They can simply use my jet. It’s proven with sss56115. 480kv on 12 s. Brings the boat on plane.
No need to compress water in this one😂
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It’s a 60mm jet right?
Do you think an 80100 350kv from Alien Power Systems would be a good choice for this jet?
…for a surfboard with a single jet drive?
sss56115 doesn’t make enough power for what i’m doing. If you feel it does lets see the test data. Any jet design compresses water. It sounds like you don’t really understand the physics of this. Kinda alarming considering you’re over here pushing a design now… out of the blue.
Example of CFD flow below. The design keeps KISS (Keep it super simple) and cost in-mind. As we know, the motor/esc/battery is a good deal of cost already.
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In 5000m deep water You get a compression of 1.5%! That’s nearly 500 bar of pressure.
And now you tell me you compress water in your 3d printed water jet? Come on! What pressure do you create? Tell us from your flow simulation. And tell us how much you compress the water in your jet. 0.0000000000001%?
And you CFD picture seems wrong as in a waterjet the highest pressure should be in the stator, and not behind it.
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I think you guys are talking about the same phenomena but use different terminology.
I guess what kuban_fpv is saying, that in a water jet you pressurise water. That in fact results in a high velocity at the outlet what generates thrust.
And the pressure difference is what causes cavitation. Not the compression!
So in summary water is pressurised, not compressed.
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Looks cool ! How does the CFD results compare te field tests ? Is this in line with your predictions ?
Indeed my mistake it’s incompressiblilty is what allows you to pressurize it. But you will see water compressions through cavitation like I mentioned. It causes literal damage to impellers.
The CFD is velocity… not pressure. In the pressure analysis the highest pressures are against the impellers. Your highest velocity should absolutely be the exit of the nozzle.
Toto where did you get your design? Looks A LOT like an MHz product. Almost identical.
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I designed it on my own. As I know MHZ is 64mm?
I think they make quite a few different sizes now. They have 65’s 80’s and I think they are making something bigger. All CNC and cast aluminum so the cost is nothing to shake a stick at.
https://www.mhz-watercraft.com/shop/en/jets/
The 52, 58, 64, and an 80 they aren’t talking about on the site yet.
I’m very interested in seeing some test data! Power draw or thrust or both?
That flow analysis is a 20K rpm flow.
The flow analysis doesn’t tell you everything. It gives you pressure at the outlet and velocity but does directly calculate thrust. I had a to do a separate thrust calculation and I came up with around 120lbs of thrust at 20K. The jet velocity as you can see in the picture is around 63fps/69kmh.
Given iv’e only tested to 9,000rpm, a bit less than half the design output and I obtained about 45lbs… i’d say it’s very close.
To Todo’s comments I very much expect this plastic design to shatter when it hits full design pressure (60psi)… but i also printed it intentionally thin to see where the thin section is going to break. We will re-enforce as needed at that point. It did quite well for only being 2.5mm thick PLA. We have carbon options we can try as well as bulking up the wall thickness in general.
You said the SSS56123 doesn’t have sufficient power for this jet.
So what size motor do you suggest?
How about an 80100 outrunner? Schoud have plenty more torque then the SSS inrunner.
Question is if the RPM will be enough at 350 KV
Are you asking me or Toto?
Toto said his jet is sufficient with the sss56114. I’d love to see some numbers but i don’t doubt it works with his current config. It’s all about what you want for a design output.
I have a sss56114 running at 50% of design speed and it’s maxed out on amps (100a) so i say it’s not enough for mine. But others may simply be okay with higher amps draws. I want mine to run for sustained periods of time so i want to stay under 100a. It’s possible i could bump my kv down to 200 and run 75V and maybe the amps are low enough on a 56mm motor… i just haven’t tested this. Either way i know at 320Kv the motor doesn’t have enough torque to get to 15,000rpm without breaking my 100amp limitation. I think 80mm will allow torque the 56 can’t, and therefor have a much less amp draw to start out with… even without high voltages. It would be cool to stay away from high voltage near water.
Why are you doubting? Check the video. It brings the boat on plane
Where does he say that he is doubting?
Or. Am I missing something?
Oh. Sorry I Read too fast. Didn’t see the don’t 
All good. Can you give us any data Toto? Like amp draw or thrust? What KV and voltage are you running? We can estimate it’s making 50-100lbs of thrust based on the take-off.
Here’s a pdf to everything TFL supplies for SSS motor.
I see a 56123 on the list at 230KV. This might support my jet at 15-20K rpm. However, would need 70V to hit the desired RPM. The high voltage winding alone would cut my amperage by the voltage increase. My 94 amp load would be something on the order of 29amp simply with the kv change.
That seems to be the problem with these hobby motors (larger motors have too low kv and size motor we want has too high kv) . I understand the problem as well. It has to do with balance. In CNC machining its required to start balancing tools that spin over 18K (in the 2" rang) or it tears spindles apart. A spindle is generally a 20-40hp 3-phase AC motor with high accuracy bearings.
I’m guessing these motor manufacturers don’t want their motors tearing themselves apart at the RPM’s we look for. Perhaps larger jets (70-80mm is the range we need with these massive 80mm motors. The 80mm motors cannot hit the desired rpm we would like (even on hv), so the only thing we can do to maintain power is bump up the flow via diameter.
Same more diameter = about the same torque : 3n/m constant with good cooling
56mm inrunner : 3
80mm outrunner :9
There is always the beast : tp100xl