## Wind Turbine blade tip speed calculations

### Haldimand example:

Sources: Sachem OWR

A Summerhaven wind turbine blade will sweep an area of almost two acres every revolution, and reach 130 meters (430 feet) into the air.

At the deceptive speed of only six revolutions per minute, the blade tip will be moving at 115 kilometres per hour, or 70 miles per hour.

At the maximum 16 revolutions per minute, the blade tip moves at a stunning 300 kilometres, or 190 miles per hour!

### Example of how to calculate blade tip speeds:

A 2.5 MW wind turbine has a diameter of 100 m. Therefore, the blade tip traces a circumference of 100 m times pi = 314.159 m / revolution. Using 16 revolutions per minute from the Summerhaven example, the calculations are:

• 16 revolutions per minute x 314.159 m = 5026.55 m per minute
• 5026 m per minute x 60 minutes per hour = 301,593 m per hour
• 301,593 m per hour / 1,000 m per km = 302 km/h!

### Oak Ridges Moraine example:

According to WPD’s draft Project Description Report for their Sumac Ridge project, the maximum tip speed  will be 72.6 m/s, the rotational speed will be up to 15 rpm & the blade swept area will be 6720 square metres.

• 72.6 m/s x 3600 seconds/hour = 261,360 m/h = 261 km/h
• 6720 square metres / 3.14159 (pi) = 2139. Taking the square root gives us a radius of 46.25 m, which equals a diameter of 92.5 m including a hub of 2.1 m