I spent the last 24 hours (sleep and work permitting) learning what mine own code could do. First thing I had to figure out was that left way / right way didn't always correspond with the short way / long way... in general, fewer synods mean the longer periods.
Another thing: I gave up finding what equation could get Aldrin's ass to Mars. Instead I just iterated from initial-velocity to the distance I wanted, using Newton's law of gravitational acceleration. This got me the time it took and the position and velocity vectors. Although that's the best algorithm we're ever likely to find, Microsoft's System.Numerics stuck me with 23-bit decimal places for accuracy. I could not improve on δT = a millionth of the inner planet's year. A half-minute here on Earth.
Soooo: from Venus 2L4's time to aphelion will be 159 days. I wasn't expecting a large velocity at the end given it is aphelion.
Where aphelion falls short, Longuski and McConaghy were subtracting planet speed from cycler aphelion speed. Why, I don't know - probably because of Mars' ellipse, so they quit caring. Venus has no ellipse (pretty much), and Earth's isn't a problem. For circular(ish) orbits I target SPL1 velocity which, covering a shorter circumference at the same time as planet P's year, will be slower than P. V∞ at STL1 is about 1950 m/s.
I confess une petite surprise that the 2L4 Venus-Earth time was (slightly) more than the usual Hohmann suspects and, indeed, than 5S10[-right] which is telling me 115 days (and 600 m/s V∞ at Earth, let alone STL1...). I note it's 53.3% of the unpatched period - and, as noted, a Left Branch where Hohmann turns Right. It looks like it dips to perihelion before running to STL1. Fry-by, one might say. Better shield it.
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