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the wing because the dynamic pressure hitting the opening is the same for each cell and the speed is the same. The cross-ports aid the complete wing in becoming pressurized during inflation and maintain - ing the pressure throughout the wing in turbulence. [Figure 2-8] 

The inflatable wing airfoil generally remains a consis - tent shape as designed by the manufacturer. However, pilot control of the wing to make a turn significantly changes the relative aerodynamic qualities of the PPC wing by pulling down the trailing edge similar to a flap on an airplane. [Figure 2-9] 

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Faster speeds from smaller wings or more weight cre- ate a higher pressure in the wing resulting in higher control forces because of the higher internal pressure. 

## Forces in Flight 

Like all aircraft, the four forces that affect PPC flight are thrust, drag, lift, and weight. [Figure 2-10] In steady PPC flight: 

1. The sum of all upward forces equals the sum of all downward forces. 

2. The sum of all forward forces equals the sum of all backward forces. 

