definitely not something that "needs" to be done. Any of the dive system types in use today can be used...even for a boat this large. Heck, even if you do decide to sue a piston-based system, bayonett rings are not even needed....though you do need some way to hold the end caps in place in the presence of the hifger internal pressure.

I would suggest evaluating the various trade-offs between systems (which I think you are doing) and choose the one that interests you and fits your needs/budget and then build it.

The way I do this is to first understand how large the ballast tank needs to be and then figure out for each ballast system type what it would take to allow the boat to dive/surface at speeds that are like the prototype.

For my various boats, I've made a point of building the dive module for each new boat of a different type. My large boats use the piston, hybrid RCABS, sealed pressurized ballast...and yes even gas.

-Jeff

p.s. even the system made popular by Skip Asay (and now being offered in slightly(?) different form by another vendor as the 'snort system' can work for a large Type VII as long as you get the correctly sized pump.
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Postby ScrumpyJack » Sun Sep 27, 2009 7:43 am

I think my mind is made up I'd like to use a vented tank like what proper submarines use ie main vents on the top of the tank free flood hole(s) in the bottom of the tank BUT that means having some method of putting a blow on the tank to surface, which means either having a small bottle group, sorry submariners speak, a tank of air to blow main ballast.
So my next option is a vented/aspirated ballast tank pumped system with perhaps a small cylinder (or two) to achieve trim and a more finite depth setting.
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Postby Sub culture » Sun Sep 27, 2009 10:20 am

A pressurized gas (be it compressed air, butane, freon etc.) combined with a trim tank is probably the best of all worlds in that you need the minimum of energy to surface.

Unless you use an external source for your pressurizing e.g propel, C02, butane or a compressed air tank (divers tank) then you will require a compressor. For your size of boat you are restricted to one of three options-

Make your own. Best but quite a lot of work.

Use a converted tyre inflator compresor. The build quality of these isn't terrific, but they do work and are cheap.

Convert an old i.c engine. Halfway house to building your own. Better quality than the second option though.

You will also need a snorkel to take onboard the air, an air reservoir and a solenoid or servo operated valve.

Perhaps when you take all this into consideration, it's unsurprising a lot of people favour a water pump system.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby ScrumpyJack » Sun Sep 27, 2009 11:31 am

Thanks Andrew I was just trying to be a bit of a purist!!! Yes you are right the pumped option is almost certainly the one I'll employ and the price of pump(s) on ebay are soooo cheap.
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