I never said it wasn't a successful test, but the only thing touted in
the media was the speed it achieved and the world record it set for
speed, and attributed that speed to the scramjet, not the rocket.
That was just wrong. The speed was almost entirely a result of the
rocket's velocity and had nothing to do with the scramjet. Seriously,
they could have dropped a Piper cub off that rocket and it could have
maintained Mach 9 for hundreds of miles. Should it get the world's
speed record for prop-driven planes? I think not. And I think that
giving the X-43A a worlds speed record is just as fraudulent.

With so little air friction at 100,000 feet, a stone would go quite
far. Give it an aerodynamic shape and it would go even further. I
would only be guessing, but maybe it would go a few hundred miles.

The point is that almost any craft with a propulsion system capable of
moving it at 700 miles per hour would make it to Mach 10 when dropped
from a rocket going Mach 9, provided it was structurally sound enough.

This thread is hilarious. A bunch of armchair propulsion engineers
pooh-poohing a significant accomplishment in engine technology, none of whom
actually could design a scramjet if their lives depended on it.

Anyway, I certainly think NASA is well within their rights to tout the
success of actually operating a scramjet in flight. It's as revolutionary
as successful operation of the first turbine engine was. What makes the
speed interesting is that no other engine is capable of operating at that
speed. Even if the test vehicle didn't wind up ANY faster than it was when
the engine was started, as long as the engine continued to operate as
designed, it would have been a successful test.

Pete