Peter Duniho wrote:
Robert Briggs wrote:

I simply think that your wording about "the scramjet [being] the
*entire* source of the speed", rather than its being "sufficiently
powerful to complete the acceleration to Mach 10" (or something to
that effect) is a tad loose.

It is the entire source of the speed.

I'm not convinced, but we seem to be disagreeing about semantics,
rather than about aeronautics.

An engine sufficiently powerful to accelerate the test vehicle from
Mach 9 to Mach 10 is sufficiently powerful to accelerate the test
vehicle from 0 mph to Mach 10.

Sufficiently powerful to accelerate the test vehicle from 0 mph to
Mach 10, yes; actually capable of doing it, no because of the nature
of the beast.

The rocket used to launch the scramjet has nothing to do with how
powerful the scramjet is, or its final speed. Only the scramjet
itself does.

The scramjet (with the aerodynamics and structural integrity of the
test vehicle) sets the *possible* final speed, but the bomber and
the rocket make an essential contribution to getting there.