Re: spouting resonance bowl

[Brian Whatcott <inet@INTELLISYS.NET>]

At 05:58 PM 1/10/02, you wrote:
> Well I bought one of those resonance bowls that are supposed to spout
> water when you rub the handles. I saw it working in a movie so I don't
> think I was taken (yet!) but I can't get it to work. Can anyone point me
> in the right direction? (It did not come with directions.)
> --------------------------------
>   Life is too short to sort socks.
>                ...........
>   kyle forinash       kforinas@ius.edu
>   http://Physics.ius.edu/
> --------------------------------

Celebrating the transitory nature of my modem line quality for the last few
days - so that a noise source abruptly switches on, initially towards
midnight, lately in the earlier evening,
to deny my internet link: I write in haste to mention that Kyle's spouting
bowl reminds me (for some reason) of a splendid talk and paper given at an
Oshkosh seminar a few years ago.
It discussed a design for a pneumatic attitude sensor to drive a wing
leveller and heading hold for homebuilt airplanes. Not to labor the details
too hard - the NASA research engineer in question started with a little air
pump to blow a thin stream of air to a target consisting of four
thermistors disposed around a small target circle where the air exhausted
from the instrument case for return to the pump. Differential cooling of
the opposed thermistor pairs was a signal source in pitch and roll with a
little yaw mix depending on the spatial orientation of the device.
 Acknowledging that an air pump failure was a single point failure mode
for his device, he next mentioned a pneumatic pump and diode - whereby a
small loudspeaker cone drives a low frequency pneumatic signal into a flat
chamber like an egg shaped cross section, where air can enter and exit in
one of two tubes - one normal to the thin end of the egg shape, the other
stuck in the big end. The pulse stream is 'rectified' by this device, which
provides an air pump likely to be exceptionally reliable - with no
mechanical valves to fail.
(Though fluidic logic cells from the dawn of computing did in fact 'silt'
up unless the air supply was filtered well, I recall....)

There you have it: a physical concept for a sound driven pump: could this
be the modus of the spouting bowl?


Brian Whatcott
  Altus OK                      Eureka!