1.1 — The Four Forces & The Atmosphere

Key insights

Key ideas from this lesson:

• In steady, unaccelerated level flight the four forces balance: lift = weight and thrust = drag.
• Lift acts perpendicular to the relative wind; weight acts toward the Earth; thrust opposes drag.
• Air density, pressure and temperature all decrease with altitude — governed by the ICAO Standard Atmosphere.
• Density altitude drives engine and wing performance: hot, high days cost you power and lift.

(Draft — refine in admin.)