API Refactor: Hohmann - poliastro/poliastro GitHub Wiki

These are the notes I took while thinking about the refactoring of the API. In this case, computing a simple Hohmann transfer.

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Vallado, example 6.1.

• Attractor = Earth
• Initial altitude = 191.34411 km
• Final altitude = 35781.34857

Find out: cost (delta v), time of flight

Refs

• [Hohmann] http://en.wikipedia.org/wiki/Hohmann_transfer_orbit
• [IPython] http://nbviewer.ipython.org/github/ipython/ipython/blob/master/examples/notebooks/Custom%20Display%20Logic.ipynb

from poliastro import *

initial = State.circular(Earth, alt=191.34411 * u.km)

# OOP (safe) API

maneuver = Maneuver.hohmann(initial, alt=35781.34857 * u.km)

print(maneuver.total_cost, maneuver.time_of_flight)
print(maneuver)  # Nice printing of all the information?

# Procedural (unsafe) API

from poliastro import maneuver

R_i = Earth.R + 191.34411 * u.km
R_f = Earth.R + 35781.34857 * u.km

res_hohmann = maneuver.compute_hohmann(Earth.k, R_i, R_f)  # This ain't a Maneuver

print(res_hohmann)