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Old Jan 17, 2012, 12:28 AM
Hooked on FPV
Joined Jan 2012
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2 Blade VS 3 Blade Prop for Multirotors?

I was just curious of what people prefer; 2 blade or 3 blade props for a multirotor?

I've heard arguments that go both ways. Airplane owners obviously will use a 2 blade prop because it is more efficient at wind speed. But what about use for quadrotors or other slower moving craft?
From what I can see the pros outweigh the cons:

3 Blade Pros:
  • I have heard that 3 blades cause less vibration and give more stability for fpv or aerial photography.
  • They say that 3 blade rotors are less affected by the wind.
  • Blade tips have better tracking with 3 blades
  • Equivalent 3 blade props are easier to bring up to speed quickly from a stop
  • I've heard that a 3 blade prop may actually be more efficient than 2 at low air speed because the motor doesn't turn as fast. (I don't really believe that though)
2 Blade Pros:
  • Faster speeds
  • More efficient?

What do you guys think?
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Old Jan 17, 2012, 01:16 AM
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Joined Nov 2005
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I already asked this question......I did not get to many responses. Most people that use 3 blade props only use them when clearance is an issue. When it comes to helicopters 3 blades or more provide more lift than 2 blades, thats why you see heavy lift helicopters using 3 or more blades. Three blades will hover at a lower rpm. Other than that, this question only starts arguments. I have read a few threads and there are always different opinions. I use 3 blade props on my x525 and Im happy with them and dont plan on going to 2 blade props at all.
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Old Jan 17, 2012, 01:24 AM
Mikrokopter Australia ;-)
simonjardine's Avatar
Australia
Joined Apr 2008
1,443 Posts
Two blades are better than three.

No arguments, they just are :-)
end of thread

Simon

(look at Microdrone, Dragonflyer etc..etc..)
They would use 3 blades if they were better!
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Old Jan 17, 2012, 01:24 AM
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Australia, QLD, Brisbane
Joined Nov 2011
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That's because the question has been asked many times. Search is your friend:

http://www.rcgroups.com/forums/showthread.php?t=1225763
http://www.rcgroups.com/forums/showthread.php?t=1113189
http://www.rcgroups.com/forums/showthread.php?t=1107558
http://www.rcgroups.com/forums/showthread.php?t=189013
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Old Jan 17, 2012, 02:26 AM
Hooked on FPV
Joined Jan 2012
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Quote:
Originally Posted by soulreaper View Post
I already asked this question......I did not get to many responses. Most people that use 3 blade props only use them when clearance is an issue. When it comes to helicopters 3 blades or more provide more lift than 2 blades, thats why you see heavy lift helicopters using 3 or more blades. Three blades will hover at a lower rpm. Other than that, this question only starts arguments. I have read a few threads and there are always different opinions. I use 3 blade props on my x525 and Im happy with them and dont plan on going to 2 blade props at all.

Thank you guys for the replies, it looks like I have some reading to do, I didn't realize it was such a hot topic

Soulreaper: I noticed that you have an x525. That is what I'm planning on getting from goodluckbuy. I snooped a little to see what kind of setup you have and it looks very nice Is that the kit from http://www.goodluckbuy.com/x525-v3-q...lticopter.html
If not then do you think that kit has pretty much the same motors as yours?
Also, I see that you have a KK board. How do you like that board so far? Do you think it will be a good stable one for FPV? I have been looking at this one and the Crius Multiwii and can't decide which one I want as the Multiwii is pretty expensive. Hope you don't mind me picking your brain.
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Old Jan 17, 2012, 02:30 AM
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South Orange County, CA
Joined Mar 2003
8,163 Posts
Personally, I like using 3-bladed GWS 9x5x3 props in place of the 10x4.5 2-bladed variety that comes with most XA and DJI kits. It takes more time to balance them, but the results are pretty dramatic. In addition to being vibration-free, they are also a ton quieter. I have no idea whether the efficiency is better or worse, and frankly, I really don't care. To me, it's all about vibration isolation.

