Why do windmills typically have 4 blades, yet all modern wind turbines have 3?

Question

Why do windmills typically have 4 blades, yet all modern wind turbines have 3?

In: 9124

Answer 1

The are many reasons and the most important are:

4 blades from the past ==> Easier construction to make it rigid. Both blads on opposite sides are actually 1 piece that crosses the rotational axis.

More blades were used as well, such as for water pumping windmills.

Why? In general you an say: More blades means more torque, Less blades means more rotational speed.

For modern wind turbines, we have a lot of better construction techniques, and as such the 4 blades for easier construction is no longer required.

3 is used because it simply is the most effective number.
These blades are very heavy and expensive.

2 blades means faster rotation and more vibration, meaning more wear and tear.
4 blades means more expensive, while not adding any real benefit. Or at least not enough benefit to justify the costs. (While knowing these blades are not easy to recycle or reuse.)

Answer 2

The are many reasons and the most important are:

4 blades from the past ==> Easier construction to make it rigid. Both blads on opposite sides are actually 1 piece that crosses the rotational axis.

More blades were used as well, such as for water pumping windmills.

Why? In general you an say: More blades means more torque, Less blades means more rotational speed.

For modern wind turbines, we have a lot of better construction techniques, and as such the 4 blades for easier construction is no longer required.

3 is used because it simply is the most effective number.
These blades are very heavy and expensive.

2 blades means faster rotation and more vibration, meaning more wear and tear.
4 blades means more expensive, while not adding any real benefit. Or at least not enough benefit to justify the costs. (While knowing these blades are not easy to recycle or reuse.)