Using __repr__ or __str__ for own printable class?

[Erik Max Francis]

Andrew Dalke wrote:

> You wouldn't really do a Hohmann orbit all the way
> out to Neptune, would you?

No, of course not (unless, say, you were sending bulk materials and were
trying to minimize fuel at any expense -- if you're sending a steady
stream of materials from a mining base on Triton to Earth, it doesn't
matter how fast any particular package gets there, it just matters that
they keep coming).  If you were doing something timely, you'd be more
interested in trading off trip duration for fuel requirements,
particularly in the supposed future where this game would take place,
where high-efficiency drives would be readily available.

There are even in some circumstances more fuel-minimizing transfers than
Hohmann, like bielliptic transfers (which is sort of like a
double-Hohmann transfer to a point way out in space), but they take vast
amounts of time (e.g., a Hohmann-like transfer out to Neptune and then
back simply to go from Earth to Mars).  Under some circumstances this
can take less fuel than a simple Hohmann transfer (although it won't be
energy minimizing).

> Aren't there any
> gravitational assists that could help out?  After all,
> it took Voyager 2 only 12 years or so to get there,
> not 30, though the planets were well aligned at
> the time.

In the envisioned game, one would be able to choose between different
transfer "modes" when selecting a course, so that one could choose
between fuel-minimizing ("Time is no object, use as little fuel as
possible"), time-minimizing ("Fuel is no object, get there as fast as
possible"), or schedule-meeting ("I need to get there by turn 192, use
as much fuel as required to get there but no more"), or budget-meeting
("I need to come back with the same fuel budget so only spend this
much") transfers.  What that means is that the entities in this big
table of transfers will actually be types and coefficients of equations
(polynomials or other similar relations, most likely) that will need to
be solved on demand, abstracting the problem one level.  At present the
calculator is not sophisticated enough to understand this, however.

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