Well anyway, thanks jetboy for the heads up on the bearings I will be watching them close. The rear bearing is exposed to the water
6x15 mm full ceramic 128.77 each and rated at 11,000 rpm.
Boca has some hybrid stainless steel races nitride balls for about 20 bucks I might try. Rated for high rpm
Sorry I havenāt responded sooner. Been busy doing covid 19 remodel work on my house. I get so busy normally that I never finish anything on my own place so Iāve been knocking out lots of projects for the last few weeks.
I have bad news for,you those 4084 motors wonāt work I used one successfully on a board using the very small jet 4 that MHZ sells for model boats, it worked great and still does actually as I had a feather weight friend put with me last week and he rode a 10ā board with that motor and jet on 6s and it worked fine but slow.
However when I tried them on the youngster set up both myself and Mark fried the windings on those motors, so on 8 and 10 s the torque that those jets were producing pulled big amps and the first time just popped the 100 amp breakers I was using then when I swapped the 100amp ones out for 200amp breakers the breakers did not pop but the motors ran like they were clogging after stripping them down the insulation on the three phase wires was melted and they were shorting against the case and each other I insulated them with much thicker insulation but when I ran them the kept cogging and I figured the coating on the windings had failed and they were not usable any more .
I told mark about this and he admitted that he had had the same problem. I was a bit ticked off because he never told me that until I told him about my experience. .
I was kinda screwed at that point because the jets were in a pelican box and it would not accept the SSS 50104 motors cause they were too long so I had to buy 2 āLeopard 5692 motors I think they were they fit and are 520 kv so plenty of torque but after I got then I saw that they were rated for continuous amp draw of 88 amps and I think that is not a realistic number for a jet board my tests have shown peaks in the 180 amp range on take off and steady amp draws of 136 but itās been difficult to test more than a few times static tests need two people and they donāt give up you the real peak number since there is no rider adding their weight to the load. And so far I have not found a power meter that goes over 150 amps that is also,small enough to fit into the battery box. The last one I tried was a 150 amp power meter and I melted a wire off last time I tried it so all that told me was that my peak was well over 150 amps right lol
Anyway what appears to be a bullet proof motor is any of the 56 series SSS ones they go as low as 420 kv in the 56104 size and if you have the room the 56114 is 360 kv so you can run 12s flat out with that motor and the rpm will still be in the acceptable range that the jets like to,run at .The higher KV Leopard motors donāt have a j
Higher amp rating but also will spin a lot faster if you use 10 or 12 s so not sure Iād use Leopard again .
I have not even tried to run the youngster set up since the last fail. Mark has not responded to my questions about the plastic melting so I havenāt wasted any more time or money on that set up.I think with my weight on the board itās doomed to fail particularly if as I suspect the plastic around the bearing race has already melted on one drive . I was hoping that he would give me a new drive that way I could take the one that keeps failing out replace it with a new unit and then cut the old one in half to see what is going on inside that would have helped both of us I think but no response from him so Iām done with youngster jet pumps Iāll stick with MHZ
Hope this helps you a bit. Math should be sharing all this date with his customers particularly when he knows a particular motor doesnāt work
Iām going to wait until my next test to respond , but thank you
I did just purchase two more jets from mark
Ok, another static test today tied to the dock, all was good until I got close to 100 amp +draw that was full throttle the motor wires, first few inches became to hot to hold again test fail. Reading the specs on the motor says max amps 105.
So thanks jetboy, I wonder if I used a 10 cell the amps would drop enough?. Ordered a pair of SSS 56104ās 500 kv I want to make this work
Plan on finishing my 10s 10p battery trying it on this setup and then the new motors
An inflatable Chinese answer to Markās design. Brand name: Kedean. Allows for standing / lying down riding with two joysticks with a wrist dead man switch.
For simplicity and extra room to store the electronics components, I had this U-shaped inflatable board design in mind to insert a bigger waterproof case receiving a hydrofoil. Wondering how much they would sell the inflatable board only.
just buying the board would be interesting. Unfortunately, I have not found one yet.
With a Jet board the bottom shape and rails become really important in how it handles and turns. While these inflatable ones are be great for a little ride-about, they handle terribly when you actually want to start turning properly.
I can imagine that. Fortunately, our hydrofoils turn airborne and such a board with a flat bottom would really interest many people looking for compactness but reluctant to buy the slot-typed inflatable board:
My dad and I just finished building an electric surfboard with the jets from the Brit (Mark).
We still needs to fine tuning the ESCās
The jets / motors are (should be) doing about 13440 RPM at WOT (600*22.4)
(That is when running freeā¦)
The most difficult part of the build by far was getting the battery and motor cover watertight.
