How much thrust do we actualy need?


The same 56mm impeller.
400A ESC Flier, waterproof and water cooled.
motors: leopard, sss motor and tp power, tp power can support more amp.
exit nozzle ok


You motors are all 56mm diameter?


jet system 56mm but my idea is try the same gearbox diameter in open prop 30mm, next tests


Wow, cool 30mm propeller is getting small, interested to see how it works
I’m a little confused though, you will use 56mm motor, with a gearbox, and a 30mm open prop?
Why the open prop? They are very dangerous


when I say open prop it means propulsion propeller, jet is ducted propulsion.
My propeller with gearbox is 120mm, you can see in my videos on youtube, in my jet I’m using 56mm impeller direct do you understand? 30mm is the diameter motor brushless.
If I first made an impeller jet it was because the propeller is dangerous.
I think the ducted propeller ( bigger with gearbox) is still dangerous


Ok I get it now, thanks Virus!


You jet system is 56mm impeller, but what is the outlet diameter of your jet nozzle. It tapers in… have you tried making this larger or smaller for more thrust? We found that if your not using the jet near the surface to mix with air the nozzle outlet hole can be a little larger than normal and you get more thrust underwater.


ok but the potential energy is not the same with bigger hole


exit nozzle looks to be about 47mm


We just redesigned our nozzle so we can easily change the exit hole to test various diameters from 37.5mm - 52.5mm (from to small, to too large, and find the sweet spot).

From my experience, the smaller the nozzle exit diameter the less low-end thrust, but a higher top end speed. But it nozzle is too large then you lose thrust also, there is a fine line, really the fine details will be more personal preference for each persons riding style and skill level to some extent.


Hello Everybody

Today I have done some thrust test of my system

Battery: 8s
Esc: hobbywing 130A
Motor: SSS, 500kv
Reduction: Neutgard 1:5
Propeller: solas 7.25 x 6"

And tha’s my recorded data:


Could you please tell me if, following your experience, the recorind are enough to foil?

Thank you very much


that’s crazy 48kg of thrust! thank you for this test, i will tell you tomorrow i have the same propeller than you,

i think it is enough to foil but may be slow you have 500/5: 100kv on 8S , i choose 130kv on 8S with the solas propeller


Thank you for your reply. You have true for the speed. With 20% of sliding of the solas impeller I can rench 20 kmh with 2700 rpm but it’s enough to begin😉

I have choose to run at 100 kv 8s because by doing the ratio of hiort impeller (140mm) surface and solas (180) one I find a ratio of 1.6 and 1.6 is approximately the ratio between 12s and 8s.

Thank you for you reply Alexandra. Can’t wait to see your run😉


size ,shape, angle of the blade give you pitch, so speed, you can have a diameter vs pitch ratio off 0,8 to 1,2 or more :wink:


ha, that’s exactly why I’m doing this. I watched Kai Lenny videos and then a light bulb went on. Then I found your you tube vids and now I’m building one. Funny the evolution of a thought.


could you do a torque test on the setup ? a torque test along with all this very promising data would give the perfect requirements everyone is looking for


With rpm we could find torque no? Because at full I was at 2800 rpm!




I could be mistaken, however I believe this is the relationship between Power, Torque, and Speed


with the solas propeller that gave me 11N on start

@Vincentbraillard : with your test assuming you have 20% rpm lost under load, we found around 11N again

the solas seems to work well with a outrunner 80-100 which is rated around 9N i think