METHODOLOGY

Flight Simulation

6-DOF trajectory prediction with integrated flutter safety analysis using RocketPy.

Overview

The flight simulator combines professional trajectory prediction with real-time structural safety analysis. It uses RocketPy, an industry-standard 6-DOF flight simulation library, overlaid with our flutter velocity calculations at each altitude point.

Physics Engine

RocketPy

v1.4.0+

Atmosphere

US Std 1976

0-86 km range

Flutter Methods

Classical & Barrowman

Unique Integration

Unlike other simulators, we overlay flutter velocity analysis at every altitude point during flight. This shows your "safe flight envelope" — where actual velocity stays below flutter limits.

Physics Engine

The simulation solves full 6-DOF rigid body dynamics:

Newton's 2nd Law

\vec{F} = m\vec{a}

Forces modeled include:

Thrust — from motor thrust curve interpolation
Drag — constant Cd approximation (0.5)
Gravity — varies with altitude
Recovery forces — parachute drag during descent

Drag Force

D = \frac{1}{2} \rho V^2 C_D A

D

Drag force (N)

\rho

Air density (kg/m³)

V

Velocity (m/s)

C_D

Drag coefficient

A

Reference area (m²)

Flight Modes

Mode	Simulates	Use Case
Boost	Motor burn only (~2-4s)	Quick thrust analysis
Ascent	Boost + coast to apogee	Altitude prediction
Full Flight	Complete flight with recovery	Landing velocity, total time

Ascent mode (default) is recommended for most analyses. It shows the complete powered ascent profile including Max-Q and flutter margin through apogee.

Flutter Safety Integration

At each simulation timestep, we calculate the flutter velocity based on current atmospheric conditions:

> 25% margin— Safe

0-25% margin— Warning

< 0% margin— Danger (exceeds flutter velocity)

Critical Altitude

The simulation identifies the "critical altitude" where flutter risk is highest — typically at Max-Q where both velocity and air density are significant.

Recovery System

Full flight mode simulates dual-deployment recovery:

Event	Trigger	Typical Settings
Drogue deploy	Apogee detection	0-2s delay
Main deploy	Altitude AGL	150-300m

Terminal velocity under parachute:

Descent Rate

V_{terminal} = \sqrt{\frac{2mg}{\rho C_D S}}

Safe Landing

Target a main parachute descent rate of 5-7 m/s for a safe landing. Higher rates risk damage on impact.

Output Parameters

Parameter	Unit	Description
Max Altitude	m / ft	Apogee (highest point)
Max Velocity	m/s / Mach	Peak speed during flight
Max Acceleration	G's	Peak acceleration (usually at burnout)
Max-Q	kPa	Peak dynamic pressure
Time to Apogee	s	Duration from launch to apogee
Min Flutter Margin	%	Lowest safety margin during flight
Critical Altitude	m	Altitude where flutter risk is highest
Landing Velocity	m/s	Final descent rate (full mode only)

SOURCES

References

NASA & Technical Reports

US Standard Atmosphere 1976
Atmospheric model used for density, temperature, and pressure calculations

Tools & Calculators

RocketPy Documentation
6-DOF trajectory simulation library powering MaxQ flight predictions

Try the Calculator

Put this methodology into practice with the interactive calculator.

Open Flight Simulator