We were using two really nice marine hatches, but they were leaking so much, and it was impossible to stop this )-:
Now we are using a cut down pelican case as motor cover (nice to keep the towels in too), and a PVC drainage lid as battery cover. The pelican case will be changed to the PVC drainage lid system later this summer.
I knowā¦ The PVC lid looks horrible, but is working great and has about a 250mm diameter!
PVC lid looks like this: https://media.wildkamp.nl/productimages/default/870px/15078172.jpg
We have cut the pipe part away to just below the screw threads, and glued it on top of a plexiglass 8mm plate. This plate is glued directly onto the foam, and put the skin of the board above it. Itās absolutely 100% water tight.
My dad and I already started on building a new version of the board with integrated hatches.
This new board will be made from wood. The weight of the new wooden board itself will be around 7 KG, and have a partly removable deck for access to the two jets and batteryās.
Video of my 2nd run on the board. https://www.youtube.com/watch?v=81WGsLw6IYQ
Top speed is 30 km/h (@ 22.4 volt (6S)), but will be a little bit more when the ESCās are tuned.
LiPoās feel a little bit warm after running the board till end of session.
ESCās and motors are nice and cool. The wires (LiPos > ESCās) do feel warm too, but nothing alarming.
There is about 1 meter of 2 negative and 2 positive wires (AWG8) between the Lipoās and ESCās
The next time out we are going to test some cap banks just before the ESCās. This should cool things down a bit.
a picture from before changing the hatches. (I have more pictures, but can only post 1 as new subscriber to this forum)
Hello Kian, very well done, I can relate to the hatch problem. The board looks like a great choice. How thick is it? What do you think your run time will be? Any details, pictures would be great, even V2.
I think that the hatch works perfect when dry starting, but as soon as you need to do a water start, it will start leaking. We have tried about everything to get it to stop leaking. We even cut 2 hatches in half and glued them together to have to leaversā¦ No luck. Not even with a new silicon seal!
The board is from where I have the jet box till past the battery compartment 90 mm thick.
The aluminum box we got made is 100 mm thick. So it was standing 10 mm above the board.
If we would have known that the hatches were as useless as an ashtray on a motor bike we could have got the box made flush with the board, and use a perspex plate as cover.
Here is a picture of the PVC drainage hatch. It does also show the thickness of the boardā¦
Running time with me is about 13 minutes at WOT.
Iām using 6 āoldā Zippy Compact: 6S 4500mah 40C.
3 parallel per motor.
Some more pictures
When V2 is done (will take some time) we will for sure mention it here.
Some more pictures after modifying the leaking hatches.
And yesā¦ I know. The case on the back looks horribleā¦
Iām glad I found this thread! If Mark is the the Brittā¦ iām the American. My name is Anthony and i use to be a designer on thingyverse. If the reference to the larger jet-drive on thingyverse is to my 85mm drive then that is me. Recently after that site took a crap I pulled most of the stuff and started looking for a new site like it. Still havenāt quite found that.
A few things.
Currently iām developing a single jet in the 65mm variety. Iām going for a single jet design. If you look to Radinn, their design encompasses this profile with electric. Its technologically possible. I donāt know about Mark but I CFD test my designs. Heavily. I strive for efficiency with my size profile. That been said, iām about 2 years behind mark in testing. I just went through bathtub phase not long ago. This weekend is the pool. A ride test is weeks out (iām also restoring a 17ft glass boat at the moment).
I think 3D printed plastics, even the cheapest of PLA, can manage 20psi of pressure without issues IF itās designed properly. I may move to carbon fiber wrapping the existing printed plastics but not aluminum. This also means creating metal supporting surfaces where required to ensure say; a bearing doesnāt wiggle in position and throw your entire shaft off-axis.
I read a comment about heat melting epoxy mounting for thrust bearing at some point? Not likely motor or impeller heat. You are flowing high velocity cool water through this device at all times. Thereās not much chance heat is transferring anywhere other than out the back of the nozzle with the water it transferred to. It suggests the bearing itself failed, heated up, and moved out of position. I make a ācartridgeā so to speak. The rear supporting bearings couple to one another with a lock-nut. It holds tension to the bearings with the impeller. In-between is NOT plastic but a steel sleeve to space the bearings from collapsing. Should prevent any movement of the bearings at all. Unless the entire bearing set is able to move back and forth (and the impeller will always push force one way).
