Suborbital Transit with Hovering

Fully Ballistic (and Deadly) Trips

For the case of Earth point-to-point passenger transit, the optimal solution has a tiny inconvenience that it would kill all the passengers on board for most randomly selected trips. Reentry is not a gentle process in the best of circumstances, and the best of circumstances requires entering the atmosphere at a low angle. The ballistic trajectory matches with this if point A and point B are 180 degrees apart. Shorter distances can better optimize fuel use by using a higher apogee, but this makes for a high reentry angle, which is deadly.

Semi-Orbital with Hovering

So the scheme goes like this:

Suborbital Hover with Constraints
Suborbital Hover Math
theta is the angle between point A and point B, and the fraction relates to the fuel saved
Range Over Which Hovering Provides a Benefit

Another Option — Propulsive Slowing

This still isn’t the full picture. You could still use the engines to adjust your trajectory at the point of reentering the atmosphere. There’s some chance that this could dominate as an optimal solution, while still keeping g-forces within tolerable ranges.



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