Suborbital is Next to Useless for Point to Point Travel

Spacetransportnews has a link to another in the long list of nontechnical space dreams.

Earth’s radius is about 7000 km. The Van Allen belts start somewhat above 500 km from Earth’s surface. Hence, ballistic arcs have to be either very short or then very shallow. And shallow arcs mean high speed. Close to orbital. New York to Paris is about 6000 km. That’s roughly one seventh of the great circle. It is very clear that to travel such a distance ballistically and at low altitude, you need most of orbital velocity. ICBM:s have very high apogees because of this.

The corridor between the atmosphere’s top and the Van Allen belts is so narrow, just a couple hundred kilometers, compared to the horizontal distances, a couple thousand kilometers, that ballistic point to point travel for humans does not make sense.

Nobody seems to recognize this fact. We get vague dreamy projections by even the normally technically hard nosed engineer people in the alt space circles. Wake up. Orbital mechanics wins. Transatlantic point to point is harder than orbital.  Never mind transpacific.

Grumpy mode off…

Word coin: Narrow suborbital ballistic corridor.

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Hypersonic Cruise for the V Prize

The Virginia Spaceport at Wallops (east coast of USA, south from New York) advocates want to create a prize to foster use for the spaceport, and have floated an idea of a “one hour to Europe” style prize, the V Prize, but the rules aren’t yet finalized.
The requirements are quite tough. About 6000 km in one hour implies a speed of over Mach 6. There’s some discussion here too.

It’s probably a useless exercise but fun nevertheless, so I propose a notional atmospheric (as opposed to purely ballistic ICBM style) vehicle design for the prize.

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