can not start engine

[layssi]

import jsbsim
import os
import time

# Set the correct path to the JSBSim assets directory
script_dir = os.path.dirname(os.path.abspath(__file__))
assets_dir = os.path.join(script_dir, "assets")

# Initialize JSBSim with the correct root directory
sim = jsbsim.FGFDMExec(root_dir=assets_dir)

# Load the aircraft model (e.g., C172P)
sim.load_model("c172p")

# Set initial conditions (higher altitude and airspeed)
sim.set_property_value("ic/lat-gc-deg", 42.3314)    # Latitude (Detroit, MI)
sim.set_property_value("ic/long-gc-deg", -83.0458)  # Longitude (Detroit, MI)
sim.set_property_value("ic/h-sl-ft", 5000)          # Altitude at 5000 ft
sim.set_property_value("ic/vt-fps", 200)            # Airspeed at 200 ft/s
sim.set_property_value("ic/psi-true-deg", 0)        # Heading north
sim.set_property_value("ic/theta-deg", 2)           # Slightly upward pitch
sim.set_property_value("ic/phi-deg", 0)             # No roll

# Set throttle, mixture, magnetos, and fuel pump
sim.set_property_value("fcs/throttle-cmd-norm", 1.0)   # Full throttle
sim.set_property_value("fcs/mixture-cmd-norm", 1.0)    # Full mixture
sim.set_property_value("propulsion/engine/magneto_cmd", 3)  # Both magnetos on
sim.set_property_value("propulsion/fuel_pump_cmd", 1)  # Turn on fuel pump

# Start the engine using the starter command
sim.set_property_value("propulsion/starter_cmd", 1)    # Start engine

# Initialize the flight model
sim.run_ic()

# Run the simulation loop for a certain period (e.g., 300 seconds)
for t in range(30000):  # 30000 steps * 0.01 seconds = 300 seconds (5 minutes)
    if not sim.run():
        break

    # Get detailed information from the simulation
    current_altitude = sim.get_property_value("position/h-sl-ft")
    current_heading = sim.get_property_value("attitude/psi-deg")
    current_pitch = sim.get_property_value("attitude/theta-deg")
    current_roll = sim.get_property_value("attitude/phi-deg")
    current_speed = sim.get_property_value("velocities/vtrue-fps")
    current_rpm = sim.get_property_value("propulsion/engine/rpm")
    current_thrust = sim.get_property_value("propulsion/engine/thrust-lbs")
    current_fuel_flow = sim.get_property_value("propulsion/fuel_flow-rate-pps")
    current_fuel_quantity = sim.get_property_value("propulsion/fuel-quantity-lbs")

    # Print out engine and propulsion state for debugging
    print(f"Time: {t * 0.01:.2f}s | Altitude: {current_altitude:.2f} ft | Heading: {current_heading:.2f} deg")
    print(f"Pitch: {current_pitch:.2f} deg | Speed: {current_speed:.2f} ft/s | RPM: {current_rpm:.2f} | Thrust: {current_thrust:.2f} lbs")
    print(f"Fuel Flow: {current_fuel_flow:.2f} pps | Fuel Quantity: {current_fuel_quantity:.2f} lbs")

    # Check if the engine is running properly
    if current_rpm == 0:
        print("Warning: Engine RPM is too low. Check the starter and fuel settings.")

    # Stop the engine if the RPM doesn't increase
    if t > 100 and current_rpm == 0:
        print("Engine failed to start. Ending simulation.")
        break

    time.sleep(0.1)

# Final shutdown of the simulation
sim.shutdown()

I always get

Time: 0.00s | Altitude: 5000.06 ft | Heading: 0.00 deg
Pitch: 2.00 deg | Speed: 199.96 ft/s | RPM: 0.00 | Thrust: -0.00 lbs
Fuel Flow: 0.00 pps | Fuel Quantity: 0.00 lbs
Warning: Engine RPM is too low. Check the starter and fuel settings.
Time: 0.01s | Altitude: 5000.12 ft | Heading: 360.00 deg
Pitch: 2.01 deg | Speed: 199.92 ft/s | RPM: 0.00 | Thrust: -0.00 lbs
Fuel Flow: 0.00 pps | Fuel Quantity: 0.00 lbs

[bcoconni]

According to my tests you are not using the correct property name for the engine RPM. It should be propulsion/engine/engine-rpm rather than propulsion/engine/rpm.

Also the magnetos should be set with propulsion/magneto_cmd not propulsion/engine/magneto_cmd but this has no effect since 3 is the default value for magnetos.

[bcoconni]

Said in other words, the engine is starting but you did not detect it because you were not checking the correct property.

[layssi]

Thank you very much.