Buy a few more rolls to tape and tape it continuously down the mast. Even with perfect jet/ prop I doubt you could foil with that much drag of the exposed cables!
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The try-out at the lake today was NOT very successful but I don’t think the motor/jet was the main problem.
This is now It looked like:
The first try:
The motor only start after holding in the throttle almost to max for about 3s. After it started I could release the throttle a little bit. But I did not get enough speed anyway to get on foil(only about 12-13kmh). I stopped and raised the max motor current i VESC to 200A (from 140A) and the battery current from 80A to 100A.
Second try:
With the higher limits I could get more speed 17-18kmh that was enough to try to get on foil. But I never managed to get on a stable foil. It was extremly unstable! I think the reason is exactly what Strongarm is saying in the post above. My “quick and dirty” running the cables on the side of the mast created a uneven drag (the board turned to the side as soon as I got on foil) . That together with the fact that I dot now have a nose-cone or cover on the mast-clamp created allot of drag everywhere.
I am printing a cable guide now to put on the trailing-edge of the mast and I am planning to make a new try tomorrow.
To be able to go 15-16kmh (on the water) I needed about 4000W power (80A battery current - about 140A motor current). The impeller was then running about 5000RPM. It is probably possible to push the motor allot more but currently my battery is wired via an BMS that is only rated at 80A. But I think I could get on foil with the current power settings if I can get it more stable.
The issue with the motor not starting until after 3s I looked into now at home and AI suggested increasing some “open loop” parameters. I will try that tomorrow as well.
The
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Interesting that could be a solution for us in Canada where only jets are legal. However given that their props where not really a good match for their motor in the past I would not jump blindly on this expecting it’s perfect for an efoil out of the box!
It’s great that you had some initial success and at least got up on foil 
I had a lot of control issues on my first build due to running wires and water tube external to the mast. I tried printed pieces to allow make things better and they helped a little (maybe ) but the fix that resolved it was running the wires etc internally.
The other thought I have is the “block” you made to attach the motor to the fuse might be severely disrupting the flow of water to the intake.
Yes, I have been thinking over night and I decided it is probably best to just run the wires in the mast. I did not want to cut a hole in the mast before I have decided where I wanted the motor. And if the Jet did not workout I was planning to use a normal 65161 with a flite-prop (that need a higher mounting point than the jet). That is the reason I was running the wires outside the mast to start with - to be able to decide the position of the hole later.
But now I am going to cut the hole anyway since this is not working. I did print some cable-guides to put on the trailing edge, but I am afraid the mast will be to wide with the guides on and will probably make it harder to turn. So lets cut the hole anyway!
I will cut the hole higher to be able to use a flite-prop in the same position later. This means I will skip the motor-support (to the fuselage) for now and only use the mast-clamp. The clamp is significant more robust than I was expecting anyway. And as Foilguy is saying the support might actually make the jet work less efficient. Also the stab might also not work very good with the jet that close.
Jonas
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I have now finished the new mount and the cables are now inside the mast:
I took the board to the lake for a short first test. The result:
The board had allot more power now. If I accelerate to much the front of the board pitch up and the foil try to engage (with failure since the speed is low). It was almost impossible to get speed and push down the nose. I changed to a smaller stab (from Curve L to Curve M) and it was much better. I finally got up on foil successfully! But I still had to be very careful not to accelerate to much other vice the board pitch up. The Curve M is the smallest stab i have but I could probably use a even smaller.
One very nice feature of the jet-drive I noticed is that it is possible to ride very high up on the foil. There is no “breaching” (resulting in crash) if the jet get to the surface it seems.
I will take a longer ride tomorrow. I get back with more details.
Jonas
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Thank you for sharing! Could you perhaps try to get some data, with regards to consumption, power, speed etc? Highly curious.
Yes, I will get more logging tomorrow.
But one thing I can say: the jet is allot less efficient compared to a flite-prop. Maybe as much as 50%. But I will collect data tomorrow.
Congrats on the improvements.
Interesting about the fast pitch up and stall problem, is this same board and foil etc that you use for the fliteprop mast setup?
Thanks!
