Why Do Wind Turbines Have Three Blades?

2 blade windmill gives the feeling the feeling of that amusement park ride that shoots you 40 meters up in the air.

We used to have a lot of smaller two bladed wind turbines in Friesland and when those things go full tilt it’s pretty scary, it’s much nicer to have the relatively slow and calm movement of three bladed wind turbines.

Finally a video that gets this answer right.

Nothing to add from this wind turbine engineer.

There's a 4th reason...
- 3-bladed turbines have a near-constant polar-moment of inertia around the vertical axis when turninging into the wind.
A 2-bladed turbine would have greatly varying gyroscopic effects & polar-moment of inertia when turning into the wind with respect to blade angular position.

2:02 Machinarium flashback

Just in case someone didn’t know, wind turbines have a mechanism to adjust the blades' orientation depending on wind conditions, to have them rotate as much as possible at that efficiency sweet spot, even in strong wind — or to stop rotation entirely if power is not needed at the moment :)

I live in West Texas where we're surrounded by wind turbines and always thought they had 3 blades because... science! Thank you for the concise explanation of that science.

I want to clarify some important points, to emphasize the effectiveness of wind turbines.

The "lamda" on the horizontal, which the video described as how fast it is spinning relative to the wind is actually a little misleading. Its actually the "Tip Speed Ratio", which is the speed of the TIP of a blade divided by the windspeed. So, smaller turbines have to spin faster (in terms of rpm) to get to the optimal Tip Speed Ratio vs a bigger turbine. Also why huge turbines often appear like they are spinning slowly, but the actually the tip of the blade is at the optimal Tip Speed Ratio of about 7, for 3 bladed turbines. So, smaller turbines (such as one mounted on a boat or something) have more blades because the then it does not need to spin as fast to get to the optimal point, and less mechanical wear.

Also the "Cp" which was on the vertical axis is basically the efficiency of the turbine, i.e. how many % of the wind's energy it can exact, from the wind which passes the "disc" of rotation. So something 47% is HUGE and i bet no one expects that from looking at one in the wild. :)

I'm glad the aesthetic aspect was brought up. People tend to underestimate how much of every day engineering is influenced by what thing look like and how it makes people feel about them and are adjusted accordingly. And honestly, I wish we put more emphasis on making things pretty just because, rather than only chasing the highest efficiency metrics.

I like how it's 3 considerations that all get to the same conclusion. No need for a compromise, everyone agrees on the number 3

Wind “mill” and wind “turbine” annoyed me. Nevertheless, this was a great explanation.

1:04, Is that a paper drawing, animated, and placed behind a masked paper drawing? Awesome!

0:43 Cool roller coaster, bro

On turbine noise, as a person who works on wind turbines, it is a non issue unless you are actually working on one. The main building I work in is only 100m away from turbines (which is honestly too close for safety from ice, but it was built long before those kinds of things were even thought about and regulated) and I never hear them. You need to remember that when they spin, the wind is often blowing, which is often much louder in your ears than any turbine. Vehicles passing by on the road are much easier to hear and much louder, heck we are even on the coast and fishing boat engines kilometers off shore are louder and more noticeable than the turbines.

I always say that if there would only exist one windmill in the world and it would´ve been made by an artist, people would fly from all over the world to see it.
They are SO elegant and enormous. Truly a sight to behold.

6 hours ago literally I was in the train in Scotland and saw a 2 bladed windmill, and told myself that I should search for a video on YouTube why most have 3 blades. And a couple of hours later this video was published. What a coincidence !

I'd just like to say, as a colorblind person, I highly appreciate the efficiency graph using symbols rather than colors to distinguish lines. I know that it was probably only done that way because it came from a black-and-white publication, but it's so rare for me to actually be able to read a line graph that it is like a breath of fresh air.

As a mathematic, I feel like there is unexplored potential in wind turbines with negative three blades.

Three shall be the number of blades thou shalt build, and the number of the blades shall be three. Four shalt thou not build, neither build thou two, excepting that thou then proceed to three. Five is right out.

That one-bladed wind turbine made me so viscerally uneasy lol. Great video!