British T-class Project

[davinci]

Hello,
My latest project is a 1/48th scale British T-class, fiberglass hull sold by 'Models by Design' and using a 3.5"dia. WTC/ballast system.
It's been a Fun project!
It's almost complete but I'm still trying to work out problems with weight and flotation balance.
Since it's tower/superstructure are heavy fiberglass and I installed a torpedo-launcher assembly high in bow, she's very top heavy, so I had to add a great deal of lead in keel to prevent rolling when surfaced.
Now it crash-dives when ballast-chamber has water in it.
There's no more space for flotation foam, so I first though I'd have to decrease size of ballast-chamber by cutting off part of it to have space for more foam but then got the idea of putting some foam inside of the ballast-chamber. I'll be testing that next.
If that don't work I may have to remove the torpedo-launchers.

[davinci]

Well, I was hoping someone

Well, I was hoping someone had an Easy-fix to solve all my problems.
But looks like it's up to me and a lot of Testing to solve this problem.
Okay, where's my Big Hammer?

[thor]

Worry about submerged trim first.

Worry about submerged trim first. Then tinker with your surface trim. If you get your submerged trim all set and running level that should eliminate your 'crash' dives to the bottom.

[davinci]

Yes, I understand, but when

Yes, I understand, but when I get submerged trim correct by removing weights, she Rolls like a dead-fish when surfaced. It's either one or the other, can't get both.
I'll test it again soon with the flotation in chamber, I've been trying to fix a slow leak in the WTC today, also, so that's delayed working on the ballast problem.
I think I just found the leak. I pressurized it using schrader-valve and saw bubbles where wire goes thru endcap. I'm now waiting for RTV to set up so I can recheck it.

[thor]

I will be driving down

I will be driving down through Dallas several times over the next 2 months. Maybe we could set some time aside where we could meet so we can get this boat trimmed right. This can be a very frustrating process at times. If I sent you my email address, would you mind sending me some pics of the boat both internal and external. I think I will be able to help you out.

Matt

[davinci]

Thanks, Matt
But let me try

Thanks, Matt
But let me try that extra flotation test first, that may be enough additional flotation to fix it. Just don't know yet. Ill post test results in next few days.
I only know of one other person that has built a model using this hull kit. He's in UK and I talked to him briefly on another forum website about it and he indicated that he had similar problems but I didn't get details on it, so I was hoping someone on this forum had experience with this specific model?
I think he said he had to hang weight below keel, but don't remember for sure, I wasn't worried about it then and no longer have access to that. And I certainly don't want to do that unless I have to.

[davinci]

BTW - I'll post some

BTW - I'll post some pics here when I get a chance.

[davinci]

Well, adding foam inside ballast

Well, adding foam inside ballast chamber definitely lifted model closer to proper level when surfaced (more at bow than at stern), and the crash dive is not as bad with water in chamber but it's still not close to neutral-bouyancy.
I've reduced the size of battery already to get it lighter and lower in hull.
I guess the only thing left to do is remove some of the lead-weight inside the keel and hang a lesser amount on outside below keel to get the weight down lower to prevent roll when surfaced.
I sure hate doing that but looks it's either that or make a Display only model out of it. I really don't want to remove the launchers, which would require a complete rework of the bow.

[davinci]

Hey, I could just completely

Hey, I could just completely fill the chamber with foam!
It would no longer be a diving submarine but at least it will operate as a surface ship, which will lob out torpedos. LOL
I'll try putting in More and see what happens.

[Guest]

I take it that the

I take it that the space between the dive cylinder and the saddle tanks is completely filled with foam?

[raalst]

I fail to see the

I fail to see the difference between a chamber full of foam and a chamber full of air, as far as (surface) trim goes.
I think you should focus on the space outside wtc and ballast tank (and preferably inside the hull).

[davinci]

There's no more space for

There's no more space for flotation foam, outside ballast chamber, inside hull.

Please read above posts, where I explained why I'm putting foam inside chamber.

I put 2 more 1" disk inside the chamber, for a total of 6", leaving only 7" of air space and it's now getting to the proper level. This may work afterall.
Doing it this way makes it very adjustable.
Just add or remove disks as needed, Great!

I had to notch 3 of the foam disks to clear the gas-storage tank mounted inside top of chamber.

Here's a picture of it when I had 4 disks in it, (the pink stuff):

[Guest]

Can you post a picture

Can you post a picture of the wtc inside the hull.

[davinci]

Okay, I took, transfered, brightened,

Okay, I took, transfered, brightened, cropped , resized and uploaded some pics 'Just for You' :
Remember this model is not complete yet, so don't go criticizing my detail work yet. But if you feel there's something Major wrong please let me know. I've used similar setup on 2 other subs with no problems. This one is just more top heavy. It also has a video camera in base of tower that adds to top weight, but 1 of the others had the camera also, with no problem.

There's 2 WTCs, the ballast-chamber is part of aft one. The battery is between them under stacked foam and the small connector WTC, in center. The bow is also full of foam except where launchers are. The stern is full also except where the prop-shaft couplers are.

Click on pics to enlarge:

[PaulC]

If the ballast weights make

If the ballast weights make it stable on the surface, and submerged trim is your problem, try foam high in the boat. It won't affect surface trim if it is above the waterline, and will counteract the ballast when submerged.

The old rule I was taught was foam high, weight low. The farther they are apart from each other the more leverage they give in righting the boat both above and below the surface.