Recent content by stevetto

Input values are just kind of some random numbers.. My purpose was to see how current, torque, efficiency changes if I use the same motor at different input voltages or compare different motors. I know that this tool is not perfect, but at least quantitively shows the tendency. I also would...

I made an Excel sheet to calculate BLDC performance curves to help compare operation conditions at different inputs. It has not been tested yet!

10s lipo will result 10*3,7*50=1850rpm which is too high. So I need to reduce it with a planetary gearbox or a 2 step timing belt reduction. Planetary gearboxes not availble with 1:2 reduction so a KV80 or KV130 motor might be necessary. Resulting 10*3,7*80=2960rpm and 10*3,7*130=4810rpm speed...

I have made some more research and found that most probably I do not need higher rpm than 1000, and the required torque is around 10Nm. So the other option would be to use this motor: https://alienpowersystem.com/shop/brushless-motors/80mm/c80100-outrunner-brushless-motor-50kv-6000w/ A 6s lipo...

I have started to thinking about this motor: https://alienpowersystem.com/shop/brushless-motors/63mm/aps-6374s-sensored-outrunner-brushless-motor-30kv-2800w

Thank you ! I know this project.

I have no idea how much torque is necessary. The 1000W power is my assumption based on the battery capacity and runtime. For example this one: nominal capacity/run time full trigger 1340Wh/1.66h = 807 W And from another manufacturer: The 1000-1500 rpm was also an assumption, now I think...

I am getting to accept the idea of using a planetary gearbox but still not found the appropriate motor (or motor with gearbox). Every added kilo of a gearbox reduces the size of the battery and thus the run time.

That is the easy part. There are aluminium and composite tubes available for the body. A custom made aluminium casting is necessary for the nose and tail. High pressure cable glands, o-rings and simerings are also available. For me the motor and controller is the biggest challenge.

I was thinking about to use water cooling as it is used in rc boats. But I still think it is too risky. There is 1 bar air pressure inside the DPV, the target depth is 200m, so there are ~20 bars water pressure outside.

Nearly perfect, just too heavy: https://www.aliexpress.com/item/90-efficiency-high-torque-24v-48v-bldc-motor-1000w/32818875603.html

I also found something interesting here: http://www.bonex-systeme.de/static/motor_e.php They are talking about servo motors but I do not think it is necessary. A simple stepper or bldc is enough and much cheaper. Do you think if it is a geared motor?

I would like to avoid gearing if it is possible, because it is noisy, needs more maintenance, can add extra unwanted weight and it also can be one more source of issues. In technical diving we do not like complicated equipments. Everything has to be very simple and reliable.

You are right, weight is not critical. It can be compensated by the volume of the DPV's body. I'm looking for something like theese motors:

Sealing is not a problem. The whole body of the DPV is watertight. The motor's shaft goes out at the tip of the tail cone and there a high pressure simering is used. The DPV itself ~20 kg. The required thrust ~300-400 N Top speed ~ 4-5 km/h Battery 10s10p, ~ 1000Wh Motor ~1000W, 1000-1500rpm...