LESSON 1.3 — AIRPLANE FUNDAMENTALS
[ 1.3.1] How do airplanes fly
BEFORE WE FLY — QUICK QUESTION
Why is an airplane mostly empty space?
Most of the structure is empty space — the lighter the aircraft, the less lift is needed to keep it flying.
KEY TAKEAWAYS
- Lightweight structures are essential: most of an airplane's structure is empty space — a Van's RV-14 weighs only ~590 kg, less than many cars — and the lighter the aircraft, the less lift is required.
- An airfoil generates lift through its shape: the curved upper surface accelerates the air and lowers pressure above, while the flatter lower surface raises it — the pressure difference is lift.
- Lift increases with the velocity squared: doubling speed from 100 to 200 mph multiplies lift by four (16x at 400 mph) — the same law you feel with your hand out of a car window.