Electric motors hate amps. You want low amps no matter what it takes to get there. You need high V and low amps. Cooling wiring is not a solution to over amping a motor. You have to realize any RC motor is not rated on a AH basis. Its rated on a C rating that doesnāt exist today. If the motor doesnāt melt in 15 minutes RC finds that relatively acceptable. I am running the SSS56114 at 360kv on only 4S and iām grabbing 50 amps. 50 amps itself it totally fine. But when i jump to 8S thatās probably going to 150 or more. What does this tell me? 56114 @ 360kv still isnāt enough. Ill continue to test with it to see the jets performance in short runs. We need a larger moment of torque. 75mm-100mm diameter stators are what we need. Something that takes the torque for less amps. Right now all i see is customized outrunners from MHZ.
MHZ.
If you want a quality premade aluminum Jet check out MHZ-watercraft. Those dudes make anything from 52mm to 80mm and its all cast/cnc aluminum. Youāll pay and personally i donāt think the efficiency is there but they do look and perform nicelyā¦ and like any commercial entity get to hold them accountable if the product doesnāt deliver.
Ill keep yaāll updated with what iām working on! In a couple months ill definitely have something going that can be ordered at least. Had a picture but new users cant upload yet.
Cheers,
Anthony
Some comparative values with my Jet-Drive design (64mm Impeller) and SSS56114 / 500KV - I pull 102 A at 6S. havenāt tried 12S yet, but Iād like to try it and see what happen.
I have not yet taken a thurst measurement. But I can pull two manned SUPs with 10-12kmh.
@kuban_fpv
Sounds interesting. That is if your new jet will give the same or more power than the 2 jets from Mark.
Mark has really helped us a lot with the build, and till now we did not have any problems with the jets itself! And believe meā¦ Iāve done a lot of hours with them (max 6S)
Howeverā¦ I love testing things, so if you need any testers, than please let me know.
Iām in the Netherlands.
Anyway. My board has 2 jest / motors (lots of things have changed after posting the 1st pictures in this thread), and each motor is powered by 3 in parallel 4500mah 6s lipos (C30)
I did some testing with a powered meter (connected between 1 of the lipos).
This is what it measures.
Again. This is only the result of 1 lipo
I did some measurements with two in series s6 (so s12).
The two in series lipos were almost empty so I did only do a very short test (in a pool)
Again. Only 1 motor.
I did not do any thurst measurement. (Donāt know how to do it), but the board is 180 cm long and with me on it it will go just over 30kmh.
Pulling 2 subs with person will for sure be no problem. 12 km/h is doable too i think
I have just finished building a 12S12P for my next build of jetboard.
Iāll report back when I have some more data.
Very awesome! Thatās essentially the same size drive iām running with a slightly higher kV. I ran a 6S test last night and was hitting about 94amps on full throttle. Thatās about 2,250 watts. What I donāt like is the amps. I want to keep my design below 100amps. Otherwise yourāe talking 15 minute run times and battery abuse. Ultimately my design is for 8-10s but i know already this motor wont get me there unless in the 200amp range.
Flipsky looks like they might be on to something with their 83100. That looks to be a water cooled plumbed 83mm outrunner. That would have stupid torque and the amps would live low even at 8-10s. Youāll get the watts(power) up and keep the amps low.
Before i buy another motor does anyone know of companies out there doing similar things to flipsky?
Hereās a link to the 6S test
Numbers you hear the ol lady yelling are servo values for this table.
| 56114 - Motor 6S | |||||
|---|---|---|---|---|---|
| servo val | throttle % | rpm (theor) | amps | rise over last | watts |
| 130 | 44% | 4032 | 6.2 | 156.24 | |
| 140 | 56% | 5040 | 14.2 | 8 | 357.84 |
| 150 | 67% | 6048 | 27.8 | 13.6 | 700.56 |
| 160 | 78% | 7056 | 46 | 18.2 | 1159.2 |
| 170 | 89% | 8064 | 67 | 21 | 1688.4 |
| 180 | 100% | 9072 | 94 | 27 | 2368.8 |
I think i have one more design change to make before I try to really build something, as well as really spec the correct motor for this unit yet. I donāt think the SSS56114 is it. Itās enough for 6S but really nothing beyond. 8S would for sure be 150ish amps and i just donāt want to run the power profile there. But let me figure that part out and i will for sure get back with you! Iād love to have some more testing going on, thatās where i fail. Shoot me a pm with your address and ill ship some goodies over as iām making them!
The shafts are the only specialized feature. I machine the ends with an M8 thread and a crosshole to pin the impeller. Bushings end up being machined as well but i think i found a source for those.
Hi Anthony. I have just received 2 different motors today and will be doing some more power usage testing.
When done I will post all the info here.
Off to bed now but will PM you tomorrow.
