windows 7, this was my first test with 140mm I will update data gps next rides :guiño:
I use the same prop with less diameter (120mm) in my gearded propulsion tp power reisenauer with aprox 60-70A average
thank you @virus for the numbers, i used swordfish last year:
- voltage recording can be off by 2-3v
- thr and remote need to be set at 99,9% if we want to use the numbers
- rpm off load: battery voltage (checked) x thr (100%) =erpm/nb of poles , then you find your kv or the nb of poles…
- max rpm should drop on load by 20% at least
- current measured is probably current motor, so it is hard to know and compare WH since most measures here are made on the battery side
anyway this set up works
Of course, these data are only a complement to compare with my experience in the water. I’ve tried many propulsions and I can feel if this works with respect to the previous tests. And now I’m trying to get the most efficient prop with this 100kv motor. First with different diameter measurements and then I will try other pitch props, between 120-140mm diam. is good with this yamaha prop. It can lift 120kg of weight easy, me and my daughter weight 120kg and is rerally fast, I will test more things but I’m very happy with the results at now and people here can be tranquility to make one without problems.
People know the most difficult thing is to remove the water in efoil system and this waterproof motor is the solution, ok? You just need to make a good enclosure for your electronics and enjoy.
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Do you have a VESC capable of running 12S? As it is a PMSM it should run better in FOC would be interesting to compare
Yes, I have the Nick VESC and Maytech vesc6 200A but I need a few days. I have a lot of work in this moment.
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hello Virus,
For me, the diameter Yamaha prop 2HP is 184 mm (7 1/4), and you talk about diameter 140 mm (or less). Can you explain ?
Thank you
Maybe he made it smaller or he means pitch 140mm. I know the pitch is 138mm.
If you look closely at the pic you can see it’s been cut down to 140mm
$760 for 195kv.
https://www.aliexpress.com/item/33055746076.html?spm=2114.12010612.8148356.4.1119435csHKnRI
Do you have to contact them directly for custom 100kv motor? and how much?
I don’t think the pitch is changing, becaus the angles of the blades are still the same. The prop wil turn faster because there is less resistance from the prop tips, but there will also be less thrust at the same rpm and there for more slip. But it could be better for your motor to not overload it.
Most propeller have variable pitch , when you cut you change the average pitch ( lower) but a lot less the thrust so you get more rpm and it compense for the speed
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Disagree
Example:
My 300mm pitch prop has a 50mm hub length.
The tip of my prop moves forward 50mm every 30 degrees of rotation.
6x30=360 degrees, 6x50= 300mm pitch.
As the diameter decreases from tip to hub, the angle must increase to maintain 50mm of forward movement for every 30 degrees of rotation.
The blade at the hub reaches 300mm in 1 rotation just as the tip does despite travelling through much less water.
Propeller pitch is not just an average of the varying blade angles. The blade angles are a function of different velocities across the blade at different diameters from hub to tip.
Wish I had a diagram to show, it would be easier to explain.
…and before someone says it, prop slip isnt factored when measuring prop pitch.
Angle and wide of the blade give distance , every propeller that I measured , FR , solas , Yamaha from center to the tip had variable pitch
Measures were taken from the front to the back of the blade every 10mm increase in diameter
I agree with you we have to take the rotation speed of the part af the blade as well , pitch increase , speed as well , area decrease , I guess it gives the same thrust across the all diameter
Propeller pitch is the distance a propeller moves through the water in one rotation,without slip.
It is not the varying angles across a single blade. ( although obviously higher pitch props have steeper angles).
This is a hard subject to communicate in text. Like most discussions on propellers we will probable end up in circles. All good.
You measure 4 points on the propeller blade at a given diameter and you calculated the pitch , the distance that the propeller will move forward , we are talking about the same thing , I am just giving my conclusion of the measure and calculated pitch
You are right, a given (uncut) point on the blade (same as a point on a screw thread) will mostly follow the same path in water as if the prop was uncut.
Altering the diameter of a prop (cutting it down) stands a good chance of changing the pitch. The reason for this is not because the pitch of the blades changes (you may even find it stays the same), but because the efficiency of the prop changes. When you cut a prop you may increase (or decrease) the prop slip which would result in a changed pitch.
For the prop in question I have measured at a few points and the 5 inch pitch falls inside the area that Virus would have cut off. So on a theoretical basis it looks to have stayed the same.
However to really calculate whether the cut was worthwhile we would need to look at all the data and graphs which are not here.
Very interesting. But why 14 to 20s only. Seem to be the same motor as maytech but cheaper!