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Dumas Akula

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Re: Dumas Akula

Postby Alexander The Great » Fri Jul 20, 2012 10:12 am

Ahab79,

As for the cylindrical WTC, are you going to make one or buy one?

Hint: if you buy one, then you should go for one that has a static dive system. Not many available WTCs use a dynamic dive system. Most use a STATIC dive system.

A boat of this size can be run of the stern planes only.

Note: Sub culture is correct about the bow planes, they are only useful if it is out of scale; do note that this boat is marketed as a "Sport scale" Akula.

Best wishes,

Alex
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Re: Dumas Akula

Postby Ahab79 » Sat Jul 21, 2012 11:37 am

I completely understand that this is a "sport" sub. I also have read numerous times that the planes are oversized. This sub is my "training" sub. I'm planning on upgrading it a moderate amount. Just because I have the time. The will and I love scratch building things.

WTC....I'm racking my brain here. I WANT the rougue sub WTC for 200. But that's a bit pricey for a practice sub. so I think I'm going to get some 3 inch PVC and buy the end caps. And fill up the interior myself. This wil leave more money for a dive system.

So please take above into account when I ask the following question. IF AND I WANT TO STRESS THIS. IF....I Decide to make the bow planes reatract (yes retract because i'm definatly going to make them functional) won't this mean that the hull will have to flood? I don't midn because I'm going to use a WTC. But this will increase the weight right? So what do I do so she doesn't sink? Use foam while I'm trimming? Also. If its a wet hull. Doesn't that equalize the pressure a bit more. Which means my hull should not be as suseptable to pressure right? So theoretically I can go lower.

So???
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Re: Dumas Akula

Postby Alexander The Great » Sat Jul 21, 2012 12:06 pm

Ahab79,

A wet hull won't equalize pressure any more than a dry hull, you are just taking of the load from the exterior hull. The only way to resist pressure without using different materials is to have the WTC pressurized. The only way of doing that is to use piston tanks/any other ballast system that produces pressure in the WTC or manually pressurize it by your mouth or a pump.

For the WTC, make a diagram so you can plan out where you are going to put things. Be realistic. Don't put the ESC at the front of the WTC, or anything else like that. Servos, main drive motor, ESC, etc should be at the rear of the WTC. The receiver should be located at the front. Depending on how everything fit, there just may not be enough room for a battery, so you may need to waterproof it and place it outside the WTC. This is fine, some other manufacturers do this as well.

If you make the WTC, do some research and study what other people's WTC look like. This will give you the basic idea as to how things are placed, located, and how you could be smart with your space.

The bow retracting mechanism will be quite tough to build. You can use a servo to operate the retracting mechanism or a electric motor.

Go to the download section of Rouge Subworks, there are several articles about making your own WTC.

Enjoy!

Alex
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Re: Dumas Akula

Postby Ahab79 » Sat Jul 21, 2012 1:56 pm

Alex thats' great advice. Thank you so much. And I never thought about pumping in air to WTC when taking on water to help with pressure. Awesome.

I'm wondering if I didn't explain myself properly however. The Dumas Akula hull is pretty thin. If the Inside of the hull, but outside of the WTC was filled with water would that not equalize the pressure allowing me to dive a bit deeper?

Mark
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Re: Dumas Akula

Postby Alexander The Great » Sat Jul 21, 2012 2:33 pm

Ahab79,

There is no pressure between the outer hull and the WTC, since it is "free-flooding". The only thing that has pressure is the WTC (that's if you choose to pressurize it).

The only factor that limits your possible depth is the integerty of the WTC, mainly the strength and condition of all the things exposed to water, like the tube, end caps, seals, etc. Pressurizing it will prevent the WTC from caving in, buckling, etc. It also strengthens the WTC over time as the pressure will compact the material that makes up the tube and the end caps making it more resistant to water pressure as well as an impact...

Unless you build the boat as a dry hull Akula, the outer hull is not subjected to any pressure, just the water.

Hope this clears things up.

Alex
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Re: Dumas Akula

Postby Alexander The Great » Sat Jul 21, 2012 2:34 pm

Forgot to say this, but depth is also limited by radio reception.
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Re: Dumas Akula

Postby Ahab79 » Sat Jul 21, 2012 9:50 pm

Subcommittee should have a link to stuff like this.... BTW I paid for my membership a few days ago..still don't have access to any membership stuff. Any idea's why? I've sent 2 e-mails. No response....thinking..... membership guy is busy?

http://www.youtube.com/watch?NR=1&featu ... hc137YKbkI
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Re: Dumas Akula

Postby Thor » Sat Jul 21, 2012 10:19 pm

I will have the guys take a look and see whats up with your membership!

Matt
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Re: Dumas Akula

Postby JWLaRue » Sat Jul 21, 2012 10:43 pm

Ahab79 wrote:BTW I paid for my membership a few days ago..still don't have access to any membership stuff. Any idea's why?

How did you pay for your membership? PayPal off the main web site, PayPal off the forum site, check, money order?

Currently the only payment option that results in the immediate change of membership status is the forum-based PayPal method. All the others require some manual effort from some folks, which can take a couple of days. The manual processes are being phased out!

