Could we just circulate the air in scramjet propulsion?

On Mar 8, 1:49 pm, Robert Clark wrote:

Are you saying it is impossible to have a high velocity air stream go
around and around many times in a torus shaped chamber?

yes. if it only has an inlet and outlet.

Molecularly smooth surfaces have been a well-known phenomenon in
materials science for several years now:


So what. They aren't commercially viable. Especially for large
surfaces and consumer use.

Dear Robert Clark:

"Robert Clark" wrote in message
...
....
Are you saying it is impossible to have a high
velocity air stream go around and around many
times in a torus shaped chamber?

No, what he is saying is that it is impossible to do that *and*
get any net thrust out of it.

David A. Smith

Robert Clark wrote:
:
: The air being circulated around and around means it would go around
:many times in one second. It would not have to go around a
:circumference of 1467 feet. The circumference hence the diameter could
:be much smaller than this.
:

So you are changing the direction of that air mass many, many times in
one second.

:
: The frictional slowing for high Mach speeds would only be a small
roportion of the entering speeds and would mostly be for the boundary
:layer against the sides. This frictional heating could also be reduced
:by using molecularly smooth surfaces and/or by injecting low viscosity
:gas along the sides at a matching speed to the entering air speed.
:

Why not just build a magic perpetual motion machine and use it to spin
a propellor?

--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw