Aviation Unison?

[John Formsma]

A mechanical engineer told me the same thing.  He was interested in
what I was listening to while tuning, and asked me if I was listening
to beats.  When I said yes, he told me about the engines.

JF

On 8/2/07, Alan Barnard <tune4u at earthlink.net> wrote:
> That's how aircraft engines were synchronized before they had computers to do it. A B29 pilot, for example would start one engine, then start the second and sync it to no beats by adjusting throttles, mixture, prop pitch, whatever, then the third, then the fourth. Otherwise the engines are "unequally yoked", as it were, and aren't as efficient and put torque stresses on the wings, I would think.
>
> Alan Barnard
> Salem, MO
>
> ----- Original message ----------------------------------------
> From: david at piano.plus.com
> To: pianotech at ptg.org
> Received: 8/2/2007 2:17:23 PM
> Subject: Aviation Unison?
>
>
> >As the Airbus 320 taxid gently to the runway yesterday at Philadelphia
> >(flying GlasgoW-Philadelphia-San Francisco-Redding), sitting in an aisle
> >seat over the wings,  I could hear the beat rate between the engines slow
> >down and speed up as their respective revs changed slightly.  For a few
> >seconds, they would slow to almost unison.  Those who sing will know the
> >phenomenon where, listening to a singer, one feeels one's throat and body
> >tense in sympathy.  On that plane, my left arm (i tune left-handed) was
> >itching to move something with a tuning lever, to achieve unison!
>