As Matt said, we'll check on what's up.

-tnx,

Jeff
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Re: Dumas Akula

Postby Ahab79 » Sun Jul 22, 2012 8:55 am

I payed with pay pal. Please keep me posted. Thanks.
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Re: Dumas Akula

Postby Sub culture » Sun Jul 22, 2012 10:14 am

I really would nix the idea of retracting planes on this boat- a lot of effort for little reward, but if you're determined to do it, that youtube flick shows the general method. It's a good idea to slot the feed to the servo that tilts the planes via a cam operated micro switch mounted on the retract servo. That way you can't operate the planes until they're fully extended.

When pressurizing WTC's proceed with caution. Even at modest pressures the loads are relatively enormous, and you need to be certain the item has been designed to take that sort of load. Most WTC's you purchase in the States will have push fit caps, and no tie rods, so if you pump in even a whiff of pressure, the caps will pop straight off.
'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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Re: Dumas Akula

Postby Alexander The Great » Sun Jul 22, 2012 1:09 pm

Ahab79,

You should use a high quality servo for the bow retracting mechanism. For me, I like to all out on it and buy a BRUSHLESS servo, which uses a brushless motor instead of the brushed one. The servos from Futaba sound awesome to have. They are digital, have dual bearings, strong samarium cobalt magnets, etc.

http://www.futaba-rc.com/servos/brushless.html

There seems to be no disadvantage to these, other than cost (that is a guess). They may not work with some of our electronics (that is a complete guess, I'm never tried).

You could use a electric motor to extend and retract the mechanism instead. Ether way, they are not that easy to build. Looks easy, sounds easy, feels easy, but in reality, they can be a PITA.

Have you read the article in the download section of Rouge Subworks? That article is a absolute 'need' if you really want to make the WTC yourself. I just read over it again, it has a "parts listing" in the back showing you where you can get your stuff.

I forgot to mention this, but just like Sub culture said, you will need retaining rods to hold the end caps on if you pressurize the the WTC. Or you can use a bayonet-ring to hold it on, these things are awesome, they are reliable, and you don't need to seal the rods if you use internal ones. External rods require space, although in most boats, there is plenty of room for these, and internal rods need to be sealed at the end caps, but they can be used to hang your tech rack.

Take some time and research how other people made their WTC. It will give you ideas as to how to make this thing.

Alex
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Re: Dumas Akula

Postby Ahab79 » Sun Jul 22, 2012 1:49 pm

Yes I have read the article. Infact I downloaded it at work. And printed it out. I've read it twice. It is the best thing I've found so far. It is just amazing. The only thing it has done badly however is confuse me. It says to use an air pump. I was under the assumption that you pump water in. Not air. But I'm sure I'll figure it out.

As for the WTC. I'm almost ready to begin. I'm gong to go wtih PVC or ABS pipe. As the clear Acrylic tube will be hard for me to aquire. I'm in a city of 150 000. The nearest major city is four hours away.

What are anchoring rodes? I have an idea. Long threaded rodes run down the interior of tube? Use them to, what? Bolt the endcaps into place? Isn't that another place to have a leak? Lol. I have an idea on how to firmly secure the end caps. That's not my issue.

Issue now is the Ballast tank. I'M TRYING TO FIGURE OUT WHICH WAY TO GO. I have access to 60 ml or 60cc syringes through work. How many of these do I need to sink a Dumas Akula?

Mark
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Re: Dumas Akula

Postby Giovanni » Sun Jul 22, 2012 3:12 pm

You can get high quality polycarbonate tube from here at very good prices.
The best method is to call them directly and ask them to find remnant tube at one of their outlets.
It is the most inexpensive way to buy.
A 3.5" OD x 8' polycarbonate tube is only $17.00@ft.
http://www.professionalplastics.com/PolycarbTube
Kind regards,
Giovanni

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Re: Dumas Akula

Postby Alexander The Great » Sun Jul 22, 2012 3:38 pm

Ahab79,
The air pump is for the ballast system. For the ballast system in the article, it pumps air from the WTC into a bladder to surface the boat. This system creates a vacuum in the WTC. There is another version of this system. It works the other way around. It is hard for me to explain so I found you some articles on ballast systems.

In the article, it did say you did not have to build it as a static diver. Just omit everything used for the ballast system.

http://www.heiszwolf.com/subs/tech/tech01.html

The link above talks about most of the system, but does not include RCABS/RCABS-R (that's the system described in the article. The following link below includes RCABS/RCABS-R.

http://www.rc-sub.com/resources/index.php5

Those rods you talk about are not needed unless you pressurize the WTC. Most people never actually pressurize the WTC on purpose. You will find that you may never send your boat to such depths in it's lifetime. There are two ways you can mount the rods. Internally or externally. Externally is preferred since you do not need to seal the threads. But it does require considerable space between the WTC and the hull. Internal rods need to be sealed otherwise you would have a leak. But you can use them to your advantage by using them to hang your tech rack. But you do need a big WTC (in terms of width).

You could just use a bayonet ring to secure the end caps in place, they are much better than rods.

First, figure out wether you want to build the boat as a static diver or a dynamic diver.

Alex
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