Aerodynamics of Paragliders

 

Paraglider aerodynamics relies on gravity and forward motion to turn a flexible fabric wing into an efficient lifting surface, balancing lift, drag, and angle of attack. [1, 2]

Core Forces

Lift: Upward force created when air moves faster over the curved top surface of the wing than underneath it.
Drag: Resistance caused by the fabric and lines moving through the air, acting opposite to forward motion.
Gravity: Acts as the engine, pulling the pilot downward to create the forward airspeed needed to inflate and fly the canopy. [1, 2, 3]

Flight Mechanics

Glide Ratio: Typically around 10:1 in standard wings, meaning the paraglider moves forward 10 feet for every 1 foot it descends in calm air. [1, 2]
Angle of Attack: The tilt of the wing relative to the oncoming air; steeper angles increase lift but also raise drag and risk a stall if pushed too far. [1, 2]
Stall: Occurs when the airflow breaks away from the top of the wing because the brakes are pulled down too much, destroying lift. [1]

The theory

The control acts as a "brake". By pulling one brake there is an asymmetry in drag, causing the wing to yaw. Due to the yawing motion a difference in airspeed in the two sections of the wing causes a difference in lift, having as a side-effect the aircraft to roll too.

Thus pulling the right brake, makes the aircraft yaw to the right, and then roll to the right.

For a quick visual overview of how an inflated flexible wing functions in the air: