ensim.core.monte_carlo

Dispersion studies over the six-degree-of-freedom flight. The statistics are explained under uncertainty.

Monte Carlo dispersion of 6-DOF flights.

Each run perturbs thrust, Isp, burn time, drag, launch elevation, fin misalignment and wind, flies the vehicle with :func:simulate_flight_6dof and records the impact point and performance. Runs are independent, so they are spread over worker processes.

Landing statistics use only runs that reached the ground before max_time; runs still airborne are counted separately.

DispersionConfig dataclass

Uncertainty model for a dispersion study.

Multiplicative factors (thrust, Isp, burn time, Cd) are lognormal with mean one and the given coefficient of variation. Launch elevation is normal, fin misalignment uniform, wind speed a normal truncated at zero.

DispersionResult dataclass

Statistics of a dispersion study.

SimulationResult dataclass

Outcome of one dispersed flight.

run_monte_carlo

run_monte_carlo(rocket: Rocket, thrust_vac: float, isp_vac: float, burn_time: float, config: DispersionConfig | None = None, launch_angle_deg: float = 85.0, launch_azimuth_deg: float = 0.0, exit_area: float = 0.0, dt: float = 0.02, max_time: float = 300.0, use_adaptive: bool = False, rail_length: float = 3.0, chute_diameter: float = 0.0, deploy_at_apogee: bool = True, progress: ProgressCallback | None = None, cancel: CancelCallback | None = None, flight_options: dict[str, Any] | None = None) -> DispersionResult

Run a dispersion study.

Parameters:

Name	Type	Description	Default
rocket	Rocket	Nominal vehicle. Each run receives its own copy.	required
thrust_vac	float	Nominal vacuum thrust, N.	required
isp_vac	float	Nominal vacuum specific impulse, s.	required
burn_time	float	Nominal burn time, s.	required
config	DispersionConfig | None	Uncertainty model; defaults to :class:DispersionConfig.	None
launch_angle_deg	float	Nominal rail elevation above the horizon, deg.	85.0
launch_azimuth_deg	float	Rail heading clockwise from north, deg.	0.0
exit_area	float	Nozzle exit area, m², for the ambient-pressure thrust loss.	0.0
dt	float	Integration step, s.	0.02
max_time	float	Time limit of each flight, s.	300.0
use_adaptive	bool	Use the adaptive integrator.	False
rail_length	float	Launch rail length, m.	3.0
chute_diameter	float	Main parachute diameter, m (0 = none).	0.0
deploy_at_apogee	bool	Open the main at apogee rather than at a set height.	True
progress	ProgressCallback | None	Called with (completed, total) after each run.	None
cancel	CancelCallback | None	Polled between runs; return True to stop.	None
flight_options	dict[str, Any] | None	Further keyword arguments for every flight (drogue, fill time, WGS-84 site, ...). They override the explicit ones.	None

Raises:

Type	Description
SimulationCancelled	cancel returned True.
RuntimeError	Fewer than two runs succeeded.

compute_cep

compute_cep(points: ndarray, center: ndarray) -> float

Radius around center that contains half of points.

compute_confidence_ellipse

compute_confidence_ellipse(points: ndarray, confidence: float = 0.997) -> tuple[float, float, float]

Covariance ellipse enclosing confidence of a bivariate normal fit.

Returns (semi-major, semi-minor, angle of the major axis from x in degrees).