Trimming the Gato to dive?

[daveee]

Gentelmen
I have got to the point of floating my Revell Gato. (The pool thawed out) Has anyone ever made a logical order of events to properly trim a submarine? Mine sinks ass first but floats level. If I move the weights forward it sinks ~ level but floats wrong etc etc. I can guess I need to move the RCABS bag or WTC or foam or weights or C fo G or ... You get the idea.
I would appreciate any help finding a link to such a site. It would save me a bunch of time.
Thanks
Dave

[tabledancer]

Dave,
If you don`t mind me

Dave,
If you don`t mind me asking what is that circular object stuck a little foward of midships on your WTC and is that your own WTC or someone elses.Just being nosey .
TD

[daveee]

Tabledancer??
I'm afraid to ask!!!
It's my

Tabledancer??
I'm afraid to ask!!!
It's my own WTC and the hatch is access to the ON-Off / charger deans plug.
The aft section is 2" OD and the forward section is 2 1/4" OD plexi. It fits nicely in the hull. I just built a test tank and am playing with lead and pink foam.
So far I have balanced it to sink more or less level with no air in the bladder. I had to drill a row of holes in the deck section chine, spaced every 1/2" to let the trapped air escape. There is a picture of GATO "Silversides (SS-236)" on page 21 of the manual that shows the real thing had these holes.
My biggest hurtle is the bladder can go above the WTC but part of it ends up above the water line which is no good. If I wrap it under the WTC, then it lowers the center of lift and fills unevenly which causes the sub to tilt to one side while the bag is filling. I ran a brass tube inside the bladder to force-ably transfer most of the air to the far side of the bladder but it will need some tweaking to get the ratio correct.
Still wish someone would help with trimming instructions... although I may get more satisfaction if I figure it out on my own.
I would like to thank everyone who shares their valuable knowledge on this web site!
Dave E

[tabledancer]

I wish that I could

I wish that I could help you out with the trim problem,as I`ll be facing that problem soon. But I have a lot to do with my boat before I need to worry about that.I`m using one of Big Daves WTC`S for my boat.I`ve got a lot of ideas and maybe they will work or maybe they won`t.I`ll keep watching this Thread,maybe I`ll learn something
TD

[cstranc]

I'm trimming a sub now

I'm trimming a sub now too. see the thread on the "Auto Pitch Control".

I had exactly the same problem with the sub listing to one side as it went down. It was level with the ballast tank full and empty though.

For me adding two columns of foam on the centerline (equal distances before and after the center of gravity) and extending to the underside to the top hull worked great.

Might be tough though if you don't have a lot of extra bouyancy with the RCABS. That might lower your waterline when you are surfaced.

Still you could see if it makes any difference then rip it out to get back to the correct waterline.

[daveee]

I just tried the sub.
My

I just tried the sub.
My hands are still wet.
The results of my test tank trimming are:
1) The sub dives level but rises stern first, which tells me the bladder needs to be a bit further forward. It is as far forward as possible considering the bulkhead.
2) The sub surfaces as soon as I apply air, meets the surface and won't break the surface tension caused by the deck. With all the air in the bladder, the sub only brings the deck ~ 1/4" above the water line. If I break the tension, it rises another 1/4", still not enough. This tells me there just isn't enough flotation from the RCABs system and the WTC doesn't have enough air volume. (The pink foam is still completely under water.)
3) If I remove the deck, and its associated weight, the sub works almost right as far a free board goes. This tells me I need a weightless deck and sail, that isn't subject to surface tension.

Questions?
Do most of you guys achieve a near perfect balance or do the model subs only keep more or less level when they are running?
I have ordered a shorter bladder which should move the center of lift forward enough, however it won't lift the hull enough. Should I start over with a different ballast system not limited to the WTC air volume?
Am I missing something???

Thanks for any advise
Dave

[steveuk]

Just a thought Dave...
how about

Just a thought Dave...
how about your working torpedo system?? Looks like a lot of brass tubing (weight?) up there in the bows. Could the torpedo tubes be made from Aluminum instead?
And is that a working folding hydroplane system also, is there a servo stuck in there - this could be additional weight you're carrying above the waterline.

I just got one of these Revell babies for my birthday - so I am watching to see how to fit it out for R/C. Did you cut away the hull to get your 2 1/4" wtc in there