• Timothy Teo
In summary, the rotor blades of a quadcopter are 10cm long and generate a total thrust force of 4N from 4 rotors. The torque on each rotor is 8mN.m and the current drawn from a 10V battery is 2A. This is calculated using the actuator disk model with the given density of air, shaft efficiency, rotor efficiency, and rotor speed of 6000 RPM.
Timothy Teo

## 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

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.

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?

## 1. How do you calculate electric current?

Electric current is calculated by dividing the total charge (in coulombs) by the time it takes for the charge to pass through a point (in seconds). This can be represented by the equation I = Q/t, where I is the current in amperes, Q is the charge in coulombs, and t is the time in seconds.

## 2. What is the formula for calculating torque?

The formula for torque is T = F x r, where T is the torque in newton-meters, F is the force applied in newtons, and r is the distance from the axis of rotation to the point where the force is applied in meters.

## 3. How does the direction of the current affect the direction of the magnetic field?

The direction of the current determines the direction of the magnetic field created by the current. The magnetic field will always be perpendicular to the direction of the current, with the direction of the field following the right-hand rule.

## 4. How can you calculate the current required to produce a certain torque?

The current required to produce a certain torque can be calculated by rearranging the formula for torque to solve for current. This would result in the equation I = T/r, where I is the current in amperes, T is the torque in newton-meters, and r is the distance from the axis of rotation to the point where the force is applied in meters.

## 5. How is torque related to rotational motion?

Torque is a measure of the force that can cause an object to rotate about an axis. The greater the torque, the greater the rotational acceleration of the object. This means that torque is directly related to rotational motion, and plays a crucial role in understanding and predicting the behavior of rotating objects.

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