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The Supersprint pump (close to 30mm diameter) is way too small to power a surfboard. To power a surfboard, you would need something like 2x 60mm pumps or a single 70mm pump. You could try taking the M-Jet 30 and scale it 2x up: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-3d-printable-jet-drive-for-rc-boats Or the M-Jet 35: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-35-3d-printable-jet-pump-for-rc-boats Also there is the M-Jet 60 specifically for surfboards, however that one does not have the newest M-Jet features: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-60-3d-printable-jet-drive-for-electric-surfboards Keep in mind that scaling up comes with many problems - hardware sizes, bearings, seals, wall thickness, tolerances, motor mount - these all stop working when a scale is applied. 15hp is enough for any of those applications, 6500 RPM is very low and might require scaling the pump even further up over 70mm to produce enough thrust even at low RPM; or increase pitch of the impeller.

@@coolcat498 I am using the Radiolink RC4GS. Has great features and seems to be a bit cheaper.

@@vmachacek I don't sell the Supersprint assembled, I only sell digital files. If you don't have a 3D printer, the closest you can get to a RTR Supersprint is the kit from RCPrinter: rcprinter.com/products/m-jet-supersprint-v1-0-build-kits You can also ask in the M-Jet facebook group if anyone is willing to sell a Supersprint: facebook.com/groups/623045356071128

@@mjetdevelopment nice, thanks!

@@zviper I am using stainless bearings which I buy from european shops, I am not sure where they are manufactured originally. For example here is a 5x19x6 www.123bearing.eu/bearing-housing/deep-groove-bearing/single-row/s635-zz-zen Unfortunately I don't know suppliers in different parts of the world

Yes, gladly. Here it is just slightly refined. It's also a bit old, today I'd process the data differently, but the observation is still very clear, most importantly the fact that RPM drop tends to have the same value as efficiency. This occurs because compared to a 100% efficient motor, our real unefficient motor loses RPM but does not lose torque, so all loss shows in the RPM. This is only valid on full throttle. On lower throttle, the ESC does some transformation of voltage which I don't understand yet, and the calculation of torque from battery current is no longer valid at lower throttle. docs.google.com/spreadsheets/d/1j3xF4OS1HBzlWBMEueXaDahvOi-Q2C9l/edit?usp=sharing&ouid=114321917833490201706&rtpof=true&sd=true

@@mjetdevelopment Thanks !!! BTW any progress with the progressive trim? :D

@@geekmidget No, first I need a new pump:)

@@mjetdevelopment ooohhh .. so are you cooking an improvement!? 😁

@@geekmidget I am cooking yes

@@zviper You can use ABS too, you might get a bit more warping tho, that's why ASA is preferred

@@mjetdevelopment I have a Voron it should be able to do it

@@mjetdevelopment I did print a abs and asa hull. Both turned out great with no warping. I did let the chamber heat soak for 40 minutes before each print and let cool to room temp. Do you have any links for the esc and motor you used in yours? it looks like a castle creations marine esc, i better put some couple rc's up for sale to fund that good lord they have gotten expensive. I bought my the first 2200kv mamba max way back when it was new and the thing was a savage setup in my losi buggy road car.

@@zviper Here are the links for what I used: www.castlecreations.com/en/hydra-x-8s-33-6v-esc-8a-peak-bec-010-0175-00 www.tfl-hobby.de/Motore--Halter--usw-/Brushless/TFL-40-mm/4092/BL-Motor-TFL--4092-1400KV.html The Castle is expensive indeed. I am absolutely amazed by both its performance and its advanced features, but to get a boat running there are cheaper options, for example Hobbywing 180A or Spektrum Smart Marine 160A (keep in mind the motor I used in the video pulls over 170A on full throttle so it is always up to you if you trust the ESC can handle it).

Yes, you are right, I hid the video. After I released it, I had some more thought around it. Right now the M-Jet Development is my only side job while I am studying. I really like it and I would like to continue. In order to keep my position on the market and my income, I can no longer give away all of my knowledge and methods. Anyone who comes to design jet pumps after me can copy what I do without having to spend those 5 years to figure it out as I did. As you can see from my videos, I like to share stuff. However, by doing it, at this point I am just putting my job in danger. Therefore I need to find a balance between sharing everything and keeping some tricks for myself. I will continue to share the results of my work; probably no longer everything which led to them. Thanks for understanding.

Oh yes the famous Marathon jet boats! They are quite optimized for speed, although perhaps not as optimized for cornering as the jetsprint-based hulls.

@@Stirlingkit Interesting! How is the maximum power output (W) your engines can produce?

