Unexpected results from Orbit.from_vectors with shared initial position

[tektrip-biggles]

🐞 Problem

Hi! I was playing around with pliastro yesterday and it may be that I'm misunderstanding something, but I'm not getting the results I'd expect when plotting 3 orbits created via Orbit.from_vectors with the same r vectors & different v vectors.

This is the code I'm using (adapted from one of the examples to try & constrain things to two dimensions):

# Data from Curtis, example 4.3
r = [-6045, 3490, 0] << u.km
v = [3.457, 6.618, 0.0] << u.km / u.s
v_2 = [3.457 * 1.5, 6.618 * 1.5, 0.0] << u.km / u.s

orb_1 = Orbit.from_vectors(Earth, r, v)
orb_2 = Orbit.from_vectors(Earth, r, v * 1.1)
orb_3 = Orbit.from_vectors(Earth, r, v_2)

op = OrbitPlotter2D()
op.plot(orb_1, label=str(orb_1))
op.plot(orb_2, label=str(orb_2))
op.plot(orb_3, label=str(orb_3))

Which produces the following output:

Or zoomed in a little:

I'd would expect each of these 3 orbits, when plotted to go through the same fixed position (6045, 3490). However it looks like the common position is instead at around (0, 6980) as if the frame of reference has been rotated?

🖥 Please paste the output of following commands

(Not using conda)