Otw upholder

[greenman407]

When I first got interested in model submarines, about 7 years ago , I was very interested in starting with this one, until I learned of the price. Ive pretty much got five submarines completed or well along. So I said, WHY NOT? Ive got to be thinking ahead. OTW is offering this Sub kit for a average price, compared to what other hulls are going for these days. Its 55" long and 6" Beam. Pretty healthy size.
In order to swing it Ill buy the hull and fittings first and perhaps the Dive Module later on. Of course Im sure Dave could come up with a Subdriver to fit it. We will see. Its got a huge 3&3/4" 7 blade prop.
I should take delivery in January.

[trout]

That is going to be really cool looking. There is a beauty to that sub, I know of a picture of one that I thought was a well done model, I will see if I can find it.
Mark looking forward to your build on this!

[Slats]

Awesome Mark
pretty sure the 3.5" Subdriver would be a good setup.

J

[greenman407]

[Albion]

Nice looking boat, but she's not entitled to fly that flag ;)

[greenman407]

Maybe she borrowed it from the "Conqueror." At any rate this model is made from GRP and its produced in 1/48 scale from the original test tank models. Just a little FYI.

[reddevil]

Superb manufacture of the model, and really impressive finishing.

[Subculture]

The model in post 4 looks like Ahmed's, with paint by Alan Taylor. Don't quote me on it, but I think this boat runs with a Sheerline module inside.

[greenman407]

Andy, Whats the difference between the Sheerline and the OTW module?

[Subculture]

About four hundred quid I think.

[greenman407]

No, I meant pump, or compressor, or gas, or what?

[Subculture]

I know, I was just being a smarty.

They both use water pump systems, although are configured very differently. Both WTC's use 110mm diameter pipe, but the sheerline uses opaque PVC pipe instead of the OTW's clear acrylic. The Sheerline has external draw bars with flat silicone rubber seals to seal the endcaps. The OTW has internal draw bars with o-ring seals. The internal bars make the cylinder more compact, but you have to seal the rods where they exit the module, plus they take up space inside the cylinder. Both systems use axial compression of the o-rings.

With regards to the ballast system the OTW uses a modified shurflo nautilus pump. This is a low pressure high volume pump (makes about 15 psi max), water is pumped into a central tank, and electronic probes inside the tank shut the pump off when the tank is about 90% full. The displaced air from the tank is vented into the dry areas of the WTC, and stored under pressure, hence why you need the probes, else you could flood the dry areas.

A solenoid valve is inline with the pump, and this prevents the compressed air pushing the water back out through the pump. To surface the pump is reversed, and the solenoid valve opened, the compressed air assists the emptying of the tank.

Probes are also mounted in the bottom of the tank to shut the pump off when the tank is empty.

The sheerline pump uses a centrifugal type pump (windscreen washer type) with a servo controlled pinch vlave. It also uses a central tank, but the tank is completely sealed and the pressurized air is stored within the ballast tank. This simplifies the system as no electronics are needed for water level detection, but it reduces tank capacity by about 20-30% over the OTW system. Therefore the tank needs to be physically larger for the same volume of water.

Both systems maintain a ballast tank with an exposed water surface, so baffles are needed to minimise c.g imbalance due to sloshing.

The OTW modules are quite a bit more expensive than the Sheerline. This is partly offset by the OTW coming with most of the electronics you require as standard e.g. ESC and leveller, you just need to add servos and receiver.

I would say in performance terms the OTW modules have the advantage for boats with large displacement. For smaller vessels, they are more closely matched with Sheerline.

[greenman407]

Thanks Andy. You can be a "Smarty" anytime you want.

[greenman407]

A Little closer.

[Subculture]

Couple of vids of that boat running-