Today I figured out how to handle the “pitch up” when starting I had problems with yesterday. I set the “ramp-up time” in the remote (VX5) to a much higher value (changed from 0,1 to 0,3). This made the motor ramp up the power slower and the pitch up was not a big problem. I therefore changed back to the original stab (Curve L) - since I had problems to keep the pitch when up on the foil with the smaller stab.
I also have to take back my statement about the jet “can not breach” from yesterday. It is possible to breach it (and crash) but I can use more length of the mast before it happens.
I can now state that the Flipsky Jet can be used for e-foiling successfully!
But it is off course less efficient. But for example in Canada it is an option (just compensate with a bigger battery). Or like me you are concerned about propeller-safety (especially for my kids).
Power needed when riding on-foil with JET(about 26kmh): 1900w (battery power)
Power needed when riding on-foil with 65161 with Flite-prop(about 26kmh): 1200w (battery power)
That means the Jet needs about 58% more power.
The full log of the ride with JET: LogTRC VESC Telemetry Log - Sverige, Stockholms län | LogTRC
For comparison a ride with 65161 and Flite-prop: LogTRC VESC Telemetry Log - Sverige, Stockholms län | LogTRC
The two rides are with the same board and wings. Only the motor is different.
The maximum RPM I reached today was 4800 and I am not pushing the motor very hard (only 50-60% duty cycle). That means it is maybe even possible to use the smaller version of the jet (the one with 65161 motor) but you are then pushing it to almost 100%. Also the 200KV I ordered the motor in is maybe bit to high. 150KV is probably enough. But is depend on your weight off course (mine is 70kg).
//Jonas
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Happy to hear you resolved your start issue.
Great comparison of riding jet vs fliteprop as the prop is used on a lot of efoil builds.
Good to know there is a viable jet option for those that want to go that way.
It would be interesting to try it without any stab on to see if would work.
Thanks again for all the detail you have produced!
How did you determine what RPM you reached?
From the ERPM logged by vesc devided by 5 (number of polepairs in the motor).
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OK thanks. Your log indicates max speed was ~30km/h. I’m not familiar with the data site and can’t determine where your RPM peaked but to my thinking it’s either when your trying to launch and giving a lot of throttle or when you are cruising on foil.
Was your 30km/h peak as fast as your comfortable foiling or were you close to or at WOT?
Duty in the jet log was 50% average and 60% max at a start, so no limit reached yet
At the peak speed of 30km/h the duty was 55%
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Yes I am a beginner in foiling and can barely stand up on the board. I am comfortable running in about 28kmh. At 30 it is getting scary…
One idea:
Look at the power consumption you use when you ride your board the way you like today and add 58% to that. Then you should be able to tell if the smallest jet is enough for you.
I understand about that little bit faster feeling spooky. As I gained confidence and stopped falling I have found the speed where my foil of choice feels “locked in” is closer to 30 than 25kmh. Going must faster than 30 and things feel twitchy.
What really helped me to get to a point where I relax and just ride is to keep the board turning - slow really wide arc side to side rather than running in a straight line.
My Watt value when I’m foiling is similar to yours with fliteprop. I’m not very concerned about efficiency as I have multiple 10S11P packs and usually take a break between full and low limit on them so that’s not a problem.
I think the jet with 65161 could work - but you would then push it to the limit. I suggest you go for the 70165 version, as I did, to have some margin. The 200KV version I ordered was probably to much since I am only using about 4800RPM. But I run on 13S battery. If you use 10S I would suggest you go for about 180-200KV.
I guess I see some logic in using the 70165 motor version as the weight and length of motor is virtually the same and the spec shows that it is more robust than the 65161 and the cost isn’t that much of an increase.
However I have found the 65161 motor a very reliable component so am a bit reluctant to move away from a tried and proven motor.
If 5000rpm is sufficient to launch and then foil at ~30kmh then I’m not sure I understand why you feel the 65161 motor version isn’t sufficient?
I get that lower V means using more A which would cause motor heat but it’s immersed so would be constantly cooled.
Hopefully you can elaborate
Also curious on how you feel about it assuming you have now perhaps had more riding time on it.