"Roy Lewallen" wrote in message
...
kd5sak wrote:

Long years ago, 50 yearsor so before I reached Ham status, a
thunderstorm
awakened me in the wee hours and proceeded to dance around in the
shallow
hill pasture near the house. Stroke after stroke occurred and all so
near I
could hear a loud click as the strike occurred and then the diminishing
rumble. I still haven't figured out the initial click sound, it came
from
outside so wasn't a house internal electric phenomenon.

I've read that this click is due to the ear's reaction to the strong
electromagnetic pulse. If that's what you heard, it comes from the ear
itself, not from outside.

Roy Lewallen, W7EL

This is the first time I have seen it mentioned the ear reacting to the
electromagnetic pulse. Most of the time it is described as the same way
the old WW2 depth charges sounded in the submarines. YOu get the click and
then the boom. I forgot the term used but it is something like an impulse
or pressure shock wave traveling faster than the speed of sound and then the
actual sound wave.

Ralph Mowery wrote:

This is the first time I have seen it mentioned the ear reacting to the
electromagnetic pulse. Most of the time it is described as the same way
the old WW2 depth charges sounded in the submarines. YOu get the click and
then the boom. I forgot the term used but it is something like an impulse
or pressure shock wave traveling faster than the speed of sound and then the
actual sound wave.

I do believe that any mechanical wave, such as a pressure or shock wave,
travels at the speed of sound, no more and no less. To travel faster, it
would have to be an electromagnetic wave.

Roy Lewallen, W7EL

I do believe that any mechanical wave, such as a pressure or shock
wave,
travels at the speed of sound, no more and no less. To travel faster,
it
would have to be an electromagnetic wave.

Also, the deaf person wouldn't hear the mechanical wave. Well,
unless they had "some" hearing still available. If it was proven that
a totally deaf person could hear it, that would pretty much nail it
down as
electromagnetic. If that came out to be true, then Coffmans theory
about the auditory nerve picking it up would probably be true unless
some other nerve was actually involved.
MK

On 18 Dec 2005 08:41:47 -0800, wrote:

I do believe that any mechanical wave, such as a pressure or shock
wave,
travels at the speed of sound, no more and no less. To travel faster,
it
would have to be an electromagnetic wave.

Also, the deaf person wouldn't hear the mechanical wave. Well,
unless they had "some" hearing still available. If it was proven that
a totally deaf person could hear it, that would pretty much nail it
down as
electromagnetic. If that came out to be true, then Coffmans theory
about the auditory nerve picking it up would probably be true unless
some other nerve was actually involved.
MK

Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

R

Russ wrote:

Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

No.

Roy Lewallen, W7EL

The denotation is supersonic, while the flame spread is subsonic.

"Roy Lewallen" wrote in message
...
Russ wrote:

Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

No.

Roy Lewallen, W7EL

On Sun, 18 Dec 2005 12:39:09 -0800, Roy Lewallen
wrote:

Russ wrote:

Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

No.

Roy Lewallen, W7EL

The definition of dentonation includes the flame front moving at
supersonic speeds.

http://www.globalsecurity.org/milita...itions/fae.htm

R

Russ wrote:
On Sun, 18 Dec 2005 12:39:09 -0800, Roy Lewallen
wrote:


Russ wrote:

Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

No.

Roy Lewallen, W7EL


The definition of dentonation includes the flame front moving at
supersonic speeds.

http://www.globalsecurity.org/milita...itions/fae.htm

Yes, I can understand the flame front moving faster than sound, if it's
not a pressure wave. I don't know the mechanism, but presume it's
propagated by radiant heat. That is, a flame occurs, and its heat
radiates and superheats nearby material, causing it to flame. That would
be propagation by electromagnetic wave, i.e., infrared "light". The
radiation would travel at the speed of light, with the apparent speed of
the front being dictated by how fast the material is heated and ignited
by the radiated heat. Propagation by this mechanism and at this speed
would end as soon as the flame front reached the outside of the vapor
cloud, beyond which the resulting pressure wave would travel at the
speed of sound.

I'm not an expert at this, but I'm quite sure that the only way you can
get a mechanical wave to travel faster than sound is if the behavior of
the air becomes nonlinear at some compression level. That could
conceivably happen as a result of an explosion, but I don't think so. If
anyone has any references describing such nonlinear behavior, I'd love
to learn more about it.

Roy Lewallen, W7EL

Russ wrote:
On 18 Dec 2005 08:41:47 -0800, wrote:


I do believe that any mechanical wave, such as a pressure or shock
wave,
travels at the speed of sound, no more and no less. To travel faster,
it
would have to be an electromagnetic wave.

Also, the deaf person wouldn't hear the mechanical wave. Well,
unless they had "some" hearing still available. If it was proven that
a totally deaf person could hear it, that would pretty much nail it
down as
electromagnetic. If that came out to be true, then Coffmans theory
about the auditory nerve picking it up would probably be true unless
some other nerve was actually involved.
MK


Doesn't the delta P of a fuel-air bomb travel at greater than the
speed of sound?

R

Also, the pressure wave INSIDE a rifle barrel travels faster than the
speed of sound. It produces velocities of the projectiles at Mach 3 to
Mach 4. Hmmm...

The air pressure profile on an aircraft wing shows supersonic, transonic
and subsonic reponses. Hmmm..

It raises a physics question. How does the velocity of sound vary in a
compressible medium as the temperature, volume and pressure change?