🤗

Wrong chat sir:)

The "seed phrase" is your back up password. Combined with your wallet "adress" it is your account. Do not share your seed phrase with anyone ever ok ?

200g will be fine!

Thank you. Currently I have no time for the M-Jet 30 TPU Warrior version, sorry:( too many projects with priority. Right now the M-Jet 35 is on black friday sale for 28 USD, maybe you'd find it attractive www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-35-3d-printable-jet-pump-for-rc-boats

By "motor", do you mean the jet pump? The files for the Ragnarok hull are free: www.cgtrader.com/free-3d-print-models/hobby-diy/other/ragnarok-3d-printable-rc-jetsprint-boat The files for the jet pumps need to be purchased. Currently, you can choose between the M-Jet 35 (more powerful) and M-Jet 30 (cheaper). M-Jet 35: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-35-3d-printable-jet-pump-for-rc-boats M-Jet 30: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-3d-printable-jet-drive-for-rc-boats

Which upgrades do you mean?

@ upgrades like the super sprit

@@herosjourney2776 Which specific upgrades? I don't understand what do you mean by upgrades

Like the super charger upgrade

@@herosjourney2776 I see you mean the Supersprint's V8 engine. The Ragnarok will not get a V8 engine. It already has the rotary engine which will stay

In this video, I used Mega 25 turn fins. I managed to make the hull stable and stop any hopping, however I am still not fully happy with the cornering, it spins out more than I'd like. Tuning the handling takes time and requires testing many different combinations of all parts. This is my full setup. Version: Ragnarok V11 with flood chamber Pump: M-Jet 35 Motor: 4092 1400KV ESC: Castle Creations Hydra X 8S Battery: CNHL G+ 6S 4000mAh RTR Weight: 2945 g CG position: 165 mm from the stern (measured from rear end of the hull) Nozzle: +2.5 Ride plate: Ride plate by Ryan Frair Turn fins: Mega 25 Trim tabs: None Intake grate: Loading grate default

@@mjetdevelopment regarding cornering: have you tried making a progressive trim for the nozzle with +2.5 at the center and +10 at the very edges? I am thinking about traditional surfboards, when surfers want to turn on a dime they move all their body weight to the stern (where fins are) and push hard (I used to practice windsurf a while ago, same principle)

@@geekmidget I haven't. It is a very good idea and definitely worth trying.

@@TheMrmanning71 Good point! The brass tube coming out of the second stage, as well as the pipe in Hull rear which connects to it, is just my custom modification for doing some measurements. The public version does not need it and does not have it, so no worries:)

@@mjetdevelopment so that's a data-logging-ready Ragnarok 😁

@@geekmidget Yeah:) this was a lot of work, the longest video I have ever worked on. It's great to have this out now! I know you commented about your further progress and I did not react - I just don't always have the energy after working on my stuff;)

@@gregschweers8124 No, I don't offer 3D printing on demand. All I can suggest is to find a local 3D printing company which would print this for you.

@@Need_more_free_time Yes you are right, good tip

Hey, This is a long-term project. Since this video (7 months ago), I did multiple tests in very hard terrain. The chassis has amazing potential and I am very happy with where this design is going. The whole drivetrain - the gears and gearboxes - still needs great amount of work. I did 2-3 versions already, still not how I want it to be. It is specifically difficult to combine 1) excellent reliability, I want to make the drivetrain unbreakable and eventually stall the motor rather than break gears 2) comfortable accessibility and easy disassembly of all parts independently. I know what to do for the next iteration and have solutions in mind, but since this video I haven't had time for such a big redesign. Apart from massive CAD work, every new iteration requires printing and assembling 8 gearboxes. Currently, my other projects have priority - new jetboat related development, and a bachelor thesis:) I will absolutely get back to this when it is possible, which could be next summer. It's been a year and half since this project started, maybe it will take a year and half to finish it. You will see it here when it happens:)

Yes, you are right, I hid the video. After I released it, I had some more thought around it. Right now the M-Jet Development is my only side job while I am studying. I really like it and I would like to continue. In order to keep my position on the market and my income, I can no longer give away all of my knowledge and methods. Anyone who comes to design jet pumps after me can copy what I do without having to spend those 5 years to figure it out as I did. As you can see from my videos, I like to share stuff. However, by doing it, at this point I am just putting my job in danger. Therefore I need to find a balance between sharing everything and keeping some tricks for myself. I will continue to share the results of my work; probably no longer everything which led to them. Thanks for understanding.

