One wind turbine blade [Travel day]

This is not the tower. This is one blade. 67 meters long. Newer ones may be 75 meters long. Meters. Transport requires two drivers: one to drive the cab in front, and one to steer the vehicle at the rear. I also took a photo of Clare standing next to the trailer, but I thought this was more impressive to show its length. On I-69 north of Muncie, Indiana (NB Pipe Creek Rest Area).
» Travel Information at Indiana Department of Transportation

I did a rough calculation in my head when we passed the wind farm on the Ohio-Indiana border. I roughly counted 5 seconds for one complete revolution of the three-blade propellor. Circumference is C = 2 π r and if π is roughly one-sixth more than 3, then the circumference of the circle traced by the blade tips is a bit more than

    C = 2 × (3 1/6) × 67m = 2 × (3 × 67 + 11)m = 2 × (201 + 11)m = 2 × 212m = 424m.

Dividing by 5" gives a speed at the tips of 424m/5sec = 85m/sec. Uh, the blades look like they're turning slowly, but those blade tips are flyin'! No wonder they catch birds unaware.

Sitting down with a calculator and using a better value for π gives C = 421m and a speed at the blade tips of 84¼ m/sec.

To get an idea of how fast that is, convert to yards per second. 84.25 m/sec = 92.14 yards/sec. That's covering nearly the entire length of an American football field — goal line to goal line — in one second.

Alternatively, Jamaican sprinter and Olympic champion, Usain Bolt holds the World Record for the fastest 100m at 9.58 seconds. Bolt would need about 8 seconds to cover 84m, so the blades are moving 8× faster than Usain Bolt's Olympic record speed for 100m.

Finally, let’s convert to automobile speeds:

    84.2 m/sec × 1 mile/1609m × 3600sec/hour = 188.3mph = 303kph.

That’s fast!

See also: “What’s new with wind” (in Illinois Country Living, Sept. 2023, from our electrical co-op)

Okay. I'm done. :)

Looking back
  1 year ago: “Ford Model T Snow Flyer”
2 years ago: No post
3 years ago: “Living Wine Labels”
4 years ago: “loathe /lōT͟H/ v. feel intense dislike or disgust for”
5 years ago: “Duct work in an empty gym”
6 years ago: “Yes, you’re spared a plant photo!”
7 years ago: “Numbers, numbers, numbers…”
8 years ago: “Bell pepper”
9 years ago: “Cardinal”
10 years ago: “Use that!” Hmmm. Maybe I'll redo this one with more depth of field…

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23rd February 2021 23rd Feb 21