For who try/have tried direct drive with outrunner

Ok thanks. So I guess you went to the 80100? I’m having the same problem. I need a bit more power…
I’m wondering if the 63100 is enough? I have been running the 6384PG in oil which works really well but with all the seals, bearings etc…I think there is too much friction and reducing torque. I want to first try direct in water to see the difference with the 6384PG in oil vs direct in water. I’m sure it will improve power.

Hi have tested 80100 also 8085. Both very powerful, the 80100 is way overkill

Hi @Bender! What 8085 did you use? Do you have a link to this motor? What was of 8085 motor?

custom model i sent you PM

I’m interested too. I’m going to try the 60100…its seems to be a bit more and that’s all I feel like I need. The other motor that looks good is the 8072. Probably overkill but not as much as the 80100…the 80100 is super heavy too.

1 Like

Hi, Mrmoebe, I ordered some flexible shafts from aliexpress, they arrived recently, and want to give it a try, I’m a little sceptical about how much they would last, and how much force can they withstand…

Hi PowerGlider,

i m at the point to see if i need to reduce diameter of my propeller SOLAS 7 1/4 or if i keep it original.
i m using a gear box 5:1, and 12 S, motor SSS 56104 500 KV. From your different testing, what is the best option ?

This answer is really hard to tell, your setup is quite different to mine. You want to foil, i only glide on my windsurfing board, so the load is much higher.
I do not have a best setup, currently just two props: Yamaha 7 1/2 x 7" and 8", and they both perform well, although i would like to have 7 1/2" pitch :wink:
But it is also dependent on the duct, load versus speed and diameter, duct inner diameter is 140mm, props are 136mm.

@PowerGlider, what max speeds did you achieve on your surfboard ?

18 to 21 km/h according to GPS data.

@Powerglider, did you turn down the diameter of your prop? 7 1/2 is 190mm.

1 Like

I am interested in your different results. Please do not copy my design but innovate it. This is the reason i do not publish, i am not convinced enough. If someone is interested seriously i would like to discuss streamlining and simulation and lots of other things. But not the diameter of my props, you can find out yourself. :wink: :wink: :wink:

??? I just wanted to know if you turn them down in diameter. Because you say you use 7 1/2 prop but later you say the prop is 136mm?
Or is it typing error?

I described it already some year ago and was linked already several times, also in this thread. So the forum app asks me if i really want to use the link again. Use the search function before asking please. If you find it hard to understand what people write in a thread, reading the thread also helps. You can also filter what an author wrote in a specific thread. Often you find the most valuable information, like “new” ideas in the beginning of a thread and everything later is only a discussion about details and alternatives.
If all that does not work, you can also write a PM. Sometimes when i answer to such PM i find out in the PM discussion what information is really missing and gather this in a new answer in the thread. So you are welcome to write a PM to me :smile:

Cant you simply answer with yes or no??

1 Like

Lets open the window and get some fresh air in:



1 Like

FFS What’s all the mystery? I thought we were supposed to help each other out!

1 Like

All the propeller out there are for small boat , so yes you have to decrease the diameter and probably the blades area as well , for the pitch most of them use variable pitch , which increases from the center to almost the end , the tip , i am not sure the given pitch is a average pitch or the one measured at 70-80% of the diameter …
This is no mystery about this , just no correct answer can or want to be posted because by shaping the blade you change the dynamics of the propeller , so i guess it is a trial and error story, and it is one way to “help”

Great, lets get into some more discussions. I just hate being reduced to saying yes or no, it’s too boring, especially if the topic is so complex.

Propellers should have more or less the same pitch over the complete radius. So in the inner section the angle is higher at the outer section it is lower. I do not only cut my propellers down at the outer section, by enlarging the hub i also take away some part of the inner section. So this is a large reduction in blade area. I want to have a safe duct, so i cannot opt for large diameter because the drag by the duct becomes too high. This design is kind of a crossover between a classic impeller and a ducted prop. It is the shortest design practically possible if you want to be able to exchange the prop.
But to really understand you need to read a lot more articles. I cannot write a comprehensive article in every thread i contribute to, so you as the one who wants to understand have to search the infomation yourself.

It seems relative easy to build a 6384PG outrunner direct cooling, but i must warn you. Mostly people underestimating the effort and needed skills to build a safe and reliable working system will struggle at one or another point.
Do you have a board with cells esc remote motor and blablabla up and running and looking for better propeller performance? Or are you about to start to think of building or buying? If you have your first experience its time to think of correcting pitch and diameter and hub. It also depends on your expectations, as on mine, if you ask for a specific prop/duct for such motors. It ends up with some compromise. :slight_smile:

1 Like

For what its worth i tried out an old 80mm out-runner i had lying around basically copying some of the ideas seen in this thread and its worked perfectly for me.

i did a quick version as i have a FR motor coming so i never intended for this to work long term but its worked so well im going to keep it and make a 2nd board for it.

  • pulled motor apart.
  • simply sprayed the magnets / motor hub with electric circuit board sealer
  • sealed up the bell end with epoxy ( not sure if this did anything for efficiency or not? )
  • 3D printed a basic prop adapter that simply matches with the original bolt holes in the motor.

and thats it, took me 2 nights from nothing to having it in the water / surf and foiling.

It no optimised in many areas BUT it got me foiling and i have had about 3 hrs of foil time on it so far in the surf with ZERO issues.

i did a test with NO prop in the air it uses 30 watts to spin the motor ( no prop ) in water it takes 300 watts. I was not expecting a 10 fold in power to spin just the motor.

runs on 6s 16 or 24Ah only and needs 60 amps to foil @ 80 % throttle on the hand held controller.

100% throttle the amp spike up to 120amps and it dose not go that much faster. it has more punch but not much which leads me to believe much past 85% throttle and the motor falls outside its torque curve and just burns amps for not much return ?