@@mjetdevelopment Fair enough, thank you for the info you have shared so far, and I truly wish you success. 👍

@@mjetdevelopmentCompletely understand your reasoning. It’s too bad though, I’ve been learning so much from you and really enjoyed that last video. It’s been very interesting following your progress. Keep up the great work, we all appreciate your efforts 🙌🏽.

BTW Stepan, even if you no longer share the internals of your data logging experiment, I would appreciate if you could at least validate how far off are my calculations in the spreadsheet I left at the RC Groups forums 🙏

@@geekmidget Yes I will take a look.

@@darkokatrasnik9810 The KV is a bit too high, 2400KV would make a good 3S setup. You can still run 3S, maybe 3S 2400-3000mAh but pay attention to how hot the ESC will get. Lower KV would be better and then you could run 4S for example. Please follow the Supersprint manual for the most detailed up to date information: drive.google.com/drive/folders/1f-epKNBlcqGcuJU5rGvYQleL7ayPnrRe?usp=sharing

@@rafc843 Thanks for your understanding, that aliexpress sellers who violate my design rights should not be supported. Nevertheless, things have been going well for me lately, so no worries. The M-Jet Development is continuing.

I only sell digital files, which you can print on a 3D printer: www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-3d-printable-jet-drive-for-rc-boats

@@petervenema9628 Most importantly, choose the filament that works the best for you, you have well tuned settings for it and your printer prints it well with good layer adhesion. I used ASA this time. PLA worked for me well in the past too. People use all different materials mostly with success.

Yes good tip:)

@@allenarceneaux The rollers go into the main big printed bearing, in the video it's yellow. Try googling "crossed roller slew bearing". In case there are more questions, feel free to send me a direct message on CGTrader: www.cgtrader.com/designers/m-jet-development

@@zohrabmamedov5446 You could try scaling it to 200% or 300%. Then theoretically, performance might be sufficient. However there is so much trouble with the upscaling process: If you upscale it, all bearings, shafts, hardware will upscale too, possibly resulting in non existent hardware sizes. Imagine 300% M3 screws -> M9, pretty much doesn't exist. The mount for motor and servo will no longer be compatible with anything. Tolerances might get screwed up randomly. Overall - the upscaling process would require great effort. Then, trouble will come as you will need enermously powerful electronics to spin the upscaled pump. Torque scales with 4th power of size here. 2x size -> 16x torque. Power consumption scales with 3.5th power of size. 2x size -> 11x power input and motor wattage.

@@Jish79 RCPrinter has a hardware kit dedicated for the M-Jet 30: rcprinter.com/products/m-jet-30-pump-build-kits

3S 2400-2800mAh for best runtime. 4S 1800-2200mAh for best performance.

@@mjetdevelopment thank you!

@@lots_haus The Supersprint has self righting. When built correctly with components placed according to the manual, it will always flip itself back to the correct position.

@@Debraj1978 I don't find it that simple to continuously dissipate 1000+W into anything. More importantly, I need to be able to adjust torque. I assume it could be possible to adjust the DC resistance on the second motor, but then it would require an adjustable resistor? An adjustable resistor capable of 100A.

@@NeverMind0113 No, I don't sell any physical pumps. You can purchase the files and build them yourself. If you don't have a 3D printer, you can ask a company to print the parts for you.

@@nej113 I measure thrust of the pump. I also know area of the exit nozzle. From these two, I can calculate mass flow. See, Thrust T, mass flow m, volumetric flow Q, nozzle area S, exit velocity v, density Ro, metric SI units: T = m*v T = Ro*S*v*v Therefore v = (T / (Ro*S))^0.5 And m = T/v Then power output P is equal to kinetic energy of water which flows out per 1 second P = 1/2*m*v^2 Hope that helps.

@@mjetdevelopment So you would start with v = (T / (Ro*S))^0.5 as the known variables are thrust, water density and nozzle area? And then go on from there?

@@nej113 Yes

@@nej113 Also keep in mind this is only valid for static thrust test. For a running boat it gets way more complicated and so far I havent managed to fully measure performance of a running boat.

@@mjetdevelopment Thank you so much! I'm in my final year of school before university and we have to do some kind of bigger project. I've been watching you since the original M-jet 30 and I thought this was a perfect opportunity to try and design my own jet drive. My plan is to design and 3d print a jet drive and then measure static thrust efficiency (input and output power) and try to optimize it to some degree. You've really been the inspiration for this project so thank you.

@@burner8126 It's barely enough for the full width of the hull. The hull itself is 20cm wide at the widest point. For more comfort I would recommend a wider cloth, alternatively you can use 2 overlapping pieces.