Re: Vintage Lunar Lander Game

On Sat, 22 Jun 2024 08:37:00 -0000 (UTC), I wrote:

    real(kind = useprec), parameter :: G = 0.001

OK, I figured out, this is lunar gravity in miles/second/second.

    real(kind = useprec), parameter :: Z = 1.8

This is I think the rocket specific impulse.

        delta_v = time_subinterval * fuel_rate / mass_total

This is not actually the change in velocity, it is the proportion of
spacecraft mass being expelled over the subinterval.

                    Z &
                * &
                    ( &
                        delta_v &
                    + &
                        delta_v2 / 2 &
                    + &
                        delta_v2 * delta_v / 3 &
                    + &
                        delta_v4 / 4 &
                    + &
                        delta_v4 * delta_v / 5 &
                    )

I think this contribution to the velocity comes from the rocket equation.
It’s a truncated power series; interestingly, it’s one with poor
convergence.