In [1]:

    

%run -i '../Common.ipynb'


    

In [2]:

    

import wernher


    

In [4]:

    

π = np.pi
deg = π/180
km = 1000


    

In [19]:

    

body = wernher.CelestialBody(
    name = 'kerbin',
    gravitational_parameter = 3.5316e12,
    equatorial_radius = 600*km,
    rotational_speed = 2*π/21600)
orbit = wernher.Orbit(
    t0 = 0,
    i  = 30*deg,
    Ω  = 0*deg,
    ω  = 15*deg,
    pe_alt  = 800*km,
    ap_alt  = 2300*km,
    M0 = -45*deg,
    body = body)


θθ = np.linspace(0,2*π,300)
rr = orbit.radius_at_true_anomaly(θθ)
R = orbit.body.equatorial_radius

fig,ax = pyplot.subplots()
ax.set_aspect('equal')
ax.set_axis_off()
ax.margins(.01,.03)

# planet
_=ax.fill_between(-R*np.cos(θθ), R*np.sin(θθ), lw=0)

# orbit
_=ax.plot(-rr*np.cos(θθ), rr*np.sin(θθ), lw=2)

_=ax.annotate(str(orbit.pe/km)+' km',
    xy=(-orbit.pe,0,),
    xycoords = 'data',
    xytext=(10,0),
    textcoords = 'offset points',
    ha="left", va="center",
    bbox=dict(boxstyle="round", color='white', linewidth=0, alpha=0.7),
    )
_=ax.annotate(str(orbit.ap/km)+' km',
    xy=(orbit.ap,0),
    xycoords = 'data',
    xytext=(-10,0),
    textcoords = 'offset points',
    ha="right", va="center",
    bbox=dict(boxstyle="round", color='white', linewidth=0, alpha=0.7),
    )