🚀 Rocket Motor Thrust Tester

Simple Arduino + HX711 thrust stand that logs force vs time and calculates impulse.

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What it does

• Measures thrust (N)
• Logs data in CSV
• Tracks peak + average thrust
• Calculates total impulse

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Setup (do this once)

1. Wire everything:

   • HX711 → D4 (DT), D5 (SCK)
   • Switches → D11, D12 (to GND)
   • Output → D8 → MOSFET/relay

2. Plug Arduino into your computer

3. Open Serial Monitor

   • Baud rate: 115200

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How to use (actual workflow)

1. Turn it on

You’ll see prompts in Serial Monitor.

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2. Calibration (important)

If asked:

• Remove all weight → press Enter
• Place a known weight → type its value (grams)

If skipped, readings will be inaccurate.

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3. Set test duration

It will ask: Enter run duration in seconds (0 = manual stop):

• Example: 3 → auto stops after 3 seconds
• 0 → manual stop

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4. Start test

Type: start

System will:

• tare automatically
• start logging immediately

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5. Run your motor

• Arm your system (if using output)
• Press BOTH switches (safety trigger)
• Fire motor

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6. Data output

You’ll see: Time(s),Force(N) 0.000,0.0000 0.010,2.1345 ...

Copy this into:

• Excel
• Google Sheets
• MATLAB / Python

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7. End test

Either:

• Wait for auto-stop or type: stop

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8. Summary

After test, you’ll get:

• Peak force
• Mean force
• Total impulse

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9. Run again

It will ask: Start a new test? (y/n)

• y → run again
• n → end session

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Commands

• start → begin logging
• stop → pause logging
• status → show current stats
• reset → reboot system
• exit → end program

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Safety

• Output activates only when BOTH switches are pressed
• Do NOT connect high-current loads directly to Arduino
• Use a MOSFET or relay for ignition
• Use a separate battery for igniter
• Test in a safe outdoor environment

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Tips

• Calibrate every session
• Secure your load cell properly
• Keep signal wires away from high-current wires
• Do a dry run before firing a motor

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An IMLABS Engineering Projects