STL files for the jetboat, M-Jet Sprint, are available for purchase! www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-sprint-3d-printable-rc-jetsprint-boat-model
beautiful work, i just bought a 3d printer just so i could print your M-Jet for my boat project. I might even try to print the M-Jet boat as well! I really appreciate that you share your hard work with us! Blessings!
You go with what works man and that works impressively!! I built a couple of jet drives from scratch using PVC pipe and the impellers that worked best in mine were 3 bladed drone props (shallow angle). Because everyone kept saying I needed to get a "real" prop in there, I ordered one and smoked the motor and 120Amp ESC on first trial run at 70% throttle. I'm sticking with what works in my mind from now on, screw the experts right. Your design rocks and I think you're on to something special with the dual stators separating the impellers. Very inspirational. 👍👍
Thanks! In my experience pump diameter matters a lot - overloading/smoking a motor could happen when too big pump diameter is used with too small motor. Also I find low kv to be better. But yeah just stick with what works for you:)
Cool! I was wondering if anybody has already tried a multy-stage design on this small scale to increase the total pressure. Have you ever tried a mixed-flow pump design to get more pressure (ideally this design should have a higher pressure to flow ratio while still having about the same thrust and power so this could help the boat hull to sit higher in the water and create less drag)
Hi, from your point of view what is the difference having a 2 stage prop compared to a single long prop having the same length of the sum of your 2 props ?
The vanes between these two impellers stabilize the flow. They remove the rotational movement of the water after leaving the first impeller and straighten the flow. I have not tried as long impeller as you are saying, but I estimate it would just spin the water in a circle, even more than a short single stage impeller.
well mate , i was have this problem on my own model , will try that , wiath type off incresse in the pitch would you recommande ? by the way awesome design
When you design your pump do you ensure that the volume of water is the same at every point along the pump? As an extreme example, say your intake opening is 10 square cm and your exit nozzle is only 5 square cm. Since water isn't compressible like air, would that cause inefficiency? Just curious if that's even a consideration for you, or if I'm thinking about it wrong.
It is definitely a consideration. The important thing is: in a wide area (intake) the water will flow slower than in a small area (nozzle). The area of the nozzle is always smaller on purpose - it has to speed the water up. Also, it is a bit hard to notice, but in my two stage pump, first impeller has a smaller cone than the second one. Therefore, the water has to flow faster around the second impeller. And because of that, I design the impellers so that the second impeller has higher pitch - the water flows faster there.
@@iandrake4683 Yes. Second impeller has higher pitch. And the second row of stator vanes has higher "pitch", too (they are more curved). But the ratio for this particular pump is only 1.06 so it probably does not make much difference.
I am not sure how you mean power requirements? The amps consumption difference was as stated 40 to 36A. Regarding efficiency, I did not measure efficiency of this particular pump. However the general suction improvement I experience in overall handling of a two stage setup is so important, that I would choose a two stage setup even if it was possibly less efficient. Anyway, my latest developed and release-pending M-Jet 35 is two stage and, according to my measurements and all experience, highly efficient.
Yes, two stage pumps make my boats go faster. With my single stage pumps, even a very little hop of the boat on a small wave would cause the pump to lose power, which would slow the boat down. So for me, a two stage pump improves the top speed thanks to the fast priming. On completely flat water, a single stage pump might theoretically perform better thanks to possibly higher thrust - but practically I have never experienced that.
@@fariskhalida I built many prop boats when I started with the hobby. Then I built my first jetboat and immediately started to enjoy it more than props. I love the handling, acceleration and the cool style overall. Now, I would always choose a jet
Hello, I have been designing a 64mm inlet jet pump for a while now, After a lot of reserch iv found that the nozzle should be approx 10%-40% of the inlet size... So my question is, what is your take on this? Im trying to get as little reprints as possible and im on Version 73 on my jet drive... What was your take on this for your jet? What did you end up with and what was your conclusion for it :)
There is no best nozzle size, it depends what your goal is. The nozzle has effect on thrust and top speed. There is a point with a bit larger nozzle where thrust is the biggest, which gives the best acceleration. If you make the nozzle a bit smaller, you will get to a point where you get the biggest top speed, for the cost of losing some thrust and increasing power consumption. On different M-Jet pumps, the nozzle diameter to pump diameter ratio ranges from 40% to 60%.
Thats what i thought, ended up going for 2 different versions, 47% and 39% I guess that in the best world an adjustable nozzle would be the best where it gets smaller the faster you go.. But feels like that wont be worth the time for programming and reliability testing. Thanks for a fast reply @@mjetdevelopment
There will probably be a difference but I have not measured it on this boat. I dont know which configuration has more thrust in this case. Generally I think it also depends on nozzle diameter and other parameters to determine which configuration will provide more thrust.
Why does a two stage pump prime so easily? I'm designing a jet and having some priming issues with a single stage. I'd love an explanation so that i can either convert to two stage or see if I can make the working principle of that work in a single stage. Thank you!
