Case 2: Tumbling brick with no damping or drag

Verifies	Rotational EOMs
Gravitation	J2
Geodesy	WGS-84 rotating
Atmosphere	US 1976 STD
Winds	still air
Vehicle	Dragless rotating brick
Notes	Damping and drag coefficients set to zero

from simupy.block_diagram import BlockDiagram
import simupy_flight
import numpy as np

from nesc_testcase_helper import plot_nesc_comparisons, int_opts, benchmark
from nesc_testcase_helper import ft_per_m, kg_per_slug

planet = simupy_flight.Planet(
    gravity=simupy_flight.earth_J2_gravity,
    winds=simupy_flight.get_constant_winds(),
    atmosphere=simupy_flight.get_constant_atmosphere(),
    planetodetics=simupy_flight.Planetodetic(
        a=simupy_flight.earth_equitorial_radius,
        omega_p=simupy_flight.earth_rotation_rate,
        f=simupy_flight.earth_f,
    ),
)

The inertial forces due to rotation needed to be modeled with a vehicle

Ixx = 0.001894220 * kg_per_slug / (ft_per_m**2)  # slug-ft2
Iyy = 0.006211019 * kg_per_slug / (ft_per_m**2)  # slug-ft2
Izz = 0.007194665 * kg_per_slug / (ft_per_m**2)  # slug-ft2
Ixy = 0.0 * kg_per_slug / (ft_per_m**2)  # slug-ft2
Iyz = 0.0 * kg_per_slug / (ft_per_m**2)  # slug-ft2
Izx = 0.0 * kg_per_slug / (ft_per_m**2)  # slug-ft2
m = 0.155404754 * kg_per_slug  # slug

x = 0.0
y = 0.0
z = 0.0

vehicle = simupy_flight.Vehicle(
    base_aero_coeffs=simupy_flight.get_constant_aero(),
    m=m,
    I_xx=Ixx,
    I_yy=Iyy,
    I_zz=Izz,
    I_xy=Ixy,
    I_yz=Iyz,
    I_xz=Izx,
    x_com=x,
    y_com=y,
    z_com=z,
    x_mrc=x,
    y_mrc=y,
    z_mrc=z,
    S_A=0.0,
    a_l=1.0,
    b_l=1.0,
    c_l=1.0,
    d_l=0.0,
)

BD = BlockDiagram(planet, vehicle)
BD.connect(planet, vehicle, inputs=np.arange(planet.dim_output))
BD.connect(vehicle, planet, inputs=np.arange(vehicle.dim_output))

lat_ic = 0.0 * np.pi / 180
long_ic = 0.0 * np.pi / 180
h_ic = 30_000 / ft_per_m
V_N_ic = 0.0
V_E_ic = 0.0
V_D_ic = 0.0
psi_ic = 0.0 * np.pi / 180
theta_ic = 0.0 * np.pi / 180
phi_ic = 0.0 * np.pi / 180
omega_X_ic = 10.0 * np.pi / 180
omega_Y_ic = 20.0 * np.pi / 180
omega_Z_ic = 30.0 * np.pi / 180

planet.initial_condition = planet.ic_from_planetodetic(
    long_ic, lat_ic, h_ic, V_N_ic, V_E_ic, V_D_ic, psi_ic, theta_ic, phi_ic
)
# The specification is for inertial angular rate, not relative
planet.initial_condition[-3:] = omega_X_ic, omega_Y_ic, omega_Z_ic

with benchmark() as b:
    res = BD.simulate(30, integrator_options=int_opts)

plot_nesc_comparisons(res, "02")

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Out:

/home/runner/work/simupy-flight/simupy-flight/simupy_flight/kinematics.py:198: RuntimeWarning: invalid value encountered in double_scalars
  x60 = x6*(2*x26*x54 + x58*(-x13 + x14) + x59*(x33 + x55))/x53
/home/runner/work/simupy-flight/simupy-flight/simupy_flight/dynamics.py:22: RuntimeWarning: divide by zero encountered in double_scalars
  x15 = numpy.select([numpy.greater(V_T, 0.0)], [(1/2)/V_T], default=0.0)
/home/runner/work/simupy-flight/simupy-flight/simupy_flight/kinematics.py:198: RuntimeWarning: divide by zero encountered in double_scalars
  x60 = x6*(2*x26*x54 + x58*(-x13 + x14) + x59*(x33 + x55))/x53
time to simulate: 1.955 s