Helicopter Blade Speed Calculation

What is the airspeed of the tip of the blades of a Chinook helicopter when they are rotating at 225 rpm?

Given: Diameter of circle = 18.29 meters, Rotations per minute = 225 rpm

Answer:

The airspeed of the tip of the blades of a Chinook helicopter when they are rotating at 225 rpm is approximately 215.43 meters per second.

To calculate the airspeed at the tip of the blades, you need to use the formula for the circumference of a circle because the blades describe a circular path when rotating. The formula for circumference is C = πd, where C is the circumference, π is a constant (approximately 3.14159), and d is the diameter.

The diameter of the circle described by the tips of the blades is given as 18.29 meters, so the circumference C is:

C = 3.14159 * 18.29 = 57.45 meters

This is the distance a point on the tip of one of the blades travels in one rotation. So, at 225 rotations per minute (rpm), the tip of the blade is covering this distance 225 times every minute.

Thus, the speed v in meters per minute is:

v = 225 * 57.45 = 12926.25 m/min

To convert this to meters per second, we divide by 60 (since there are 60 seconds in a minute):

v = 12926.25 / 60 = 215.43 m/s

Therefore, the airspeed of the tip of the blades when they are rotating at 225 rpm is approximately 215.43 m/s.