PVC Submarine

[ericclark]

Hey everybody, I heard about this site on RCGroups but couldn't find it at first. Now that I have, I'm glad, there's a lot of cool stuff here! Anyway, this thread is more of me asking any of you veterans a bunch of questions about the basic principles of submarines. I'm new to the world of RC watercraft just having finished up my first and only boat, the USS Crockett, and more recently, I've started an ambitious project of constructing a fully functional, RC submarine mostly out of PVC. Its strong, cheap, and easy to work with. I started a little build log over in RCGroups here, http://www.rcgroups.com/forums/showthread.php?t=1236361, but I'm gonna post stuff here as well. I'm not entirely naive when it comes to subs cause I've been doing a lot of research but even so, every time I read a page I learn something new, so I don't think I know it all.

So, advice, suggestions, hints and tips, things to watch out for, anything useful will be most appreciated.

Eric

[boss subfixer]

Re: PVC Submarine

Welcome aboard Eric! After watching your Crockett build you should do quite well with your submarine project. Fire away with your questions.

[ericclark]

Re: PVC Submarine

Thank you sir! Well, my first question is this. How feasible is it to make a ballast chamber that has holes in the bottom and a valve on top. It functions by simply flooding when the valve on top opens and and when it shuts, compressed air gets blown in sending the water back out the holes in the bottom from where it came in? I've seen all kinds of fancy ballast systems with all kinds of bells and whistles, but will a simple setup like this work?

Eric

[skip asay]

Re: PVC Submarine

It's worked for me (and a whole heck of a lot of others) for close to 40 years!

Skip Asay

[ericclark]

Re: PVC Submarine

Awesome! Thanks. Now I just hope that its large enough to let the sub run well on the surface but still have enough displacement to bring her under.

[ericclark]

Re: PVC Submarine



If anyone is interested in pics like this one, they are all posted at RCGroups. Use the link I posted in my first post and it will bring you right to the thread.

[ericclark]

Re: PVC Submarine

Been working on my USS Crockett lately, although I'm going to try and run some ballast tank tests later this week (hopefully). Been doing some math and it seems that because I've increased my ballast tank size from what I was originally planning, its only going to be able to do about 3 dive cycles. Thats still acceptable to me but the biggest concern is actually being able to sink the submarine. Turns out I only have a ~6oz difference in displacement (ballast and sail) in my favor but its a very slim margin. And thats just taking a quick measurement and rounding the numbers with the math. Its an estimate to give me an idea of what I'm dealing with. Good thing is, it looks like the ballast chamber will add enough to displace the whole sail and a little more, but it will have to be riding low in the water when surfaced to be able to submerge I think. Well, thats what I hope to find out later this week with the tests. I'll post my results when I can.

Eric

[pirate]

Re: PVC Submarine

You were concerned as to whether your ballast tank was large enough to float your boat. Simply put your boat in the water, or something that weighs the same, and add blocks of closed styrofoam on to it with rubber bands (blocks of a standard measure so you can figure the total volume when done). Once the object floats as high as you want, then figure the volume of foam and that equals your ballast tank volume needed (approximately, but usually very close).

[ericclark]

Re: PVC Submarine

Thanks.

[ericclark]

Re: PVC Submarine

I have another question for you guys. I'm starting construction now and I'm finding that the o-ring seals are watertight but some are tight enough on the pushrods to cause unnecessary strain. Is there any way to reduce stress on the servos without compromising the seal? Grease, reducing rod diameter, etc?

Eric

[ericclark]

Construction





I know the hatches look rough right now, but I just cut them and they are no where near complete. It will look nice (I hope) when its all said and done.

Eric

[ericclark]

Re: PVC Submarine

Also, my ballast tank tests proved valuable. I found that with my original T fitting design, the ballast chamber was just the bottom part and it was just barely enough to submerge the sail section. After testing and researching, I found that I can buy a waterproof case for my HD camcorder so I don't need the top part of the T fitting to be watertight and so I thought if I just flood the entire T section, I would be able to have a sub that rides higher in the water because the ballast doesn't need to overcome the sail displacement, as its actually the ballast chamber! I only need to route a large tube through the T to connect the bow and stern sections for the electronics. I plan on having a "double seal" in the stern as you can sort of see in the pictures. I drew a diagram (below) illustrating it more thoroughly.

[solo]

Re: PVC Submarine

Hi Eric

Do you want a sérious PVC Submarine Look the french subs

http://www.club-contrex.levillage.org/projet01.htm

http://www.sub-rc.c.la/

[ericclark]

Re: PVC Submarine

Very cool.

[ericclark]

More Progress....





Nothing is permanently attached in any way. At this point I merely have a layout and I can still modify anything, change design, swap out parts, etc. Therefore, I would appreciate any input from you experts out there about anything at all that you see wrong/right, would change if you were building this, or any kind of advice really. Like I think I said before, I'm completely new to this.

Eric