ISA (International Standard Atmosphere) defines temperature, pressure, and density as a function of altitude. The tropopause at 11 km marks the boundary between the temperature-decreasing troposphere and the isothermal stratosphere. Speed of sound and viscosity directly affect aerodynamic forces and Reynolds number.

Drag vs Thrust — intersection at max level speed. The shaded green region shows where thrust exceeds drag. Power — excess power drives climb rate. L/D — peak marks the best glide and range speed.

Vy (max rate-of-climb speed) gives the fastest altitude gain. Excess thrust and power represent the energy available for climbing beyond level flight. Service ceiling is where ROC drops to 100 ft/min; absolute ceiling is where ROC → 0.

The V-n diagram defines the structural and aerodynamic maneuvering envelope. Corner speed V* is the slowest speed at which n_max can be achieved — below this, the aircraft is CLmax-limited; above, it is structurally limited.

SAR (Specific Air Range) shows fuel efficiency at each speed in km/kg. Breguet range shows total distance if all fuel is burned at each cruise speed. Best endurance speed is always slower than best range speed for a jet.

2D maps showing how Rate of Climb and L/D efficiency vary across the full velocity–altitude flight envelope. Green = climbing, red = descending. White contours are iso-lines. Stall-masked regions are blank.

Sweep two design variables simultaneously. The ⭐ star marks your current configuration. These maps reveal the most sensitive levers for each performance goal.