February 5, 2001

2:13 PM

Hey! What's this thing suddenly coming toward me very fast? Very, very fast. So big and flat and round... Are you one of those people in search of a new extreme sport? Have you considered spacediving?
posted by Aaaugh! (6 comments total)

Very cool link. Go directly to http://www.xprize.org/ for more info.

Wouldn't suborbital flight make long distance travel a lot quicker? Couldn't a 10 hour flight to Japan from California be cut down to 2 or 3? Or, has the science fiction of my youth lied been lying to me?
posted by Neb at 2:49 PM on February 5, 2001

Indeed it could. You must not have been around when the President announced the National Aero Space Plane (NASP) project ... in the 1984 State of the Union address. The X-30, as it was designated, would have been a scramjet-based suborbital passenger vehicle for crossing the Pacific and spurring Asian-American trade ties. Unfortunately, it proved much more difficult and expensive than originally thought, and after the end of the Cold War reduced the need for military aircraft using its technologies, it was cancelled around 1992.

Of course, the "quicker" part can also be achieved with supersonic flight, but that hasn't proved more than marginally viable for commercial flight.
posted by dhartung at 5:38 PM on February 5, 2001

Actually I have considered this. It occured to me when I was a teenager in one of those dreams that sticks in your head after you wake up, and for a while had a place on my List Of Things To Do When I Get Rich. Now it seems a little pointless.

-Mars, who used to be a space nut
posted by Mars Saxman at 9:56 PM on February 5, 2001

Can anybody explain why suborbital flight would be any quicker. Couldn't we just fly that fast without having to go out to the edge of space? And if not, why not? Is it because of friction from the atmosphere or some kind of silly environmental concern?
posted by willnot at 12:21 AM on February 6, 2001

willnot, I'm sure the aviation industry would welcome developments in either arena.

The suborbital space plane needed two key things that didn't happen: advanced composite materials that would survive the enormous heat, and an effective scramjet engine. (A ramjet is a jet engine with no moving parts. A scramjet is a "supersonic combustion" ramjet.)

The hypersonic development projects, less visible, have also fallen by the wayside. They would have advanced us from just under Mach 2 (Concorde) to just under Mach 3 -- only the military's Blackbird has achieved that. But engine and materials development also proved too expensive, and the planes would have had to be twice as large as the Concorde to be profitable. Answering your final question, I suppose, is that they also failed to find ways to mitigate the sonic boom. People just don't like them. And they tend to break windows.

"Friction from the atmosphere" is, I suppose, part of it. At base that's what you need to overcome in any type of aviation technology. When you move from subsonic to supersonic, you essentially multiply the stress on the vehicle by an order of magnitude -- it isn't just making it go faster. That means you need a stronger frame. But stronger frames are usually heavier. So you need to make the plane smaller. But you have to carry fuel, so you can only make it so small. So you can only carry a few passengers. So they have to pay a lot of money. So most will choose other modes. That's the basic problem.
posted by dhartung at 9:43 AM on February 6, 2001

I was under the assumption that suborbital flight could decrease travel time by:
-leaving the atmosphere
-letting the world rotate while you head in the opposite direction of rotation until you are over your destination
-making your decent
posted by Neb at 11:05 AM on February 6, 2001