01 · Overview
Engineering for flight
Aerospace engineering designs vehicles that fly: aircraft that move through the atmosphere and spacecraft that cross the vacuum beyond it. The two branches are aeronautical and astronautical engineering.
Every vehicle balances aerodynamics, propulsion, structures, and control. Slide the altitude to climb through the atmosphere.
02 · Aerodynamics
How wings lift
A wing makes lift by turning the airflow downward and holding lower pressure above it than below. Lift grows with air density, speed squared, wing area, and the lift coefficient: L = ½ρV²S·CL.
Tilt the wing up and lift climbs until the flow separates and the wing stalls. Try more than 14° of angle of attack.
03 · Propulsion
Turning fuel into thrust
A turbofan pulls air in with a fan, squeezes it in the compressor, burns fuel in the combustor, and extracts energy with a turbine that drives the fan. Hot core gas and bypass air push the aircraft forward.
Rockets work on the same principle, thrust from throwing mass backward, but carry their own oxidizer. Push the throttle.
04 · Structures
Strong, light, certain
Aircraft structures carry flight loads with as little weight as possible. Spars carry bending along the wing, ribs hold its shape, and stringers stiffen the skin. Aluminum, titanium, and carbon composites do the job.
Airliners are designed for up to 2.5 g, fighters like the F-22 for 9 g. Raise the load factor and watch the spars take the stress.
05 · Flight control
Staying in control
An aircraft rotates about three axes through its center of gravity: roll about the nose-to-tail axis, pitch about the wingtip-to-wingtip axis, and yaw about the vertical axis. Ailerons steer roll, elevators pitch, the rudder yaw.
Agile fighters are built with relaxed stability, so flight computers correct them many times a second. Pick an axis, or drag the jet to turn it yourself.
06 · Spaceflight
Orbits and trajectories
A spacecraft in orbit is falling around the planet, moving sideways fast enough that the ground curves away beneath it. Orbits are ellipses with the planet at one focus.
Changing orbit costs delta-v: Δv = Isp·g0·ln(m0/mf). Stretch the orbit and watch the equal-area sweep change shape.