(Don French) wrote:

Peter,

You apparently never took high school physics.
Pot calling the kettle black?

Look up Newton's first
law of motion, the law of inertia. The scramjet only had to provide
enough power to overcome the friction of air to continue at Mach 9.5
forever or until it hit something, like the earth.
Odd use of the word "only". Like "only" 850-odd times as much power as
it takes to fly at Mach 1. Or does the velocity cubed relationship not
apply for air friction in supersonic flight?

To accererate the
jet from Mach 9.5 to Mach 10 takes exactly the same amount of power as
accerating from 0 mph to Mach 0.5, not very much. And that is all that
the scramjet did.
BZZZT! It takes a little more power (how much more determines how
rapid the acceleration will be) to accelerate from 0 to Mach0.5 than
it takes to maintain Mach 0.5. It takes a little more power to
accelerate from 9.5 to 10 than it takes to maintain 10. And using the
cube rule, it takes 8000 times as much power to maintain mach 10 as it
does to maintain mach 0.5.

Yes, if you towed a Yugo behind a Porsche, and released it at 150 mph,
it would continue at 150 mph if there were no friction of air and
road. But it could not accelerate to 180 because the means of
propulsion depend on that same friction,
No. It has the means of friction (it's tires are on the road, at least
in this thought experiment; I'd hate to think about it in real
lifeg), just not enough power to overcome drag at 150, much less to
accelerate from that point.

unlike a jet plane, which
does not use the friction, but only has to overcome it.

This is elementary physics, a subject that it seems fewer and fewer
people have a grasp of these days.
Yes, so it seems!


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