750kv Brushless Thruster Design Explanation / Assembly

[njs552]

Hi,

Below is a video I shot a few days ago about how my thrusters are put together.

When I was planning my ROV and looking for thruster designs, there were many conflicting opinions on prop size, type, kv rating, etc. I wanted to show what has worked for me, and maybe this will help some ROV builders with their decision.

Each thruster costs a little bit less than $20 in parts.

https://www.youtube.com/watch?v=hSLH7MzWLSA

I have some in water testing as well on my YouTube channel. These are very powerful, and power hungry. They draw about 8A at full power. I will be throttling the motors in my software, so they should only draw about 3.5A. I will be doing some thrust test soon to get some actual numbers, but I hope they get somewhere betweem 0.5 to 1lb of thrust @ 3.5A, 12v.

Motor: http://hobbyking.com/hobbyking/store/__ ... _140w.html
Prop Adapter: http://hobbyking.com/hobbyking/store/__ ... _Pack.html
Drive Dog: http://hobbyking.com/hobbyking/store/__ ... e_dog.html
43mm Prop: http://hobbyking.com/hobbyking/store/__ ... x9mm_.html

Thanks,
njs552

[Rover]

Nice video, thanks for sharing.

I have been using the collet type prop adapters with no problems, but I like the prop adapter you are using.

We put our motors in a PVC nozzle, Click here for more info. viewtopic.php?f=18&t=757


Rover

[njs552]

Thanks!

I am by no means saying that the collet type prop adapters do not work well, but I feel that they are less secure than ones that are bolted to the outrunner. The collet style obviously works great because most R/C motors are made for them, but for undewater use where there is a lot of drag and resistance to movement I think that they are more secure.

I really like that design. I a thinking PVC as well because it is light, strong, and easy to machine.

Thanks,
njs552

[zimmerm]

Great design, we are excited to give it a try. After some work we have been able to program or calibrate the car30 (with reverse) esc using the arduino. But we had to set the servo commands for the esc to be full reverse 15 and full forward 165. We get the beep code from the esc that it has saved our full forward and full reverse values, and it recognized out throttle neutral (90).

When we try to operate the motor, the motor will rapidly beep, and twitch but not spin. The ESC gives red led for reverse and greed led for forward.

Do we need to change advanced timing or anything?

[scubersteve]

did you get any thrust numbers off this setup yet?

[theinlinaung]

Hi there,
I see your Aquaprop propeller is 4 mm diameter and propeller adapter shaft is 5 mm diameter. How does it fit into the propeller?
I am planning to use this propeller with my 800kv motor. http://hobbyking.com/hobbyking/store/__ ... _1pc_.html
What do you think?

[njs552]

Hi,

I drilled out the 4mm hole with a US #19 drill bit, then used an M5 tap to thread the new hole. There is plenty of material left around the hole even after drilling the old hole out and tapping it as well.

Thanks,
Nick