Drone Course - Part 1 - Lift Force
Image source: wikimedia.org

Drone Course - Part 1 - Lift Force

Lift force is the fundamental force that allows aircraft to stay in the air. In this post I will try to explain it as easily as possible to build some foundations for better understanding of mechanics of flight of all drone platforms we will be discussing in this course (multirotors, helicopters and fixed wings).

A Pressure Difference

The image below is a representation of a wing cross-section (imaging someone cutting a wing from top to bottom and that you are directly looking at it).

Fluid distribution on airfoil
Air distribution on airfoil. Credit: Aviation History Online Museum

The curved shape of the upper part part of the wing makes the air stretch out, decreasing the pressure. It’s exactly opposite on the bottom part of the wing, where the air is squeezed into smaller place thus increasing the pressure.

So at this point we have a low pressure above the wing and high pressure below the wing, causing an upward push.

Angle of Attack (AoA)

Angle of Attack (sometimes referred to as AoA) is the angle between relative flow of air and the chord line of the wing (as shown below).

Angle of attack
Angle of attack. Credit: Wikimedia

By increasing an angle of attack you can increase lift coefficient, however this causes more wing area to be facing the flow directly thus increasing drag. Here is your homework: Find out what happens when the angle of attack is too large (hint you follow the article from further reading section).

Further reading

  1. NASA on inclination effects on drag

Coming soon

Anxious for the next chapter? Spoiler: we will cover the principle of flight for multirotors!

Mateusz Sadowski

Mateusz Sadowski
Robotics consultant

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