Hi Robbie (and List),

On Fri, 22 Mar 96 01:05:39 PST  Automatic Music Mailing List 96.03.21,
Robbie Rhodes wrote:
>
> Subject: Force versus distance of a pneumatic
>
> Has anybody any numerical data on how the force of a simple "board"
> pneumatic varies with the opening?

     <snip>

        I'm a bit confused here, could this be an apples/oranges type
discussion?  The "force" of this pneumatic would effect the SPEED of
operation of the hammer rail but would NOT (IMHO) directly affect the
loudness of the note.  (This assumes that you consider the positioning of
the hammer rail "binary", that is, either at rest or raised to its
maximum.)  Note intensity would be affected by the action geometry, i.e.,
regulation, blow distance, amount of lost motion (and to what degree that
is compensated for), etc, but would, I believe, be independent of how
fast the hammer rail reached its raised position.  (Again, notes struck
while the rail is in motion are outside this discussion.)  I'm also not
so sure that having the blow distance shortened to 50% of its normal
value necessarily produces  (or even predicts) a 3 dB reduction in sound
intensity.  The physics of a moving hammer, i.e., mass, acceleration,
kinetic energy, etc. are QUITE beyond my ability to analyize, but they
ARE complicated.   The physics of why a simple wedge pneumatic develops
is greatest force at its full open position has, I believe, been
discussed in one or more articles in the AMICA bulletin, although I have
no specific references at hand.  Perhaps someone else can provide this.
Have I missed some other subtle point here?

        -John Grant