def test_soyuz_standard_gto_numerical():
# Data from Soyuz Users Manual, issue 2 revision 0
r_a = (Earth.R + 35950 * u.km).to(u.km).value
r_p = (Earth.R + 250 * u.km).to(u.km).value
a = (r_a + r_p) / 2 # km
ecc = r_a / a - 1
argp_0 = (178 * u.deg).to(u.rad).value # rad
argp_f = (178 * u.deg + 5 * u.deg).to(u.rad).value # rad
f = 2.4e-7 # km / s2
k = Earth.k.to(u.km**3 / u.s**2).value
a_d, _, t_f = change_argp(k, a, ecc, argp_0, argp_f, f)
# Retrieve r and v from initial orbit
s0 = Orbit.from_classical(
Earth,
a * u.km, (r_a / a - 1) * u.one, 6 * u.deg,
188.5 * u.deg, 178 * u.deg, 0 * u.deg
)
# Propagate orbit
sf = s0.propagate(t_f * u.s, method=cowell, ad=a_d, rtol=1e-8)
assert_allclose(sf.argp.to(u.rad).value, argp_f, rtol=1e-4)
def test_soyuz_standard_gto_delta_v():
# Data from Soyuz Users Manual, issue 2 revision 0
r_a = (Earth.R + 35950 * u.km).to(u.km).value
r_p = (Earth.R + 250 * u.km).to(u.km).value
a = (r_a + r_p) / 2 # km
ecc = r_a / a - 1
argp_0 = (178 * u.deg).to(u.rad).value # rad
argp_f = (178 * u.deg + 5 * u.deg).to(u.rad).value # rad
f = 2.4e-7 # km / s2
k = Earth.k.to(u.km**3 / u.s**2).value
_, delta_V, t_f = change_argp(k, a, ecc, argp_0, argp_f, f)
expected_t_f = 12.0 # days, approximate
expected_delta_V = 0.2489 # km / s
assert_allclose(delta_V, expected_delta_V, rtol=1e-2)
assert_allclose(t_f / 86400, expected_t_f, rtol=1e-2)
def test_soyuz_standard_gto_delta_v():
# Data from Soyuz Users Manual, issue 2 revision 0
r_a = (Earth.R + 35950 * u.km).to(u.km).value
r_p = (Earth.R + 250 * u.km).to(u.km).value
a = (r_a + r_p) / 2 # km
ecc = r_a / a - 1
argp_0 = (178 * u.deg).to(u.rad).value # rad
argp_f = (178 * u.deg + 5 * u.deg).to(u.rad).value # rad
f = 2.4e-7 # km / s2
k = Earth.k.to(u.km**3 / u.s**2).value
_, delta_V, t_f = change_argp(k, a, ecc, argp_0, argp_f, f)
expected_t_f = 12.0 # days, approximate
expected_delta_V = 0.2489 # km / s
assert_allclose(delta_V, expected_delta_V, rtol=1e-2)
assert_allclose(t_f / 86400, expected_t_f, rtol=1e-2)
def test_soyuz_standard_gto_numerical_safe():
# Data from Soyuz Users Manual, issue 2 revision 0
r_a = (Earth.R + 35950 * u.km).to(u.km)
r_p = (Earth.R + 250 * u.km).to(u.km)
a = ((r_a + r_p) / 2).to(u.km) # km
ecc = r_a / a - 1
argp_0 = (178 * u.deg).to(u.rad) # rad
argp_f = (178 * u.deg + 5 * u.deg).to(u.rad) # rad
f = 2.4e-7 * u.km / u.s**2 # km / s2
k = Earth.k.to(u.km**3 / u.s**2)
a_d, _, t_f = change_argp(k, a, ecc, argp_0, argp_f, f)
# Retrieve r and v from initial orbit
s0 = Orbit.from_classical(
attractor=Earth,
a=a,
ecc=(r_a / a - 1) * u.one,
inc=6 * u.deg,
raan=188.5 * u.deg,
argp=178 * u.deg,
nu=0 * u.deg,
)
# Propagate orbit
def f_soyuz(t0, u_, k):
du_kep = func_twobody(t0, u_, k)
ax, ay, az = a_d(t0, u_, k)
du_ad = np.array([0, 0, 0, ax, ay, az])
return du_kep + du_ad
sf = s0.propagate(t_f, method=cowell, f=f_soyuz, rtol=1e-8)
assert_allclose(sf.argp.to_value(u.rad), argp_f.to_value(u.rad), rtol=1e-4)