Arny Krueger wrote:

"Eiron" wrote in message


Air blowing out of the port is more directional than air
sucked in.

Not necessarily. In fact, making a port so that it is symmetrical in this
regard could be a worthy goal. More worthwhile is just plain keeping the
velocity down.

The forces may be measurable but are too small to propel
a cabinet.

Not necessarily.

I've done some fun things with the mouth of an EV Sentry IV bass horn !

Graham