I can only guess but this seems logical: when spinning air and no water yet, it generates more negative pressure, therefore pulling water inside faster. Compared to a single stage, where the "vacuum" at the first impeller is not powerful enough. Also think of a long chimney and fire. I dont have anything more scientific so far:)
@@altaccount4697 Without a massive redesign you may be able to add a small "Inducer impeller" in front of the main impeller that being closer to the intake can grab some water and prime the drive. I did this on one of my scratch built (PVC pipe & 3Dpen) jet drives and it helped it over not having it, but I think his design kicks all others to the bank. #MHzJetBoats
Hi, from what I have seen, the tfl pumps should work quite well, but I have no personal experience with them. The quality seems to be better than most jet drives you can buy online. I have read some people reporting some water leaks, so I would suggest you to read some reviews first. There is some information here: www.rcgroups.com/forums/showthread.php?3156866-jet-boat-options/page6
@@pongsapak_am More vanes do straighten the water more, but also add a lot of friction. There must generally be a compromise between these two effects.
Hi, the best case would be if you had a friend with a 3D printer. Otherwise you would need to find a local 3D printing company, I do not know how these prices are. Still, I cannot really recommend buying these files without having your own 3D printer because you cannot print spare parts. On the other hand, buying your own 3D printer is not that expensive, for example the Creality Ender 3 costs under 200 dollars.
There would be probably no further advantage and it would consume even more power. But actually I might do a crazy experimet and build a 5 stage pump or so
![CAMPปลิ้น | EP.76[2/2] เดินมาสิบกว่าป่า วันนี้รู้แล้วว่าโจโฉกลัวอะไร!](http://i.ytimg.com/vi/R7Yor-t2Au0/mqdefault.jpg)
![[TH] VCT Pacific Stage 2 - Week 1 Day 2 // GEN vs T1 | PRX vs TLN](http://i.ytimg.com/vi/ZkFjjJNwzH0/mqdefault.jpg)
STL files for the jetboat, M-Jet Sprint, are available for purchase!
www.cgtrader.com/3d-print-models/hobby-diy/other/m-jet-sprint-3d-printable-rc-jetsprint-boat-model
Máš to vymakaný.Líbí se mi ten dvoustupňový šroub i způsob natáčení trysky.Pěkný!
Good video and excellent way to compare. The difference is very clear.
beautiful work, i just bought a 3d printer just so i could print your M-Jet for my boat project. I might even try to print the M-Jet boat as well! I really appreciate that you share your hard work with us! Blessings!
Nice, good luck!
You go with what works man and that works impressively!!
I built a couple of jet drives from scratch using PVC pipe and the impellers that worked best in mine were 3 bladed drone props (shallow angle). Because everyone kept saying I needed to get a "real" prop in there, I ordered one and smoked the motor and 120Amp ESC on first trial run at 70% throttle.
I'm sticking with what works in my mind from now on, screw the experts right.
Your design rocks and I think you're on to something special with the dual stators separating the impellers.
Very inspirational. 👍👍
Thanks! In my experience pump diameter matters a lot - overloading/smoking a motor could happen when too big pump diameter is used with too small motor. Also I find low kv to be better. But yeah just stick with what works for you:)
ordered it so exited for it to come il put a 90a flycolor in it and a 3670size brushless motorwith 3100kv i can even run it on 4s
Cool! I was wondering if anybody has already tried a multy-stage design on this small scale to increase the total pressure. Have you ever tried a mixed-flow pump design to get more pressure (ideally this design should have a higher pressure to flow ratio while still having about the same thrust and power so this could help the boat hull to sit higher in the water and create less drag)
Hi, I have not tried any mixed flow design yet, partly because I believe there is still a lot of potential in optimizing my current two stage design.
Amazing didn't know it makes such a big difference. Would you be kind enough to share the design so that other people can try it? Thanks.
Thanks! I am selling STLs for a new version of the whole boat:) check my video "M-Jet Sprint Release":
th-cam.com/video/ft1p1KqpupI/w-d-xo.html
Hi, from your point of view what is the difference having a 2 stage prop compared to a single long prop having the same length of the sum of your 2 props ?
The vanes between these two impellers stabilize the flow. They remove the rotational movement of the water after leaving the first impeller and straighten the flow. I have not tried as long impeller as you are saying, but I estimate it would just spin the water in a circle, even more than a short single stage impeller.
well mate , i was have this problem on my own model , will try that , wiath type off incresse in the pitch would you recommande ? by the way awesome design
Thanks! How do you mean that? In this video I used 31mm pitch on the first impeller and about 33mm on the second one because it has a wider cone.
@@mjetdevelopment each little jump was stopping the pump
When you design your pump do you ensure that the volume of water is the same at every point along the pump?
As an extreme example, say your intake opening is 10 square cm and your exit nozzle is only 5 square cm. Since water isn't compressible like air, would that cause inefficiency?
Just curious if that's even a consideration for you, or if I'm thinking about it wrong.
It is definitely a consideration. The important thing is: in a wide area (intake) the water will flow slower than in a small area (nozzle). The area of the nozzle is always smaller on purpose - it has to speed the water up. Also, it is a bit hard to notice, but in my two stage pump, first impeller has a smaller cone than the second one. Therefore, the water has to flow faster around the second impeller. And because of that, I design the impellers so that the second impeller has higher pitch - the water flows faster there.
