Dave Welch's Type 7 WTC build

[anonymous]

Decided to start a new thread on my Type 7 now being re-fitted with one of Dave Welch's WTC made just for this model.

I have to say this WTC is a breeze to build. Part of it is I've built three of his kits now and it's becoming second nature to build these. But still it's so well thought out and documented it's hard to go wrong.

Here's some pictures of what I've done in the last two days. I should finish it tomorrow. I still have to mount the pump assembly and finish the wiring.

Then make some t-valves and connect the two bladders up top. Of course then there's mounting the WTC inside the boat.

More tomorrow.

Steve

[tabledancer]

Steve,
VERY GOOD,just the type of

Steve,
VERY GOOD,just the type of info and picts that I was looking for,keep it all coming.
T.D.

[wingtip]

steve ,
what seals and

steve ,
what seals and tube is that? so far im only familiar with the bronze oilite stuff ive bought .......

[anonymous]

Wingtip,

I got them from D&E

Wingtip,

I got them from D&E miniatures. Very much the same as the subtec seals Mike's Subworks sells.

Tabledancer. I will and thank you.

Steve

[wellington]

Hi Guys
anyone interested in doing

Hi Guys
anyone interested in doing a wtc for me for my type 7 revell boat. I have Dave's wtc parts and the cd but I am not the I mechanically inclined.Electronics and stuff get me all nervous. I would send parts and you give me a fair price to build it. Maybe you are interested steve as the pictures of your version look great and the hull is not cut.
Thanks guys
Dave Goddard

[anonymous]

Hi Guys
anyone interested in doing

Hi Guys
anyone interested in doing a wtc for me for my type 7 revell boat. I have Dave's wtc parts and the cd but I am not the I mechanically inclined.Electronics and stuff get me all nervous. I would send parts and you give me a fair price to build it. Maybe you are interested steve as the pictures of your version look great and the hull is not cut.
Thanks guys
Dave Goddard

David,

got my hands full right now but if someone else could help this gentleman out that would be great.

Steve

[anonymous]

So here's some more pictures

So here's some more pictures of the build to date.

You can see the air pump in the middle compartment and the servo that activates a micro switch which turns on the pump. Move the servo the other way and it hits the tire valve sucking the air out of the bags and back into the WTC.

Aft compartment is the 2 motors and the servos to drive the elevator and rudders.

In the forward compartment you can see the battery terminals. The gel cell I'm using will run wet. The other seal is for the forward dive planes. The servo is located next to the pump servo.

Except for hooking up the prop shafts she's all done. I tested the WTC in the water Sat. and it was a complete success.

Today I spent installing the WTC in the boat and making new control rods. I still have to add brass supports to the deck from the under side. This keeps the deck from lifting when the bladders fill up with air.

Tuesday I get my dog bones. I ran out and had to order more. Then I can finish off the shafts.

Steve

P.S. So far this has taken 6 full days to do.












<img src="http://www.subcommittee.com/SubComm/images/photos/unfinished _WTC2.jpg" border="0">








Edited By U812 on 1113808618

[JWLaRue]

Steve,

From the photos it appears

Steve,

From the photos it appears that the RCABS bladder sits on top of the WTC and above the designed waterline of the hull. Am I seeing this correctly?

When you did the WTC test on Saturday was it installed in the hull...and did it then lift the hull up to the correct waterline?

-tnx,

Jeff

[Guest]

Jeff and Steve,
There seems to

Jeff and Steve,
There seems to be some confusion about the position of the bladder and the desired waterline. Think of the inflated bladder as an inflated balloon, sitting on top of the water. Only the bottom of the bladder needs to be at the desired waterline. Therefore, the portion of the inflated bladder that is above the waterline is not really wasted.

[anonymous]

Art,

Well put. That answers that

Art,

Well put. That answers that question.

Jeff,

Although from the top view it looks like it sits above the water line the bottom of the bags is right at the water line. It's just about perfect.

Now to get those dog bones and I'll trim and test the boat.

Steve

[JWLaRue]

Okay...now I'm a bit confused.

It's

Okay...now I'm a bit confused.

It's not clear to me how a ballast tank (RCABS or otherwise) is able to provide lift for a hull to get to the waterline when the ballast tank is at and above the waterline....at that point the portion above the waterline is just parasitic weight and not contributing to lifting the hull.

The analogy of a ballon sitting on top of the water is not a good one. The balloon sits on the "top" of the water because it takes very, very little of the internal (air) volume of the balloon to lift the weight of the balloon out of the water. In other words, I think it's a misleading analogy.

-Jeff

[anonymous]

Jeff,

I'll let Art explain it.

Jeff,

I'll let Art explain it. However it's enough for me that it works. I know it does because I've seen Big Daves in the water and it works great.

Art?

Steve

[JWLaRue]

Steve,

No, no, no....I am not

Steve,

No, no, no....I am not in any way saying that the RCABS system does not work. I've seen Art's original version of it an it works quite well.

However, a closer look at how Big Dave's WTC is configured. will show an important difference. (We're talking the Seawolf/Kilo models, yes?) He has the 'bag' inside his WTC tube, which has it's top at the waterline....which means that the 'bag' is always no higher than the waterline. Having the top of the ballast tank, in this case the 'bag', at the waterline is the perfect location for it.

-Jeff

[boss subfixer]

Steve,
I was just sifting through

Steve,
I was just sifting through the pictures that came with the WTC that Dave makes and there are a couple that show better how the WTC sits in the hull. The WTC sits pretty low with the bladder sitting just at the waterline. This seems to me at least, how you achieve the right waterline. That and how the boat is trimmed. Maybe I'm off base here but this is how I understand the setup.
Look for these pictures DSCN 1306 and DSCN 1246.
Hope this helps.
BSF



Edited By Boss subfixer on 1113871873

[bigdave]

I guess I should step

I guess I should step in and give my findings. When I ran my prototype I was able to get the hull to sit close to waterline. But I was not able to get a lot of testing done on it before the weather forced me inside. Given the design of the RCABS and the limited space inside for the bladders, (or anything else) I was left with the space above the WTC under the deck for placement. This turned out great as it is dead center in the hull, and left me with enough foom for two bladders, which was needed to lift the sub. It was a trade off, if I wanted to use the RCABS system and have a model that ran well and was easy to convert, I would have to maybe suffer with a little less waterline. I figured a sub that works is better than one that sits at exact waterline and does not work. This is the same with the Kilo also. To fit the bladder and all the R/C gear into the hull it will not sit at exact waterline either, but it works, and that I feel this is the main objective. Dave.