Rocket Dynamics & Stability Calculator

Rocket Flight Dynamics Calculator

Estimate stability, forces, and performance for altitudes up to 15,000ft.

Design Specifications

Mass & Geometry

Flight Environment

Estimated Peak Drag

-- N

At max velocity

Required Min Thrust

-- N

For TWR of 5:1

Estimated CP Position

-- m

From nose tip

Stability Margin

-- cal

Calculate to see status

Physics Reference

1. Aerodynamic Drag

Determines how much force air exerts against the rocket's motion.

D = 0.5 * ρ * V² * A * Cd
  • • ρ (Rho): Air density (decreases with altitude).
  • • Cd: Drag Coefficient (~0.45-0.75 for rockets).
  • • A: Reference area (Cross-section).

2. Thrust-to-Weight (TWR)

Crucial for leaving the launch rail safely. Aim for > 5:1.

TWR = Thrust / (Mass * g)

If TWR < 3, the rocket may weathercock severely or fail to gain enough velocity for fin stabilization.

3. Static Stability

The distance between Center of Gravity (CG) and Center of Pressure (CP).

Margin = (CP - CG) / Diameter

Optimal margin is 1.0 to 2.0 calibers. Over-stable rockets (>3) turn into the wind; under-stable rockets tumble.

4. Air Density vs Alt

Calculated for 15k ft using the barometric formula.

ρ = P / (R * T)

At 10,000ft, air is roughly 30% less dense than at sea level, reducing both drag and fin effectiveness.