March 26th, 2018

## This is Part 3 in the ‘Diary of a Flying Car Engineer’ Series

### Physics

The Rotors act as wings. They generate thrust by rotating at Fast speeds, which pulls the air downwards and keeps the quad in the air.

• The Thrust cancels out the acting weight and the quad hovers.
• A directional Thrust causes the quad to move in that direction.
• Or a decrease in Thrust overall causes the Drone to lose height.

Setup:

The setups for Flying is simple:

• Two adjacent motors spin in the opposite direction.
• Two opposite motors spin in the same direction.

A,C spin Clockwise (From our point of view)

B,D Spin Counter-Clockwise

### Why?

Physics says to be in stability the net forces acting on a body should be zero.

So if all the rotors were to spin in the same direction, it would result in a net Torque causing the complete Quad to rotate.

Source: Wikipedia

### Attitude

Source: Video

The attitude is defined with analogy from the Naval World.

We will use these terms to define the motions of our drone.

• Roll: Moving to left or Right with respect to the Front.
• Pitch: Moving Forward or Backwards.
• Yaw: Rotation about the centre.

### Taking Off

Source: Video

• To Rise above the ground, you need a net upward Force.
• The Motors generate Thrust that is greater than the Weight, making the quad rise upwards.

### Hover

Source: Video

• Hovering in Air is simple.
• Motors generate Thrust.
• The Thrust should equal the weight of the System.
• The two forces cancel and our drone Hovers.

### Roll

Source: Video

• To Roll towards the Left (Our Left), the Thrust is increased on the Motors on the Right.
• We also decrease the Thrust on the motors on the Left.

Why?

• To keep the Net Torque zero and allowing an Leftward Net Force.

To Roll Rightwards (Our Right)

Source: Video

### Pitch

• To Pitch Forwards (Towards us)
• The Power to the motors rear motors is increased.

This creates a net forward force which causes the Drone’s nose to Pitch Downward.

• We also decrease the power to the two front motors to keep the angular momentum conserved.

To Pitch Away from us

### Yaw

Source: Video

• To Yaw Clockwise.
• We increase the Thrust on the Anti-Clockwise moving Motors.
• Decrease the Thrust on Clockwise Rotating Motors.

Why?To keep the Net upward/downward force zero.

• There is a resulting Anti-Clockwise Torque.
• The Quad rotates Clockwise to conserve the Angular Momentum.

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