On Mon, 1 Mar 2004 23:18:55 -0000, "Keith Willshaw"
wrote:


"Bruce Simpson" wrote in message
.. .
On 29 Feb 2004 18:57:36 -0800, (Eric Moore)

There are significant problems to using PDEs as a propulsive source.
The magnitude of the shockwaves produced is extremely high as are the
levels of vibration.

A craft using such a power-plant will need some very special attention
paid to the acoustic and physical isolation of the engine.


Hmmm

The British edition of scrap heap challenge recently had a program
in which teams had to build a jet propelled car.

The winner built a pulse jet and the 'high tech' isolation of engine
from vehicle seemed to consist of welding the bugger to the frame
though there was lots of duct tape in view

That was me -- I was the "expert" on that episode.

Fact is almost every motor car on the road runs with a
pulse detonation engine, its just that the pulse drives
a piston rather than being used for jet effect.

No, that's incorrect.

A conventional piston-engine does not detonate its fuel -- it uses a
process called deflagration which is a *far* gentler combustion
process.

It's also worth noting that a pulsejet (such as the one we used on
Scrapheap) also uses deflagration rather than detonation.

To give you an idea of the difference (in terms of shock, vibration
and noise) -- in a deflagration, the flame travels at just a few
meters per second, in a detonation the flame front effectively travels
at several times the speed of sound.

--
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