FLIGHT LAB / AERODYNAMICS
Stall Speed Explorer
What happens when an aircraft gets heavier—or its wings get larger? Change an assumption and explore the physics.
Educational aerodynamic estimator only. Not for flight planning, aircraft design approval, certification, operational takeoff speeds, or runway suitability.
01 Set up your example
Presets are hypothetical teaching scenarios, not aircraft specifications. Every preset uses an assumed CLmax of 1.50.
MODELED TRUE AIRSPEED · IDEALIZED 1-G FLIGHT
Estimated stall speed
Assumptions in this estimate
Airspeed relative to the surrounding air, not groundspeed. This is a model estimate of true airspeed at the entered density; it is not an indicated or calibrated airspeed prediction.
Do not use this result to determine rotation speed, takeoff speed, or safe aircraft operation.
02 / UNDERSTAND THE RELATIONSHIP
More weight needs more lift.
More wing needs less speed.
With density and CLmax fixed, doubling mass increases estimated stall speed by 41.4%. Doubling wing area reduces it by 29.3%. These are square-root relationships.
Changing wing area also changes real aircraft mass, drag, structure, and handling. Here, all other inputs stay fixed.
The equation behind the estimate
Vs = √(2W / (ρ S CLmax))
W = mass × 9.80665 m/s²
Lift is approximated as equal to weight. No bank, gust, maneuver, thrust, climb, or safety margin is modeled.
Cessna 172C comparison · inconclusive
The supplied master plan reports 2,250 lb and an inferred wing area of 2,250 ÷ 12.9 = 174.4186 ft² (about 16.2040 m²). This area is inferred from rounded secondary wing loading, not verified aircraft geometry.
The hypothetical coefficient below is not a measured or certified Cessna coefficient. Secondary speeds of 49, 52, and 58 mph reported in the plan have unresolved configuration and speed-definition differences. No agreement with published performance is claimed. Back-calculating CLmax from those speeds would be circular validation.
Before a valid comparison, an independent reviewer must verify the original manual revision, model, mass, wing area, flap and power settings, atmosphere, speed definition, and an independently sourced CLmax.