On Wed, 17 Nov 2004 18:22:14 -0500, Aardvark
wrote:

Don French wrote:

How fast was the rocket going when it released the record-setting
scramjet? If the rocket was going Mach 9 in the thin atmosphere at
100,000 feet and released a stone, for example, the stone would travel
several seconds at close to Mach 9. I assume that the rocket was not
going Mach 9, but I haven't seen any information on how fast it was
going.

Regardless, it seems to me that the rocket's speed has to be
subtracted from the jet's speed to arrive at the actual jet speed when
you talk about the world's record for speed of a jet plane.

-- Don French
Quoted from some web site.

"The telemetry showed the X-43A was set free by the booster at a speed
well in excess of Mach 9 but was able to maintain its cruising velocity
under the thrust from its scramjet.

Engineers followed the X-43A as it travelled more than 1,000km (620
miles), eventually losing speed and plunging into the Pacific. "

Now if the rock went 620 miles after release

That's interesting. I wonder how far it would have glided without
lighting the scramjet. At mach 9, the miles go by pretty quickly...