I thought I post some pics of my first sub... about 80% done. This is going to be a simple dynamic diver, with two motors run wet, and an elevon mixer used for steering. I plan to just make it a little "nose heavy" so that forward thrust will submerge it. The front nose "cap" will be permanently sealed with silicone caulk, and the rear will be sealed with that ugly black rubber cap and hose clamp, so I can remove it to get at the electronics and charge the battery. The motors are mounted in the center of the small PVC pipe with stainless steel bolts. These motor "pods" are then glued to the main hull tube with ShoeGoo glue!

Now I just have to figure out the best way to run the wires from the ESC (in the main, hull tube) to the motors. I'm considering the following... any comments or suggestions are welcome...

1) Run wires out a small hole in the main hull tube and seal it with silicone caulk.
2) Drill & tap 4 holes (2 per ESC-Motor connection), and use bolts to run power out to the motors (solder the ESC wires to the bolts on the inside, and solder the motor wires to the bolts on the outside).

Thanks!

Here's a picture of the electronics. The battery and ESCs are overkill for the two tiny 140 motors, but I wanted to reuse the ESCs in a larger sub in the future, possibly driving dual 540 motors! If the battery ends up being too heavy for my hull size (i.e. it sinks my sub), I'll just use some AAs instead! That pack is a standard 6-cell SC stick pack. I have just a 2ch AM RX with an airplane elevon mixer controlling the ESCs. I disconnected the power wire on the RX connector of one of the ESCs so the BECs don't fight each other.

I know little of RC things, being that I just got my first rc thing a month ago (besides a few things like 6-8 years ago)

but I think with your configuration, the motor inside the pvc will suffer problems, as A: the amount of water capable of moving around the motor will be blocked by the motor itself (it convers like 1/3 of the space) which will slow the craft. and, your pvc won't off alot of protection if something gets sucked into the tube, as a peice of plant material would most likely wrap around the prop and the motor housing, 9/10 times severly slowing or stopping the motor.

As for running the wires to the ESC, I think either would work, but if you solder, would rust be a problem?, I think it would be best to insulate all open wire... I'm not sure though...

if anyone out their wants to prove me wrong about this, go ahead, I'm just making guesses

Well, as far as the thrust being limited because of the motor blocking part of the PVC pipe, that's really not a problem. Before I glued the motor pods to the PVC hull tube, I tested them out first... I taped the motor pods to a milk jug, put my electronics and batt inside, and gave it a run. The thrust is pretty amazing for a couple of little 140 motors! I meant to get a photo of this goofy "floating RC milk jug" test vehicle before I dismantled it, but I couldn't find my camera before I was ready to glue the motor pods to the PVC hull!

As far as being protected from plants and debris, I think this setup protects the prop pretty well compared to an open prop. I am concerned about something getting sucked in and clogging the area between the PVC motor tube and the motor, but I don't plan on running this in water that has much stuff to clog it up... haha... that's the plan, anyway... I guess I'll see when I really get it out in some ponds! Something like a leaf or piece of paper/plastic could possibly get sucked up, flat, against the intake and block the water flow, but hopefully some full reverse thrust will blow it clear!

A very experienced model sub builder in the RCGroups forum recommended using the bolt approached for the ESC connections, so I think I'll try that. I don't believe stainless steel bolts and solder would rust, but I will most likely cover the ends of the bolts, where the connections are made, with some silicone caulk. This will protect the metals from corrosion (if any), and provide electrical insulation, so I don't accidently short out my ESC outputs with a screwdriver or other conductive object. Instead of solder, I might just use some ring-tongue terminal connectors (basically a washer with an electrical crimp connection on it). I am a little concerned about soldering bolts that are screwed into PVC... I suspect that I might melt the PVC! I'll have to try it on a test piece of PVC tube before actually doing it on my sub hull!

Thanks for your comments and suggestions! Keep them coming!

Could you give some comments about the 2 ESCs?

What I mean is, could I plug 2 ESCs into a receiever (both ESCs using BEC)?? that is actually my only worry...

Great sub...very similar to the one I am building, though, I'd rather call it a ROV-sub...
Great work, nice pics

Cheers

Wis

Wis,

Since each ESC has a built in BEC, or voltage regulator, you need to use only one of the BECs to power the receiver. To do this, you simply cut the power wire on one of the ESC's receiver plug. For example, Futaba type wires/plugs use a black wire for ground, a white wire for the control signal from the receiver, and a red wire for the power... this is the red wire that you want to cut on one of your ESCs.

The battery needs to be connected to both ESCs, if you look at my photo of the electronics, you'll notice I have a Y-connector or splitter for the batt connector to power the two ESCs. Both ESCs get their power from the batt, and both ESCs regulate the batt voltage down to about 4.8V on their red receiver plug wire. So, when you cut the red receiver plug wire on one of the ESCs, the other ESC is providing power to the receiver, and the second ESC's BEC/regulator is unused.

Hope that helps!

BTW Futaba uses red/white/black as I described here, but there are other color schemes as well, be sure you know which wire is the power wire on your ESC's receiver plug! When in doubt, check the ESC manual!

Thanks a lot...Clears all doubt

Well... soldering to bolts that are screwed into/through PVC doesn't work... the PVC melts way before the solder melts on the end of the bolt! The bolt just conducts the heat too fast to get localized heating to melt the solder, and keep the PVC from melting! So I'll just have to use ring-tongue terminal connectors and nuts to hold them on... plan B!

I'll post some pics when I get it together... maybe even get some bathtub run pics...

The six SC cell pack sunk my ship! Have to go to a six-AA cell pack. Here's a picture of estimated electronics placement to get a nose down attitude for dynamic diving (checked it out in the tub)! Now I have to make up the AA cell pack and connectors and then install the bolts for the ESC-motor connections in the hull, and I'll be ready to start playing with this thing!

keep up the good work...looks promissing