-- Gary
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Old Jan 17, 2012, 03:44 AM
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United Kingdom, England, Redcar
Joined Jan 2006
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The efficiency of a 3 blade is less than a 2 which is less than a 1 from all accounts they also consume more amps but give a little more thrust. Personally i quite like 3 bladed props but they can be a pain to balance so i have been using the 2 bladed variety.
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Old Jan 17, 2012, 04:06 AM
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Australia, QLD, Brisbane
Joined Nov 2011
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Quote:
Originally Posted by scousethief View Post
The efficiency of a 3 blade is less than a 2 which is less than a 1 from all accounts they also consume more amps but give a little more thrust. Personally i quite like 3 bladed props but they can be a pain to balance so i have been using the 2 bladed variety.
If you remove material from the heaviest of the 3 blades, it's easier then trying to add tape to the lightest blade like you might have done on a 2 blade.
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Old Jan 17, 2012, 08:48 AM
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Quote:
Originally Posted by ferrocium View Post
Thank you guys for the replies, it looks like I have some reading to do, I didn't realize it was such a hot topic

Soulreaper: I noticed that you have an x525. That is what I'm planning on getting from goodluckbuy. I snooped a little to see what kind of setup you have and it looks very nice Is that the kit from http://www.goodluckbuy.com/x525-v3-q...lticopter.html
If not then do you think that kit has pretty much the same motors as yours?
Also, I see that you have a KK board. How do you like that board so far? Do you think it will be a good stable one for FPV? I have been looking at this one and the Crius Multiwii and can't decide which one I want as the Multiwii is pretty expensive. Hope you don't mind me picking your brain.


I purchased my kit from ebay, for $154.00 dollars shipped. Yes the kit from GLB is the same. I like the kk board. I have not changed the firmware. I already have all my FPV equipment, and I will have all of it mounted soon. Im going to fly FPV with the stock kk board, and see how it does. If I decide to get another board I will get a ff free flight board, it has auto leveling and its plug and play.
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Old Jan 17, 2012, 09:06 AM
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United States, CA, Los Angeles
Joined Aug 2009
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My experimenting with two verse 3 bladed props, they required difference PID settings. This is where the oscillation comes from. The Three bladed requires less gain because they have more mass creating more gyroscopic forces.
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Old Jan 17, 2012, 09:16 AM
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Copperopolis, CA
Joined Sep 2003
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Quote:
Originally Posted by GGoodrum View Post
Personally, I like using 3-bladed GWS 9x5x3 props in place of the 10x4.5 2-bladed variety that comes with most XA and DJI kits. It takes more time to balance them, but the results are pretty dramatic. In addition to being vibration-free, they are also a ton quieter. I have no idea whether the efficiency is better or worse, and frankly, I really don't care. To me, it's all about vibration isolation.

-- Gary
Gary,

Would you mind describing your balancing tools & technique?

Thanks.


Jack
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Old Jan 17, 2012, 09:17 AM
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United States, TX, Austin
Joined Sep 2004
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I use 3 blade on micro's because finding proper pairs of 2 blade 5x3 props means waiting forever for them to get here from Hobbyking, unless someone has a US source.
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Old Jan 17, 2012, 12:03 PM
Jakub J's Avatar
Krakow/POLAND
Joined Dec 2009
1,743 Posts
Quote:
Originally Posted by ferrocium View Post
I was just curious of what people prefer; 2 blade or 3 blade props for a multirotor?

3 Blade Pros:
  • I have heard that 3 blades cause less vibration and give more stability for fpv or aerial photography.
  • They say that 3 blade rotors are less affected by the wind.
2 Blade Pros:
  • Faster speeds
  • More efficient?

What do you guys think?
You are right.
My choice is 3-blade - much lower vibrations, only slightly shorter flying time. One cons - 2-blade are much more friendly in transport.

Jakub
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Old Jan 17, 2012, 01:06 PM
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South Orange County, CA
Joined Mar 2003
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Quote:
Originally Posted by jforkner View Post
Gary,

Would you mind describing your balancing tools & technique?

Thanks.


Jack
First of all, you need one of those magnetic balancers. I think mine is a TowerPro. Basically it is just a frame that holds a magnet on each arm. A steel shaft goes between the magnets, and has rubber slide on pieces to hold the prop in place. I then just use two different grain pieces of sandpaper, one coarse and one fine.

You start by letting it rotate on its own, and one blade will end up pointing down. You sand this one with the coarse/fine sandpaper until it doesn't point down anymore, and you get one blade to point up. Rotate to the next blade, to try and get it to point up. Whichever way it falls, that blade you sand next, until that 2nd blade will point up. Rotate it to the next blade and repeat.

-- Gary
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Old Jan 17, 2012, 01:32 PM
Hooked on FPV
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Well that settles it... I'll just have to get both
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