"Rich S." wrote:

"Jay" wrote in message
. com...
In an earlier post I read somewhere that the pulse jet is a device
that converts fuel into noise. Someone else had suggested firing 2
engines 180 degrees out of phase with each other to cancel the sound.
If the 2 engines were stacked one over the other, then you might
actually be able to cancel a lot of the sound at least in a circle
around the aircraft in the plane of the earths surface. Below the
aircraft it would be just as loud but twice the frequency, but
standing on the ramp 50 yards from the aircraft, it might actually be
made to cancel somewhat. What do you guys think?

Makes my teeth hurt just thinking about it. Have you ever tried to
sychronize two piston engines?

Besides, to really cancel, one would have to be pointing forward, and
one back (not the most efficient configuration).

I suppose it would be possible to use active electronic noise
cancellation, but it would take a HUGE transducer to make it work (and
a bazillion watts to drive it).

Besides, lookit all the Harley riders. As far as I can tell, loud
must be desirable.

Mark "can't even hear my BMW when I'm riding with a HD" Hickey