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Homework Help: Helicopter rotor has four blades

  1. Sep 10, 2004 #1
    A model of a helicopter rotor has four blades, each of length 3.90m from the central shaft to the blade tip. The model is rotated in a wind tunnel at a rotational speed of 480rev/min .

    A.) What is the linear speed of the blade tip?

    R= 3.9
    T = 480

    would it just be V= 2*pi*R/t
    and got = .05105

    someone helped me(not at this forum) and the answer is wrong. can someone help? isnt it just asking for the velocity?
    Last edited: Sep 10, 2004
  2. jcsd
  3. Sep 10, 2004 #2
    Well you say the rotational velocity is 480 rotations / minute
    1 rotation at a distance R from the center is the cirumference of a circle, so the distance the tip travels in one rotation is : 2*Pi*Radius meters

    D = 2*3.14159*3.90 = 24.5 meters

    You say 480 Rot/Min => 480 (rotrotations/minute) * (24.5 meters/rotation) = 11760 meters per minute.
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