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Incorrect Hohmann maneuver when not at pericenter? #740

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astrojuanlu opened this issue Jul 20, 2019 · 4 comments
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Incorrect Hohmann maneuver when not at pericenter? #740

astrojuanlu opened this issue Jul 20, 2019 · 4 comments
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@astrojuanlu
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馃悶 Problem

I think there is a potential problem here:

if orbit_i.nu is not 0 * u.deg:
orbit_i = orbit_i.propagate_to_anomaly(0 * u.deg)

return cls((0 * u.s, dv_a), (t_trans, dv_b))

in that the time to get to the pericenter is not being taken into account for the maneuver, and therefore perhaps doing an apply on the initial orbit won't have the intended effect.

馃挕 Possible solutions

Note I didn't check whether this is an actual bug or not yet

Do not hardcode the initial maneuver to 0 * u.s and use the time to get to the pericenter.

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@jorgepiloto
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Interesting... The same happens in Bielliptic ones. Some possible solutions that came to my mind:

  • We could raise ValueError("Not in pericenter...") so the user is forced to propagate before solving the maneuver.
  • In case-solving internally time to pericenter, the set of impulses should be like:
{propagation: till periapsis, second: first hohmann impulse, third: second hohmann impulse}

That propagation impulse always has deltaV = 0 * u.km / u.s and time may vary between [0 and T)

@astrojuanlu
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I would rather do the latter instead of raising the error.

@astrojuanlu astrojuanlu added this to the 0.14 milestone Jul 21, 2019
@astrojuanlu
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Fixed in #744.

@astrojuanlu
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I think I forgot to close this. Doing it now.

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