Boats rc submarine design

K

kratata

Member
I know this is a submarine thing in the boat area but there is no submarine area, so yeah. I am going to convert a rc boat to a rc submarine. The ballast system will be controlled by a different transmitter and seperate electronics than the rudder and propeller due to the lack of channels on the first transmitter. I was wondering if there are any flaws in my submarine design that I'm not seeing: 0624151448.jpg The electronics are going to be bigger, I don't know why I drew them small. The ballast system will work by pumping water into the ball and the water will push the air in the balloon. To surface, the water will be pushed out of the ball into the open waters and the air in the balloon will go back to the ball. I moved the rudder and propeller to the bottom of the sub due to leaking issues I would have with the rudder if it were directly behind the sub. I will put mesh over the propeller and rudder to protect them from the water bed and other stuff. Yes I know that putting mesh on the rudder and propeller will lower my speed and efficiency. Please let me know of any flaws before I attempt this.

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The inside of the sub will be full of air, not water. I know that won't make it easy to lower the buoyancy but I'll put friggin 50 pound torpedoes on the sides if I have to. Also, the antenna will be a long wire floating at the surface because I'm not going to hunt down and then pay $250 for a 2 stick 72mHz transmitter just to make it wireless.

0624151448.jpg
 
Tony

Tony

Staff member
I happen to have a 72mHz Tx sitting here... Let me know if you are interested in it. I cna assure you, it's not $250 lol.

And if this were mine, I would find some way to put a sliding ballast in there so that you can pitch the nose up and down more easily. Something attached to the elevator. Push up on the elevator to make it dive, and the weight goes forward. Pull back, and the nose comes up and the weight moves back. Set the stick in the middle, and the weight centers right at the CoG.

I know you can find a waterproof propeller bearing and/or cage. Most of the boats have a shaft going out the rear and they don't take on water. More than likely it's just a few O-Rings that seal against the shaft, just like the body of a shock (on an RC car) to the shock shaft. Might do a google image search for "Rc Shock diagram" of something to that sorts and see if it gives you any ideas.

And sorry for the no sub category. As far as I know, you are the first lol.
 
K

kratata

Member
I was told from some rc subers that for a 72mhz transmitter it would be around $250. But the ones they showed did have a lot of switches and knobs lol. I'm just gonna do this as a cheap learning experience. Definitely gonna make a bigger/better one if I enjoy it. Maybe I'll add a fpv camera but I would have to have a pretty long wire that would reach the surface, since the signal won't go under water very well. As for the propeller and rudder going directly behind the sub, the propeller shaft wouldn't be the problem. It's how the stick connected to the rudder turns left and right to turn the rudder. There would have to be a decent sized side ways hole for it to turn. That I have no idea how to seal, and the pressure from being under water would not do me any good. That sliding ballast thing is a great idea! I'll see if I can make room for it. Might have to change the balloon idea for it though. Do you have a rc submarine??
 
Tony

Tony

Staff member
Nope, I don't have one. Not much of a water person. Can't stand it actually. Usually stinks or has a bunch of urinating people in it. I will just stick to my shower for my water times lol. As for the Tx, I will have to go out to the garage and take some pictures of it. It came with two planes that I purchased (see the video linked below). I wanted the planes, but everything else came with them as well. And wouldn't you know it, I still have yet to finish either plane hahahahaha.

https://youtu.be/hLnpUrQZPBQ
 
K

kratata

Member
I think I'm gonna hold off on the tx. Simply because a 72mhz transmitter will give signal under water but not very well at all. With the antenna floating above water I should be able to get some nice range. You gotta get those planes done thoe man!!
 
Tony

Tony

Staff member
They are still torn apart. I thought there was more footage of the Tx in that video, but I guess not lol. Sorry for the long video.

Can't wait to see what you come up with though on this design.
 
9

97warrior_rider

Member
Actually tony the sealing agent for a boat propeller shaft tube is simply just a coating of epoxy nothing real fancy


Sent from my iPhone using Tapatalk
 
Stambo

Stambo

Well-Known Member
Looks interesting, I have always been intrigued by RC subs.
Everything I have seen has the prop at the back, with the system you have drawn and the angle of the prop shaft I would be concerned that it may want to pitch down when you apply power.
Also you will probably need some sort of elevator too.
As for the radio, why not a 72mhz module for an existing radio, or how does 433 operate under water as there are plenty of 433 long range systems available.
 
Smoggie

Smoggie

Well-Known Member
Pumping water as your only 'up/down' control is likely to give very slow response. I'd have thought that supplementing with controllable hydroplanes might be worth considering?.. Real subs all have them.

You also have the very real risk that the sub will have negative buoyancy when ballasted. If the pump then fails the sub goes straight to the bottom. I guess one of the advantages of a long floating antenna is it could be made strong enough to haul the sub back up if it did sink.
 
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