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If you try to keep the prices low and buy from aliexpress for example, this is around what you can buy it for: 90€ motor+ESC+servo 30€ battery 50€ transmitter+receiver Obviously if you choose local resellers or different brands it gets more expensive, sometimes you get what you pay for

I believe the reason is, single blade has less surface and causes less losses due to wall friction. The wall friction effect is very important at such small scale, where walls are close to each other and the flow area is small compared to the surfaces enclosing it. Of course with big pumps, there is so much space everywhere that the wall friction is no longer so important. The single blade impeller is not fully balanced, but this only creates a problem with higher density materials. Plastic is lightweight enough to just work without having 100% balance. On the M-Jet 35, which uses a 3D printed metal impeller, full balance is achieved by using counterweights. For more insight, you can take a look at more videos and playlists on this channel.

Thank you that makes a whole lot of sense

This is the 3.2% champion: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-sprint-3d-printable-rc-jetsprint-boat-model

Thanks! The STLs will probably be available for purchase once I finish it. But I am not rushing the development and it's still long way to go. I will be uploading more progress on this channel.

There is no discord server, we have a facebook group: facebook.com/groups/623045356071128/ Alternatively if you don't like facebook, you can contact me personally on CGTrader: www.cgtrader.com/designers/m-jet-development

Yes! Everything is compatible, you only need to print the new V0.4 impeller. The pump is not changed.

Thanks! I first found the efficiency advantage of the single blade design when I tried to gradually cut away blades from a 3-blade design in this video: th-cam.com/video/_XM2nKv9fks/w-d-xo.htmlsi=GXoH_2MRuJHwTeWP

@@mjetdevelopment Looks like you are a friend of your Czech German compatriot Joseph Ressel. He invented the modern ship propeller as he (accidentally) lost the main part of an Archimedes propeller and realized it had much less friction and was thereby significantly superior. I wonder if your discovery would also apply to a propeller (rather then impeller).

@@SamuelLanghorn Yeah it's a great story, but for me it was still unexpected😀 I don't think this will aply to regular props, these have been tested in different combinations by way more people, so someone would have already found if there was improvement.

You can just mirror all parts of the pump in your slicer. Then spin them the opposite directions. But keep in mind that with the Supersprint, the pump housing is completely integrated into the rear hull. So if you wish to use the pump for a catamaran, you would need to heavily modify that rear hull file or create your own housing.

That would require supports which would end up worsening the surface

Thanks! I am using stainless bearings and I don't know their ABEC rating. I haven't tried different ones, but I am convinced that they don't have any noticeable impact on the pump performance. The pump is a high torque machine, the pump in the video requires about 0.4Nm to be spinned. Quick calculation on SKF website, and the main bearing which takes all load will only produce about 0.00045Nm of resistance, making this source of power loss negligible.

The Supersprint's pump is smaller. It is based on the M-Jet 35, but it is scaled down and modified purposedly for the Supersprint. The Supersprint files include the Supersprint's own pump, they do not include the M-Jet 35.

Right now it is not my focus, but it would be worth testing how much gain there can be from optimizing this parameter on M-Jet 35. I will also consider which improvements people report with this update on the Supersprint when actually running the boat. Primarily thanks to being larger, even the stock non-smoothed version of M-Jet 35 is still slightly more efficient than the smoothed Supersprint V0.4 pump.

@@mjetdevelopment Thank you for the input. I don't run rc boats but I have a lot of interest in using electric jet pumps on kayaks. Your work is some of the best that I have seen and I'd love to see something scaled up for small electric pwcs.

Only the impeller and the Lid_base is changed compared to the V0.3. Everything is compatible.

Perfect, I haven’t printed either of those yet :) Thank you! Your quick and helpful responses to questions from the community is very much appreciated, and makes this process more enjoyable and less intimidating. Thanks again!

Yes, good point, using a smoother printing technology will improve the performance even further

Yeah, plotting thrust per kw would also be a good metric and information. The only disadvantage of that metric is, that this does not include the exit velocity, which is very important for top speed. You can have 20kg thrust but very low exit velocity, then top speed will be low. Therefore I am plotting the relative efficiency, which results from output power / input power, compared to the Sprint. The output power already includes the exit velocity, too.

@@mjetdevelopmentdo yo7 know how a speed meter device looks like on bottom of getski? U can easily do something same, and measure velocity.. or if u somehow can collect all outputted water in 3 seconds with 5kg thrust, u can calculate a velocity.. e=mc2/2.. c2=e*2/m.. c*c=5kg*9.8*2/m

@@elyaperestigli2774 No need for that, I am calculating the exit velocity from thrust and exit nozzle area. The equations are shown at 0:38 here: th-cam.com/video/un8rdTVPTKM/w-d-xo.htmlsi=QLlE8AJtOyFXXgPo

Yes, good point, it would be the best method as long as the resin is strong enough

@@mjetdevelopment i use SUNLU ABS like resin. its very strong

Thanks! Yes, plotting thrust per watts and including the whole RPM range would also give good information.

Strength of the impellers is usually not a problem. Which material did you use, and which motor are you using on which voltage?

@@mjetdevelopment pla+ filament And a 3650kv spectrum motor on 4s

I haven't, I don't have a resin printer. Presumably, for efficiency a resin print would be even better.

Standard 2.2" crawler tires. About 145mm outer diameter.

Good point

less than 5% of world population has English as first language 🤷

Amazing, glad to hear!

Some people prefer high KV no matter the cost, so those will literally build one😁

Yes. Could you please specify what information in the video you find missing, or what you find incorrect that leads you to this conclusion?

Most people don't care about efficiency. They just want more power, even it if melts their connectors lol

Haha even if they prefer melting connectors, there is nothing wrong with it, it might just be useful to think about why it's happening😀

There is always haters commenting with nothing useful to add and produce nothing useful themselves.

Thanks. I haven't measured a 40xx motor, but I assume that for example a 4074 1800kv motor would achieve more RPM than the 3660 1800kv, staying more efficient even though the same RPM is demanded from it, making 1600-1800kv a viable choice. However a 40xx motor is too big for the Supersprint.

@@mjetdevelopment Makes sense! Thank you!

Thanks, I'm pleased to see you interested in building this despite how intricate it might look! The Kolos 8x8 files are not available yet. I am looking forward to the point when this design gets ready for a public release, but so far at this moment I enjoy this more like a personal project rather than a refined build for the community. Long way to go:)

900W power output. But it could probably be more, motor was the limit here. It can generate plenty of torque load, problem is the RPM, as the rotor has big diameter, I would be scared of it falling apart at higher RPM.

Thanks! Yes sure, this was just a quick first camera mount but I will come up with some better angles next time. This project is a long way to go

​@@mjetdevelopment... Thanks for replying... The suspension shots would sure allow;... help my inquisitive pensioner brain cells... Well what few I have left working... ROFL... Understand why on my Mobility Scooter it bounces over;... say a 2" tree branch instead of;... not only the 2" but plus being ejected a further 2" by the so called suspension system... I have slackened all four so they is no pretension... Perhaps I just need thinner coil springs... Yes I've watched many videos on suspension & how they work;... but when they start going into all the mathematical equations that just go over my head... Enough rattle... You have a great day... I look forward to more great videos from the England's;... Robin Hood County...

@@ElTelBaby Thanks man, looking forward to discussing the suspension with you next time the camera captures it properly:)

Yes! Chassis inspired by Tatra 813. That one did not have a cycloidal gearbox in every wheel tho😀

@@mjetdevelopment Well... then Off-road capabilities will be near endless!!! With the MAN Kat 1, probably the best Off-road trucks ever built ..... curious to see the progress