@@mjetdevelopment got it. Is there a pitch difference between the stages?
@@iandrake4683 Yes. Second impeller has higher pitch. And the second row of stator vanes has higher "pitch", too (they are more curved). But the ratio for this particular pump is only 1.06 so it probably does not make much difference.
What are the power requirements of that? It's impressive, but is it more efficient in terms of overall use?
I am not sure how you mean power requirements? The amps consumption difference was as stated 40 to 36A.
Regarding efficiency, I did not measure efficiency of this particular pump. However the general suction improvement I experience in overall handling of a two stage setup is so important, that I would choose a two stage setup even if it was possibly less efficient.
Anyway, my latest developed and release-pending M-Jet 35 is two stage and, according to my measurements and all experience, highly efficient.
멋지네요
Nice work man.
Is if effects the speed?
Yes, two stage pumps make my boats go faster. With my single stage pumps, even a very little hop of the boat on a small wave would cause the pump to lose power, which would slow the boat down. So for me, a two stage pump improves the top speed thanks to the fast priming.
On completely flat water, a single stage pump might theoretically perform better thanks to possibly higher thrust - but practically I have never experienced that.
@@mjetdevelopment agreed. Thanks for the info. Nice build btw.
Jet n regular propeller? Which one do you prefer?
@@fariskhalida I built many prop boats when I started with the hobby. Then I built my first jetboat and immediately started to enjoy it more than props. I love the handling, acceleration and the cool style overall. Now, I would always choose a jet
@@mjetdevelopment Thats more interesting.. I will subscribe for more your videos. Thanks man
Hello,
I have been designing a 64mm inlet jet pump for a while now,
After a lot of reserch iv found that the nozzle should be approx 10%-40% of the inlet size...
So my question is, what is your take on this? Im trying to get as little reprints as possible and im on Version 73 on my jet drive... What was your take on this for your jet? What did you end up with and what was your conclusion for it :)
There is no best nozzle size, it depends what your goal is. The nozzle has effect on thrust and top speed. There is a point with a bit larger nozzle where thrust is the biggest, which gives the best acceleration. If you make the nozzle a bit smaller, you will get to a point where you get the biggest top speed, for the cost of losing some thrust and increasing power consumption.
On different M-Jet pumps, the nozzle diameter to pump diameter ratio ranges from 40% to 60%.
Thats what i thought, ended up going for 2 different versions, 47% and 39%
I guess that in the best world an adjustable nozzle would be the best where it gets smaller the faster you go.. But feels like that wont be worth the time for programming and reliability testing.
Thanks for a fast reply @@mjetdevelopment
Do you have any different in pushing power between the one and two impellers?
There will probably be a difference but I have not measured it on this boat. I dont know which configuration has more thrust in this case. Generally I think it also depends on nozzle diameter and other parameters to determine which configuration will provide more thrust.
Why does a two stage pump prime so easily? I'm designing a jet and having some priming issues with a single stage. I'd love an explanation so that i can either convert to two stage or see if I can make the working principle of that work in a single stage. Thank you!
I can only guess but this seems logical: when spinning air and no water yet, it generates more negative pressure, therefore pulling water inside faster. Compared to a single stage, where the "vacuum" at the first impeller is not powerful enough. Also think of a long chimney and fire. I dont have anything more scientific so far:)
@@mjetdevelopment that sounds pretty solid. Thanks so much, and great jet design!
@@altaccount4697 Without a massive redesign you may be able to add a small "Inducer impeller" in front of the main impeller that being closer to the intake can grab some water and prime the drive.
I did this on one of my scratch built (PVC pipe & 3Dpen) jet drives and it helped it over not having it, but I think his design kicks all others to the bank.
#MHzJetBoats
I'm thinking on buying a jet drive do you know if those 29mm tfl pumps are any good?
Hi, from what I have seen, the tfl pumps should work quite well, but I have no personal experience with them. The quality seems to be better than most jet drives you can buy online. I have read some people reporting some water leaks, so I would suggest you to read some reviews first. There is some information here: www.rcgroups.com/forums/showthread.php?3156866-jet-boat-options/page6
@@mjetdevelopment Thank you ill look into it
Clarkson sorta brought me here
If it has more fin for the 2nd stage and nozzle what will it happens
Because I have the issue of swirling water when it came out of the nozzle
@@pongsapak_am More vanes do straighten the water more, but also add a lot of friction. There must generally be a compromise between these two effects.
I don't have a printer. Who can print for me and what would it cost?
Hi, the best case would be if you had a friend with a 3D printer. Otherwise you would need to find a local 3D printing company, I do not know how these prices are. Still, I cannot really recommend buying these files without having your own 3D printer because you cannot print spare parts. On the other hand, buying your own 3D printer is not that expensive, for example the Creality Ender 3 costs under 200 dollars.
How about 3-stage pumps?
There would be probably no further advantage and it would consume even more power. But actually I might do a crazy experimet and build a 5 stage pump or so
Vtec kicked in