Propulsion System - Motors, Gears, etc


#323

really? your acrylic bathtube fed by a plastic pipe is grounded by shell or wire?

You are right there was a regulation till 2002 in germany…

What I wanted to say is, that the system shorts itself (like a faradays cage) doesn’t really work if you have approximately same resistance (your body is 70% water).


#324

Just found the perfect prop!

The EDF group project in France, Britain


#325

I’m having trouble seeing the down side to direct drive. From my looking around it looks like direct drive avoids a whole ton of issues with gear boxes and sealing and such. Can you run motors directly in the water without sealing if your only ever in fresh water?

Just starting to gather up my parts and from looking I rather go with direct drive if I can avoid all the sealing issues and get away from a gear box.

Sorry I know this is probably a super noob question


#326

not enough torque mate!

well at the moment, not enough torque.


#327

I heard that brushless motors are more efficient at high rpms. Also, as DavidC said, it’s hard to get the high amount of torque needed while also making the diameter of the motor as small as possible to reduce drag.


#328

so is this aliens new motor?


#329

Could you use that motor with a gear box and not have to worry so much about sealing everything up?


#330

No, I think this one is the new one:

I am very tempted, it runs on 24s, but Alien has a 300A ESC for that, so that is ok. I am just not sure if it will have enough torque and if 24s are much more dangerous than 12s.


#331

I would personally have worries with 24S, that‘s over 100V with charged batteries. You could of course run it only at 12s and have all the torque. It just wont reach it‘s max rpm. I, for myself, could not justify having voltages higher than 60V DC in my board. That does not even account for the information in Risk of electric shock. If I research the european extra low voltage or safety extra low voltage directives, I have to conclude that 60V DC is the max in wet areas when protection against touching can not be guaranteed. One could for sure make the system absolutly watertight, but without an isolation supervisor device I would not be trusting it.
Just my opinion on it, from having touched varios voltages before and felt the discomfort of 60V. Feel free to build it your way, I just wanted to leave this here.


#332

Well. I have no idea how dangerous 100V is. So I am undecided at the moment and looking for more input.


#333

I just checked the torque of the APS 56115 (claims 4.5Nm) versus the 56014 (calculated from specs 2.7Nm) pacaficmeister used in his BOM. Do you want to try a direct drive prop or do you want a gearbox with lower ratio?


#334

Direct drive would be nice. I am in contact with gear manufacturers in Germany to find a Neugart replacement.


#335

Most anti-shark devices push a spike of 125V every half a second. In very salty water you can feel the small pulse. But they have a very low resistor that takes most of the current so that the current you or the shark will see is seriously low.


#336

max 50A? that seems quite low.


#337

At 100V…So 5000 Watts.


#338

Well lets assume most people don’t want to run greater than 12s.

Then we’re at 2500W…


#339

Strange thing, from the pictures it looks like an inrunner, but the title says outrunner.
I think it has much more torque than the other motor discussed here because of the increased diameter.
I also think it has higher power than the other motor. It is only specified strange in relation to each other, but maybe there are other restrictions, e.g. magnet system or rotor design.
Maybe its an incapsulated outrunner?


#340

Forget it. 100V is too dangerous. If you are in fresh water, your body conducts better than the surrounding water. The time, energy and the resulting current through your body and hands is important.
With your knowledge and skills it is going to harm you until you stop using it or it kills you directly.
50V with high precautions, 24-30V with some risk, 12V definitely without risk of life.
Please tell me why you think 100V is not dangerous.


#341

I don’t think its not dangerous. I said I don’t know about the dangers. I am a mechanical emgineer, so I get the electric basics, but I don’t know how dangerous 100v would be.

Running the motor at 50v would be pretty much pointless. So its probably the SSS for me and some gearbox. Unlesd you guys have a different candidate?


#342

ithink im going to look at a twin motor twin esc impeller setup… any ideas? maybe a dual drive 6k watt electric skateboard setup could be an idea?