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Calculate Current and Torque

  • #1

Homework Statement


The rotor blades of a quadcopter are 10cm long. Given that the thrust force generated by each rotor is 1N (giving a total of 4N for 4 rotors), calculate the torque () on each rotor, and the current drawn (I) from a 10V battery, given the following:

  1. Density of air, a = 1 kg/m3.

  2. Shaft efficiency, Nsh = Psh/Pe , where Psh & Pe are the shaft power and electrical power, respectively, is 0.95.

  3. Rotor efficiency, N =P/ Pe , where P is the power generated by the rotor, is 0.8.

  4. The rotor blades are rotating at a speed of 6000 RPM.
(Hint: Use that actuator disk model to compute the power required by the rotor)

Ans: 8mN.m , I= 2A


Homework Equations


P = I V
KE = 1/2 mv^2
F = mv

The Attempt at a Solution


F = mv. Found velocity of the air exiting the propeller. Tired to use KE equation to find power but it doesn't match the answe.
 

Answers and Replies

  • #2
scottdave
Science Advisor
Homework Helper
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Where did you get F = mv ? Mass times velocity is momentum, not force. Can you show calculations that you made in your attempt at the solution?
 

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