LibrePilot Forum
Users => Vehicles - MultiRotors => Topic started by: jtrout19 on November 02, 2016, 04:13:22 am
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Anyone ever used these? Saw that gemfan made them. Just wondering if anyone has experience? Seems crazy to have 6 blades.
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(http://www.dollhousehair.ca/media/2013/11/many-blades.png)
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More blades are always better right?! ;)
But seriously, Ive never used them or seen them used. Would be interested to know if they are better than usual 2 blades
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That is funny!! I saw some testing done between 2 and 3 bladed. 3 bladed performed better with the motot/esc combo they were using
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I am not an engineer in aeronautics, but intuitively I see it like this
- More propellers or pitch, higher interference between blades / vibrations or risk of entering Vortex Ring State (VRS) and loss of control.
- More propeller or pitch, also increases surface. This means that you need to spin at lower RPM to deliver the same lift. The RPM is determined by PWM signal which kind of regulates the voltage (average square wave) the motor is receiveing. Higher surfaces can increase current drain (Amps), but voltage needed also drops. I think of it also as 1W converts to 1J/s, this suggest that if motor needs to spin less in certain amount of time, it does less work in that time, so Watts are a bit smaller and possibly slightly longer flight time.
Correct me if I am wrong with above. I am not an expert just trying to explain myself observations :)
Also there might be plenty of factors that affect propeller efficiency, surface (pitch, length), shape, weight, angle of the pitch..etc I think it's hard to compare one propeller just based on one parameter, as many companies produced props that often differ by more than just that one parameter.
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I was reading a study that was done with several different props 5030 and 5040 and 5045 of different brands in that study when increasing pitch it increased amp draw and watts used. Increasing pitch gives you more performance at the expense of flight time. I believe it is the same when you take 2 bladed vs 3 bladed. That is how i understood it anyway. Vibration should not be an issue if you balance. Which i do and i take it one step further i make all my props weigh the same. I have not read about vrs. Going to do that now
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Here is a link to a video with a guy flying with the 6 bladed props.
https://www.youtube.com/watch?v=eG0W44VJVOk (https://www.youtube.com/watch?v=eG0W44VJVOk)
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After watching that, I just realized I have no idea how to fly drones and should immediately sell all of my stuff.
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Do I sense some sarcasm there.......LOL ;D
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The fewer the blades, the more efficient the prop. Back in the old days, the free flighters even ran one blade props for this reason. One blade props are like two blade props with one blade cut off and replaced with a stub metal counter weight.
Generally, the reason you run more blades is that you have a lot of power and don't have room for a 2 blade prop so you run a 3 blade prop with shorter blades. The WWII P51 used a 4 blade prop for that reason.
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On my 4" bladed quads I've tried using 4 bladed props and really had no power. I'm told that with 4" props you need high kv motors (3000kv or higher) to really get the benefit. The 5" 4 bladed prop worked ok but I still prefer the 3 bladed bullnose props on everything for sheer power and I also get longer flight times.