📘A verdadeira simulação de foguetes | AULA 5 🚀Curso Introdução à Simulação de Foguete com OpenRocket

Main Ideas / Concepts Taught

Purpose of Rocket Simulation in OpenRocket (Ozifog Course, Class 5)

• Use a completed rocket structure from previous steps.
• Run simulations to predict flight behavior and make design decisions based on simulation outputs.
• Focus on learning how to interpret simulation graphs and flight event warnings.

Setting Up a Simulation

• Go to Flight Simulations to open the simulation screen.
• If needed, create a New Simulation; otherwise use Edit to access existing simulation settings.

Environmental (Atmospheric) and Launch-Site Configuration

• Adjust atmospheric conditions (can use International Standard Atmosphere or customize).
• Modify launch temperature with the note that actual launch altitude changes pressure/temperature during flight.

Rocket Launch Physical Constraints

Configure the launch rail/rod constraints:

• Rod length determines the straight-line travel distance (e.g., 100 cm / 1 m).
• During this phase, wind does not alter behavior because the rocket is constrained by the rod/rail.

Set the launch angle:

• 0° = straight upward.
• Oblique launches are possible (example mentioned: 45°), but in this lesson they choose 0°.

Set the launch direction relative to wind:

• There is an option to automatically orient with/against wind; they explicitly disable this.
• Manually choose a cardinal direction (North/South/East/West).
• Example guidance: 90° corresponds to East (as described by the instructor).

Technical Simulation Options and Warnings

• Model Earth geometry as:
  • Spherical approximation (default example),
  • Flat earth or ellipsoid,
  • (Geoid mentioned as difficult/rare for calculations).
• Add schedules/codes and set maximum simulation time/events (described generally).

Common warnings discussed:

• Diameter discontinuity warning
  • Triggered by a transition not covered by the current rocket design.
  • Plan to fix later.
• Parachute activation at 184 m/s
  • Indicates the rocket was too fast at deployment.
  • Can cause problems such as poor behavior and disconnecting elements.
• Supersonic calculation accuracy limitation
  • Software may be less accurate at supersonic speeds.
  • Lesson emphasizes understanding this limitation.

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Methodology / Workflow (Step-by-Step)

1) Run the First Simulation and Graph Only Altitude

• Open the Graphing Data tab/screen.
• Set graph axes:
  • X-axis = time
  • Y-axis = altitude
• Start the simulation and generate the chart.

2) Interpret the Chart Using Flight Event Markers

• Identify icons/markers for flight events, such as:
  • Engine combustion
  • Engine ignition
  • Stage separation
    • Explained as occurring when the previous stage burns out and the next stage ignites.
  • Parachute / recovery deployment alerts
• Learn to zoom into graph sections:
  • Select a region and drag to create a zoom window (purple highlight region).
  • Return using the reverse method described.

3) Diagnose a Recovery System Timing Problem

• The parachute warning indicates the parachute opens before apogee (peak altitude).
• Key lesson: Do not deploy the parachute before peak altitude, because it slows the rocket too early, reducing recovery effectiveness and altitude efficiency.

4) Adjust Recovery Deployment Timing

• Modify the parachute/recovery ejection timing so it occurs after apogee.
• Baseline apogee mentioned: 4,726 m.
• Change the ejection configuration:
  • Format example: 149N-dash-two
  • “dash two” refers to the second ejection charge timing relative to combustion.
    • Numbers after the hyphen are seconds after engine combustion for that load to be expelled.
  • Conclusion: 2 seconds was not enough, so deployment must be assumed to occur after apogee.
• New plan:
  • Deploy recovery at apogee + 1 second.
  • Reasoning: after apogee + 1 second, the recovery device ejects to slow the rocket only after it has reached maximum altitude.

5) Re-run the Simulation to Confirm the Fix

• Go back to Flight Simulations and run again to update changes.
• Expected outcome achieved:
  • The earlier parachute timing warning disappears.
  • A parachute deployment marker appears after the peak.
  • Apogee improves to a stated range: around 4,000 to 5,621 m, framed as achieving correct efficiency.

6) Additional Analysis Options Shown

• Trajectory map view (2D coordinates)
  • Set axes to:
    • North position (X-axis)
    • East position (Y-axis)
  • Used to visualize the flight path from above (map-like).
• Stability/attitude analysis
  • Plot time vs. angle of attack/orientation angle to study rocket tilting along the trajectory.
• Data export note
  • OpenRocket can export simulation data, but the instructor defers detailed exporting to a later lesson.

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Main Lesson Conclusions

• OpenRocket simulation graphs are used to:
  • Detect problems via warnings and flight event markers.
  • Improve design by adjusting timing parameters—specifically, deploy recovery after apogee.
• Instructor demonstrates an iterative loop:
  1. Simulate
  2. Interpret warnings/events
  3. Modify configuration
  4. Re-simulate and verify improved results

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Speakers / Sources

• Speaker / instructor: Vinícius Leandro (monitor/instructor for Class 5)
• Software / source tool: OpenRocket
• Course / event reference: Ozifog (Brazilian Rocket Simulation Olympiad)